PRECISION ENGINEERING

AND

INSTRUMENTATION LABORATORY

RESEARCH ACTIVITIES

2006 – 2007

DEPARTMENT OF MECHANICAL ENGINEERING

INDIAN INSTITUTE OF TECHNOLOGY MADRAS

CHENNAI – 600036

1

PRECISION ENGINEERING & INSTRUMENTATION LABORATORY

The Instrumentation Laboratory in the Department of Mechanical Engineering, established four decades ago, received substantial inputs from Germany. The laboratory was renamed as Fine Technics in line with the German Institutes of Feinwerktechnik to include areas such as Precision Engineering, Control & Instrumentation, Fluid Power, Measurements & Technical Optics. Subsequently the Precision Engineering & Instrumentation Laboratory was formed about two decades ago as this field received a thrust in the country and the need was felt for R&D and academic programs. This is a unique laboratory in the country dealing with multi-disciplinary scientific and engineering skills and techniques. In addition to teaching for undergraduates, the laboratory offers a postgraduate program in Master of Technology in Mechanical Engineering with specialization in Precision Engineering. Incidentally this laboratory is the first to introduce a course on Mechatronics in the country more than a decade ago. The facilities available in the laboratory include Hydraulic test stand, Roundness & Roughness measuring instruments, Dynamic Balancing machine, SCARA Robots with CCD Camera, Test rigs for - Active Noise Control in ducts, Hydrostatic Transmission, Sintered Bearings and Active Suspension. Several research projects have been successfully completed integrating Computerized Control, Fluid Power Technology, Sensors & Instrumentation: such as Adaptive Control, Modeling of Gyros, Magnetic Suspension, Hydraulic Actuators, Active Suspension, Hydraulic Systems & critical Components for Defence and Aerospace, System Simulation and new Control Strategies. The R&D projects completed by students include µP based Microbalance, Programmable Process Controller, Intelligent Network Controller, Self Guided Vehicle, Magneto-rheological Fluid Damper, DSP based systems: Cardiac Monitor & Power Analyzer, Ultrasonic Flow Meter using Process Tomography technique, High Temperature Piezo-resistive Micro Pressure Sensor, Extrude Honing, Parallel Manipulators, Microactuator applications: SMA, Magnetostrictive & Piezoelectric. In addition, several Software for Signal Analysis, Modeling, Control, Neural Network, Condition Monitoring etc. have been implemented. Several of these activities incorporate effective integration of real time software, electronic & mechanical elements in embedded systems - the domain of Mechatronics. This laboratory organized the First National Conference and the SERC School on Precision Engineering. The laboratory has initiated R & D work in several new areas of exceptional strength within its core competence such as High Precision Manufacturing, Precision Metrology, MEMS, Microsensors & Microactuators, Smart Structures, Active Suspension, Microplatforms, Interacting Robots, Serial & Parallel Manipulators, and Hydraulic Controls etc. The Precision Engineering & Instrumentation Laboratory can effectively collaborate with R & D organizations and Industries towards integration of multi-disciplinary activities for system based engineering design.

2

PRECISION ENGINEERING & INSTRUMENTATION LAB.

CONTROL

MECHATRONICS PRECISIONMANUFACTURING

ROBOTICS HYDRAULICS

ROBOTICS Parallel Manipulators Under Water ManipulatorsMobile & Networked Robots Medical Robotics Tactile Sensors

CONTROL

• Active Noise Control• Active Suspensions• Embedded Controllers• MR Fluid Dampers

PRECISION MANUFACTURING

Micro-Joining Micro-Fabrication Abrasive Flow Machining Ablative Machining

MECHATRONICSShape Memory AlloyMagnetostrictive ActuatorsMicro-Pressure SensorMagnetics

HYDRAULICS High Pressure Hydraulics Micro Hydraulics Servo Hydraulics Jet Pipe Servo Valve

3

CONTENT

1. Contour generation and active vibration isolation using a 3-3 Stewart Platform Satheesh Kumar.G, T. Nagarajan, Y.G. Srinivasa (pg.4)

2. Hardware in Loop Design, Fabrication and Testing of Real-Time Closed-Loop Micropump P. Verma, Y.G. Srinivasa, Nagarajan T. (pg.6)

3. Design and Implementation of Distributed Networked Robotic System based on

Network Controller RM. Kuppan Chetty, M. Singaperumal, T. Nagarajan (pg.8)

4. Modeling and Control of Micro EDM Process with Piezoactuated Tool Feed Mechanism Muralidhara, N.J. Vasa, M. Singaperumal (pg.10)

5. Modelling and Control of Underwater Manipulator of intervention tasks T. Periasamy, T. Asokan, M. Singaperumal (pg.12)

6. Laser Annealing of Silicon Wafers by Pulsed Nd:YAG laser I.A. Palani, Nilesh J. Vasa, M. Singaperumal (pg.14)

7. Dynamic Modeling and Simulation of two shaft gas Turbine Aero Engine for the Development of Robust Control Strategy V. Rajasekar, Y.G. Srinivasa, Nilesh J. Vasa (pg.16) 8. Development of an optical sensor for measurement of two orthogonal components of electric field using second harmonic generation with electro-optic crystal Anshul Garg, Nilesh J. Vasa, M. Singaperumal, S. Sarathi (pg.18)

9. Detailed Analysis of Process Parameters in Micro Electro Discharge Machining. Saswata Majumder, Nilesh J. Vasa, M. Singaperumal (pg.20)

10. Previous research works (pg.22)

4

Contour Generation and Active Vibration Isolation using a 3-3 Stewart Platform

Satheesh Kumar.G (PhD scholar), T.Nagarajan, Y.G.Srinivasa

1. Introduction: From the time the potential of Stewart platform as a six degree-of-freedom mechanism was identified by Stewart in flight simulation researchers have tried the PKMs in various other fields. The most important fields where it has solved the time immemorial problems pertinent to it are Machine tool applications and Vibration isolation applications.

The systems that have been developed and available in the market for various applications have been problem specific and flexibility is not allowed when we want to use the same platform for another application. While facing the demand for modularity much of research is needed to be done and this research work tries to do the initial investigations with the above mentioned applications as the primary objective. 2. Variation in Principles:

3. Objectives: The objectives of the research work are as follows:

• To develop an algorithm for stiffness analysis of Stewart platform for contour generation

• To develop theoretical models for vibration isolation systems with control algorithms

• To develop a Stewart platform test rig for the above applications and perform error analysis

• Design and implement real time control algorithms and perform an extensive study on the characteristics which makes it viable to both the applications

4. Modeling and Experimentation: A theoretical model for stiffness has been developed and simulated for machinetool application with different contours. PD control law has been used to simulate the model for Vibration isolation application. An experimental test rig has been developed for the purpose of testing the results obtained with simulation. The simulated results are to be validated. The accompanying table provides the specifications of the developed Stewart platform.

Vibration Isolation

x z

y

Supporting Floor

Contour Generation

Vibrating Floor

5

5. Summary: • The trajectory with maximum stiffness for complex contours has been obtained with

the above model • 3-3 configuration provides better stiffness performance • Spiral trajectory has lesser workspace demands on the platform • Serves as a standard offline method for finding the set of positions and orientations of

the moving platform • PD control law used for AVI provides a 20dB attenuation • An experimental test rig has been developed for both the applications integrating

sensors

6. References: [1] Bhaskar Dasgupta, T.S Mruthyunjaya (2000), The Stewart platform manipulator: A review, Mechanism and Machine Theory, 35, 15-40. [2] B. S. El-Khasawneh, P.M. Ferreira (1999), Computation of stiffness and stiffness bounds for parallel link manipulators, International Journal of Machine Tools and Manufacturing, 39, 321–342. [3] Tsai, L.W., Robotic Analysis: The Mechanics of Serial and Parallel Manipulators, John-Wiley & Sons, New York, 1999. 7. Publications: International Conference:

• Satheesh G. Kumar, Srinivasa Y. G and Nagarajan T, “Active Vibration Isolation Using Multi-Axis Robotic Platform”, ICSV10, July 7-10, Stockholm, Sweden, 911-918

• Satheesh G. Kumar, Bikshapathi M, Nagarajan T and Srinivasa Y. G, “Stiffness Analysis and Kinematic Modeling of Stewart Platform for Machining Applications”, ASPE, 19th Annual Meeting, October 24-29, 2004, Orlando, Florida, 169-172

• Satheesh G. Kumar, Nagarajan T and Srinivasa Y. G, “Stiffness Analysis for Complex Trajectories”, ACIAR 2005, The 4th Asian Conference on Industrial Automation and Robotics, May 11-13, 2005, Bangkok, Thailand

International Journal: • Satheesh G. Kumar, Nagarajan T and Srinivasa Y. G, “Variation of Stiffness in a Stewart

platform for Different Contours”, Mechanisms and Machine Theory, under review.

Actuators Micro-stepping Joints Spherical joints Configuration 3-3 configuration Natural frequency 166Hz Payload capacity 10 kg

Dimensions Top platform diameter 140mm Top platform thickness 10mm Bottom platform diameter 390mm Bottom platform thickness 10mm Height of platform (Nominal) 293mm

6

Hardware in Loop Design, Fabrication and Testing of Real-time Closed-Loop Micropump

Verma P., Srinivasa Y.G., Nagarajan T.

1. Introduction

During the past decade microfluidics the science of designing and manufacturing micro-

scale devices capable of handling microscopic amount of fluid has emerged as a new

engineering discipline. Numerous fluidic applications in areas such as medicine,

chemistry, environmental testing and thermal transport have potential to be scaled down

for reasons of sample size, device cost and portability. The ability to accurately transport

fluid within integrated microfluidic systems is essential for them to become reliable and

more commonplace. Cost-effective fluidic components like micropumps are required for

internal flow control in such microfluidic systems. [1]

An outstanding diversity in micropumping concept and principles has been reported in

recent years [2]. Much attention has been devoted to diaphragm-based reciprocating

micropumps due to their ease in miniaturizability. Electrostatic, electromagnetic, and

piezoelectric actuation principles have been used. Further, diaphragm based valveless

pumping principles have been proposed, using conduits for fluid flux rectification instead

of check valves. A piezoelectrically actuated, diffuser based micropumping system is

shown in Fig 1. Due to preferential flow characteristics of the diffuser element, a higher

flow rate in the diverging direction is obtained. Piezoelectric actuator is used to provide

the required pressure fluctuations in the pump chamber. Different manufacturing

technologies have been used to fabricate valveless micropumps since the first prototype in

brass was reported by Stemme & Stemme [3]. Deep Reactive Ion Etching (DRIE),

Thermoplastic replication and Printed Circuit Board technologies have been demonstrated

as possible means to fabricate in bulk valveless micropumps. Further, integration of the

micropump with sensors and programmable electronic components is desirable for

modular and self-contained microfluidic systems.

(b)

Fig1 a) Principle of operation b) Fabricated micropump

7

Even though the structure of piezoelectrically actuated valveless micropump is quite

simple, predicting its performance is quite complex due to coupled electrical-mechanical-

fluidic domains. Moreover small changes in geometrical, material and operational

parameters of the micropump components can result in large differences in performance

characteristics. Analytical, FEA, CFD and Electrical Equivalent Network techniques have

been applied to understand the characteristics of the system emphasizing the complexities

involved and need for further work.

Reference 1. Nam-Trung Nguyen, Steven T. Wereley, Fundamentals and applications of microfluidics, Artech

House, ISBN1-58053-343-4 2. Laser D. J., Santiago J. G., 2004, “ A review of micropumps” Journal of Micromechanics and

Microengineering, 14, R 35-R 64 3. Stemme E., Stemme G, 1995, “ A valveless diffuser/nozzle-based fluid pump”, Sensors and

Actuators A, 39 (1993) 159-167 4.

2. Work done

1. Lumped parameter analysis of the system

2. Empirical correlations between micropump performance characteristics

3. Open loop programmable valveless micropump design fabrication and testing

4. Integration of micropump driver and controller on PCB

3. Future Work 1. Bond Graph analysis of the system

2. Closed loop configuration testing

3. Space and automotive application development

Publications Verma P., Srinivasa Y.G., Nagarajan T., Nayak M.M., 2006, Experimental Investigation of Real-Time Valveless Micropump, First International & 22nd All India Manufacturing Technology Design and Research Conference, 21st -23rd December, IIT Roorkee: 65-70 Verma P., B. Bhaduri, N. Krishna Mohan, M. P. Kothiyal, Y. G. Srinivasa.,2006, Modeling and Optical Characterization of Piezoelectric Actuator for a Valveless Micropump, VIII International Conference on Optoelectronics, Fiber Optics and Photonics, December 13 to 16, 2006, Hyderabad, MMM:11

G. Satheesh Kumar, M. Babu, RM. Kuppan Chetty, Parikshit Verma, K. Rajesh, 2006, Design and Fabrication of MOBOT-A search and Rescue Robot, First International & 22nd All India Manufacturing Technology Design and Research Conference, 21st -23rd December 2006, IIT Roorkee: 1-6

8

Design and Implementation of Distributed Networked Robotic System based on Network Controller

RM.Kuppan Chetty (PhD scholar), M.Singaperumal, T.Nagarajan

1. Introduction

Recent technology advancements in the robotic environment provide the capability to design a robotic system which can be networked and useful to remotely control the robots within the work space and to support interobot interactions. One of the most promising technologies today is the integration of virtual reality and robotics on a network, creating a new field called “Networked Robotics”.

The field of Networked robotics poses a number of technical challenges related to network deployment, reliability, coverage, safety, localization, sensor - actuator fusion and user interface design. Recently there has been an increased research interest in networked robotic systems composed of multiple autonomous robots exhibiting cooperative behavior by the introduction of distributed sensing and communication capabilities. The communication capability could be wired or wireless, and based on a variety of protocols such as TCP, UDP, or 802.11 standards. 2. Objective The main objective of this research is to design a “Networked robotic system having coordinated motion of robots using Network Controller”. This involves

• Design and integration of sensor-actuator-controller configuration for robotic applications

• Development of network architecture. • Optimization of control algorithms and protocols for distributed sensing and

communication capabilities between robots. • Final implementation of hardware and performance testing.

3. System architecture The area of networked robotic systems has focused on the understanding of physical interactions and constraints among robots, and between robots and physical environment. The proposed system of Networked robots contains a master controller and several local link controllers. The overall task for the robot is distributed to each one of the local link controllers. The master controller has the central processing unit and a communication unit. This system depicts a multiprocessor platform which provides the distributed sensing and control capability by a sophisticated decentralized control algorithm. This algorithm has the control over the sensor -actuator fusion, deployment of network architecture, congestion control and dynamic resource management such as powering the sensor node, CPU execution speed, memory management and communication bandwidth. As a preliminary work towards our research, a generalized wireless mobile robot platform, mostly concentrated towards the search and rescue applications was devised. This devised mobot consists of various sensors and signal conditioning circuits, actuators and its drivers, and a centralized wireless Microcontroller ATMega8535 (designed in house) to have the sensing, data processing and control over the environment. In this framework each and every sensor or actuator is equipped with a suitable signal

9

conditioning circuits which acts as a data communication interface between the sensors/actuators and the centralized microcontroller unit. We plan to integrate the IXP 4XX X scale network controller for networking purpose along with the ATMega8535 Microsystem nodes to realize the hardware setup and Behavior based control algorithm for the coordination of robot; to test the networked architecture by implementing the control algorithm with the robots, providing the network control capability. 4. Reference [1] Michael Bramberger, Josef Brunne, Bernhard Rinner, “Real-Time Video Analysis on an

Embedded Smart Camera for Traffic Surveillance”, Proc. of the IEEE Real-Time and Embedded

Technology and Applications Symposium (RTAS’04), 2004.

[2] Prassana Balasundaram, Kartik Vaidyanathan, Andrew Mason, “Micro System Controller for Sensor

Network Control and Data Correction”, Proc. of the IEEE, ISCAS, pp809-812, 2004.

[3] Tae-Kyung Moon, Tae-Yong Kuc, “An Integrated Intelligent Control Architecture for Mobile Robot

Navigation within sensor Network Environment”, Proc. of the IEEE, 566-570, 2004.

5. Publications a) International Conferences 1) RM.Kuppan Chetty, M.Singaperumal, T.Nagarajan, “Design of Distributed Networked Robotic System based on Intel IXP4XX X-Scale Network Processor”, Proceedings on 2006 Intel Embedded and Communications education Summit, Hudson, Massachusetts, USA. 2) Kuppanchetty et.al, “Design of a Mobot – a search and rescue robot”, Proceedings on first Internaional and 22nd AIMTDR conference, IIT Roorkee, 2006, 1-5. b) International journal 1) Kuppanchetty et.al, “Design of a Mobot – a search and rescue robot”, special issue on 22nd AIMTDR, International Journal of Advance Manufacturing Technology, Springer, under review.

ROBOT 1 ROBOT 2 ROBOT nROBOT 3

Network processor based control system

Intelligent Robotic Nodes

Low Level Control (wireless) Common bus

High level control (TCPIP)

ROBOT 1 ROBOT 2 ROBOT nROBOT 3

Network processor based control system

Intelligent Robotic Nodes

Low Level Control (wireless) Common bus

ROBOT 1 ROBOT 2 ROBOT nROBOT 3

Network processor based control system

Intelligent Robotic Nodes

Low Level Control (wireless) Common bus

High level control (TCPIP)

10

Modeling and Control of Micro EDM Process with Piezoactuated Tool Feed Mechanism

Muralidhara; N. J. Vasa; M. Singaperumal

1. Introduction Micro Electro Discharge Machining (Micro EDM) is a non conventional, non contact

micromachining process where the material is melted and removed from the work surface

by the sparks produced between anode and cathode. The work piece and the tool form the

positive and negative electrodes, which are immersed in the dielectric medium, a voltage

is applied and when the gap between them is sufficiently small (few μm -100μm), the

dielectric breakdown takes place leading to the formation of plasma. The high plasma

temperature (5000K-7000K) melts and vaporizes the workpiece and tool materials at the

end of the spark. The main difference between the Micro EDM and Macro EDM is in the

magnitude of discharge energy involved, the size of the tool used and the resolution of the

X, Y and Z-axis movements. Special tool holding and work holding devices are required

in Micro EDM.

2. Objective The main objective of this research work is to model the Micro EDM process with the

piezoactuated tool feed mechanism to control the tool feed rate and to achieve the

required depth of micromachining. This involves

Modeling the piezoactuator as an electromechanical model considering Hysteresis

for accurate tracking control of the piezoactuator

Modeling the Micro EDM Process for accurate estimation of tool and workpiece

material removal rates which in turn utilized for the estimation of the required tool

feed rate which will result in continuous and stable machining

Integrating the models developed for Micro EDM process and piezoactuator and

to simulate the micro EDM process along with the piezoactuated tool feed control

Develop a Micro EDM with piezoactuated tool feed mechanism and to carry out

experiments to validate the simulation results obtained from the models developed

for Piezoactuator and Micro EDM process

3. Piezoactuator Modeling

A piezoelectric microactuator with a maximum displacement of 400μm (CEDRAT

Technologies, APA400M) is used in this research work. An electromechanical model of

the piezoactuator is developed for accurate displacement control based on the Maxwell’s

Slip model. A PID controller is designed together with the Model Reference Controller to

achieve the tracking control of the piezoelectric actuator as shown in Fig 1. From

11

the simulation results it was found that the tracking error is minimum when model

reference control together with PID controller is used to control the displacement of the

piezoactuator. Hardware–in-loop simulation for the piezoactuator is in progress.

4. Prototype Micro EDM

A prototype Micro EDM is developed in-house with piezoactuated tool feed mechanism

and with dielectric recirculation and filtering system. Workpiece is mounted on X-Y-θ

stage and tool is mounted on piezoelectric microactuator along Z-direction. A pulse

control circuit is developed to control the gap voltage, sparking frequency and the duty

cycle. A feed back circuit is designed to monitor a constant gap voltage and this signal is

utilized to control the tool feed rate. Different 3-dimentional micro structures are

machined by using different types of tool and workpiece materials. The effects of

machining parameters on side spark gap, MRR, TWR and surface roughness are studied.

5. Modeling Micro EDM Process

Micro EDM process modeling is very essential to estimate the MRR and TWR which is

used for theoretical estimation of the amount of tool wear compensation required for

controlling the proper gap between the tool and the workpiece. The tool feed rate is

determined considering the actual tool and workpiece removal rates and the spark gap to

be maintained. Micro EDM process model is to be integrated with the piezoactuator

model to achieve continuous machining and to achieve the required depth of micro

machining.

6. References

[1]. Yu. Z. Y., Kozak J., Rajurkar K. P., “Modeling and simulation of Micro EDM

Process”, Annals of the CIRP, Vol. 52, No. 1, pp 143-146

[2] Michael G., Nikola C., “Modeling piezoelectric stack actuators for control of micromanipulation”, IEEE Control Systems, June 1997, pp 69-79

Fig. 1 Closed Loop Control of Piezo Actuator

PID Controller

Piezoactuator

Sensor Signal Conditioning

Piezoactuator Model with Hysteresis

Compensation

Reference Displacement

Actual Displacement

Reference Displacement Xref VMRC

VPID Xerror

Xactual

VPiezo

Xactual +

+

+ -

Xref

12

MODELLING CONTROL OF UNDERWATER MANIPULATOR FOR INTERVENTION TASKS

T.Periasamy; T.Asokan; M. Singaperumal

Although ocean covers two thirds of our world, it remains poorly explored and

only vaguely understood. The autonomous underwater vehicles are providing a new

alternative for exploring the undersea environment. The need of underwater robotic

vehicle has risen in recent years and the applications are many and varied. The

applications include oil exploration, pipe laying, cable laying, surveying, construction,

salvage operations etc. Underwater robot manipulators are used for intervention tasks

such as opening and closing of valves, welding, contact type inspection etc. Though it is

being used for many applications, the level of autonomy is limited largely due to lack of

modeling and control strategies. The proposed research on “Modelling and Control of

Underwater Manipulator for Intervention Tasks” will focus on improved control

strategy for coupled vehicle manipulator systems.

The main tasks in this research are the modeling and control of the manipulator in

a moving platform (vehicle). Dynamic modeling of the manipulator in the fixed platform

is quite straight forward. But the dynamic equations of the underwater vehicle and

manipulator are highly coupled and hydro dynamic forces will affect the motion of the

vehicle and manipulator. Therefore solving such system is complex one. Detailed

modeling will be carried out considering the coupled dynamics of the whole system. The

hydrodynamic effects such as added mass, viscous drag, fluid acceleration and buoyancy

forces are considered while developing the model. Bond graph method being a powerful

tool in modeling of dynamic system is used for modeling and simulation. Control of the

manipulator is one of the very important tasks in this work. A suitable controller is to be

designed for the coupled dynamics of the manipulator. Suitable control algorithm and

control strategy will be derived for the above task. Simulation and analysis will be carried

out for different operating conditions and environments to study the behavior of the

underwater robot manipulator.

Bond graph model of three degrees of freedom planer manipulator is developed by

using 20-sim. Bond Graph Model of three degrees of freedom Planer manipulator is

developed and simulated using 20-sim.The development of bond graph model for

underwater manipulator considering the hydrodynamic effects such as added mass,

viscous drag, fluid acceleration, and buoyancy and intervention forces is on progress.

13

Fig1. Bond Graph model of a one link underwater Manipulator

The proposed research work will improve the operational efficiency of the total

underwater robotic system. The newer control strategies developed will be used to make

the system more autonomous and easy to implement.

References:

[1] Yuh, J., 1990, “Modelling and Control of Underwater Robotic Vehicles,” IEEE

Trans. Syst. Man Cybern., 20, pp. 1475–1483.

[2] McMillan, S., Orin, D. E., and McGhee, R. B., 1995, “Efficient Dynamic Simulation

of an Underwater Vehicle With a Robotic Manipulator,” IEEE Trans. Syst. Man Cybern.,

25(8), pp. 1194–1206.

[3] R. Fostu-Ngwompo., S.Scavarda., and D.Thomasset., 1997, “Bond Graph

Methodology of an Actuating System: application to a Two – Link Manipulator”, IEEE

Conference on Systems, Man, and Cybernetics, 1997. 'Computational Cybernetics and

Simulation.

[4] P. J. Gawthrop., 1991, “Bond graphs: A Representation for Mechatronic systems”,

Mechatronics vol. I, no. 2, pp. 127-156.

14

Laser Annealing of Silicon Wafers by Pulsed Nd:YAG laser

I.A.Palani (PhD scholar), Nilseh J. Vasa , M.Singaperumal 1. Summary In the recent technological advancement there is a rapid usage of semiconductors in many

areas which includes from microchips to photovoltaic application such as solar cells.

Conventionally, photovoltaic cells are made with a crystalline silicon wafers to achieve

high efficiency. However the resulting cost is high and overall size is limited. An

alternative cost-effective approach may be to consider a thin-film poly-crystalline wafers

combined with a laser annealing technique. Crystallization and grain growth technique can

be used to improve the cell efficiency and lowering the cost of the solar cells and

microchips. The surface modification of silicon by using a laser beam is of great interest.

Laser annealing technique is widely used to repair the defects caused during ion

implantation process for various types of semiconductors. The technique can also be

extended to induce recrystallisation on silicon thin films to produce poly silicon films and

modify amorphous silicon and also to reduce defect density by recrystallisation

mechanism. Conventionally, excimer lasers, such as KrF laser (248 nm), are used for

annealing and to modify the physical properties of thin films on amorphous silicon

surface. However maintenance cost is high and gas replacement on a periodic basis is also

necessary. Alternatively, pulsed, solid-state lasers, such as Nd:YAG laser can also be

considered for laser annealing of amorphous silicon film to produce polycrystalline

structure. Recently available diode pumped Nd:YAG lasers (fundamental wavelength:

1064 nm) are cheaper and almost maintenance free.

2. Objective

• To investigate the application of Nd:YAG laser for annealing of silicon films .

• Optimization the grain size for efficient Electron mobility.

• Investigate the characteristics of silicon films for Different Pulse width

(nanosecond and Pico second ) by laser Annealing

• Optimize the grain size for Efficient Electron mobility.

• To investigate the process parameters and processing time for laser annealing with

a focused sheet-shaped laser beam.

15

3. Proposed Experimental setup:

4. Reference

[1] H. Azuma, A. Takeuchi, T. Ito, H. Fukushima, T. Motohiro, M. Yamaguchi, ”Pulsed Krf laser

annealing of silicon solar cell,” Solar Energy Materials & Solar Cells, 74 (2002) 289-294.

[2] D. Klinger, E. Lusakowska, D. Zymierska, “Nano- structure formed by nanosecond laser

annealing on amorphous Si surface,” Material Science In Semiconductor Processing, 9 (2006) 323-

326.

[3] A. Mittiga, L. Fornarini, R. Carluccio “Numerical modelling of Laser induced Phase transition

in silicon,” Applied Surface Science, 154-155 (2000) 112-11.

[4] K. Milan., S. Trtica, Biljana, M.Gakovie “Pulsed TEA CO2 laser surface modification of

silicon,” Applied Surface Science, 205 (2003) 336-342.

5. Publications:

National Conference:

I.A.Palani, Nilesh J .Vasa,M. Singaperumal “Study On Feasibility Of Nd:YAG Laser in

Annealing of silicon Films”, National Conference for Research Scholars in Mechanical

Engineering 2007(NCRSME 07), IIT Kanpur.

16

Dynamic Modeling and Simulation of a Two Shaft Gas Turbine Aero Engine for the Development of Robust Control Strategy

V. Rajasekar; Y. G. Srinivasa; Nilesh. J. Vasa.

Introduction Gas turbines power plants are widely used in aero and marine propulsion and

electric power generation as they offer better performances over reciprocating diesel

engines in terms of lower weight per unit of power output, low emission, and improved

heat recovery cycles, etc. Linear dynamic models are required for developing control

systems to guarantee improved performance and stability of the engine. As models

predicting gas turbine engine’s dynamic behavior closely over its entire operating

envelope is difficult to realize, only less accurate models are available for control design.

The objective of the research work is to build the dynamic model of a two shaft low

bypass turbofan engine employed in a military aircraft for the development of robust

control strategy.

Dynamic Modeling and Simulation

In the present work dynamic modeling is done in state space framework by

cascading the engine components connected by plenum volumes. Two shaft speed and six

pressure variables downstream of engine components are considered as state variables.

Fan, compressor, combustor, turbines, afterburner and nozzle are assumed to exhibit

quasi-static behavior and they are represented as artificial neural network (ANN) maps.

Lumped equations of energy, mass accumulations are solved for deriving the pressure

state variables inside the volumes.

Engine Control Design and Proposed Control Strategy The control of turbine engines using optimization techniques has received

significant interest over the years as reported in [1], [2]. The present research work

attempts to apply H∞ optimal control design method to the gas turbine engine.

17

As the controller design requires linear model of the plant, nonlinear engine model

was linearized at various steady state operating points covering the entire operating

envelope of atmospheric condition and core turbine speed. The linear model at design

point (sea level static, 100% rotational speed) was considered as nominal model and

others were considered as real parameter variations around this model. An optimal H∞

controller has been proposed for the nominal model with Power Lever Angle (PLA)

tracking as performance requirement. The Robustness of the proposed controller is tested

by transforming the closed loop system as linear fractional transform as shown in the

figure. 1 with real parametric uncertainty.

References 1. Ariffin, A. E., Munro, N., Robust control analysis of a gas-turbine aeroengine, IEEE

Transactions on control systems technology, 1997, Volume.5-2, 178-188.

2. Samar, R., Postlethwaite, I. Multivariable controller design for a high performance

aero-engine, IEE control’ 94 conference, 1994, 1312-1317.

Linear Engine Model

System Nonlinearity (Structured Uncertainty

Block)

Controller

(Disturbances) PLA Variation

(Performance Signals) Tracking Error

Fig.1.Closed loop engine system as Uncertain Linear Fractional Transform

18

Development of an optical sensor for measurement of two orthogonal components of electric field using second harmonic generation with

electro-optic crystal

Anshul Garg, Nilesh J. Vasa, M. Singaperumal, S. Sarathi Introduction

Conventional systems for measuring the electrical field on high voltage applications such as plasma arcs, lightning strokes or surface-discharge experiments widely use active metallic probes, i.e., coils, capacitors, dipole antenna. These metallic components distort the electric field leading to noise during measurement. The use of optical sensors eliminates this problem since: 1) remote measurements are possible, 2) contain no electrical circuit and power sources in the proximity of measurement resulting in less EMI noise, 3) direct measurement of the field is possible, 4) non-contact type of measurement, 5) possess sufficient insulation and have high reliability, 6) provide a wide operating frequency range.

Traditionally available optical probes - utilizing either Pockels effect or Kerr

effect - work by measuring the phase change of the transmitting light beam leading to high noise to signal errors. In the proposed technique, the output SHG intensity is used for the measurement of the applied electric field. When the interacting input laser beam and the corresponding SHG wave satisfies the phase matching condition within certain limits, the second-harmonic output (SHG output) can be obtained. Subsequently, when an external electric field is applied, the refractive indices in the birefringent crystal alter due to the electro-optic effect and in turn, the corresponding phase matching condition also changes. As a result, the SHG output intensity varies, which can be used for the measurement of the applied electric field. Also the phase matching conditions can be offset to monitor different magnitude of electric fields. Experimental work

In the experiment, a collimated output of the continuous-wave (cw) diode laser (1064 nm) was focused into the KTiOPO4 crystal of size 3 mm × 3 mm × 12 mm long. The phase matching was attained in the xy-plane (horizontal plane) and the angle θ was set to 90° (vertical). The room temperature phase matching was obtained with the angle φ equal to 23.5°

Collimating lens Lens (f =80 mm)

Electrodes

Detector

KTiOPO4 crystal (3x3x12 mm)

1064 nm cut filter

eo(2ω o(ω

eo(ω

0--5 kV Optical isolator

Diode laser (1064 nm)

o : Ordinary ray eo : Extra-ordinary ray x

z

x y φ

θ = 90o

= 23.5o z

Experimental setup for electric field measurements with KTiOPO4 crystals

19

The theoretical estimation based on the SHG theory was made by considering the values of the electro-optic coefficients γ13, γ23 and γ33 as 9.5, 15.7 and 36.3 pm/V, respectively. Based on the electro-optic relations of the crystal, it was observed that the maximum field measurement up to 13.5 kV/cm is possible with a crystal of length 12 mm while only up to 6.5 kV/cm with a crystal length 25 mm when an electric field is applied along the z-axis of the crystal. In another experiment the angular bandwidth was found to be 1.7o which is near to the theoretical value. References [1] R.E. Hebner, R.A. Malewski and E.C. Cassidy, “Optical methods of electrical measurement at high voltage levels”, Proc. IEEE 65 (1977), pp 1524-1548. [2] C. Barthod, M. Passard, J. Bouillot, C. Galez and M. Farzaneh, “High electric field measurement and ice detection using safe probe near power installations”, Sensors and Actuators A: Physical, Vol. 113 (2004), pp 140-146. [3] J. D. Bierlein and C. B. Arweiler, “Electro-optic and dielectric properties of KTiOPO4“, Applied Physics Letters, Vol. 49 (1986), pp 917-919. [4] B. Boulanger, J.P. Feve, G. Marnier, “Calculation of phase-matching electro-optic modulation of SHG in KTP”, Optics Communications, 101 (1994), pp 129-132. [5] “Laser Fundamentals”, W.T. Silfvast, Cambridge University Press, (1999).

20

DETAILED ANALYSIS OF PROCESS PARAMETERS IN MICRO ELECTRO DISCHARGE MACHINING

Saswata Majumder, Nilesh J. Vasa, M. Singaperumal

Introduction

In Micro EDM the shape, size and finish of the cavity produced during machining

depend upon various parameters. These parameters may be electrical, mechanical or

chemical. Frequency of the pulse, duty cycle of the pulse, polarity of the machining, input

voltage, current limitation, etc are the electrical parameters. Vibration of the tool, tool

feed rate electro rotational speed, feeding mechanism for tool and dielectric circulation,

etc are the mechanical parameters. Chemical parameters are characterized by the

dielectric medium used, composition of the work piece and tool material, etc.

Technological parameters are surface roughness, material removal rate, wear ratio and

circularity. Hence parametric study is important for detailed understanding of the EDM

process.

The main aim of the project is to study the relationship between MRR (Material

Removal Rate) and TWR (Tool Wear Rate) of different tool by varying the open loop

voltage and feed back voltage of the micro EDM process.

In micro EDM, both tool and workpiece materials are being eroded by the action

of the spark, and since the tool dimension is usually few micrometers in size, this erosion

is very much considerable when compared to the final dimensions required on the part.

The tool feed compensation is required to obtain the continuous spark and to obtained the

required geometrical tolerances. At the same time it is required to maintain a constant

optimal gap to avoid formation of arcs which will occur when the gap is too small and to

avoid increase in delay time which is due to the larger spark gaps. Hence, for a given

applied voltage between the tool and workpiece, there exists an optimal gap which is to

be estimated by conducting the experiments at different open loop voltages and by

analyzing the MRR, TWR and surface roughness of the machined surface.

Gap control is one of the most important parameter affecting the EDM

characteristics. Adaptive servo control is used generally in conventional EDM to keep the

gap length within the range which allows consecutive pulse discharge without causing

short circuiting. Since pulse energy supplied to the working gap is very small in Micro

EDM, the working gap is extremely shorter than that of conventional EDM. Hence to

achieve higher resolution and accuracy of feed control piezo actuators is used for the

21

purpose. The objective of the feed back circuit is to maintain constant voltage throughout

the process. Hence a reference voltage is required for constant comparison of gap voltage

and thus monitoring the gap distance. In the present setup, reference voltage is 0.5 V

which may not ensure optimum gap for different open loop voltage. By changing this

reference voltage, how the material removal rate (MRR) and tool wear rate is going to

vary is investigated.

Work done 1. Setup of Optical Microscope with CCD camera.

2. Relationship between Open loop voltage and material removal rate of silicon

wafer and wear ratio of copper wire and silicon wafer.

3. Study of form characteristics of drilled Hole and machined micro channel on

silicon wafer.

4. Modification of feed control circuit with an objective to vary the reference voltage

of the feed back circuit.

5. Relationship between feed back voltage and MMR of the silicon and wear ratio.

References 1. Yao – Yang Tsai , Takahisa Masuzawa , “ An index to evaluate the wear resistance

of the electrode in micro-EDM” Journal of Material Processing Technology, 2004.

2. D.T. Pham, A Ivanov, S. Bigot, K. Popov, S. Dimov, “ An investigation of tube and

rod electrode wear in EDM drilling” , Journal of advanced Manufacturing

Technology , April 2006.

3. Kunieda M., Lauwers B., Rajurkar K. P., Schumacher B. M., “Advancing EDM

through fundamental insight into the process”, Annals of the CIRP, Vol 54, No. 2,

2005, pp 599-622.

4. Yu. Z. Y., Masuzava T., M. Fujino “Micro EDM for three dimensional cavities – Development of uniform wear method” CIRP Annals - Manufacturing Technology, Vol. 47, No. 1, 1998, pp 169-172.

22

Previous Research work

23

Finite Element Modeling and Analysis of Fluid Structure Interaction in

Hydraulic Servovalve Somashekhar S. Hiremath, M.Singaperumal, R.Krishnakumar

1. Objective:

To develop the complete design methodology to study the dynamics of FSI of hydraulic

component – Jet pipe EHSV with built-in mechanical feedback using the FEM.

2. Basic Principle Jet Pipe EHSV

• No-load : C1 and C2 are interconnecting - Ps-C1-C2-T

• Second Stage Null Leakage : C1 and C2 are blocked then

Flow to tank through radial clearance betn. Spool and sleeve Cr = 2 to 4 microns

•Dn = 0.345 mm dr. = 0.345 mm

• w = 0.01 mm

• δjet = 0.2 mm

Left receiver Nozzle

Qout1 Qout2

Qin1 Qin2

Right receiver

First Stage - Area Modulation

Second Stage - Area Modulation

1 X 45°

5.7

5.7

PE

PE

KE

dr drdn

w

Solid and FE Model of Combined Assembly

Feedback spring assembly

Jet pipe assembly

• Loading- Force on armature

• Boundary Conditions- Flexure tube- Connection pipe- Support spring- Disp. at FBS end

• Problem size- No. of elements = 7749- No. of nodes = 8555

24

Chart T itle

-120

-100

-80

-60

-40

-20

0

Phas

e an

gle,

deg

Chart T itle

-14

-12

-10

-8

-6

-4

-2

01 10 100 1000

Frequency, Hz

Am

plitu

de ra

tio, d

b

14 54

• Magnitude Plot :Band width: 14 Hz

• Phase Angle PlotPhase lag : 54 Hz

)(

)(var

lowestf

f

yingf

f

iQ

iQ

AR

=

Amplitude Ratio Phase Lag

Instantaneous time separation betn. (i) and (Q)corresp. X f X 360 per cycle

Frequency Response of Complete valve

3. Concluding Remarks

The complete design methodology for prediction of servovalve characteristics has

been developed incorporating into the FE model the FSI between the valve stages

as also between the valve and actuator.

The dynamics of fluid flows, flow reaction forces, friction forces and

electromagnetic part of the torque motor can be incorporated into the proposed

model to obtain a more accurate representation of the complete servovalve

dynamics.

The performance of the servovalve implemented in a hydraulic system has also to

be verified experimentally.

The proposed technique can be extended to study other hydraulic components

involving FSI.

25

Profiled Pistons of Hydraulic Actuators

• Systematic analysis of different piston profiles• Optimum configuration arrived at for piston profiles• Unique test-rig for dynamic friction measurement• Good agreement of theory with experimental results• Suitability of profiled pistons for high speed servohydraulic cylinders

Dynamic Friction Measurement on Seal less Piston

26

Effect of Form Errors on the Performance of Hydraulic Actuator

• Iso-Geometrical out-of-roundness• Theoretical Investigations

- centering force, - viscous friction, - instantaneous torque, - efficiencies• Experimental Investigations

- Single piston dynamic friction, - Commercial hydraulic motor- standard pistons, - pistons with form error

• Improvements in Characteristics- starting torque, - Slow speed

Surface and Form Error Characterization By CSOM

• Non contact focus detection• Computer controlled• Measurement and Characterization of

- 3D surface roughness- Form errors: Circularity, Cylindricity, Sphericity, Flatness

• Software-parameters and analysis

27

\

Active Impedance Control

• Electrohydraulic servosystem interface• Theoretical investigations :

-Stability analysis through passivity-Bond graph for dynamic analysis

• Experimental investigations• Impedance variation achieved by damping variation in EHS• Eliminates inverse dynamics problem

Extrusion Honing Machine

28

Helium Pressure Regulator – for space application

Precision Pressure Regulator• Operating medium : Helium and other gases• Narrow regulation band• Extremely low leak rates• Design incorporates

- special type of metal to metal seat- a new concept of lever to reduce effect of supply pressure variation- use of solid lubricants to reduce friction- special materials for reference springs to counteract temperature effects

• Application areas : Pressurant system of Communication satellites

29

Hydrostatic Steering System in Tracked Vehicles

• Theoretical Estimation of- Hydrostatic Steering Power- Turning radius with slip- Steering speedFor different terrain conditions

• Experimental Investigations- development of HST test rig- Track loads for different operating conditions: Turn-radius, neutral, S, 8

• Optimum Configuration of HST

Hydrostatic Steering Test Rig

30

Self Guided Vehicle (SGV)

• A free-roving autonomous vehicle• Compact and Easy manoeuvrability• Navigation through ‘Las-Nav Position Sensor’• Guidance via on-board controller• Application areas

Nuclear reactors, Undersea mining, defense etc.

3C-SiC Based Piezoresistive Pressure Sensor for High Temperature Applications

31

Ultrasonic Flow meter

• Sea bed mining : about 6000 m depth• Flow rate of manganese nodules

Nozzle size : 20 – 70 mmPipe diameter: 200 mm

• Algorithm to measure the concentration• Microprocessor based instrumentation

Trajectory Planning for Stewart Platform Manipulatoralong specified paths

• Objectives

1. To develop an algorithm for optimising the location of the path within the workspace for maximum structural stiffness and minimum actuator forces.

2. To develop an algorithm for optimising the velocity profile of the manipulator such that the total time required is minimum.

3. To develop an optimal trajectory planning algorithm– Minimum time

4. To study & compare the performance of the algorithm

– Tracking accuracy– Time

32

Hydraulic Stewart Platform

Overview of the Test setup showing the sinusoidal displacement generator, calibration spring assembly and the first stage servovalve

Jet pipe Servovalve