Machine Monitoring

Sensing and Robotic Control

of a Mechanical

Fragmentation Machine

by

Naji Aboufadel

A Thesis submitted to the Department o f Mining Engineering

in Conformity with the requirements for the

degree of Master of Science (Engineering)

Queens University

Kingston, Ontario, Canada

July 1997

Copyright 0 Naji Aboufadel, 1997

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ABSTRACT

MACHINE MONITORING

SENSiNG AND ROBOTIC CONTROL

OF A MECILANICAL

FRAGMENTATION MACHINE

The monitoring and sensing of a Continuous Mining Machine (CMM) and its interaction

with the rnining environment is studied. Vanous aspects of the machine design and

material handling requirements are critically examined. Correlations between rock-mass

properties and machine variables are developed for automatic sensing of rock properties

based on Specific Energy principles. The tests and analysis show potentid benefits fiom

monitoring of machine variables for improving the cutting performance of the machine and

increasing its production rates.

1 would iike to express my sincere appreciation to Dr. L.K. Daneshmend of the Mining

Engineering Department at Queens University for his extreme patience, guidance and

support in wnting this research thesis.

Funding for this research was provided by the Federal Government under auspices of the

National Networks of Centres of Excellence Program: Specifically the Institute for

Robotics and Intelligent Systems, under prcjject ISDE - 1 .

HDRK Mining Research Ltd., Onaping, Ontario, provided access to technical information

and data on the CMM. 1 would like to thank Jeff Repski fomerly of HDRK, for his

assistance in this regard.

TABLE OF CONTENTS

PAGE -

ABSTRACT

ACKNOWLEDGMENT

LIST OF F I G U E S

LIST OF TABLES

LIST OF GRAPHS

Chapter 1

Introduction

Historical Overview on Mechaniration

of Rock Tunneling in Mining

Mechanical Excavation as a Substitute

for Drill and Blast

Mobile Excavators and Tunnel Development

in Minkg

New Mobile Excavator Technology For

Cutting Hard Rock

Scope of the Study

iii

Chapter 2

Literature Review

Other Mining Mechanical Excavation Technologies

2.1 . 1 Tunnel Boring Machines

2.1.2 Heavy-Duty Roadheaders

2.1.3 Raise Boring Machines

2.1.4 Mobile Excavators

Introduction To Machine Monitoring

Applications in Mining

Machine Sensing of Rock Properties

in a Dynamical Mining Environment

Machine Automation and Control

Cha~ter 3

Robotics and Control Issues of the

CMM Machine

3.1 An OveMew of the CMM as a Mining Robot

3.2 Machine Kinematics and Dynamic Behavior

3.2.1 Definition

3.2.2 Machine and Controller Inputs

3 .Z.3 Arrn Kinematics

PAGE -

3.2.4 Arm Dynamic Disturbances / Extemal

3.2.5 Arm Dynamic Disturbances / Intemal

3.3 Relationship Between the Control System

and Machine Behavior

General

Machine Controller Functions and

Design Configuration

Controller Limitations

System Responsiveness - Relation Between

the Controller and Time Delays

Ratio of (Peak PressurdAverage Pressure)

versus Controllability

3.4 Actual Machine Profile Generation

3.4.1 Effects of Disturbances on System Response

3 A.2 Machine Guidance and its Effects on Arm

Motion and Profile

PAGE -

Cha~ter 4

CMM Cutter Design, Fragmentation and Materials

Bandling Requirements

4.1 Introduction

4.2 Effects of Muck Removal on Mining

Excavation Machines

4.3 Muck Removal Modes for Tunnel Construction

4.4 Machine Supporting SeMces and Muck Transport

4.4.1 Auxiliary Equipment

4.4.2 Basic Muck Removal Techniques

4.4.3 CMMConveyor Systemversus

Ot her Haulage Systems

4.5 Muck Chip Size and Form Based on the CMM

Performance in Herdecke, Germany

4.5.1 RockConditionsat theHerdecke Site

4.6 Effects of Cutter Design on Machine Performance

CMM Cutter Design Based on TBM's

Cutter Performance

Effects of Increasing 1 Decreasing Disc Parameters

on Machine Design

The Theory Behind Cutter Wear

CMM Cutter Life Estimation

PAGE -

Cha~ter 5

Erperimental Data and Preliminary Analysis

5.1 Hardware and Software Instrumentation

5 .1 .1 CMM Signal Selection and Identification

5 . 1 .2 Hardware

5.1 .3 Software

5.1.4 Digitizing Procedure

5.2 Filtering

5.2.1 Noise

5.2.2 Filtering in Viewdac

5.2.3 Filtenng in Matlab

5.3 Processing of the Digitized Data - Initial Conclusions

5.3.1 Processing Methods

5.3.2 OveMew on Pattem Recognition

5.3.3 Pattern Recognition in Relation to

Sensing of Rock Properties

5.3.4 Specific Energy - Profile

5 .3 .5 Specific Energy Computations based on

the CMM Machine Design and Operation

PAGE -

vii

Chapter 6

Application of Specific Energy for Sensing of

Rock Properties

Relationship Between Specific Energy and Compressive

Strength of Rock

OverMew of Specific Energy Investigation

and Machine Sensing of Rock Properties

Specific Energy Computations

6.3.1 Quany Site, Herdecke, Germany

6.3.2 Creighton Site, Sudbury, Canada

Conclusion

Cha~ter 7

Conclusions and Future Work

7.1 Conclusions

7.2 Suggestions For Specific Future Work

REFERENCES

APPENDlX A

PAGE -

83

LIST OF FIGURES

FIGURES

I l .

DESCRIPTION

CMM Machine

C M . Machine Cutting Profile

TM60 Machine

Alpine-Tunnel-Miner (ATM 1 O 5 )

Robbins Mobile Miner (MM 1 30)

Details of a Design-Test loop

Building Blocks and Links Between the

Vanous Aspects of the Machine D u h g Testing

Elements of the Arms Feedback Control Loop

Arm velocity components while extending

Cornponents of Reaction Forces from the Rock

(Fr is the Resultant of Fx & Fz)

(a) Disc parameters and @) Contact area

with Rock

Result of a Typical Positioning Error on the Profile

Division of the Face Cut into Sub-areas

Effect of Hydraulic Delay on Aîm Position

PAGE -

FIGURES DESCRIPTION

Resulting Efféct of the Delay on the Arm Position

while Extending (Under Penetration)

Discl ring Panuneters

Actual Cutter Wear

Block Diagram for Recording and Digitizing Data

Slock Diagram for Pattern Recognition

and Classification

CMM Machine Dynarnics & Kinematics -

h s II Cutting Profile

Specific Energy Parameter Computations Based

on CMM Machine Dynamics and Kinematics

Face Map for Cut # 93072004

(Sandstone and Shale)

Face Map for Cut # 94 12080 1

(Nonte and Granite)

PAGE -

53

LIST OF TABLES

TABLE DESCRIPTION - PAGE

Arms II proportional gain settings 44

Ratio of time delays caused by a decrease 46

in the Kp and Ki gains of the controller

Arm 11 2 typical piston pressure ratio 47

peau average

Profile shifi due to hydraulic delay for

dlfferent RPM values

Quarry Sequences used for

Specific Energy Anaiysis

Creighton Sequences used for

Specific Energy Analysis

GRAPH

LIST OF GRAPHS

DESCRIPTION

Specific Energy versus Time

for Cut #9307 1903

Specific Energy versus Tirne

for Cut #93072202

Specific Energy versus Time

for Cut #93072004

Specific Energy versus Amis II

Radial Position for Cut #93072004

Specific Energy versus Amis II

Angular Position for Cut #93072004

Zone (1700 mm to 1800 mm)

Specific Energy versus Amis II

Angular Position for Cut #93072004

Zone (2500 mm to 2600 mm)

Specific Energy versus Time

for Cut #94 12070 1

PAGE -

xii

GRAPH

8.

9.

DESCRIPTION

Specific Energy versus Time

for Cut #94 120702

Specific Energy versus Time

for Cut #94 12080 1

Specific Energy versus Arms II

Radial Position for Cut #94 12080 1

Specific Energy versus A r m s II

Angular Position for Cut #94 12080 1

Zone (2 100 mm to 2200 mm)

PAGE -

99

1 O3

xiii

Chanter 1

Introduction

1.1 Historieal Overview on Mechanization o f Rock Tunneline in Mining

Mechanization of rock tumehg has been progressing since 1846 when Henri-Joseph

Maus mounted a group of mechanical rock drills on a frame to speed the excavation of the

Mount Cenis tunnel between Italy and France. Drill and blast methods are progressing

today with high speed hydraulic powered drills and cornputer controlled jumbos, but

drilling a tunnel continuously without the cyclic blasting has obvious advantages. The

challenge has been to develop a machine and cutting tools capable of the job.

mobbins, 19951.

In 185 1 an Amencan engineer, Charles Wilson, developed a machine which was to

become the first successfùl continuous tunnel borer for rock. However, many problems

with disc cutter tools and other difficulties made it uncornpetitive with the developing

techniques of drill and blast tunneling.

Other attempts were made and abandoned both in the US and in Europe fiom the late

1850's to about 1920 when mechanical tumeling in rock seemed to be gradually

appearing. Practically no senous attempts were made for a period of 30 years until the

1952 developments by James Robbins which combined drag pick cutters with rolling discs.

These early attempts were also unsuccessful in hard rock until the building of a machine in

1956 which used only rolling disc cutters for cnishing the rock in a manner similar to

Wilson's design of 100 years earlier. During the next thirty years more than 200 rock

tunneling machines were used successfully in soft and medium hard rocks and more

recently in very hard rocks.

1.2 Mechanical Excavation as a Substitute for Drill and Blast

The mechanical excavation industiy is continually developing as machines are becoming

more versatile and capable of excavating through any type of ground conditions. The

economics of mechanical excavation compared to drill and blast techniques have been

steadily improving for both the civil underground construction and mining. Continua1

improvements in the understanding of rock fragmentation principles allowed for more

efficient machine design and operation which served to achieve further productivity

increases. An example on this is the introduction of new mechanical excavation

technologies such as Mobile Mining Machines. These machines attack rock a portion of

the tunnel at a given time whereas other mechanical excavation technologies such as

Tunnel Boring Machines (TBM's) attack rock full face. It is therefore believed that

current and future anticipated developments in mechanical excavation technology will

make it the "conventional" technique of the future.priant, 19951.

Mechanical excavation offers numerous advantages over drill and blast methods for al1

types of underground constmction, including tunnels, raises, shafts and chambers.

The first and most important issue in a mine is safety. By eliminating the use of blasting,

the personnel safety is greatly improved. There is no handling of blasting agents and no

generation of toxic fumes. Machines create practically no ground vibrations which anse as

an important factor in urban construction. In fact, drill and blast is not allowed in most

urban areas around the world simply due to the vibrations created from the blasting

operation which could potentially cause structure damage, both surface and underground.

Secondly, blasting imparts ground disturbance and damage which increases ground

support requirements to provide a safe and stable opening. With machine excavation,

ground disturbance is practically nonexistent which results in significantly reduced support

requirements and enhanced opening stability. In fact, the ground support savings provided

by the use of mechanical excavation techniques can alone justih their application. The

smooth excavation walls created by machine bonng also mean reduced ventilation

requirement S.

Unlike drill and blast, machines generate a unifonn muck size which allows for the

implementation of continuous material handling systems, such as conveyor belts with a

substantial improvement in machine utilization and the overall productivity of the

excavation system. Pei1 et al., 19941.

One of the more important advantages of mechanical excavation is that the machines are

conducive to remote control or full automation, which is a growing trend in the

underground construction and mining industry in order to remove workers fiom

hazardous environrnents and enhance safety. On the other hand, a drill and blast operation

is difficult, if not impossible, to automate due to its cyclical nature. [King, 19881.

The last significant advantage offered by mechanical excavators is their potential to

achieve high rates of advance at reduced excavation costs compared to drill and blast.

Despite being a relatively new technology, it is not uncommon for mechanical excavators

to attain advance rates several fold higher than what the drill and blast systems are capable

of achieving. Al1 of these advantages have thus contributed to a wider use of mechanical

excavation in rock. [Ozdemir, 19901.

1.3 Mobile Excavators and Tunnel Develo~meat in Mining

The circular profiles produced by tunnel bonng machines (TBM's) are well-suited for

most applications. However, there are cases where a non-circular opening with a Bat floor

is preferred, such as for highway tunnels and mine drifts. In the past, this has been

accomplished on several occasions by removing the boaom comers of a machine bored

tunnel with drill and blast techniques. Designs have also been developed for mounting

wheel type excavators fitted with disc cutters at the afl section of the TBM for cutting out

the comers to provide a more or less horse-shoe shaped opening. One major difficulty in

these applications has been effective dust control fiom the secondary cutting operation.

Passner and Sklansky, 19801.

Various types of hard rock mobile excavators such as the Continuous Mining Machine

(CMM) are cumntly under further development. In the underground mining industry,

there is a great need for mobile excavators which can efficiently excavate openings of

vatious shapes and sires in hard rock while incorporating sufficient mobility for easy

relocation within different working headings of the mine. Similar needs also exists for civil

underground constmction where short tunnels or chambers need to be excavated using a

mobile piece of equipment. Such applications are not suited for TBM's because of their

lack of mobility and the circular cross-section which they produce. To address these

needs, extensive efforts have been done worldwide for the development of mobile hard

rock excavators.

One of the more exciting new developments in the mining automation area is the

advancement towards automatic steering of mobile excavating machines. In addition, the

automatic optimization of the machine performance in response to changes in rock and

ground conditions is now being investigated. [Belanger, 19901.

1.4 New Mobile Excavator Technolon;v For C u t t i n ~ Bard Rock

The innovative approach of developing mechanical excavation equiprnent as a substitute

for the cyclical nature of drill and blast served as a need for the mining industry to develop

a powefil technology suitable for rnining hard rock. The result was a multi-phase

research project that was carried out under Hard Rock Mining Research Limited p R K )

for the development of the Continuous Mining Machine (CMM) project. See Figure [l].

CMM Cutting Pnnciple 2

Control Room 4

Subsequent Full Face Cuts

Pivot ( Rotor

(a) CMM - Side View

Disc Cutter

(b) CMM (Rotor & Arms) - Front View

Crawler

Cutter

(Provides

of Torque

(c) CMM Arms II (II 1, II 2 & II 3) - Side View

Figure [l]: CMM Machine

As a joint venture between INCO, Noranda, Falconbridge and Wirth (Germany), the

HDRK CMM project was organized and carried out under a clear mandate to establish an

efficient principle for cutting hard rock. In order to achieve this goal, the CMM was built

and tested in both Germany (Soft Rock) and Canada (Hard Rock) with the main objective

of ascertainhg the relative importance of a sound project foundation that would lead to

the successful development and performance of the machine. pepski, 19951.

The excavation process of the CMM machine is accomplished by the use of four

hydraulically activated cutting arms fitted with large diameter disc cutters. The arms are

hinge-mounted on a rotating support plate. As the plate rotates, the arms are swung out to

create spiral cuts to break the rock. The center am creates a "pilot" hole by slewing

towards the cenier of the bore. Once this Free face is created, the other three arms start

cutting spiral tracts outwards toward the edges. This provides an undercutting action

which is a highly efficient way of breaking rock. When the three arms reach the maximum

inner circular profile of the tunnel, they can be extended farther to cut the desired final

shape of the opening. See Figure [2]. This is al1 accomplished under cornputer control,

allowing for excavation of different site and shape openings.

Throughout the testing phase of the machine in both Gemany and Canada, a rigorous

approach to the engineering development process was incorporated, including a

comprehensive program of data collection, evaluation, etc. This ngorous approach served

in the advancement of the technology which was manifested in the cutting ability of the

CMM machine in both sofi and hard rock.

Front View of Cut

/ Edge OfCUt

Disc Cutter Maximum Inner Circular Profile Corner Cut

Arm II3 - Disc Cutter

---\ \j Disc Cutter

Ann II2 Disc Cuttei

\ 7 /tC,cut Portion of Rock Face (Center of Bore)

\ Start Positions v

Maximum Outer of Arrn 1 and Circular Profile of *' II Il2 and n3) Arms (11 1, 112 and 113)

However, the CMM machine is considered to be a proof of concept unit despite the fact

that HDRK has achieved its initial objective of designing and implementing a novel

machine design for hard rock cutting. Nevertheless, it still has lots of potential. It is

expected within the next five years to more than double its performance and have

reliability figures comparable to mature mechanical excavation technologies. Moreover,

many of the modifications and advancements in the CMM technology would serve to

improve the performance of the machine in areas such as continuous cutting, consistent

matenal size, continuous ground support, reduced ground support, ease of automation

and orelwaste sorting.

1.5 S c o ~ e of the Studv

This thesis deals with the concept of automatic sensing of rock properties based on

monitoring of machine variables. The study has been camed out with the main objective of

ascertainhg the relative importance of correlations between the machine variables and the

rockmass properties involved in the excavation process. Data analysis was perforrned on

collected data taken h m the HDRK Continuous Mining Machine operation in both sofl

and hard rock. This was primarily accomplished by analyzing the mechanical and control

aspects of the CMM machine based on its operating conditions and performance in rock.

The results of this study will help to define the process behind automatic sensing of rock

properties dunng an excavation process, which in tum is essential for future remote

control or fùll automation of any type of mechanical excavators. Furthemore, knowledge

of the machine variables in view of the corresponding rockmass properties is important

for improving the cutting performance and production rates of the machine.

The remainder of this thesis is written to address the following topics:

Chapter 2: Provides a comprehensive literature review that enforces the originality

of this work, and discusses other progress in this field.

Chapter 3: Gives a detailed description of the CMM machine ftom the perspective

of robotics and control.

Chapter 4: Addresses issues of fragmentation and matenal handling in relation to

the CMM operation in a mining environment.

Chapter 5: Presents the hardware and software implementation details that are used

for recording and preprocessing of data files pertaining to CMM testing

in both soft and hard rock. Introduces pattern recognition and specific

energy techniques as means for analysis.

Chapter 6: Uses specific energy techniques to identify rock types and strength

based on the cutting pnnciple of the CMM machine and its interaction

with different rock geological character in a mining environrnent.

Chapter 7: Concludes by presenting thesis conclusions and offers recommendations

for fiirther work.

Chaoter 2

Literature Review

2.1 Other Mininn Mechanical Excavation TechnoIonies

2.1 . Tunnel Bannn Machines

Developmed efforts are undenvay for Tunnel Bonng Machines (TBM's) with the

capability to make short-radius tums, as well as bore through existing intersections. These

machines are pnmarily directed to rnining applications where the short radius turn feature

is highly desirable to achieve the most effective utilization of the machine to suit the mine

development and production needs. In addition to negotiating tighi turns with radii as

small as 20 metres and boring through existing intersections, the machines can also make

tumouts fiom existing tunnels. Several hard rock mines around the world are considering

the use of these machines with significant potential savings to the mine development costs.

[Trondheim University, 19931.

A rather primitive, compressed air driven TBM was developed by Beaumont and English

as early as 188 1 and used to, amongst others, drive two early pilot tunnels under the

English Channel. The era of the modem TBM did not start until the 1950's, when a

machine developed by James S. Robbins and Associates was put to work excavating a

diversion tunnel for the Oahe Dam Project in South Dakota, USA. [Janzon, 19951.

In 1990 a consortium of Falconbridge, Placer-Dome, J. S. Redpath and Boretec teamed

up to design and manufacture a small TBM Compact Underground Borer (CUB) for mine

development. It was to be short, compact, capable of short radius tums and could quickly

be disassernbled for rapid moves within a mine. It was to be a powerfùl unit and utilize 46

cm diameter cutters for Wear life. The 2.4 m diarneter machine was only 3.8 m long.

pewis, 19911.

Mer only a short trial the CUB had to be removed. In broken ground, the configuration

had little room for installing rock support. The open style cutterhead also had problems

ingesting rock eficiently and without damage to the cutterhead. In hard ground, the very

large cutters, which were too widely spaced, created problems. In addition, the unit

featured a complex lattice arrangement of dual purpose thnist/ torque reaction cylinders.

Control is complex as each cylinder must have a slightly different pressure and thus

steering was a problem as well. Finally, the Compact Underground Borer (Cm) was an

interesting concept design which had the potentiai of having the maneuverability needed in

a rnining environment.

2.1.2 Reaw-Dutv Roadheadera

One of the recent advancements in Roadheader Machines is the TM60 which was built by

Eimco (subsequently part of Tamrock) in 1990 and delivered to Canada for KDRK

mining, in 199 1. [Ozdemir, 19951. See Figure [3].

Loading Apron

Crawler Electrical Control Equipment

Figure [3]: TM60 Machine

The TM60 technology is based on the concept of a stable machine, a pivotal boom

attached to a horizontal-axis turret, and a low-speed, high-torque cutting head fitted with

ningsten carbide-tipped picks. The production rates range fkom 6m3/hr to 25m3/hr

depending on how hard the rock is. Presently, the machine has gained sufficient matunty

to be considered an economic proposition in a wide variety of hard rocks (Compressive

Strength> 180 MPa).

The advantages of the TM60 are indicated as follows:

Selective cutting - continuous ore handling

Minimal dilution

Greater variety of profiles, sizes

Smaller radius curves, tum-offs

Broader application in stoping and drifiing

Up-fiont space for supporiing while cutting

Excellent operator visibility

Finally, and in order to optimize the potential of the technology, future TM60

machines may incorporate up-fiont bolting capability and a means to deal with oversize

matenal.

Development efforts are also under way for heavy-duty roadheaders such as the

Alpine-Tunnel-Miner (ATM 1 OS). See Figure [4].

Electric Power + Generat ion

Crawler Apron Cutting Head -- - - - - - - - - - - - -

Figure [4] : Alpine-Tunnel-Miner (ATM 1 OS)

This machine uses cutting picks and incorporates a two-speed system which has al1 the

advantages of the Alpine Miner Series, but is brought to the most updated standard

available. [Tellian, 19951. As a result, production rates were increased to approximately

15 m3/hr exceeding any previous expectations.

2.1.3 Raise Borine Machines

Raise bohg is a well-developed and widely used technique for construction of raises and

shafis in underground mines. [Ozdemir, 19951. The technology continues to improve with

the introduction of more powerful machines and new reamer designs.

One of the new developments in raise boring technology is the Robbins BorPak system.

pobbins, 19951. This machine works very much like a TBM with its own hydraulically

actuated packer gripper system which provides the thnist and torque reaction for the

cutter head. Contained within a launch tube for underground transportation, the machine

is easy to set up and move fkom site to site. Steering is accomplished with a laser guidance

system. Cuttings pass through the cutterhead and are guided down a centrally mounted

rnuck tube and ont0 a conveyor. Al1 machine controls are located on a panel outside of the

raise, adding to the safety of the system. The present models offered for this machine can

excavate raises in diameters of 1 to 2 meters with 30 to 90 degree angles fiom horizontal

and up to 200 meters in length. The machine can also be fiilly automated for continuous

operation.

2.1.4 Mobile Ercavators

Different types of hard rock mobile excavators are presently under development for the

purposes of excavating non-circular openings. Until now, the major concern has been to

improve on the performance of these machines so that they could compete with the high

advance rates of TBMs which attack rock full-face, while mobile excavators cut only a

portion of the tunnel face at a given time.

One of the developments in hard rock mobile excavators is the Robbins Mobile Miner

( MM 130 ). See Figure [ 5 ] .

Rotating Wheel / Roof Support Electric Power Distribution Fitted with Disc

Figure [ 5 ] : Robbins Mobile Miner (MM1 30)

This machine is a crawler-mounted excavator which features a rotating wheel fitted with

disc roller cutters and mounted on an articulated boom. Rock excavation is accomplished

by sumping the rotating cutterhead into the rock and slewing it sideways. The goal is to

utilize the proven hard rock cutting capability of disc cutters to fragment the rock while

maintaining system mobility so that the equipment can be easily moved to different

wcrkings. The machine excavates a nearly rectangular opening with flat roof and floor

with elliptical shaped walls. It is capable of making tight turns and working both in inclines

and declines. Furthemore, its muck removal system is operated by gathering type anns

that Ioad muck ont0 a conveyor belt which in tum discharges it behind the machine into

mine cars or trucks. [Willoughby, 19951.

Atlas-Copco of Sweden is also developing a hard rock mobile excavator called the Disc

Boom Miner. Again, the intent is to build a machine which has mobility and can

economically excavate different sites and shapes openings in hard rock. The machine

features a rotating circular head fitted with disc cutters. The cutterhead is mounted on an

articulated boom. After sumping into the rock to a prescribed depth, the cutterhead is

swung in the vertical and horizontal directions with the extent of the swing angle

detemiining the final shape and site of the opening created. Again the machine is track-

mounted to provide a high degree of mobility. This machine is still in the conceptual

development and design stage and has not been built, as yet. [Ozdemir, 19951.

As previously mentioned in Chapter 1, the Wirth Company of Germany has also

developed a hard rock mobile excavator called the Continuous Mining Machine.

[Repski, 19951. The machine again uses the proven hard rock cutting capability of disc

cutters for rock excavation. It is also crawler mounted to provide the desired mobility.

The Continuous Mining Machine has been tested in Herdecke, Germany and is currently

undergoing extensive underground trial testing in Sudbury, Canada where the machine has

shown to be very challenging and successful in hard rock tuiinel excavation. This machine

is the focus of this thesis.

2.2 Introduction to Machine Monitoring Ao~iications in Mining

Dunng the past ten years, the Canadian mining industry has recognized the urgent need to

develop and implement new technologies to remain cornpetitive. Recent advances in

underground communications have dernonstrated the feasibility of teleoperation and

automation in Canadian underground hard rock mines. Machine monitoring is an integral

part of any teleoperated or automated machine.

As a joint effort between Laurentian University and University of Arizona, a study was

made on the development of a real time production monitoring concept for electrically

driven Load-Haul-Dump vehicles (LHDs). pever and Vagenas, 19941. In order for the

monitoring system to measure the current drawn by the vehicle durhg a typical load-haul-

dump cycle, a current transducer was installed at the power center (where the L m ' s

power cable is co~ected) . As a result, current fluctuations were recognized and classified

accurately by applying pattern recognition algonthms to the corresponding vehicle

operational activities such as loading, dumping and trimming. Furihermore, production

performance data was obtained and processed on a PC for timely effective decision

making regarding improvement of LHD fleet efficiency and productivity.

Pasminco Mining are also in the process of developing a monitoring system for their

Mobile Miner ( MM1 30 ). [Dollinger and Moore, 199 11. This computerized control

system monitors the machine performance and calculates the optimum cutter penetration

and cutter path. The machine is also equipped with an on-board Programmable Logic

Controllet (PLC) that is used to control the operation of the machine, while a Basic

Language Module @LM) is used to analyze machine performance data for the purposes

of maximizing penetration rates during cutting.

A monitoring program [Hulshizer, 199 11 was used to evaluate major activities of TBM in

the Seabrook Nuclear Station north of Boston, Massachusetts. The ment of this

monitoring program resides in its expediency and the detail to which it reaches into each

shift component. Moreover, convincing accuracy in pin pointing the activities affecting

excavation production has been fiirther improved by the use of a graphical display.

2.3 Machine Stnsinn of Rock Pro~erties in a Dvnamical Mininn Environment

The Earth Mechanics Institute of the Colorado School of Mines has been recently

involved in working on a system for probing rock for anomalies ahead of a tunneling

machine using seismic reflection techniques. [Ozdemir and Descour, 199 1 1. The concept

uses the train of impacts associated with the rock failures produced by a selected disk

cutter as the source of seismic signals. Reflections of these signals are then analyzed to

locate and characterize anomalies ahead of a machine. Preliminary results have s h o w that

S-waves are more effective than P-waves in detecting anomalies. Furthermore, S-waves

were several times stronger in directions perpendicular to the cutter loading force prior to

rock failure. Consequently, the dynamics of S-waves which are reflected h m anomalies

ahead of an excavator can be significantly increased by using cutters that are mounted at

large angles to the tunnel axis as seismic sources.

Recent work mguyen and Cohen, 19901 has show that the automatic recognition of the

geometrical configuration of an ore depoïit on a mine face is an important issue in the

development of modem mining systems. The ability to reliably and robustly extract the ore

distribution map from visual data cm be used for selective cutting operation or machine

guidance. As a result, a potential application of a texture analysis technique to the problem

of automatic recognition of the mine ore distribution is selected to perform the analysis.

This technique uses Markov Random Fields [Hassner and Sklansky, 19801 to model the

texture and the region processes. The segmentation problem is then formulated as a

Baysian estimation procedure, which can be decomposed into local decisions, thus

allowing the development of a highly parallel and fast segmentation algorithm. Results

from this study have been successfully applied to real cutting face images taken from an

underground potash mine, located in Saskatoon, Saskatchewan (Canada) and owned by

Noranda Minerals Inc.

Research [Steele et ai., 19911 has also focused on the development of an intelligent self

navigating underground mining machine with the use of ultrasonic sensors. Initial results

have shown that ultrasonics are very appropnate for identifjhg features in underground

mine settings because of the highly diffise character of the drifi walls. Further testing has

aiso show that senson specifically designed for tough duty are required. One important

aspect of this study has been the safety and reliability of such machines where they would

be considered effective in actual production. Thus by removing humans fiom operating

these machines, we would be eliminating any human exposure to dangerous hazards in

mining operations.

The Noranda Technology Center and the Canadian Center for Automation and Robotics

in Mining have been developing a dernonstration prototype of an optically guided Load-

Haul-Dump vehicle. [Hurteau et al., 19911. This guided vehicle uses a simple vision

system, a set ot'movement and positioning sensors and a basic communication system.

The purpose of this study is to evaluate practical operating problems to amve at a viable

underground automatic guided vehicle.

2.4 Machine Automation and Controi

The research and developrnent of a first and necessary step in reaiization of the

autonomous operation of a mining excavation machine is referred to as Self-Learning

Cutting Pattern Control. In many mining situations manual operation requires that several

repetitive operations be executed by the operator. Current research [Zaho, 19951 has

identified systern and control requirements necessary for repetitive operations to be

executed automatically once a desired cutting pattern has been established by the operator.

Based on simulated results fiom the Voest-Alpine Miner (AM-1 00), researchers have been

successfblly able to show that a cutting pattern control could be achieved.

Research Fuentes-Cantillana et al., 19951 has been aimed at achieving full automation of a

selective cutting operation camed out with an Alpine Miner (AM- 100) roadheader in a

Spanish potash mine. Results fiom this study have shown that the possibility of

transfoming the Alpine AM-1 00 machine into an intelligent robot could be achieved by

the use of cornputer vision techniques and a powerful control system.

The Chamber of Mines Research Organization in South Afnca [Oberholzer, 199 11 have

been working on the design ctitena for an integrated machine and management control

system that would enhance the operator's ability to operate his machine, and enable

section supervision to control the activities of the section better. Thus, a control system

was designed to visually indicate the position of the boom in the horizon and incorporate

any time lags caused by the reflexes of the operator. Apan from a horizontal plane, the

system is able to cope with any inclining seams, therefore any change of orientation of the

continuous miner in the vertical plane would have no significant effect on detemining the

right horizon. Finally, the degree of benefit to be gained ftom this project would be

largely dependent on the implementation of t he control system and the successful

operation of the continuous mining machine in the underground environment.

The Robbins Company has recently introduced a new remote controlled raise boring

machine, the BorPak 1200-7001. plliott and Ljungholm, 19941. This machine is a second

generation of the BorPak machines that the Robbins Company has developed. While the

prototype machine was a purely hydraulically powered and controlled machine, the 700 1

machine is electro-hydraulic controlled. A substantially more sophisticated monitoring

system is included in this machine that includes controlling the various machine tiinctions

and remote manipulating of al1 valves inside the sel'propelled mise boring machine.

Besides a more sophisticated control system, the number of trading lines and cables has

been drastically reduced thereby making the handling and operation of the machine easier.

A semi-automatic remote steering system is also included and proven to be working well.

The machine communication system has also been improved by adding a graphical touch

screen communication to the operation console in order to monitor and control the

machine more effect ively .

Robotics and Control Issues of the CMM Machine

3.1 An Overview of the CMM as a Mininn Robot

This chapter focuses on the mechanics and control of the CMM (Continuous Mining

Machine).

The CMM represents robotic manipulation since its parts and tools are moved around in

space by its own mechanism. The major parts of the CMM are its cutting ams which are

mounted on a rotating head that can advance horizontally to a maximum of one meter.

This configuration raises the need to represent positions and orientations as well as forces

on these arms, which in retum is essential for understanding the interaction of the machine

with the rnining environment.

The CMM onginated from a need of the Canadian hard rock mining industry for an

efficient machine that would be able to drive drifts with different geometries. As it is the

case in any industrial manufactunng, the building of the CMM production mode1 had to

pass through successive development stages.

In the first stage, a proof of concept prototype was designed and tested where a strong

emphasis was put on optimizing machine engineering, thus reflecting sufficient technical

and econornic data to propose modifications towards building a production prototype.

Once this was achieved, the machine entered its second development stage where testing

and design modification loops were aimed to integrate and operate the machine in the

mining environment as well as facilitate the ease of maintenance. Should this stage be

correctly incorporated, the building of the production mode1 becomes easier and more

successfU1.

In this chapter, and throughout the design and test loops of the development stages of the

CMM machine, the following four issues were constantly addressed:

(a) The optimization of machine maintenance

(b) The optimization of operations

(c) The optimization of mining aspects

(d) The optimization of testing and performance evaluation

Therefore, testing of the CMM machine had to be constantiy justified in terms of the

conditions outlined in Figure [6].

Design Obiective: Develop an Eff'tive Mining Tool

Optimize Machine Maintenancc Optimizc Operations

Optimize Mining Aspects Optimize Engineering r- CMM Testing

Coilect Data D I L 1

lmplement Analyze Modifications Data

A a !

Propose Modifications

I,

Figure [6]: Details of a Design - Test Loop

The CMM optimization greatly depended on trade-offs between the technical aspects of

the machine and the economics of it. See Figure [7].

Positioning Accuracv of Arms

Production Rates -

Figure [7]: Building Blocks and Links Between the Various Aspects of the Machine

During Testing

-

-

Figure [7] shows the links between the main six building blocks that characterize the

CMM design successfully. These blocks include:

t

Cutting Variables

Depth of Cut Penetration

RPM

i

Motion Control

System Stifiess Position Error

Hydraulic Delays

t

Cont roller Movement Gains - of

Kp, Ki, Kv, Kd VPIVCS m o l

(1) The CMM user-input parameters such as depth of cut, penetration, head RPM

factors and individual controller gains

(2) The cutting am's kinematic parameters such as profile position, velocities and

accelerations

Resulting - Forces on Arms

-

+

Machine Variables

Ann Pressures Head Torque

Oil Flow

The CMM limitation parameters such as head power (or torque), arm hydraulic

pressure and oil tlow

The CMM main design characteristics such as the ami dimensions (lever effect

and hydraulic stifiess), and disk variables such as outer diameter, tip radius

and angle of attack

The CMM controller aspects such as its user input gains and the resulting arm

stifbess I responsiveness, and profile error reduction

The economic factors that will ultimately decide the optimization of the machine in its current set-up and what could be done to make it more efficient keeping in mind the following key parameters:

(i) Achievable profile accuracy

(ii) Production rates

(iii) Wear rates of cutting disks

(iv) Overall machine reliability

Machine Kinematics and Dvnamic Behavior

3.2.1 Definition

Kinematics is the science of motion which treats motion without taking into consideration

the forces that cause it. [Craig, 1 9861. Thus, the study of the kinematics of the CMM

machine refers to al1 the geometrical and time based properties of the motion such as

position, velocity, acceleration, and al1 higher order derivatives of the position variables.

On the other hand, the study of dynamics deals with the relationships between these

motions and the forces and torques that cause them, which in our case is essential for any

dynamic analysis that would be perfonned on the CMM machine.

3.2.2 Machine and Controller Innutg

The user input machine parameters such as RPM, penetration and depth directly affect

the resulting forces on the arms and thus influence the head torque and a m pressures. In

retum, these parameters will affect production rates achieved by the machine since lower

depth and penetration means less production per cut.

On the other hand, the resulting effect of the input controller gain settings is to infiuence

the positioning accuracy of the amis by reducing as much as possible positioning errors.

This is achieved by moving the valve spool dong its range. Any movement of the valve

results in a change in oil fiow and pressure to the arrn cylinder. The precision of the a m

response to the movements of the valve depends on the combined effects of interna1 and

extemal disturbances such as reaction forces fiom the rock as well as fiction and the

accuracy of the valve.

The gains selected by the operator also affect the rate at which the valve spool responds.

Controller gains must be carefully selected since oscillations resulting in over-penetration

of the am, or sluggish am response resulting in under penetration, can occur. Therefore

the exact response of the a m will depend on the combined effects of the am dynamics,

the valve dynamics, the controller transfer function and the above mentioned intemal and

extemal disturbances. The diagram shown in Figure[â] shows two major blocks; The

control elements which consist of the PID-F controller and the a m position feedback

device (a transducer that measures actual cylinder position), and the system under control

which consists of the servo-valve and the ann-cylinder assembly. As for the disturbance

variable, it refers to the m-valve-cylinder assernbly.

e = Position Error x = Actual Position r = Set Position ( 3D Forccs, Inertia, Other)

r

Feedback Element (Position Meter)

Controller System Under Control (Valve Cylinder)

Figure [8]: Elements of the Arms Feedback Control Loop

-

3.2.3 A m Kinematicg

Extending the arms to the drift wail decreases the RPM. Thus, in order to achieve

constant rolling speed of the disk, the RPM fùnctions were selected as hyperboias. These

functions were equai to k/D in the circular portion of the cut, and to e/D in the corner

portion of the cut. The " D term is the outermost diameter of the tunnel, and the " k and

"e" terms are the fiinction factors.

Figure [9] show the components of the arm velocity resulting fiom the rotating movement

of the head and the extending/retracting movement of the cylinder. The first velocity

component is referred to as the perpendicular velocity and is denoted by Vp. It is a

fiinction of the head RPM and thus follows the am's radial position. The second velocity

component is normal to Vp and is referred to as V,,, which signifies the

extendinghetracting velocity, and equals the arm's rate of change of actual position.

The resultant of these two components is the path velocity, Vpath. This component of

velocity is tangent to the path followed by the tip of the disk. The magnitude of the Vp

component is at least 7 times larger than the Vdr component which implies that the

V(path) velocity is mostly af5ected by Vp.

P I + Constant Extending I

Disc Ve/r p. 1 Cutter

ingular Position /& Vr- Pivot

I

Figure [9]: Arm Velocity Components while Extending

3.2.4 Arm Dvnamic Disturbances / Erternal

The arm-valve-cyiinder assembly is subjected to interna1 and extemal disturbances. The

main component of the extemal disturbances are the 3-dimensional forces exerted by the

rock on the arms and are labeled Fx, Fy and Fz as shown in Figure[ 1 O].

Figure[lO]: Components of Reaction Forces fiom the Rock ( Fr is the Resultant of Fx & Fz)

Force Fx is the force exerted on the disk in a direction normal to its axis. Fy is the force

exerted on the disk in a direction normal to the disk axis and perpendicular to Fx. Fz is the

force exerted on the disk in a direction parallel to its mis. These force components are

measured o n a m I (inner single a m ) and am II 2 (one of three outer ms) using strain

gauges. Each component is vital in interpreting the behavior of the machine and its

interaction with the geology of the face. This is illustrated as follows:

(1) Force Fx is resolved along the am cylinder axis affecting cylinder pressure. Its

amplitude depends on the hardness of the rock and its homogeneity as weil as

the user-input depth of cut. Its fiequency depends on the head RPM and the

extendingt retracting velocity of the arm; it also depends on the a m stifhess

which, in tum, is a function of the controller gain parameters and hydraulic

stifiess. Force Fx also resolves in a direction parallel to the face Le. tangent to

the disk vertical contact area with the rock. This component of Fx affects cutter

Wear.

(2) Force Fy is parallel to the am pivot, therefore it does not affect cylinder

pressure. However, this force causes the rotating motion of the disk and, by

summing-up the four a m combined effect of this component (provided al1 arms

were equipped with strain gauges), this force would provide an indication of the

actual toque resisting the rotating head. Force Fy is thus an indicator of the power

eficiency of the head. The fiequency and amplitude of Fy depend on rock geology,

head RPM as well as hydraulic stifhess of the head .

(3) Force Fz acts somewhat similarly to force Fx in a sense that it affects cutter

Wear and cylinder pressure; its amplitude and frequency also depend on rock

geology, head RPM, controller gains and hydraulic stiffiess of the arm loop.

Usually, Fx is higher in the beginning of the cut. Then it goes through a minimum towards

the middle where its amplitude increases once again near the end of the cut. This behavior

is mainly due to a combination of effects such as the changing hydraulic stifkess in the

system, the decreasing head RPM and the changing disk contact area with the rock as the

arm extends towards the drift edges.

The change in hydraulic stifiess is a function of the bulk modulus of the oil and the

combined oil volume in the cylinder and the hydraulic lines. [Spotts, 1984). The disk

contact area is a function of the a m radial position, the disk outer diameter, the disk edge

radius, the penetration as well as the edge angle. These parameters are shown in

Figure[ 1 1 1.

(a)

Edge Radius

Dise Radius

Disc Centerline -

The area decreases as the am extends into the cut because of the increase in the tunnel

radius. The outcome is a decrease in forces required to cut the rock which on the other

hand has a positive effect on disc Wear.

Moreover, force Fz displays a behaviour similar to that of Fx but has a lower amplitude.

The resolving of a component of Fx and Fz dong the cylinder axis causes disturbances in

the cylinder pressures. The amplitude of these disturbances aside fkom the local variations

in the geology is a function of the arm geometry. As the arm extends into the drift edges,

the lever effect of the am first increases rapidly, goes through a maximum then starts

decreasing again.

On the other hand, peak values were found to be much lower in the circular cut than they

are in the corners. This is in part due to a sliding action on the back of the disk and the

increased confinement in the rock as the a m progresses into the cut. Other suspected

factors are protruding rocks left from under-penetration in the previous path as well as

fiequent direction changes in the corner when going from the extending portion to the

constant radius portion and vice-versa.

3.2.5 Arm Dvnamic Disturbanced Interna1

As we have seen in the previous section, 3-dimensional forces can cause variations in the

cylinder and head pressures. But extemal forces are not the only type offorces that affect

the dynamics of the system. Intemal forces have also been show to affect am pressures.

These forces are mainly due to gravity, rotating centripetal effects due to head rotation

and arm rotation around its pivot, as well as fnctional forces at the arm and cylinder

pivots.

These disturbances occur at different levels in the arm-valve-cylinder assembly. This is

illustrated as follows:

At the hydraulic circuit level:

(1) The oil compresses under load i.e. the arnount of compression is proportional to

the forces on the cylinder. The compression yields positioning errors which are

corrected by the controller. The oil inside the cylinders, valves, pumps and

hydraulic lines act like a series of springs with different stifiess coefficient.

Leaks at the valve and other locations of the hydraulic circuit add a friction

(energy dissipating damping effect) component to the spring effect.

(2) The hydraulic tubing in the circuit expands as pressure buiids-up (when the

amis are loaded). Thus, the tubing acts like a spring. Intemal fnction also

dissipates energy which again translates to a dashpot eflect. One direct

consequence to the expansion and contraction of the hydraulic lines is the

variable resistance to oil flow causing oscillations in the oil flow rate.

At the valve level:

(1) The oil stifiess compression effect mentioned before is influenced by the

constriction due to the valve opening. When the valve is completely closed,

one can assume that only the oil inside the valve and cylinder will undergo

compression. As the valve opens, the effect of the oil insida the lines gets added

to that of the oil in the cylinder yielding higher error (the amount of compression

being a function of the tube length and cross-sectional area).

( 2 ) Leaks in the valve prevent production of a precise flow rate to the cylinder as

comrnanded by the controller. Although these leaks are usually accounted for by

the manufacturer, the amount of leakage will increase as the valve wears out.

(3) The valve's intemal dynarnics and response time, accuracy and repeatability

may also have an effect on how predictable the valve response is.

At the arms level:

(1) The effect of gravity. As the arm rotates around its pivot with the head, the

amplitude and direction of the resulting force along the cylinder axis changes.

(2) The effect of centnpetal forces due to the head rotation. As the head rotates, a

centripetal force which tends to pull the arms outwards is generated.

(3) The effect of the a m rotation around its pivot. Every time the a m penetration

increases, the a m inertia causes the a m to resist that movement.

At the overall ann-cvlinder assemblv level:

Frictional forces which ultimately affect cylinder pressure exist at the following contact

points:

(1) Cylinder pivot

(2) Rod-am pivot

(3) Arm cutter head pivot

(4) Rod-piston intemal contact surface

(5) Rod-cylinder cap contact area

Finally, the amplitude and direction of the resulting fiction force depends on the

direction and amplitude of the resultant of al1 3-dimensional forces (Fx, Fy, Fz).

3.3 Reiationshi~ between the Control Svstem and Machine Behavior

3.3.1 Ceneral

The problem of optimization of a control system may be formulated if the following

information is given: [Spotts, 19841.

1. System equations

2. Class of allowable control vectors

3. Constraints on the problem

4. Performance index

5. System parameters

Therefore, the solution of an optimal control problem is to determine the optimal

control vector within the class of allowable control vectors. Mainly, this vector depends

on:

1. The nature of the performance index

2. The nature of the constraints

3. The initial state or initial output

4. The desired state or desired output

Consequently, and for the exception of special cases, the optimal control problem may

be so complicated for an analytical solution that a computational solution has to be

obtained.

3.3.2 Machine Controller Funct ions and Dmigp Confimi ration

In order to achieve optimum performance in the cutting time as well as reduce possible

interruptions due to the errors in the profile, the a n s position must be accurately

controlled. The comrnand flow used is the following:

(1) At any instant in time, the position feedback device measures and sends the arm

cylinder actual position to the controller.

(2) Using this information along with a set position sent by the PC and the profile

generating software, the controller gets a rneasure of the instantaneous

positioning error of the am.

(3) A valve position command is then sent by the controller; The valve reacts to

this command by moving its spool and thus causing an increase or decrease in

oil flow and pressure to the cylinder.

The closed-loop position control system allows, through the setting of the user-input P D -

F gains, influencing of the dynamic behavior of the cylinder which is mainly its stifiess

and response speed. The stiffhess of the system (when it is stationary) is proportional to

the loop gain which, in mm, is proportional to the individual amplification gain of al1 the

elernents of the loop. This is shown in equation (1). The multiplication of al1 gains of the

closed-loop is called the " closed-loop gain ".

As shown in the equation, the stiffhess is also equal to the ratio of the disturbance force on

the system or the reaction forces fiom the rock on the arms over the displacement. This

implies that in order to make the am stiffer Le. more resistant to a reaction force from the

rock, the closed-loop gain must be increased by increasing one or more of the individual

controller gains which in retum affects the valve position.

In spite of the fact that the overall response of the electro-hydraulic valve depends on the

closed-loop gain, the individual gains have different contributions to the response.

Equation (2) shows the control algorithm of the Parker controller [Parker, 19921. While

the servo-valve conunand value "c" ultimately translates to a position of the spool, it is the

result of the contribution of al1 the elements on the right hand side of the equation (2).

As defined by the [Parker, 19921, we have:

KP = User input proportional gain coefficient

Ki = Internai integral gain coefficient

Kv = Intemal velocity feedfonvard gain coefficient

Kd = Interna1 derivative gain coefficient

e = Position error = r-x

r = Commanded or set position

x = Position feedback actual position

s = Laplace transform of the derivative d d t

As the feedback positioning transducer sends the actual position of the am "x" to the

controller, the latter compares it to the commanded position or the advanced set point

position "r". The difference (r-x) is equal to the positioning error "e". These position-

related variables are multiplied by one or more of the controller gains as shown in

equation (2). The proportional gain K, affects the amplitude of the error. Thus, as the

error increases or decreases, the system will respond by opening or closing the valve by an

arnount proportional to the error amplitude. The proportional gain is the most vital of the

controller gains since it provides adequate response to transient variations in the system

caused by the random forces at the arms. If the value of the proportional gain is set too

low, the arm will not react strongly and fast enough to the disturbing force fiom the rock.

This would result in the am position undershooting its set position. On the other hand, if

the proportional gain is set too high, the am would then correct any enor too fast and will

ultimately overshoot the set position.

The integral gain " (K, * Ki* e) / s " in equation (2) above is mainly used to correct static

inaccuracy of the system. The integral gain multiplies the integral of the error with respect

to time. This means that its response builds up with time. Thus, the area under the curve

becomes larger. This characteristic allows the integral terni to deal adequately with static

error. Overshooting and cycling will result if the integral gain is set too high. In other

words, the controller output will eventually become faster than the arm system can

respond to, and the integral time becomes higher than the am dead tirne.

Conceming the velocity feedforward tenn, Kv, this term is very important when one wants

to build anticipation into the system. The velocity feedforward gain terni [(Kv*s)*r] acts

on the rate of change or "slope" of the profile set point function. In other words, the

steeper the set point function, the higher the effect of the feedforward gain. Therefore, by

knowing that the set points require faster position increments h m the arms, increasing

the velocity feedforward gain reduces the am following error when faster variations of the

set point occur. See Figure(l21.

Actual Position 1

4

I

O Undtr Penetration I

* I

I

* 1

4

D Transition Point m I

m I

I

I

I

m I

I

m I

l * I

l I b # Over Penetration m

l a ,-*.-..-*...-.-.-.--.--......-.-*.--*..-..*..*.-.-.-......., 1

Figure [12]: Result of a Typical Positioning Error on the Profile

Therefore, increasing the Kv gain will eventually cause the system to respond too abniptly

to the rate of change of the set point which would result in an overshoot of the system's

set position. In other words, the actual position of the arm will cross the set point curve.

As a consequence, an error of opposite sign will occur.

Finally, since the gain terms associated with Kp, Ki and Kv are al1 added together and are

al1 positive, their sum represents the first portion of the valve response to the disturbance

forces. But the tenn containing the derivative gain [(Kd*s)*x] is subtracted fiom the

previous three terms. Keeping this in mind, and knowing that the derivative gain acts on

the rate of change or "slope" of the actual position of the am, one could deduce that this

terrn has a very similar behaviour to that of the velocity feedforward t e n .

3.3.3 Controller Limitations

The type of controller installed on the CMM machine is the Parker controller. This

controller has a major limitation. It only allows the user to input two sets of controller

gains for a whole cut perfoned by the machine. These sets are referred to as P(extend)

and P(retract). We would like to note that the "extend" and "retract" terms do not

necessarily mean that the first one applies to the extending cylinder and the latter to the

rettacting cylinder; they are merely designations used by [Parker, 19921, and any one of the

two sets can be used whenever judged necessary.The limitation of having only two sets of

gains resulted in not being able to fine-tune the control loop. This is because of the

changing kinematic and dynamic behavior of the arrns under vatiable loading. The solution

to this problem would be to change gains in a manner that follows the behavior (response)

of the ann through the positioning error and therefote control the a m movements

accuratel y.

Changing the gain between the first and second half of the cutting process in a corner cut

is necessary to compensate for the slower reaction time when the cylinder retracts; this is

due to the fact that for identical system pressure on the piston and the rod side, the piston

area is twice the rod area. Thus, half of the force is available on the rod side. Faster

reaction is therefore necessary to compensate (partially) for that inherent limitation of the

hydraulic cylinder. In order to recti& the problem and achieve faster reactions, higher gain

settings should be given on the cylinder retraction side.

Table[l] clearly illustrates this concept where a cornparison between the combined gain

settings P(extend) and P(retract) is performed. Also the ratio of the gains is stated. In

both tests 1 and 2, the ratio of the Retract / Extend is > 1, which means that the

combined retracting gain is higher than the combined extending gain. -

ARMS II COMBINED GAIN SETTMGS

RATIO (RETEXT)

0.943

2.3

O. 94

1.335

Table[l] : Anns iI proportional gain settings

RETRACT(%)

O. 15

0.635' IO-'

O. 15

0.447 12* 1 O-)

EXTEND (%)

0.159

0.276* IO+

O. 159

0.3348.

CYCLE

1

2

ARM TYPE

1 ,

II

i

II

Finallv, despite the limitations of the Parker controller [Parker, 19921, the evaluation

of the changes in the values of the gain settings was still successful. This was because

these settings were in pan done by calculating the following:

(1) The time delay between the extending side and the retracting side of the profile

(2) The ratios of peak to average values for key machine parameters.

3.3.4 Svstem Resmnsiveness - Relation Between the Controller and Time Deiavs

Different tests were performed where the Kp gain was decreased by a factor of 2.5, while

the Ki gain was decreased from 0.0 1 1 to O % (integral gain switch tumed-off). This

simultaneous decrease of gains has caused a decrease in the am responsiveness, that is the

arms became slower to react. An indicator to this response variation is the time delay

between the set point position curve and the actual radius position curve.

While such delays are normal Cor hydraulic systerns behavior, they cm be influenced by

changing the controller settings. The ratios of time delays when arms (111,112 and 113) are

extending into the corner and retracting out f'rom the corner are shown in TabIe[Z]. These

ratios show that the delay is 2.5 to 3.5 higher when Kp and Ki are decreased as pointed

out earlier .

TIME DELAY (Seconds)

Table[2]: Ratio of time delays caused by a decrease in the Kp and Ki gains of the controller

Extending into the comer

I st cut

2nd cut F

Ratio of delays

3.3.5 Ratio of (Peak Pressure/ Average Pressure) vcrsus Controllability

Retracting fkom the comer

When calculating peak.1 average ratios, panicular care is taken for evaluating average

pressures or forces. Since rock failure seems to occur after only a few millimeters of disk

penetration, peak pressures occur right before failure. Once failure has occurred, the amis

basically reach the set penetration level after which their function would be basically

lirnited to clearing the remaining rock chips. Consequently, the arms would require much

lower piston pressures than they normally use.

0.0205

0.0717

3 .508

Furthemore, after the larger chunks of rock are cleared, the arms might be in a position to

cut in air until the next rock is encountered. This means that in order to correctly evaluate

0.053

O. 135

2.5 5

the tme ratios of [peau average] piston pressures, these ratios must be calculated when

the am is in rock and not in air. This procedure was done for three typical test cuts where

the depths of cut was 100rnrn for the first test, followed by 125rnm and 150mm for the

second and third test consecutively. The penetrations were kept constant at a value of

12mm for the three tests. The results are shown in Table[3]. Looking at these results, it is

obvious that the ratios of the [peakl average] pressures are consistent and range tiom 1.5

to slightly beyond 1.6, therefore, demonstrating good levels of controllability of the amis.

ARA4 II 2 TYPICAL PISTON PRESSURE RATIO PEAK/ AVERAGE

CUT RATIO P E N

AVERAGE

Table[3]: Ann II 2 typical piston pressure ratio peaW average

3.4 Actual Machine Profile Gentration

3.4.1 Effects of Disturbances on Svsîem Resmnse

The resulting effect of disturbances on the system is manifested in the way the systern

responds. If one envisions the am-cylinder assembly as having a certain spring stifiess

(mechanical + oil stifiess) and a certain amount of darnping (due to fnctional forces),

then the am-cylinder assembly can be modeled as a mass attached to a spring and a

dashpot in parallel. The assembly would then be subjected to forced vibrations by

components Fx, Fy and Fz. When a piece of rock fails, the am is suddenly released into

the air, and provided that it does not touch the rock for a short period of time, it oscillates

at its damped natural fiequency which may Vary between 0.5 to 2 Hz depending on the

am positions. Since the a m is in air, positioning errors do not matter and thus the effect

of the oscillations is very Iimited. If on the other hand, the forces excite the a m at a

fiequency close to its natural fiequency, large oscillations will result fiom operation near,

or at, resonance, a potentially harmful situation. Fortunately, this only occurs rarely (most

forcing frequencies being well below system natural frequency). Furihermore, when this

happens the forcing frequency changes very rapidly and the arm gets quickly out of the

resonance condition.

Since each arm can be modeled as a mass-spring-dashpot assembly, it becomes clear that

the natural fiequency of the damped oscillations of the arm changes during a particular

cut. This is basically due to the changing stiffhess of the arm as well as smaller changes in

fiction. Therefore, the natural fiequency of arm 1 decreases as it converges towards the

drift center-line, and the natural fiequency of arrn II decreases as it expands towards the

edges of the drift.

3.4.2 Macbine Guidance and i ts Effats on A m Motion and Profile

In this section, focus is on the algorîthm followed to guide and supervise the motion of the

arms as well as to calculate their profiles.

As we have seen earlier, al1 electro-hydraulic systems have inherent delays due to several

factors:

( 1 ) Inertia of the mechanical componeiits

(2) Friction and non-linearity in the system

(3) Processing delays due to lirnited computational capabilities and the complexity

of the mathematics and their computer algorithms.

(4) Others

Mainly, al1 systems have a finite response speed. For the case of the arms of the CMM

machine, the delays in the system were evaluated at 120 to 1 50 msec. A value of

145 msec was used for compensation purposes.

In the CMM machine, the position of the anns determines the geometncal shape of the

profile. See Figure [ 131.

A m II Corner Cut End of Circle Cut

Figure [13]: Division of the Face Cut into Sub-areas

Assuming perfect controllability of both the arms and the cutter head, and provided there

are no delays in the system, no oscillation of the head aiid the piston has unlimited force to

limit the effect of the inertia to close to zero. Then, the am should be reaching

instantaneously its set position with an accuracy within the limits of its measuring

instruments. This is a hypothetical situation, and in order to understand the dificulties in

controlling positioning enors, each one of these issues would be presented clearly.

Leaving aside the control aspects of both the head and arms, and focusing on the arm

positioning algorithm, the first step would be to calculate the shift in profile due to delays

in the system. The hydraulic delay implies that at the instant a set point is given to an am,

it takes 145 msec for the system to react. Meanwhiie the head is turning. This implies that

by the time the am starts responding to the set point, the head has rotated by an angle

which is a function of the angular velocity (RPM). At RPM = 10 (equivalent to 60

degfsec) in 145 msec, the head would have rotated by 8.7 degrees. Some values for

different RPMI delay combinations are provided in Table[<(]. It is to be noted that the

upper limit of 10 rpm used in the table occurs at the end of the circular cut which is

basically the beginning of the corner cut.

RPM

10

Table[4]: Profile shifi due to hydraulic delay for dflerent RPM values

ANGüLAR SHIFT DüE TO DELAYS RADIUS (mm)

(3 VALUES S H O W AS SAMPLE) DELAY (msec) SHLFT@eg)

The position shift resulting fiom the delay at different radial positions as show in

Figure[l4], is calculated as follows:

Equivrlent .. . Distance Equrl to . .

.*.. ' .

I I 342 mm rt Rad --.

2260 mm Head Angular "..-.-.. ... Rotation in 145 msec ""-....+

1

Figure [ 141 : Effect of Hydraulic Delay on Arm Position

By the time the a m starts to react (&er 145 msec), the angular position of the a m would

have moved from point A to point C, the distance AC being equal to 342 mm. At point 4

the arm is supposed to start extending. But because of the delays, it only starts extending

at point C. Since the radius AWBC, the am lands too short at point D as shown in

Figure [15 ] on the following page. From triangle ABC, one can compute the following:

If AB=2260 mm and the RPM= 1 O, then the radius of the arm afier 145 msec should

be equal to:

CB = 226O/(cos(8.7)) = 2286 mm

Therefore: The position error = 2260 - 2286 = -26 mm (under-penetration)

which resuits in a 26 mm under-penetration position error. This error, if constantly

repeated for al1 points dong the extending profile, will cause an angular shift in the

profile.

This is clearly shawn in Figure [15] where the angle of shifting is calculated using

triangle ADC knowing that AB=BD. The shift is equal to 8.7 degrees and is calculated

by using equation (3):

Angular shifl= arccos

Resulting A m Positioning Error (Under Penetmtion)

- - . .. . , -.*.._ -.- .... .-.* .. . . Head Angular Rotation i

in 145 msec

Figure [15]: Resulting EfTect of the Delay on the Arm Position while Extending (Under Penetration)

Finally, knowing the relationship between the RPM and the resulting shift at different

rpm's, one is able to anticipate the system's behaviour by generating a profile based on

an advanced set point. As a result, this profile generates the set point 145 msec earlier

in order for the ann to reach the correct position.

CMM Cutter Desimi. Fragmentation

and Materials

Handline Reauirements

4.1 Introduction

This chapter provides an overview of materials handling systems that are in use today in

the tunnel construction industry. The chapter also stresses the importance of chip size

formation as well as cutter design and their effects on machine performance.

Dunng tunnel construction, the materials handling systems must be designed and used in a

manner that would include provisions to transport everything in the way of materials or

personnel in and out of the tunnel while the work is being perfonned. As a result, the

following items must be taken into consideration:

1. Muck removal

2. Personnel transportation in and out

3. Air for ventilation

4. High pressure air for air-operated tools or equipment

S. Material for temporary support system

6. Water supply or removal

7. Grouting materials and equipment

8. Permanent lining system

Out of these items, the decision on a muck removal system that would be able to

provide a smooth and efficient tumeling operation is of major concem. Nowadays, a

time anaiysis of an overall tunneling operation is expected to show that muck removal

is basically one of the controlling elements goveniing the progress of the work.

[Mathews, 1 9801.

Furthemore, handling and transportation of the other items necessary for the

construction of the t u ~ e l can be usually accommodated by either the muck removal

system or by a suppiemental compatible system.

4.2 Effects of Muck removal on Minin? Excavation Machines

It is clear that any improvements in the excavation efficiency of Tunnel Boring Machines,

as indicated by current advertisement of a continuous advance TBM, requires that

advances be made in muck removal systems. Without such advances, the added costs of a

similar machine would be a wasted investment. [Janzon, 19953.

The significance of muck removal in the case of the Continuous Mining Machine (CMM)

was also of profound importance. This was noticed while the CMM mac!iine was

operating in the Herdecke mine site in Germany. Muck generated during cutting was

removed by conveyors located at the CMM discharge. The conveyors were of smaller

capacity than the CMM conveyor. This caused occasional interruptions to the mns,

particularly when overtlowing conditions occurred at the headsnd of the conveyors.

Chips were then selected fiom the muck pile as well as from the conveyor discharge for

supplemental study. Results of chip analysis and its effects on muck removal strategies are

bnefly discussed in later sections of this chapter.

4.3 Muck Removal Modes for Tunnel Construction

The following are the basic materials handling systerns currently available for tunnel

muck removing: [Yu, 1 9721.

1. Rail

a. Conventional

b. Monorail

3. Belt conveyor

4. Pipeline: Hydraulic

Pneumatic

Most likely, no one system will handle al1 of the materials handling requirements for any

given tunnel task, therefore some combination of systems or modes will be required. A

discussion of these modes and their advantages and disadvantages for an overall materials

handling system is presented in the next section.

4.4 Machine S u ~ ~ o r t i n n Services and Muck Transport

4.4.1 Aurilirriv Eauinment

The availability of a suitable excavation mining machine alone will not get a tunnel

through. The machine has to be served by many supporting seMces such as the

following: [Holden, 19801.

1. Electric Power

Though some machines are equipped with hydraulic motors for cutterhead rotation and al1

machines have a hydraulic system for thrust, gripping and many subordinate functions, the

primary power is always supplied in the fom of electricity.

2. Water

Water is definitely needed for cooling purposes and dust suppression. It is basically piped

in from outside the tunnel wall and connected to the water system on the back-up Ma a

hose to allow continuous machine operation.

3. Com~ressed air

Because of the increasing use of hydraulically powered rock drills for probing or dnlling

rock bolt holes, compressed air requirements nowadays are limited to powenng maybe a

few hand tools or for additional flushing of probing holes.

4. Ventilation

Fresh air must be supplied to the tunnel face for the crew working there. It is also used to

dilute and remove exhaust fumes from diesel engines

5 . Tracks

T U M ~ tracks are installed for railbound transpon of people and materials to and from the

face and, in most cases, of muck out of the tunnel. This is achieved by using a single track

because a double track would require partly refilling the invert to obtain a wide enough

road bed.

4.4.2 Basic Muck Removd Techniaues

The muck can be taken out of the tunnel by a variety of means or systerns, the most

common methods are listed below: [Holden, 19801.

1. Trucks

Trucks are basically used in large diarneter tunnels that are of short length. The large

diameter is required to permit two trucks to pass each other in the tunnel and to be able to

tum behind the excavating machine. The disadvantage of this method is that it requires a

large fleet of trucks. This is because the loaded muck will be mn out by the same truck to

be unloaded out side the tunnel.

2. Muck trains

Trains of muck cars moved by a diesel engine or battery powered locomotives are loaded

from the back up conveyor belt located behind the excavating machine. The train is then

mn out to a tip arranged at some short distance outside the tunnel where the muck

emptied.

3. Convevor svstems

Conveyor systems are in most cases used for muck transport in long tunnels of such a

small cross section that a muck train system would be hard to keep up with the excavation

rate of the machine.

4. Fluid ~umping systems

The method of moving solids suspended in water or a slurry is by pumping them through a

pipe line. This method is comrnon in ore treatment plants and lends itself for muck

transport under certain conditions where:

(a) The availability of a sufficient quantity of water exists

(b) The excavated material is not too abrasive, and

(c) A high percentage of fines in the excavated material and a specified

maximum particle size can be regulated

From the above, it wili be clear that such a pumping lends itself admirably for use with a

slurry shield but would be hard to visualize for use with hard rock.

S. Pneumatic svstems

Such systems have the following basic elements:

An air source, such as a blower, discharges into an air lock injector for the matenal to be

transported and forces the material into a pipe line which in tum directs it to its

destination. It has to be noted that sufficient air pressure is required to maintain a high

enough particle transport velocity throughout the system.

As is the case of hydraulic systems, lirniting particle size is necessary. Few systems have

ever worked satisfactorily with larger than 50 to 75 mm particles, somewhat depending on

the specific density of the material. They are aiso lirnited in transport length and require

the installation of booster blowers at comparatively short distances dong the line. If the

material is abrasive, the cost of pipe lines maintenance becornes high. Thus, pneumatic

systems will oniy be applicable for muck transport under very specific, project dictated

circumstances.

4.4.5 CMM Convevor Svstem venus Other Eaulaee Svstems

The continuous conveyor haulage system used in the Herdecke mine to support muck

removal fiom the CMM machine has been shown to provide important benefits over the

other muck removal systems discussed earlier.

The CMM conveyor haulage system is continuous and always available. In other words,

there is no interruption in the boring cycle and no downtime waiting for muck cars. It is

also safer since most locomotive diesel fumes are eliminated and tunnel traffic is reduced.

Moreover, this system has been show to greatly reduce rnanpower requirements where

very little maintenance was needed in spite of the faster and more productive muck

removal performance.

The advantages of the conveyor haulage system used for the CMM machine over other

systems as show above is basically due to the following:

1. The conveyor system, could be directly attached to the CMM machine trailing

gear, thus the systems advancing tailpiece permits the advance rate to be totally

dictated by the CMM machine.

2. The installation of an advancing tailpiece window ailows carrying idlers to be

installed without stopping the system.

3. A belt storagekake-up unit enables tu~e l ing operations to advance as much as

300 meters before additional belting is required.

4. Tripper-booster drives make possible conveyor belt runs 10 km long.

Thus, the result of using this tumeling conveyor system has been shown to be

very efficient in terms of productivity and profitability.

4.5 Muck chi^ Size and Form Based on the CMM Performance in Aerdecke. Germany

4.5. t Rock conditioiis ai the Herdeckc Site

The rock conditions at the Herdecke site are classified as medium hard with medium

abrasivity . The Unconfined Compressive Strengt h (UCS) ranges between 10 1 to

15 1 MPa for sandstone and 25 to 55 MPa for shale. [Repski, 19951.

4.6 Effects of Cutter Design on Machine Performance

4 . 6 CMM Cutter Desien Based on TBM's Cutter Performance

Based on previous experience from TBM's, it is well known that increasing the cutter

diameter reduces the penetration rate for the same force level. This is primarily because of

a larger contact area under the cutter. Thus, a thinner edge results in lower forces, smaller

chips and slightly different chip angles. This indicates that one should use a cutter edge

that is as thin as possible.

Also, it was shown that for TBM's the cutter diameter in hard rock conditions should be

at least 43 cm, to get sufficient penetration rate and cutter life in

sm3/ cutter (depth of cut * volume per cutter) .

Assuming that the CMM will need average cutter loads ofapproximately 220 - 250 kN to

cut efficiently in hard rock, one should not start testing with less than 43 cm diameter

cutter rings because the strength of the steel is not good enough to apply the force level

needed to utilize the CMM fully.

Furthemore, if chipping of steel fiom the rings becomes apparent, the solution would be

to increase the cutter edge width or use smaller cutters with 46 to 48 cm radius.

Moreover, an optimum diameter rnay be found when tiirther testing of the machine reveals

more data on Wear, forces and penetration.

4.6.2 Effccts of Increasind Dccreasine Disc Parameten on Machine Desirn

The cutting discs are the interface between the machine and the drift. They convert a

certain portion of the power generated by the machine into a cutting action on the rock.

They are therefore one of the most critical components of any excavating machine.The

design of the disc directly affects the following:

a) Thetechnicalaspectsofthemachine.Thatis,itscuttingabilityin

different types of rock, and the efficiency with which machine power is

converted to actual rock cutting.

b) The economics of the machine. The Wear rate of the discs will dictate

how efficient the machine is in terrns of maintenance.

The disc parameters that most influence these technical and economic aspects are:

a) The actual dimensions of the discs; this includes the outer diameter, edge radius and edge angle. See Figure [16].

b) The material of the disc Le., physical properties such as strength and ductility.

&

Dise Outer Diameter

w Edge Radius

Figure [ 1 61 : Disc / Ring Paramet ers

As we have seen in the previous section, larger contact area with the rock implies that

more pressure must be supplied at the cylinder level to compensate for the fact that the

tip of the disc is spread over a larger surface.

On the other hand, increasing disc size dso implies slower Wear rates since equal amounts

of energy are spread over a larger area. Finally, the deeper the disc penetrates rock, the

larger the contact area; therefore, increasing penetration will increase contact area. In view

of these facts, it is apparent that optimizing the disc sizes will imply making a compromise

between forces required to perfonn a cut and Wear rate of the disc.

4.6.3 The Theorv Behind Cutter Wear

To mathematically quanti@ the amount of wear on the discs is very difficult due to the

intncacy and the number of factors that affect such wear. However, this does not mean

that good predictions on cutter life cannot be achieved.

For the C M . machine, Wear of the discs is linked to several major areas of concem:

a) The cutting pnnciple involved i.e., how the rock fails under the disc force.

b) The mechanical properties of the materials involved. This includes such factors

as hardness of the disk as well as drillability and abrasivity of the rock.

c) The effect of geological parameters such as the degree of fracturing on the face.

It is well established that mechanical Wear results fiom the fiction that occurs when the

discs move relative to the rock face. This Wear is due to the sliding action of the discs. The

Wear rate is a direct function of the amplitude of the forces on the discs and the fiequency

of occurrence. Therefore, one can conclude that if both the amplitude and frequency of

the forces exerted on the discs by the rock are reduced, this will reduce Wear on the discs.

From basic mechanics, it is clear that to properly estimate the amplitude of the fiction

force due to the forces at the disc, one must have precise values of both the static and the

dynamic fiction coefficients. Furthenore, a distinction between the different types of

Wear has to be divided according to the following categories:

a) Cuttinn wear:

It is noted to [Spotts, 1 9841 that cutting Wear results " when a hard rough surface is

rubbed over a sofier one with or without lubricants". Thus, onless the materials have

widely different hardness, cutting Wear soon ceases as the parts become wom in. This

statement is essentially correct for machinery Wear - such as a drilling operation - since the

bit and the piece of material remain in contact for a relatively long period of time i.e. ,

enough to even out the material surface at the drilled spot. For the CMM, and due to

continuous rotation of the cutting head, the disc remains in contact with any instantaneous

rock location for a short period of time; This implies that the disc is constantly cutting new

rock surface i.e., the rock surface never evens out. Therefore, cutting Wear is always

present throughout the cut , but is limited.

b) Abrasive wear:

It is also noted to [Askeland, 19941 that "Abrasive Wear occurs when the material is

removed from the surface by contact with hard particles, which may either be present at

the surface of a second material or may be present as loose pa~icles between two

surfaces". Abrasive Wear is the most common type of wear for machinery. Typically,

materials with high hardness and high hot strength (ratio of the strength at the operating

temperature to the strength at room temperature is close to 1 ) will be more resistant to

the abrasive Wear resulting fiom cutting. It seems that Wear on the CMM discs is strongly

related to abrasive Wear; as a matter of fact, preliminary findings suggest that when a

metal disc is used to cut rock, a boundary layer forms between the disc and the rock

surface. The disc surface and the rock surface are then linked through this boundary layer

which is typically made of small rock fragments which cause abrasive Wear of both the

disc and the rock surface. These findings are supponed by the calculations and cornparison

of the fnction coefficients of rock to rock and rock to metal contact. The rock to metal

fnction coefficient came out to be equal to that of the rock to rock friction coefficient

which confirms the boundary Iayer assumption. [Askeland, 1 9941.

Wear is also affected by adhesion of the surfaces rubbing together as well as increases in

surface temperature. As the disc rubs the rock surface, fnction causes a temperature

increase at the disc ring. Temperature increase causes a change in the mechanical

properties of the ring steel, particularly, its ductility, tensile strength and yield strength.

However, for the change to be substantial, a noticeable increase in temperature must be

measured (in the 100 to 300 OC range).

4.6.4 CMM Cutter Life Estimation

Cutter Wear on the CMM machine was measured by estimating the Wear on the discs

attached to arms II and arm 1. (See Figure [17]). This Wear was only due to contact

between the cutter and the new face because at the tip of the ring the Wear was found to

be to negligible.

I Figure [17]: Actual Cutter Wear

The CMM Cutter Life was estimated to be equal to the following:

(Volume Bored by CMM) I (Total # of Cutters Used)

where:

Total # of Cutters Used =( # of Cutters Used on Arm 1) + ( # of Cutters Used on Arms II)

and:

# of Cutters Used on A m 1 =

(Wear on Disc * Wear Rate)/ (Maximum Recommended Wear on Discs)

# of Cutters Used on Arms II =

[(Wear on Disc * Wear Rate)/ (Maximum Recommended Wear on Discs)] * 3

Exoerimental Data and Preliminaw Analvsis

5.1 Hardware and Software Instrumentation

S. 1.1 CMM Simal Selection and Identification

Monitoring and control of the CMM machine was performed by the use of sensors and

transducers which generated signals that were sent to a patch panel. These signals were

then taken fiom the patch panel and recorded on a Teac Cassette Data Recorder. A

strip chart recorder was also used to check for dead signals resulting from defective

transducers. See Figure [ 1 81.

Control Sensors , O Panel

Viewdac 1

Teac Recorder Rnw Data

Excel L

Analogue

i

k

r I

Figure [ 181: Block Diagram for Recording and Digitizing Data 68

PC - A/D- 16 Channel

0

Viewdac ASCII Binary

Out of the 100 sensors connected to the CMM machine and sent to the patch panel to

be recorded by the Teac Cassette, only the following 16 signals were digitized using the

Viewdac data acquisition system:

Arm 1 radius actual

Arm II 2 radius actual

Arm 1 rod pressure

Arm 1 piston pressure

Arm II 2 rod pressure

Arm 11 2 piston pressure

Arm I Fx ( force exerted on the disc in a direction normal to its axis)

Arm 1 Fy ( force exerted on the disc in a direction normal to the disc axis and perpendicular to Fx)

Arm I Fz ( force exerted on the disc in a direction parallel to its axis)

Arrn II 2 Fx

Arm 11 2 Fy

Arm II 2 Fz

Rotating pressure left (head feed pressure)

Rotating pressure right (head retum pressure)

Rotor RPM

Rotor angular position

S. 1.2 Hardware

Teac Cassette Data Recorder

The Teac recorder is a magnetic tape recording unit that can record and play 2 1 tracks on

a VHS tape simultaneously. Each track can record data through either Frequency

Modulation (FM), Pulse Code Modulation (PCM) or Direct Recording. In this study, and

for the purposes of digitizing the data, the Pulse Code Modulation (PCM) was used.

S t r i ~ Chatt Recorder

Strip chart recorders provide simultaneous data recording and displaying (through a

limited memory buffer). One stnp chart recorder was used during the digitizing process

which provided continuous monitoring of four signals. Because of the limited ability of

stnp charts due to paper plotting space, the recorder used only provided a quick look at

selected monitored signals. More detailed analysis was perfonned at a software level using

Viewdac, Excel and MatLab.

5.1. 3 Software

Viewdac

Viewdac is an integrated package for data acquisition, control, analysis and graphies.

Viewdac allows for performing mathematical manipulations of data such as moving

averages, filtering and Fast Fourier Transfomis (FFT). For our case of digitizing the data,

Viewdac was programmed to read 16 signais simultaneously and plot these signals on-

screen. In order to allow data importing to Excel or MatLab, the software provided the

capability to Save the raw unfiltered or filtered signals in ASCn files. This was performed

because of Viewdac's limited graphics capabilities and its lack of flexibility in data

manipulation.

Matlab

Matlab is mathematics software that allows the manipulation of tabular data loaded

from Viewdac ASCII files in a matrix form. By the aid of a special program written in

Matlab language, we were able to filter the raw ASCII data imported from Viewdac.

Excel

Excel is a spreadsheet software that could also handle large amounts of data and present

this data in tabular or graphical form. This software was used in parallel with Matlab in

the post processing stage of analyzing the data.

Digitking the data was performed by playing previously recorded tapes on the Teac recorder and copying them to the cornputer using a data acquisition system. These tapes contained previous recordings of cuts performed by the CMM machine in both Canada and Gemany.

5.2 Filtering

5.2.1 N o i e

The signals recorded from the CMM machine contained two types of noise:

(a) 50 Hz EMF-ind~ced

(b) Digital noise

The 50 Hz noise was due to the proximity of signal lines to power lines and various

electrical equipment. In an attempt to block this 50 Hz interference, al1 cables were

shielded, but this did not completely block the interference. Therefore, the amplitude of

the 50 Hz noise was added to the amplitude of the recorded signal. Please note that these

noisy signals can be removed by using either hardware or software filters as shown in the

next section.

As for the digital noise, it was a very high fiequency noise which could have been

either generated within the electronic circuits or was caused by the Viewdac data

acquisition system itself Whatever the reason, it was characterized by a very short

blip that had a very high amplitude and short nse and fdl times that seemed to occur at

random. In general, this had no effect on the test results that were generated.

5.2.2 Filtcrinp in Viewdac

The data acquisition and monitoring software developed in Viewdac provided lowpass

filtenng capabilities that could be performed on certain data by filtering each column

separately. The user also has the choice of either saving the filtered or unfiltered data in

ASCII files. Having this choice as an option, the opponunity of understanding important

information regarding those signals that were aflected, or not, by the 50 Hz noise was

moaly provided.

The CMM machine data was digitized and filtered in Viewdac using a lowpass filter of

approximately 48 Hz. The sampling frequency was kept the same at 256 Hz.

5.2.3 Filterinr in Matlab

Mer digitizing the data using the Vieadac data acquisition system, it was saved as

ASCII files. In order to open these files in Matlab and filter them, a program had to be

written using programming in the Matlab language. See Annex [A].

5.3 Processinn of the Dinitized Data - Initial Conclusions

5.3.1 Pmcessin~ Mcthods

In order to make use of the digitized data, a decision on the issues or methods of how to

analyze this data had to be taken into consideration. In Our case and for the purposes of

this thesis, two methods of analysis are discussed:

(1) Pattem Recognition

(2) Specific Energy

Pattern recognition is only discussed from the theoretical point of view, whereas specific

energy is used to perfonn the actual analysis.

5.3.2 Oveiview on Patîem Recognition

Pattem recognition refers to the analysis of the complex processes involved in recognizing

patterns. The senses and the brain perform these tasks in the human being. [Duda and

Hart, 19731. The field of pattern recognition is involved especially with the manufacture of

artificial systems that achieve similar ends, whether using the same methods or not. Pattern

recognition is used in the recognition of sensory input, but also applies to information

already stored. This entails looking, for exampie, at a set of events and trying to detect a

recumng pattern or sorne other feature that makes prediction possible. A statistical

technique that provides for such an analysis is called the Stochastic Process.

Statistical pattern recognition is based on a well-founded mathematical theory which has

proven to be usefbl in numerous applications in the rnining industry, and especially in the

automatic recognition of different rock types and geologic conditions. pollitt and Peck,

19911. ~oreover, this method is well suited for coping with noisy and distorted patterns.

For the case of classification problems, the objective is to find the pattem class that a

given input is most likely to belong to. Thus, the input is described in tetms of "features"

where the set of features defines a "feature space" of al1 possible measurernents. Thus, for

a given input, features fiom the raw data are measured to form a feature vector. In other

words, if we have n features, this implies that the feature space is n-dimensional.

In general, a good feature extractor makes the job of designing a classifier trivial,

whereas a reliable classifier could use raw data as features. See Figure [19].

Figure [19]: Block Diagram for Pattern Recognition and Classification

Subsequently, if the features are defined appropriately, then al1 feature vectors derived

from patterns belonging to the same class fonn a cluster in the feature space. In order to

classify, we must know or estimate the probability distributions of the features for each

pattern class, or we could use other altemate techniques such as the " K-Nearest

Real World

, Classifier , Receptor I , Featun Extractor

Neighbor" classification, where the rule classifies a set of n samples by assigning them one

by one to the label rnost fiequently represented among the k nearest samples.

[Tou and Gonzalez, 19741.

5.3.3 Pattern Recomition in Relation to Sensinn of Rock Proaertics

The automatic identification of different rock types is based on monitoring of machine

variables by extracting correlations between machine parameters and rockmass properties.

Thus, in order to achieve these correlations, we should nomalize for al1 system variables

so as to clearly identiQ the effects of changes in the geology.

For the CMM machine, the machine parameters are the 3 dimensional forces on the cutter

arms along with the piston pressures of the a m actuators. As for the çeological

parameters, the compressive strength (UCS) is used for the purposes of the analysis.

Based on testing of the CMM machine in both Germany and Sudbury, it was shown that

the variables that mostly affected the machine parameters are divided into the following

two categories:

(1) User-Selected:

(a) Penetration of the arms

(b) Depth of cut

(CI

(d) Disc size (edge radius, disc diameter)

(e) Arm kinematics-geometry

(2) Other:

(a) Disc Wear

(b) Geology

(c) Leaks in the system

(d) Wear in the system

(e) Calibration changes

Therefore, reducing the effect s of these variables on machine sensing of rock properties

reduces the performance error of the CMM machine in discriminating between different

types of geological pattems while operating in a mine.

Pattern recognition concepts and techniques are well suited for the analysis of relatively

unstructured data where they require a training session of the data set. This training

data set or Labeling is representative of the various different pattems corresponding to

the different conditions or classes that are to be discriminated. [Bieniawski, 19741.

In terms of the CMM machine data analysis, pattern recognition techniques could be easily

used to divide the data into separate classes. Thus, one could divide the separate classes to

Shale and Sandstone under the sofi rock category, and to granite and norite onder the

hard rock category. In addition, more classes could be found by further looking into rock

structure, faults and rock strength that are representative of the various locations of

different edges and geometries in the rock.

The most important step in using pattern recognition for the data analysis of the CMM

machine would be in the gathering of the data. This is usually done under controlled

conditions in which the class is reliably established by direct observation such as by

looking at core logs. Once this is established, the labeling of the data is set and different

rock types are separated under different classes.

Following the labeling of the data, an inspection of the vanous variables is performed in

order to rank which of the variables are to be used for decision making. Not only that, but

a knowledge of the machine/rock interaction is a step forward towards fomulating

intermediate variables that can have a higher correlation with the classes than the raw data.

An example of this is the calculation of the rock strength based on variables such as thrust,

torque, speed and advance.

Once the relationship between the machine parameters and the rock mass properties has

been established, various statistical tests and approaches could be performed in order to

detect the degree and ranking of the various correlations. Thus, the resulting analysis

forms the basis for choosing between the various pattern recognition techniques and their

different algonthms.

As far as testing for pattern recognition techniques and algorithms, it is essentially a

programming methology which is not covered in this thesis.

5.3.4 S~ecific Energy - Profile

Specific Energy (SE) is the energy required to remove a unit volume of rock. Other

definitions of SE are also specified in terms of the new surface area created. Moreover, SE

can be closely approximated to be equal to the compressive strength of the rock.

[Bieniawski, 19741.

During a typical cutting process, the hardness of the rock varies randomly. Thus, adjusting

the cutting parameters according to these changes can significantly improve the cutting

performance of the machine if an on-line measurement of the rock hardness is possible.

However, calculation of this property dunng the cutting process is quite hard and

troublesome. Altematively, the Specific Energy can be calculated on line

during a cut, and because it is considered to be one of the quantities that gives an

approximate estimate of the rock hardness for any particular cut perfonned by the

machine, it is therefore usefùl to study its effects on the performance of such machines.

[Brady and Brown, 19851.

5.3.5 S m i f i c Enernv Com~utations Bsiscd on the CMM Machine Desien and Oaeration

In this study, two different methods of computation for the Specific Energy per unit

volume are suggested:

(1) Computation of Specific Energy based on manufacturer

recommended values of operation specific to the CMM machine .

(2) Computation of the Specific Energy by on-Iine caiculation of the CMM

machine dynamics. (forces, torques and RPM etc) .

In the fint case " Computation of Specific Energy using CMM Machine Manufacturer

Guidelines ", the following is provided:

- - - -

Radius of Cut (mm) *

O -1278

Where RI1 000= (am radius in mm) / (1000 mm 1 m)

1278-2270 (end of circle) 2270-2640 (end of cut)

and A p = (head feed pressure - head return pressure) in bars

-- -

~ o G u e (KN.m)

0.917 Ap

But each bar = 10' Pa. Using this conversion factor would give the pressure in Pa.

-- - -

Specific Energy (MJ / m3)

0.7 18*(R11000) * h p 1.66* Ap

From the above, the total Specific Energy would be:

(T'orque * Rotation) / volume

S.E ={ [0 .917*~p + (O.7l8*(R/lOOO)*A p) + (1.66*A p)] *RPM)/ volume (4)

Where the Volume = (Area of Face Cut ) * @epth of lut).

For the second case " Specific Energy Calculations using Machine Dynamics and

Kinematics" the Specific Energy is calculated as foilows: See Figure[26].

Where:

Fy provides an actual measure of the torque resisting the rotating head

R is the vertical distance from the a m to the center of cut (moment am)

hij*(~verage Arm I Radius Actual) = [Ri$ Rij]/ 2

h i~~(Avefage Ami II Radius Actual)= [Ra+ RnjY 2

0 fi,= am 1 angular Position

8 1iij= am II angular Position

Volume(ij) = volume excavated during time (ij)

to= start time of cut

tg end time of cut

Computation of thz parameters in Equation (5) are depicted in Figure [20].

Front View ( Arms II ) Side View (Arm fi 2)

Figure (201: CMM Machine Dynamics & Kinematics - Arms II Cutting Profile

Force y-direction) -

Favg Penetratjon (P) DepJh (d)

Arc

ti tj Tirne

th\ Figure [2 11: Specific Energy Parameter Computations Based on CMM Machine

Dynamics and Kinematics

Since the recording frequency was equal to 256 Hz, the period = 11 frequency =

0.0039sec. Looking at Figure [2 1 a] we can approxirnate the distance between time (i) and

time (i) to be equal to a straight line. Thus F, = (Fyi + Fyj)/ 2 &

The angular position of Ann I is aiigned with the center of the rotor head and is therefore

equal to the angular position of the rotor (0 1 =@R~,..) . On the other hand, the

angular position of Arm II2 is digned at 120 degrees away from the center of the rotor

head, thus ( 0 11 = 0 Rota + 120 degrees). See Figure [2 1 b].

Finally, the volume excavated duhg the time (ij) is computed as follows:

( See Figure [2 1 b]).

Tan = x/R where x is the Arc length. See Figure [21 b]

But for small angles, x= R

Where =g j -e j

R = ( R i + R j ) l 2

Therefore, Volume (ij) = x*d* p

Aaolication of S~ecific Enernv for Sensing of Rock Prooerties

6.1 Relationshi~ Between Sne- and Com~ressive Streneth o f Rock

Based on tests perfonned on rock samples fiom Herdecke and Creighton Mine sites, it

seems that rock failure occurs after the disc or indenter has penetrated by 1 to 2 mm.

[Repski, 19951. Typically the rock volume located right under the cutter fails in

compression in what is referred to as the plastic zone. Failure then propagates out of the

plastic zone into an elastic zone using pre-existing flaws of minimum critical size.

parton et al., 19741. The force generated causes a main crack to propagate towards the

force surface following the path of least resistance which causes the rock to peel off. As a

matter of fact, the propagation of the crack is also known to have a velocity that is mostly

dependent on rock homogeneity and type. [Hoek and Brown, 19801.

The Specific Energy calculated from the CMM test data in both Germany and Canada

depicts the strength of the rock being cut by the machine. It can therefore be compared to

rock strength properties such as compressive strength, tende strength etc. [Repski, 19951.

During a cut performed by the CMM machine, the rock is broken by chipping, and

therefore the breaking action is work against the compressive strength of the rock. As a

result, Specific Energy calculations used in the analysis are considered to be representative

of an approximate measure of the compressive strength of rock within an accuracy of

about 70 to 80 %, which in tum, is an accurate representation of the rock type.

In order to sîudy machine sensing of rock properties with regards to changes in Specific

Energy of rock, a set of data is selected for analysis fiom CMM test logs based on the

following criteria:

(i) The data used in this analysis is taken from the soft rock

Quarry Mine in Herdecke, Getmany and fiom the hard rock

Creighton Mine in Sudbury, Canada.

(ii) Three sequences fiom each mine site were taken for analysis and results

pertaining to some of these sequences were compared to face maps. See

Tables [SI & [6] .

(iii) Selected data does not include the stop and start tirne of the CMM

machine.

Quany Sequences

Sequence # Depth of Cut Penetration of 1 Arm UArm II Time for arrns tl to perfiorm a full cut

(Sec) "Assume a full cut

with no interruptions"

705

705 93072202

9307 1903

Table [ 5 ] : Quarry Sequences used for Specific Energy Analysis

125

100

6 1 6

21 118

Sequence # Depth of Cut (mm)

Penetration of Arrn YArm II

(mm)

-

Time for arrns II to perfom a full cut

(Sec) "Assume a f i l 1 cut

with no interruptions''

705

Table [6] : Creighton Sequences used for Specific Energy Analysis

6.2 Overview o f Specilic E n e m Investination and Machine Sensing o f Rock Pro~erties

In this chapter the Specific Energies of sandstone, shale, norite and granite are computed

based on the CMM machine dynamics and kinematics. Refer to equation (5 ) of

Chapter [SI. Furthenore, the computed Specific Energy is then compared to the

compressive strength of rock which in tum is an indication of the rock type being cut

under compression.

Once the rock type has been identified for each of the above rocks separately, the

rernaining task would be to identie different rock types fiom different rock geologic

conditions using Specific Energy cornputations. Moreover, results fiom analysis are then

compared to face maps for fùrther investigation on the application of Specific Energy and

its uses in sensing of rock properties.

6.3.1 Ouarrv Site, Herdecke, Cennanv

Sandstone

The Specific Energy of sandstone is computed based on the CMM operation in the Quarry

site in Herdecke, Germany. Using equation { 5 ) of chapter [ 5 ] the Specific Energy was

calculated for Cut # 9307 1903 for a total duration of 23 5 seconds.

Graph [1] shows that the Specific Energy ranged between 120 and 130 ~ j l r n ~ which is

approximately equal to the compressive strength of sandstone that ranged between 10 1

and I 5 1 MPa. [Repski, 19951.

Shale -

Applying Equation(5) of chapter[S], the Specific Energy is also calculated for shale by

using Cut # 93072202 for a duration of 705 seconds. Results pertaining to the Specific

Energy of the cut versus time show that the Specific Energy ranged between 34.5 and

40.2 ~ j l r n ) . See Graph[Z]. These results seem to be very close to the actual compressive

strength of shale which, according to [Repski, 19951, ranged between 25 and 5 5 iWa.

Gnph [l]: Sprcinc Enorgy venus Tima for Cut ''93071903w

Gnph [a: SpecRc Enorgy vwsus Tima for Cut "93072202

Sandstone & S hale

Having established that Specific Energy computations using the CMM machine dynarnics

are very close to the actual compressive strength of the rock, we are now able to use this

method to detect digerent types of rocks by cornparhg Specific Energy to compressive

strength. For this case we have chosen Cut # 93072004 which is represented by a face

map showing a combination of shale and sandstone. SeeFigure [22]. By making use of

Equation ( 5 ) of chapter [ 5 ] , Specific Energy is cornputed and plotted with respect to

time. See Graph[3]. Looking at Graph [3], we are able to identiS, the type of rock the

machine is currently cutting in, at any specific instant of time or at any position and

location of the h s " II" or " 1 " with respect to the center of the cut. See Graph [4].

For example, during the first 216 sec of Cut # 93072004, Graph [3] shows that the CMM

machine is cutting in sandstone where the Specific Energy ranged between 12 1 ~ j l r n ' and

129 ~j / rn) , afler which shale started to appear gradually. This gradua1 increase in shale is

clearly shown on Graph [3] where one could notice a fluctuation characterized by a drop

and rise in Specific Energy ranging tiom 128 ~ j / r n ~ to 40 ~ j l m ) and vice-versa.

Also, Graph [4] is another important plot where Specific Energy is shown with respect to

the radiai distance of Arms II or A m 1 relative to the center of the cut. From this graph,

we are able to detect the exact positions of the h s II or A m 1 and provide the Specific

Energy at that particular location. For example, a time period of 2 16 seconds on Graph [3]

would be equivalent to an Arm II position of 1700 mm on Graph [4]. Furthemore,

Graphs [3] and [4] both codrm that there is no shale, ody sandstone before the 1700 mm

radius distance from the center of the cut. Companng results from Graph's [3] and [4] to

Figure [22] we notice that Specific Energy values presented on these graphs are in

agreement with the face map depicted for this cut on Figure [22], which shows to be a

good indication of the correctness of the Specific Energy method being used in the

anaiysis.

A plot of Specific Energy versus A r m s II or An 1 angular position provides new

information related to the variation of Specific Energy dong a specified zone located at a

certain distance fiom the center of the cut. Once the distance from the zone to the center

of cut has been specified as illustrated earlier in Graph [4], we are then able to plot the

distribution of Specific Energy in that zone. See Graph [5]. For example, if we refer to

Cut # 93072004 and take a zone between 1700 and 1800 mm, we notice that the variation

of Specific Energy ranges between 122 and 130 ~ j l r n ) which shows a clear indication of

the presence of only sandstone in that zone. Furthemore, Cut # 93072004 was perfonned

at a penetration of 6mm which resu!ted in .4rms II rotating about 17 cycles in order to

excavate zone 1700 to 1800 mm from center of cut. Refer to Graph [ 5 ] . (1 7 cycles are

equivalent to 6 120 degrees).

- Joint

- Singie Joint F i i r e

C a - . . . .

Center of Cut -. ... .

---------- Y The mdial distance for which Shale starts to appear at 1700 mm away from the center of cut

Figure [22]: Face Map for Cut # 93072004 (Sandstone and Shale)

Onph m: Sp.ciRc Emrgy vanus Tima for Cut "93072004"

Gnph 141: Spacific Enargy venu8 A m II Radial Position for Cut "93072004"

Graph [û): Spoc lc Energy vanw Amr II Anguiai Position for Cut 'a93072001" Zona (1700mm to 1800mm)

Gnph [al: Spacific EMIQY vamua Airna II Anguki Position for Cut "9307200Jn Zona (2S00 mm to 2600 mm)

Comparing what was found here to what we found in the previous paragraph, it is clear

that both plots confirm that there is only sandstone present in zone " 1700mrn to

1 800rnm".

On the other hand, if we take a different zone location such as "2500 mm to 2600 mm"

and use the same Cut # 93072004 as before, we find out that there is a variation in

Specific Energy which is due to the presence of both sandstone and shde in that region.

Using Graph [4] to specifj the time for the zone location mentioned eulier and utilizing it

to plot Specific Energy versus Arms II angular position distribution, we are clearly able to

identiS, the different locations of sandstone and shde dong the

17 cycles perfomied by Arms Il to cut the zone. See Graph [6]. From this graph, we

observe that the required cycles by A m i s 11 to cut zone "2500 mm to 2600 m m al1

confirm the following:

(a) O to 160 Degrees: Only sandstone is present

(b) 160 to 270 Degrees: Only shale is present

(c) 270 to 360 Degrees: Only sandstone is present

Comparîng Graph [6] to Figure [22] we notice that the Face Map of cut # 93072004

contirms the above distribution of sandstone and shale in what was found by Graph [6]

using the Specific Energy method.

6.3.2 Creiatoa Site, Sudbury, Canada

Granite

The Specific Energy of granite is computed based on the CMM operation in the Creighton

site in Sudbuiy, Canada. Using equation (5) of chapter [SI the Specific Energy was

caiculated for Cut # 94 12070 1 for a total duration of 705 seconds.

Graph[7] shows that the Specific Energy ranged between 227 and 240 ~ j / r n ~ . These

results are closely comparable to the compressive strength of granite which, according to

[Kazakidis, 19941 ranged between 226 and 268 MPa.

Norite

Applying Equation(5) of chapter[5], the Specific Energy was also calculated For norite by

using Cut # 94 120702 for a duration of 705 seconds. Results pertaining to the Specific

Energy of the cut versus time show that the Specific Energy ranged between 203 and 2 18

~ j l r n ~ . See Graph [SI. These results seem to be close to the actual compressive strength

of nonte which, according to [Kazakidis, 19941, ranged between 182 and 22 1 MPa.

Gmph m: SpocMe E m r ~ y waua Tinn for Cut W34120702n

Granite & Norite

For the case of cornparhg Specific Energy computations to compressive strength of rock,

Cut # 94120801 is chosen for the analysis. This Cut is represented by a face map showing

a combination of granite and norite for the CMM test location in the Creighton mine site.

See Figure [23]. Using Equation ( 5 ) of chapter [SI, the Specific Energy is computed and

plotted with respect to time. See Graph [9].

In Graph [9], it is clear that dunng the fïrst 425 sec of Cut # 94 120801, the CMM

machine is cutting in Norite where the Specific Energy ranged between 203 ~ j / d and

2 18 ~jlrn' , aAer which granite started to show successively. This caused higher Specific

Energy values of about 25 ~ j / r n ~ due to the fact that granite is a stronger rock than norite,

and therefore it is expected to have a higher Specific Energy per unit volume.

In order to calculate how far from the center of the cut granite will start to appear,

Specific Energy versus h s il radiai distance is plotted based on a tirne span of 425

seconds. See Graph [l O]. This graph shows that the mixed zone between granite and

norite starts between 2 100 mm to 2200 mm away from the center of the cut. Comparing

this result to Figure [23], we find that the Face Map of Cut # 94 12080 1 is in agreement

with Graph [IO] and that there is no granite before the 2100 mm to 2200 mm region.

Having located the start of the zone for which we have a mixture of granite and notite, the

next step would be to identify the different occurrexes of granite and norite in that zone.

Results fiom Giaph [ I l ] are presented as follows:

(a) O to 160 Degrees: Only norite

(b) 160 to 205 Degrees: Oniy granite

(c) 205 to 360 Degrees: Only norite

By looking at Figure [23], the face map of Cut # 94 12080 1 shows that granite exists in

zone 2100 mm to 2200 mm in only an Arm II angular position located between 160 and

205 degrees. This totally agrees with results obtained fiom Specific Energy computations

where the above distribution of norite and granite presented in Graph [ l I l is confirmed.

Center of Cut

Norite

Shale -

Singk Joint

Water \ Joint

I Figure [23]: Face Map for Cut # 941 20801 (Norite and Granite)

Gnph m: Sp8cific Energy venu8 tim for Cut "94120801w

Gmph [1 O]: Specfic Energy venus Anns II Radial Position for Cut "941 20801n

Grrph 11 11: Spocitic Enargy venus Ami8 II Angubr Position for Cut "94120801" Zona (21 00 mm to 2200 mm)

6.4 Conclusion

The data acquired for CMM cutting in sofi and hard rock was analyzed in this chapter.

The relationship between the compressive strength and Specific Energy was discussed.

This reveals that there easts approximately a one to one ratio between Specific Energy

and unconfined compressive strength.

It can therefore be concluded that Specific Energy is an important measure in cutting rock

and can be employed for discrirninating different types of rocks. Thus, the Specific Energy

of sandstone, shale, nonte and granite is computed for each of these rocks separately and

results have shown to be very close to actual rneasurements of compressive strengths in

both Herdecke "Soft Rock" and Creighton "Hard Rock.

A detailed analysis was also conducted to separate sandstone fiom shale and norite fiom

granite. It was found that there exists a range for Specific Energy that is unique for each

different type of rock during a cutting sequence performed by the CMM machine, thus

making it possible for the machine to detect different types of rocks.

Conclusions and Future Work

7.1 Conclusions

This study has shown that here existed strong links between the face geology

(or mechanical properties of the rock mass) and the dynamic behavior, the Wear

and maintenance aspects of the CMM machine. This was confirmed by observing

lower forces when cutting in soft rock as opposed to cutring in hard rock. In

addition, changing controller gains as well as machine input parameters such as

head RPM, penetration and depth of cut have shown to greatly affect machine

kinematics and dynamics.

CMM signal monitoring and data aquisition was achieved by the use of sensors

that recorded signals to a data recorder. Data was then transferred to the computer

through a data acquisition system where filtering at the software level was applied

to reduce noise in the recorded data. Specific Energy was then used for the actual

data analysis.

On-line computations of Specific Energy based on the CMM machine dynarnics

pnnciple have shown that Specific Energy is representative of an approximate

measure of the compressive strength of rock, and therefore is representative of

the type of rock being cut. Furthemiore, the availability of face maps from certain

cuts of CMM tests has confirmed that there exists a range for Specific Energy that

is unique for each type of rock during a cutting process. Moreover, it is also

possible to prove that by using Specific Energy techniques, the CMM could

separate sandstone from shale and norite from granite while cutting in a mining

environment.

Results from this study would serve to provide an understanding of the process

behind monitoring and sensing of rock properties. It also contnbutes to the

knowledge of machine variables with respect to rockmass properties which

are essential for irnproving production rates and enhancing the cutting

pedormance of the CMM machine. Finally, it should be clear that this study

only reveals a glimpse of the capabilities of Specific Energy and takes one of

many steps needed for its full development to a productive tool for sensing of rock

properties.

7.2 SyMcstions For Soccifie Future Work:

O The availability of a suitable excavation machine such as the CMM is not alone

sufficient to get a tunnel through. Therefore, fiiture work should be focused on

improving many of the machine supponing services. This should primanly include

more efficient provisions to transport everything in the way of matenals or

personnel in and out of the tunnel while the work is being performed.

O Pattern recognition could be used in the recognition of sensory input as well as

for information already in store. It has proven to be usefùl in many applications

in mining and especially in the automatic recognition of different rocks and

geologic conditions, where monitoring of machine variables is based on

extracting correlations between machine parameters and rockmass properties in

order to account for the effects of changes in the geology. In the case of the

CMM data analysis, pattern recognition techniques could have been used to

divide the data into separate different classes where sandstone and shale would

have been categorized under sofi rock and granite and norite under hard rock.

Finally, future work should also be focused on looking into rock structure, faults

as well as strength which would be more representative of various locations of

different rock geologic conditions and edges in an excavation process. Therefore,

enhancing future remote control sensing or full automation of any type of

mechanical excavators.

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% PROGRAM NAME: % AUTHOR:

APPENDIX A

OPEN, FILTER AND SAVE N M ABOUFADEL

% THE PURPOSE OF THIS PROGRAM IS TO OPEN A 16-SIGNAL ASCII FILE, FLTER AND % SAVE THE: RESULT M ANOTHER ASCII FILE.

Q/o F M ) THE ASCII FILE AND OPEN 1T

fit-name = input (' PImsc entcr file namc : ' , ' s' ) ; fidopen = fopen (fi'namc, 9');

if fid-open == - 1 fprintf'('in\n Sony, You cntcrcd a wrong filc name. Rc-cntcr thc filc plcascùh'): rcturn else fprintf('\n\n File is successfully acccsscd');

cnd

naf = fscanf (fid-open, '%g,%g,%g,%g,%g,%g,%g,%g,%g.n/g,%g,%g, %g,%g,%g,%g8);

% This is to idcntify file size and dividc main matris of data int O 16 columns.

data-sixe = size (04; matri-sizc = data-sizc (: , 1); num-rows = matrix-size / 16; end-time = num-rows 1256;

% To assign each coiumn a variable name

time = 0:0.00390625:end~tirnc-û.00390625; IRad-A = naf (1 : 16:matn;u_size- 15); ii2Rad A = naf (2: 16:matri-size - 14); ~ o d - f = naf (3 : 16: matrix-size - 13); Piso = naf (4: 16: rnatrix-size -12); II2Rod-P = naf (5: 16: matrix-size -1 1); IIîPis-P = naf (6: 16: rnatrix-size - 10); IFx = naf (7: 16: rnatri.u_size - 9); FY = naf (8: 16: matrix-size - 8); JFz = naf (9: 16: rnatri.x-size - 7); IIîFx = naf(l0: 16: matri~size - 6); f I2Fy = naf (1 1: 16: maüix-size - 5); n2Fz = naf ( 12: 16: matrix-size - 4); R . L e f i = naf ( 13 : 16: matriqize -3);

RP-Right = naf ( 14 : 16: matrix-size -2); Rot-RPM = naf ( 15: 16: matrix-size - 1); Rot-Aps = naf (16: 16: matris-size ); fil-Iow = input ('Please enter thc cutoff frequcncy: '); filord = input (' PIease enter the filtcr ordcr: '); simple-rate = input ('Please enter the samplc rate'); nom-cutoff = fil-low / (sample-ratd2);

= filtfilt (xy.x,yyy, IRad-A); = filrfilt (x.~,yyy, II2Rad-A); = filtfilt (xux,yyy, IRod-P); = filtfilt (xy.~.yyy, Pis-P); = fildllt (sxx,yyy, II2Rod-P); = filtfilt (xx.,yyy, II2Pis-P); = filtfilt (xxx,yyy, Ex); = filtfilt (xsx~yy, IFy); = fildilt (X~~,yyy, IF@; = fittfilt (xxx,yyy, I12Fx): = filtfili (x~u,yyy, IISFy); = filtfilt (xy.x,yyy, II2Fz); = filtfilt (xxcu,yyy, RP-LeR); = filciif t (xs..,yyy, RP-Righi); = filtfilt (~.x,yyy, Rot-RPM); = filtfilt (x. ,yyy, Rot-Apos);

filtcr = [time;FIRad-A';F112WA'; F1Rod-P'; FIPis-P'; FI12Rod-P'; FII2Pis-P'; Fffx': FFy': FEZ'; FII2Fx'; FII2Fy'; FII2Fz'; FRP-Lefi'; FRP-Right'; FRot-RPM': FRot-Apos]: fil-save = input ('Please enter the file name for the filtercd data using the correct path: Y s ' ) :

fid-write = fopcn (fil-savc, 'w'); if fid-writc ==-1

fprind('\nh Sorq p u have entercd an invalid ID file namc; \nui'); clse fpmtf ('\n\n The file has been successfully opened io be savcd \n\n');

end fprintf (fid_\Mite,?4&.2f, %6.2f, %6.2f, %.2f, %6.2f. %.2f. Yd.2f. %.2f, %6.2f. Y&.2f, %6.2f. Yi .2f . %6.2f, %.2f, %6.2f, %6.2f\n7. fillcr); fclose(fid-wri te); fprintf ('Mn The file saving operation is completed\n\n'); plot (time, IRad-A, 'r', time, FiRad-A, 'g'); grid; zoom; % End of Program