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Online Monitoring and Intelligent Diagnosis System Based on Hybrid Wireless

Network for Large Complicated Equipment

ZHANG Jinyu, CAI Wei, HUANG Xianxiang, XIE JianXian Research Institute of High-tech

Xian, Shaanxi 710025, ChinaE-mail: mejyzhng@hotmail.com

Abstract Aimed at the characteristics of huge systems,

complicated distributed structures and difficult fault diagnosis

of large equipments, an extensible system of distributed online

monitoring and multi-level intelligent fault diagnosis based on

hybrid wireless network techniques was presented and

designed. The entire system includes four hierarchys

subsystems. The first subsystem is monitoring sensors and

Zigbee network. It is responsible to gain various data of

equipments in a non-intrusive mode. The second one is

monitoring and transmission network. It consists of embedded

system ARM920T and relative multiple single-chips, and isresponsible to receive and integrate all information of the

previous subsystem. The third one is online and offline

monitoring subsystem based on wireless protocol 802.11b. The

final one is multi-level intelligent diagnosis and management

system. The results of practical operation show that, because of

the using of hybrid wireless network, embedded system and

multilevel intelligent diagnosis, the system may be flexibly

deployed, have powerful capability of monitoring, diagnosis

and management, and can implement expeditious and accurate

fault positioning and diagnosis for large equipment system.

Keywords-Technology of Instrument and Meter, Online

Monitoring, Hybrid Wireless Network, Embedded System,

Intelligent Fault Diagnosis

I. INTRODUCTIONLarge-scale complicated mechanical and electrical

equipment, because of the characteristics such as its hugestructure, complicated function of the large number of

professionals involved in a wide range, complexity of theoperation control, poor working environment, the use of highrequirement, huge failure loss and so on, has been attachedgreat importance in the engineering area. Their on-linemonitoring and fault diagnosis have made more cost-effective benefit [1]. Its difficulties are the on-linemonitoring system design, integrated research anddevelopment of intelligent diagnosis [2]. In recent years,

with the development of wireless networks, sensors and faultdiagnosis technology, many scholars have carried out an in-depth study based on the proposed wireless network. Themonitoring and diagnosis system also made clear effect [1-3].However, it is not difficult to find that in these reports thesework are the basic work of a single subsystem, either themain electronic control system or the major mechanicalsystems for the service, not a comprehensive and flexiblemonitoring and diagnosis for the entire large-scalecomplicated mechanical and electrical equipment all aspectsof the system. In particular it is very difficult to meet the

needs of operation on site and replacement of modern large-scale complicated equipment system. Therefore, in this paper,we will work on the exploration of structure, compositionand key technologies of new distributed wireless on-linemonitoring and intelligent diagnosis system.

II. CHARACTERISTICS OFALARGEANDCOMPLICATEDEQUIPMENT

A large-scale complicated system is a large collection ofmechanical and electrical equipment such as electronic,

hydraulic, optical, precision machinery, computers, and

automatic control technology in one. Because the mainchain of control uses its closed-loop control system, the

equipment uses multiple industrial control computers and

complicated relay logic control circuits. The system is large,

and needs multi-step operation. The degree of automation is

very high. The complexity of the signal transmission,complicated conversion nodes, together with the equipment

often in a state of traffic, poor working environment and

changes in temperature and humidity, and thus theequipment is prone to take place a variety of equipment

failure. In site to achieve rapid fault detection and diagnosis,

to ensure its health is in good condition, the on-line real-

time monitoring and comprehensive intelligent diagnosis tothe system must be implemented.

The equipment, in the structure, includes a power supply

system, a hydraulic system, an electronic control system and

a mechanical system. The main power supply system

consists of a diesel generator units and its distributionsystem, which is responsible for the system providing a

wide range of AC and DC power supply. The electroniccontrol system is the control center of the main terminal and

program-controlled device. It controls the scattered devices

of the measurement and implementation. The hydraulic

system is mainly composed of a gear pump, fuel tanks andall kinds of electromagnetic valves and so on, which is the

main executor. The mechanical system is the foundation ofthe entire system and transport platform. These systems are

independent each other and close contact with the structure.

They possess a large number of functions, high degree ofautomation as a whole.

The information which needs to be monitored in systemsincludes the digital codes in the serial port communication,

switch signals, analog signals and so on, which contains

three categories of information of several hundreds of points.

Here the serial port information includes control orders, the

2009 Ninth International Conference on Hybrid Intelligent Systems

978-0-7695-3745-0/09 $25.00 2009 IEEE

DOI 10.1109/HIS.2009.188

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condition information of sensor and actuator between thecomputer terminal and control computer. The information is

such large amounts of data, changes in the fast. Theswitching information is mainly all kinds of condition

information from additional sensors of a variety of card and

implement device. This information indicates if the relevant

parts and components are working properly. The objectnumber of this kind of information is big one, but smaller

capacity. The analog information mainly comes frommechanical and hydraulic system components by sensors,

which is such rich information, high sampling requests, has

large amounts of data. In addition, the system still exist alarge number of knowledge and text information which can

be used to describe the fact. In terms of a detailed analysis

of information sources and characteristics, we know thenature of the information, content, capacity, time and space

are not the same. They need not only being able to do an in-

depth exploration of large flow of digital and high switching

capacity information of the various boards within the system,

but also monitoring the various switches information and

condition information of the distribution of a larger spacescope. To achieve more efficient and accurate diagnosis of

this type of large-scale complicated systems and equipment,

the specific work steps and step-by-step process automationmust be equipped with information collection and synthesis

of the rational and appropriate use of a variety of knowledgeand rules to cross the evidence to determine the current

equipment specific work step and the state of equipment.

III. SOLUTIONOFTECHNOLOGYAccording to the structural characteristics of the

equipment and working mechanism, we have carefully

analyzed the characteristics of the system signal

distribution, calculated the flow of information betweensubsystem and subsystem, taken into account the time-delay

request of various types of information on the test, adopted ahybrid testing network combined with Zigbee based low-

speed networks and IEEE 802.11b high-speed network. As

the complexity of large equipment, many of the components

(such as electro- magnetic valve) scattered by space andhave less information, but the information to their

equipment condition is very critical to determine. So a large

number of few information points are formed. There arealso some important scattered analog information points. By

means of the small size of Zigbee-node set on these parts

and the low-speed low-power Zigbee network, themonitoring data are sent to control node, which is installed

in the information-intensive electronic control system in the

vicinity. A large number of the real-time measurementinformation is synchronized and encoded, then upload the

data to the host system to monitor by the high-speedIEEE802.11b wireless network. As the flow of information

and treatment asymmetric requirements, a multiple single-

chip system cascade solution is requisite. By means of thematch band width and ad hoc network protocol design

technology, the different types of network are combined into

a more convenient and better information flow of mixed

WWireless

Node B

BusNode

WBHybrid

Node

Bus Data Wireless Data

B

W

W

WB

W

B

W

Equipment

Memory

Data-bus

Zigbee

Network

Control

Node

USB Bus

Monitoring &

Diagnosis

Monitoring &DiagnosisIEEE 802.11

Channel

Figure.1 Hybrid network for data acquisition of large system

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monitoring network. The system mainly includes the

ZigBee protocol wireless-node, field-testing bus node,

hybrid node, control node, 802.11b communicationschannel transmission, and monitoring and diagnosis

computer. The system block diagram is in Figure 1.

IV. HYBRIDNETWORKMONITORINGSYSTEMA. ZigBee Wireless Monitoring Network Design

ZigBee (IEEE802.15.4) is a rising short-range, low-

power, low-speed, low-cost wireless networkingtechnology. Thousands of such tiny sensor nodes can

cooperate and communicate at relay mode in an efficient

and safe way. It mainly applies to the network-building of

local scene in the peer-to-peer networks. The wireless

network monitoring in figure 1 is one containing a control

node on equipment, a series of nodes installed in theterminal equipment, some bus nodes and some hybrid

nodes. The control node communicates with the terminal

wireless nodes and hybrid nodes through the ZigBee

protocol. The control node is configured to a coordinator.The hybrid node is full function device, but terminal nodes

generally are some tidy function devices. Analog signalwireless terminal nodes are mainly responsible for the data

collection and transmission of large amounts of data of the

test point of scattered location. For example, the hydraulic

electromagnetic valve, motor, as well as oil pump, etc.,

which are the key components in equipment. In the past fewgo on-line monitoring, it has not been a good way to

monitor. In order to monitor the movements of valve core

and the changes of the magnetic field, we installed an

accelerometer and a magnetic sensor on the JN5121 modulecircuit board, and the circuit board fixed on the valve in the

middle by a permanent magnet, shown in Figure 2. JN5121module will sample and send the analog signal of solenoid

valve sensor through ZigBee node. The corresponding

JN5121 module in control node will receive the data. The

single-chip then read them through the serial port, as shown

in Figure 3.

Fig.2, Electromagnetic valve sensor layout

Digital wireless node is mainly responsible for the data

acquisition and transmission of spread few information

points, because of its large number of simultaneous requests,

also belonging to the necessary information of the electroniccontrol system to monitor, so the nodes directly connect to

monitoring single-chip of electronic control system through

the hybrid node. And a large number of digital

communications and control information of the electronic

control system are directly acquired and adjusted by the

monitoring single-chip of electronic control system throughbus-node in a non-intervention way, then synchronized and

integrated with the former, and put in the final control node.

In order to achieve the non-involvement in the monitoring

of the digital information we have adopted a parallel way to

bring out the signal. Generally, a pair of plugs and sockets

are joined in the cable between the plug and socket adaptersto detect signals from the joints in the lead. In order not toaffect the actual signal parameters, the system has adopted a

high-input impedance probe. This work will be able to

process all types of signals effectively and can monitor real-

time control system running, and would not affect the

normal operation of the entire equipment, and get betterseparation of detection equipment and instrument, lay a

solid foundation of on-line monitoring for the realization.

Fig. 3 solenoid valve sensor data acquisition and receiving network

B. Design of Multiple Single-chip Mixed-cascade WirelessNetwork

802.11b networks is a similar protocol to Zigbeedeveloped by IEEE for wireless communication standards,which used a transmission mode of high-rate direct sequencespread spectrum (HR / DSSS), 2.4G in the ISM band, and11Mbps, 5.5Mbps, 2Mbps or 1Mbps in the light ofenvironmental changes and several hundred meters awaywith the wireless transmission of high-level agreement. So itis more suitable for wireless computer local area network. Bya wireless bridge connecting relay, you can cover a widerarea and more equipment and form a complete on-sitemonitoring network. By means of WEB technology and fibernetwork operational command, the remote monitoring andremote diagnostics services can be achieved. As a result, itworks as the protocol of communications network of theintelligent diagnosis system to achieve a greater rangewireless connection. However, in order to achieve a perfectonline monitoring and diagnosis system, these two wirelessnetworks need to be seamlessly connected to form a high-speed data security chain. Therefore, we first need to cascadethe testing single-chip of electronic control system and thesingle-chip of control node together, then integrate them andthe ARM9 embedded system with 802.11b through the serial

port, where ARM will be responsible for data exchange,integration and forward, form a mixed set of wireless datacollection, transmission and monitoring network. Intelligentmonitoring and diagnosis system commonly used notebook

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computers to collect data of the machine through on-sitemonitoring and 802.11b networks. The upper monitoring andlower computer form a digital master-slave mode. In termsof actual needs of one or more large-scale equipment, anumber of uppers may be installed and are responsible for alltypes of real-time sensor data collection, standardize

processing and data upload. The notebook computer is

generally put at the scene edge or away from the scene towork as a server of real time on-site monitoring, and carryout intelligent diagnosis. As a backup, host PC can also use aUSB interface to connect to the on-site network andcomplete the work of the monitoring and diagnosis.

V. DESIGNOFON-LINEMONITORINGSYSTEMThe primary task of on-line monitoring system is

quickly to get the data from on-site monitoring network of

hybrid wireless, then to determine the work state of the

equipment, and to judge equipment failure.

A. Communication Software DesignCommunication software first needs to create a wirelesscommunications server environment and a wireless access

point AP in the notebook computer, and set up the necessary

parameters, then establish a wireless client in the ARM andconfigure relative parameters, finally, design two sets of

special interactive communication software. The first set

client program is achieved by using DELPHI7 and Indy9

control in the ARM under the Linux environment. Thesecond set server software is also programmed by usingDelphi7 and Indy9 control program under the Windows

environment. The monitor server listens to the designated

port and IP network at any time. Once a request occurs, the

server immediately verifies its legitimacy and security, then

sends back a shook hands information. After the client

receive a permission server send, the client immediatelysends the norms data that client have acquired. The server

uses the same definition of norms to read data and transmit

to the on-line monitoring system. In order to improve

network speed of real-time monitoring, we specially

designed a multi-thread process, and created an independentspace in the computer memory to serve data transmission

between two independent processes. At the same time, we

designed a process of inter-messaging mechanisms, and

timely informed relevant process to receive new monitoring

data.

B. Design of On-line Monitoring SystemThe main functions of on-line monitoring system is to

actualize the on-line real-time monitoring, program control,

synchronous simulation display, timely diagnosis as well as

the preservation of data of the entire work state of the

equipment. The on-line monitoring module is responsible

for monitoring the process of communication to send data.If finding new data, it reads data at once, and then checks

the integrity of data. If the checking fails, the diagnosis

window will show "checking fails" information and return.If passed, go to the next step.

The program control module is responsible for achieving

the control of whole modules, data flow, information flow,

as well as error-oriented processing and so on. The entiremonitoring program adopts multi-threaded parallel work

mode. The advantages of parallel mode are suitable to

efficient processing of uncertain data flow. The basic

control processes include data validation, data interpret-

tation, synchronous simulation display, preservation of themonitoring data, the state timing, the state cross reference,fault diagnosis, issuing diagnosis results and so on.

There are four diagnosis rules. The rule 1: the condition

has been determined by the front-end equipment, such as a

communication failure, a failure of IO port, directly shows

it. The second rule is to judge the condition based on the

comparison of the real measured state of program and orderwords of the communication between the man-control

computer and program-control computer. The third rule is

time control. If the interval of issuing appropriate action is

more than a standard working hours of the process, or after

the man-control sends an order, any information of the

relevant movement cant be gotten by the right time, wemay judge it belongs to the parts failure or slow under this

rule. The fourth rule is to call a special tool of the signal

processing for analysis, feature extraction, monitoring and

diagnosis to the analog data.

Aiming to simulation display module design, we used aset of industrial control software of virtual instrument to

design exactly a set of the same man-machine interface with

the man-control terminal menu, which can in time display

the same information of man-control terminal according to

the work condition of the equipment, can also be manualcontrol to facilitate the monitoring personnel to graspflexibly the state of equipment.

Because the diagnostic modules works in a parallelmode with a lot of flexibility, it may easily realize the

condition monitoring and fault diagnosis of four work mode

such as the positive step-by-step process, the negative step-

by-step process, the positive simulation process and thenegative simulation process of the equipment.

VI. DESIGNOFINTELLIGENTDIAGNOSISSYSTEM

The service object of the on-line monitoring and

diagnosis system is mostly the electronic control system andpart of the hydraulic system of the equipment. The objects

of the monitoring and diagnosis are always limited and with

a limited extensiveness. In fact, large complicatedequipment involves in many questions in the work. In order

to achieve a high level diagnosis, an intelligent diagnosis

system must be introduced. That is why we speciallydesigned three separate intelligent diagnosis system basedon the monitoring and diagnosis.

A. CLIPS-based Expert Diagnosis SystemCLIPS is a genuine rule-based expert system tools in

Windows environment. The main design objectives and

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