2

CERTIFICATE

This is to certify that, the thesis entitled “Some Theoretical and Experimental Studies

on Computer Controlled Pneumatic Semi-Active Suspension Systems for Ground

Vehicles” which is being submitted herewith for the award of the degree of Doctor of

Philosophy in Mechanical Engineering under the faculty of Engineering and

Technology, of SHIVAJI UNIVERSITY, Kolhapur, is the result of the original

research work completed by Shri. Ranjit Ganptrao Todkar under my supervision and

guidance and to the best of my knowledge and belief the work embodied in this thesis

has not formed earlier the basis for the award of any Degree or similar title of this or any

other University or Examining body.

Research Guide

(Dr. S. G. Joshi)

Formerly Professor and Head,

Department of Mechanical Engineering,

Walchand College of Engineering, SANGLI.

Place : SANGLI .

Date : 21 - 10 - 2009

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TITLE 1

CERTIFICATE 2

INDEX

Section Contents Page 1.0 RELEVANCE OF THE RESEARCH TOPIC 4

2.0 LITERATURE REVIEW 7

3.0 FOCUS OF THE RESEARCH WORK 8

4.0 ORGANIZATION OF THE THESIS 10

5.0 CONTRIBUTIONS BY THE RESEARCH WORK CARRIED OUT

TO THE FIELD OF DESIGN OF ROAD VEHICLE SUSPENSION

SYSTEMS

14

6.0 PUBLICATIONS RELATED TO THE RESEARCH WORK 16

7.0 SELECTED REFERENCES 17

8.0 FIGURES

Fig. 1 SDOF Quarter Car Suspension System with Air Damper (Air Tank System not shown)

Fig. 2 2DOF Quarter Car Suspension System with Air

Damper (Air Tank System not shown)

Fig. 3 Block Diagram of the Air Pressure Control System

Fig. 4 Experimental Setup for 2DOF Pneumatic (Air Damped) Semi-Active Road Vehicle Suspension System Model (µ<< 1 )

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9.0 PLATES

Plate 1 Air Damper Cylinder and Slider Assembly Plate 2 SDOF System with Cylinder-Piston and Air Tank

Plate 3 Experimental Setup

Plate 4 Air Tank and Capillary Pipe System.

Plate 5 Instrumentation

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4

SYNOPSIS

SOME THEORETICAL AND EXPERIMENTAL STUDIES ON

COMPUTER CONTROLLED PNEUMATIC SEMI-ACTIVE

SUSPENSION SYSTEMS FOR GROUND VEHICLES

1.0 RELEVANCE OF THE RESEARCH TOPIC

The vehicle system designers have been grappling with the problem of vehicle

suspension design with a view to improve the ride quality, road holding, active safety and

vehicle reliability. The basic functions of a good ground vehicle suspension system are

i) Primarily to isolate the occupants of the vehicle from the irregularities in the road

surface , ii) To carry or support the weight of the vehicle while being flexible enough

to absorb road shocks , iii) To react to the changes in load generated by changes in the

number of passengers and luggage , iv) To react to the changes in load through inertial

inputs generated during acceleration braking and cornering , v) To minimize variations

in tire load caused while accelerating, braking and cornering, otherwise tire load

variation may lead to loss of adhesion of tire with road (loss of road holding) and

vi) To provide control over pitch and roll motions of the vehicle body.

Thus, a good suspension system should be perceptible by the customer in terms of

vibrations and ride comfort. It ensures optimal tire performance, supports chassis and

offers good standards of comfort by minimizing the transmission of road surface

irregularities and also by effectively filtering noise generated between the tire and the

ground.

A typical vehicle suspension has the ability to store the energy via suspension spring and

dissipate it via a damper. The dampers provide damping for both the body (sprung mass)

and the unsprung mass , while providing damping for the body at resonance frequency

( around 1 to 2 Hz ) , at higher resonance frequencies including the wheel hop frequency

( around 12 Hz) . The system provides a transmission path for vibration which degrades

the ride. Consequently a good ride characterized by low body ( sprumg mass)

5

accelerations ( Ref Fig.1.3) is obtained with relatively modest damping (around 20%

critical) at the expense of suspension displacement and dynamic tire force. To minimize

suspension displacement and dynamic tire force, it is necessary to use higher damping

ratios (around 50% critical). Higher damping rates are beneficial during cornering

maneuvers to reduce dynamic tire force and transient roll rate. Reducing transient roll

rates makes the vehicle feel more composed and better controlled as it turns into the

corner quickly. Low transient rates are also desirable for increased passenger comfort.

The requirements of a good suspension system are i) it should be a soft suspension for

good ride comfort, ii) it should be a stiff suspension to become insensitive to applied load

and its variations and iii) it should have a setting between soft and stiff suspension for

good handling. The values of the spring and damper parameters of a conventional passive

suspension system are fixed. Hence the character of the passive suspension system

changes a little once it is installed in the vehicle. As such, a passive suspension design

can not satisfy the above mentioned requirements. Therefore, the conventional and

current passive suspension design, according to Williams of Jaguar Cars, is a

compromise brought out by conflicting demands of ride and handling.

The improvements in the passive suspensions have been brought out by the changes in

the principle of working to satisfy most of the performance criteria. These changes in the

principle have become commercially viable with the development of active, slow active

and semi-active suspension systems, which show improvement over the conventional

passive suspension in respect of vibration isolation properties and attitude control of the

vehicle body. Active system involves replacing conventional suspension elements by

actuator (placed between sprung mass and unsprung mass), which acts as force producer

according to some control law. The actuators operate with force transducers providing

inner loop feed back signals to their controllers and are imagined to track faithfully a

force demand by the control law. The actuator controlled band extends substantially

beyond the wheel hop frequency determined by the unsprung mass and tire stiffness

and typically near 10 Hz. The control law may contain the information of any kind

obtained from any where in the system and an important part of the active system design

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problem is the determination of the control law which will give a good system

performance. The active suspension system has been very attractive to control engineers

seeking applications for various optimal control theories. Recently with the advent of

active control technology utilizing microprocessors, sensors and actuators, practical

systems have been designed and applied to such concepts as automobiles, railways

and magnetically levitated vehicles. Slow active systems are the active systems as

described before except that, the actuator control band width is much reduced embracing

the normal range of body resonant frequencies in bounce, pitch , roll and the frequency

range of interest , as far as responses to steering control are concerned but not exceeding

as far as wheel hop frequencies.

Semi-active systems are considered to be derived from and are closely related to active

systems just described, the difference being that the actuators are replaced by

controllable dampers. In the design of the semi-active systems, efforts are made to

achieve maximum possible benefits of active suspension technology at reduced initial

and regular maintenance costs.

For semi-active systems, controlled (variable damping force) damper units are needed.

Various types of dampers which can provide variable damping have been proposed in the

literature. These are Hydraulic Fluid Damper, Hydro-Pneumatic Damper, Electro-

Rheological (ER) Fluid Damper, Magneto-Rheological (MR) Fluid Damper, Dry Friction

Damper and Pneumatic Damper etc. Pneumatic (air) Damper is a Cylinder-Piston Type

Damper, using gas / air as its working fluid. These dampers are categorized as a) Gas /

Air Cylinder-Piston and Air Tank Type Damper, in which both the sides of the cylinder

are connected to two air tanks through capillary pipes. The damping effect in the system

is adjusted by selecting length and diameter of the capillary pipe, ratio of tank volume to

cylinder volume and operating gas / air pressure in the system and b) Gas / Air Cylinder-

Piston Type Damper, in which area available for fluid flow is the annular area due to

the difference in the cylinder diameter and piston diameter and this provides the desired

damping effect in the system. Also the Cylinder-Piston and Air Tank Type Air Damper

has a number of advantages over the other types of damper units. The advantages are that

7

it provides a variable damping force, the damping has practically no dependence on

working temperature , there are no long-term changes in damping properties and the

damper has less manufacturing and maintenance costs.

In a Cylinder-Piston and Air Tank Type Air Damper, both the sides of which are

connected to two surge tanks through capillary pipes, an arrangement can be provided to

set the desired damping properties by allowing the changes in (i) Tank volume to

cylinder volume ratio (ii) Operating air pressure and (iii) Capillary pipe length and

diameter. Thus this type of air damper is capable of providing variable air damping ratio

by changing any one of the above parameters or a suitable combinations of the

parameters. Taking into consideration the above mentioned plus points of Cylinder-

Piston and Air Tank Type Air Damper, this damper is used in the research work carried

out.

2.0 LITERATURE REVIEW

A number of theoretical and experimental investigations on the dynamic response of

passive, active and semi-active suspension systems for ground vehicles have been

reported. In these investigations, various aspects of suspension system design such as

ride comfort, road holding, vehicle handling, road safety and reliability have been

studied. An extensive literature survey has been carried out on the above mentioned

and other related topics connected with design of passive, active and semi-active

suspension systems by referring various International and National Journals such as,

Vehicle System Dynamics, Transactions of the ASME : Journal of Mechanical Design,

Journal of Dynamic Systems Measurement and Control , Journal of Vibration and

Acoustics etc., JSME International Journal Series C , IEEE / ASME Transactions on

Mechatronics , Journal of Sound and Vibration, Computing and Control Journal ,

Institution of Engineers (I) Journal, Proceedings of Institution of Mechanical Engineering

(London) , SAE Technical Papers etc. and Proceedings of International Conferences such

as, American Control Conference , IFToMM World Congress , Biennial ASME

Conference on Engineering Systems Design and Analysis , IEEE Conference on Control

Applications etc., and National Conferences on the topics of modeling , dynamic

8

response and performance of vehicle suspension systems. From the literature survey,

some selected research papers have been reviewed, taking into consideration, the

followingaspects. …

i) Studies on basic concepts, types and applications of suspension systems for roaroad

ve vehicles and types of damper units etc.

ii) Studies related to the research work on modeling of suspension systems, theoretical

and experimental analysis, merits and demerits of active, semi-active, slow active and

passive suspension systems for ground vehicles.

iii) The research results on modeling and dynamic response of active control systems,

control system hardware and control system laws etc. .

iv) Studies related to active, semi-active and passive suspension systems: tOptimal values

of damping, methods of optimization etc. Detailed review of about forty six papers

has been presented in Chapter 2 and the list of selected references reviewed and

consulted during the research work is given at the end of the write-up.

3.0 FOCUS OF THE RESEARCH WORK

From the literature review it was observed that a good ride is obtained with relatively

modest damping around 20% critical damping and to minimize suspension displacement

and dynamic tire force, higher damping rates around 40% to 50% critical damping are

required . It implies that the damping provided by the damper unit should be variable. A

conventional passive suspension design cannot satisfy the above requirement since the

values of the spring and damper parameters are fixed. Therefore, it is necessary to

improve conventional passive suspension system with a change in the principle. Such a

change in principle can be effected by the development of semi-active type suspension

systems which are derived from and are closely related to active suspension systems with

a difference that the actuators in the active suspension systems are replaced by

controllable dampers to provide variable damping. Also such systems should be

comparatively less costly, simple in design and requiring less manufacturing and

maintenance costs. In the light of the above discussed requirements of a good suspension

9

system for ground vehicles, “ Some Theoretical and Experimental Studies on Computer

Controlled Pneumatic Semi-Active Suspension Systems for Ground Vehicles ”

(Hereafter in the write-up the Pneumatic Damper is referred to as an Air Damper) have

been carried out in the form of design, development and testing of the developed

suspension system for providing good isolation properties in the neighborhood of

resonance, when it is subjected to the base excitation due to road surface irregularities.

For this purpose, it was proposed

i) To design, develop and test the performance characteristics of an Air (Pneumatic)

Damper based on the Maxwell type model and to formulate design equations for air

damping ratio and air spring rate ratio of the air damper.

ii) To formulate a 2DOF Pneumatic Semi-Active Vibrating System using the developed

air damper with an attendant air pressure control system, to determine the motion

transmissibility characteristics of the main mass, with a view to control the amplitude of

the bounce motion and to determine the optimal air damping ratio of the air damper for

which the motion transmissibility of the main mass is minimum, in the neighborhood of

the resonant frequencies.

iii) To formulate a 2DOF Pneumatic Semi-Active Suspension System using the

developed air damper a with an attendant air pressure control system, to determine the

motion transmissibility characteristics of the sprung mass and unsprung mass, with a

view to control the amplitude of the bounce motion and to determine the optimal air

damping ratio of the air damper for which the motion transmissibility of the sprung mass

is minimum, in the neighborhood of the resonant frequencies.

iv) To design and develop an experimental setup along with a computer controlled air

pressure control system to study the motion transmissibility characteristics of sprung

mass of a 2DOF air damped suspension system at selected values of air damping ratios

and at the selected optimal value of the air damping ratio and to correlate the results of

the experimental analysis with those obtained by theoretical analysis.

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4.0OORGANIZATIONOOFTTHETTHESIS

Chapter 1 : In this chapter , the relevance of the research topic , focus of the research

work and organization of the thesis have been discussed.

Chapter 2: In the past, a number of theoretical and experimental studies on passive,

active, slow-active and semi-active suspension systems for ground vehicles have been

reported in the literature. In these studies, various aspects of suspension system design

such as, ride comfort, road holding, vehicle handling, road safety and reliability have

been investigated. An extensive literature survey on the above mentioned topic was

carried out referring to various International and National Journals, Proceedings of

International and National Conferences etc., in the area of research topic. From the

material collected, some selected research papers have been reviewed.

Chapter 3 : Design, development and testing of performance characteristics of cylinder-

piston and air tank type air damper has been carried out. It has been shown that a

variable damping ratio can be obtained from such a damper, by allowing the changes in

the capillary pipe diameter and length, operating air pressure in the damper cylinder and

the ratio of air tank volume to cylinder volume. Such an air damper has been designed

and its performance characteristics have been obtained when the air damper is modeled

as a Maxwell type model. To test the effectiveness of this damper to control

resonant response, a 2DOF vibrating system has been formulated and analyzed for the

motion transmissibility characteristics of the main mass. (Refer Figure 1, Plate 1 and

Plate 3 )

Chapter 4 : Taking into consideration the necessarily of providing variable damping for

semi-active suspension system , a 2DOF quarter car air damped (pneumatic) semi-active

suspension system has been designed and developed for ground vehicles using the

developed air damper. Equations of motion have been derived and solved to determine

the motion transmissibility characteristics of sprung mass and unsprung mass. The effect

of the parameters such as mass ratio, air damping ratio and air spring rate ratio on the

motion transmissibility characteristics of sprung mass and unsprung mass has been

11

studied. Also the design of a system to control the operating air pressure in the developed

air damper has been presented. (Refer Figure 2 and Plate 3 )

Chapter 5 : The optimal value of the air damping ratio provided by the air damper is

determined i) for a SDOF air damped road vehicle suspension system discussed in

Chapter 3 , ii) for a 2DOF air damped vibrating system described in Chapter 3, and iii)

for a 2DOF quarter car air damped (pneumatic) road vehicle semi-active suspension

system investigated in Chapter 4 .This was necessary because it was observed that, with

the increase in the value of damping ratio of the air damper incorporated in the semi-

active suspension system , there is a limit to reduction of motion transmissibility of

sprung mass and unsprung mass. The curves of motion transmissibility versus air

damping ratio for various values of spring rate ratio have been obtained from which

the values of optimal air damping ratio have been determined. In addition, the effect of

mass ratio on the optimal value of air damping ratio is determined. (Refer Figure 2 ,

Figure 3, Figure 4, Plate 3, Plate 4 and Plate 5 )

Chapter 6 : The development of the experimental setup and the computer controlled air

pressure control system has been presented. Using this the setup , the motion

transmissibility of sprung mass versus frequency ratio curves have been obtained for

certain values of air damping ratio and optimal air damping ratio i) for a SDOF air

damped suspension system discussed in Chapter 3 , with system damping and with air

damper modeled as a Maxwell type , ii) for a 2DOF air damped vibrating system

described in Chapter 3, with system damping and with air damper modeled as a Maxwell

type when mass ratio greater than unity and iii) for a 2DOF quarter car air damped

(pneumatic) semi-active road vehicle suspension system described Chapter 4 when

mass ratio less than unity. For setting of desired air damping ratio, a computer controlled

air pressure control system has been developed. The flow diagram of the operation has

been described. In the air tank system, a facility provided for changing the air tank

volume is described with necessary instrumentation. (Refer Figure 3, Figure 4, Figure 5 ,

Plate 3, Plate 4 and Plate 5 )

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Chapter 7: A discussion of theoretical and experimental analysis has been taken up and

conclusions are presented as follows……

1. The cylinder-piston and air tank type air damper, both the sides of which are connected

to two surge tanks through capillary tubes has been designed and developed for the

suspension system. This arrangement can be used to set the desired damping

properties by allowing changes in i) air tank volume to cylinder volume ratio (pi /Nt )

, ii) the operating air pressure pi and iii) capillary pipe dimensions lpipe and dpipe .

Design equations for k and ζa have been derived and the air damper characteristics

k vs (pi /Nt ) and ζa vs (pi /Nt ) have been obtained to set the appropriate value of

ζa to be obtained from the air damper. Thus the ratio (pi /Nt ) plays a very important

roll in determining the values of air spring rate ratio k and damping ratio of the air

damper ζa. The representation of the developed air damper by the Maxwell type

model is superior to its Vigot type model. From the theoretical and experimental

investigations carried out, it is seen that the addition of the air damping in the system

improves substantially the motion transmissibility characteristics of the sprung mass

of the 2DOF quarter pneumatic (air damped) semi-active suspension system for

ground vehicles over a range of excitation frequencies in the region of resonance.

2. The developed air damper based on the Maxwell type model is effective in controlling

the resonant response of SDOF and 2DOF quarter semi-active road vehicle

suspension systems. Motion transmissibility characteristics of the sprung mass and

unsprung mass of the 2DOF quarter semi-active road vehicle suspension systems

decide the quality of ride comfort to the occupants of the vehicle. The system

damping ratio, mass ratio, air spring rate ratio and air damping ratio influence the

motion transmissibilities of the sprung and unsprung masses.

3. The increasing values of air damping ratio reduce the values of motion transmissibility

in the region of resonance. However, the motion transmissibility of the sprung mass

of 2DOF quarter car semi-active road vehicle suspension system taken for analysis is

a non-linear function of the air damping ratio. This functional non-linearality develops

a limit for reduction of the value of the motion transmissibility, which implies that,

13

there is an optimal value of the air damping ratio for which the motion transmissibility

is minimum. As such, optimal value of air damping ratio has been determined for

suspension systems under investigation. From the results of the analysis, it is seen

that, optimal value of air damping ratio depends also on the value of air spring rate

ratio and for increasing values of air spring rate ratio, the optimal value of air

damping ratio increases with substantial decrease in the motion transmissibility of the

sprung mass. The change in the value of mass ratio in the range 0.1 to 0.5 has no

significant effect on the value of optimal air damping ratio. This result is very

important from the point of optimal performance of the air damped suspension

system.

4. The experimental setup designed and developed with necessary instrumentation has

been used to determine motion transmissibility characteristics of sprung mass of the

suspension system and to compare the results of analysis with those obtained from the

theoretical values of motion transmissibility. A computer interfaced air pressure

control system is useful to control operating air pressure in the air damper to obtain

variable air damping ratio. The experimental results obtained for motion

transmissibility of sprung mass of SDOF and 2DOF quarter car semi-active

suspension systems, for different values of air damping ratio and at optimal damping

ratio, are in good agreement with those obtained from theoretical analysis.

5. The conventional and contemporary passive suspension system is unable to satisfy the

conflicting criteria of ride comfort and handling. Also it is unable to provide variable

damping required for good ride and for minimizing suspension displacement and

dynamic tyreforce. Therefore, it is necessary to improve, conventional passive

suspension with a change in the principle i. e. to develop a semi-active suspension

system, in which controllable dampers are used to provide variable damping as per the

need.

As such, the research work carried out has been focused on the theoretical and

experimental investigations of dynamic response analysis (motion transmissibility

studies) of SDOF and 2DOF computer controlled pneumatic (air damped) quarter car

14

road vehicle suspension systems. From the results of the theoretical and experimental

investigations, it is observed that, there is an overall improvement in motion

transmissibility characteristics of the sprung (body) mass analysis of SDOF and sprung

and unsprung mass of 2DOF quarter car semi-active suspension systems. Substantial

reduction in the values of motion transmissibility in the neighborhood of resonance has

been achieved by the variable damping ratio provided by the developed air damper.

These results are consistent with the objective of the research work.

Thus, from the results of present research work, it is observed that a change in the

principle of passive suspension system to semi-active suspension system is an effective

and feasible solution to satisfy the conflicting requirements of vehicle ride comfort and

handling of a road vehicle. This suspension system is less complex in construction and

less costly as compared to a comparable active suspension system.

The semi-active suspension system designed and developed uses a cylinder-piston and air

tank type air damper of which damping ratio can be varied by changing any one of the

parameters such as, tank volume to cylinder volume ratio Nt, the length lpipe, the diameter

dpipe of the capillary pipe between the damper cylinder and the air tank and the operating

air pressure pi which can be controlled by using computer interfaced air pressure control

system.

The theoretical and experimental analysis of such an air damped semi-active suspension

system shows that the motion transmissibilities of the sprung and unsprung masses of the

vehicle can be effectively controlled at and near the region of resonance. This is an

essential requirement for improving the ride comfort of the occupants of the vehicle.

5.0 CONTRIBUTIONS BY THE RESEARCH WORK CARRIED OUT

TO THE FIELD OF DESIGN OF ROAD

VEHICLE SUSPENSION SYSTEMS

The road vehicle system designers have been constantly seeking solutions to improve the

suspension characteristics of the conventional and contemporary passive suspension

system and to change its principle to have better ride quality, road holding, active safety

and vehicle reliability. The research work carried out has been focused on the theoretical

15

and experimental investigations of dynamic response analysis ( motion transmissibility

analysis) of SDOF and 2DOF computer controlled pneumatic (air damped ) quarter car

road vehicle suspension system with a view to achieve an overall improvement of the

motion transmissibility characteristics of the sprung and unsprung masses of the quarter

car suspension system ( change of principle of passive to semi-active). In the light of the

above mentioned objective, the research work carried out has made some contributions to

the field of road vehicle suspension systems. These are as follows…

1. The design equations for the development of a (pneumatic) Cylinder-Piston and Air

Tank Type Air Damper and expressions for its performance characteristics have been

formulated. The air damper is able to provide a variable air damping ratio and air spring

rate ratio by allowing changes in i) the ratio (pi / Nt ) where pi is the operating air

pressure in the air damper cylinder and Nt is the ratio of air tank volume vt to the air

cylinder volume vc and in ii) the capillary pipe length lpipe and diameter dpipe . A

computer interfaced air pressure control system has been developed to set the desired

value of air damping ratio ζa.

2. Using the developed Cylinder-Piston and Air Tank Type Air Damper, a method of

the theoretical and experimental motion transmissibility analysis is presented. The air

damper has been analyzed using the Maxwell model.

3. A method of optimization of the air damping ratio of the Cylinder-Piston and Air Tank

Type Air Damper has been formulated and is validated by experimental analysis.

4. The air damped semi-active 2DOF quarter car suspension developed and analyzed in

this research work achieves the objective of reducing the motion transmissibility of

the body or sprung mass in the neighborhood of resonant frequencies . It also brings

out the effect of interaction of sprung and unsprung mass motions on the overall ride

comfort achievable by semi-active suspension system.

5. The research work carried out provides a practical solution for the design and

development of a road vehicle suspension system which improves the motion

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transmissibility characteristics of a comparable conventional passive suspension

system, with the added advantage that, the developed semi-active suspension is less

costly, as compared to a comparable active suspension system. The system requires

less maintenance.

6.0 PUBLICATIONS RELATED TO THE RESEARCH WORK

[1] R. G. Todkar and Dr. S. G. Joshi, “Some Studies on Transmissibility Characteristics

of a 2 DOF Pneumatic Semi-Active Suspension System”, Proceedings of the

International Conference on Recent Trends in Mechanical Engineering October 4-6,

2007 Ujjain Engineering College, Ujjain , pp. DES-19 - DES-28

[2] R. G. Todkar and Dr. S. G. Joshi, “Design, Development and Optimization of the

Damping Ratio of an Air Damper for a typical 2 DOF Semi-Active Suspension

System of a Road Vehicle”, Accepted for Presentation at Proceedings of the 9th

Biennial ASME Conference on Engineering Systems Design and Analysis ESDA08

July 7-9, 2008, Halfa, Israel , ESDA2008-59172

[3] R. G. Todkar and Dr. S. G. Joshi, “On the Resonant Response of a 2DOF Quarter Car

Air Damped Suspension System: Effect of Mass Ratio, Air Damper Spring Rate

Ratio and Air Damping Ratio”. The manuscript of the paper has been submitted to

The Journal of Institute of Engineers, (I), Kolkatta.

[4] R. G. Todkar and Dr. S. G. Joshi , “The Effect of Mass Ratio and Air Damper

Characteristics on the Resonant Response of an Air Damped Dynamic Vibration

Absorber ”. The manuscript of the paper has been submitted to The Journal of

Institute of Engineers, (I) , Kolkatta .

[5] R. G. Todkar and Dr. S. G. Joshi, “Design, Development and Testing of an Air

Damper to Control the Resonant Response of a SDOF Quarter-Car Suspension

System”. The manuscript of the paper submitted for International Conference on

Mechanical Engineering (ICME 2010) to be held at Cape Town, South Afrca,

January 27-29 , 2010.

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7.0 SELECTED REFERENCES

1. M. Nagai, “Recent Researches in Active Suspensions for Ground vehicles”, Series C , Vol. 36 , No.2 , 1996 , pp 161-170

2. R.A. Williams, “Electronically Controlled Automotive Suspensions”,Computing & Control Engineering Journal , June 1994 , pp 143-148

3. R.S.Sharp and D.A.Crolla, “Road Vehicle Suspension Design – A Review”, Vehicle System Dynamics, 16 ( 1987 ), pp 167-192

4. C. Kim and P.I.Ro, “An Accurate Full Car Ride Model using Model Reducing Techniques”,Journal of Mechanical Design, December 2002, Vol.124 , pp 697-705

5 . K. Lee, “Numerical Modeling for the Hydraulic Performance Prediction of Automotive Monopipe Dampers”, Vehicle System Dynamics ,29 (1997) , pp 25-39

6. . P.V.Kumar and P.S.Rao, “Vibration Isolation Performance of a Full Car Suspension System Model using Delayed Resonator Vibration Absorber”, Proceedings of The National Conference on Advances in Mechanical Sciences AIMS07 , 22th – 24th March 2007, Sponsored by AICTE , New Delhi , pp 85-90

7. T.R.Gawade , Dr.S.Mukharjee and Prof.D.Mohan , “Wheel Lift-Off and Ride Comfort of Three-Wheeled Vehicle Over Bump ”, IE (I) Journal MC ,Vol. 85, , July 2004 , pp 78-87 8. R.Majjad, “Estimation of Suspension Parameters”, Proceedings of The 1997 IEEE International Conference on Control Applications, Hartford, CT, October 5-7, 1997 , pp 522-527

9. N. Karuppaiah , P.S.Deshapande , C.Sujata and V.Ramamurti , “Vibration Analysis in a Light Passanger Vehicle by Rigid Body / Finite Element Modeling”, Advances in Vibration Engineering,2(2) 2003 © Universities Press (India) Pvt. Ltd., pp 107-120

10 A.Sueoka , T.Ryu , T.Kondu , M.Togashi and T.Fujimoto , “Polygon Wear of Automobile Tyre”, JSME International Journal ,Series C,Vol. No.2 ,1997, pp 209-217

18

11. N.Al-Holou ,A. Bajwa and D. Joo, “Computer Controlled Individual Semi-Active Suspension System ”, Ch 3381-1/93/So1.00 © 1993 , IEEE , pp 208-211

12. J.Wagner , P.E. and X.Liu , “ Nonlinear Modeling and Control of Automotive Vibration Isolation Systems ”, Proceeding of The American Control Conference,Chicago ,Illinois , June 2000, pp 564-568

13. S.Behrens , A.J.Fleming and S.O.Reza Mohermani, “ Passive Vibration Control via Electro-Magnetic Shunt Damping ”, IEEE / ASME Transactions on Mechatronics Vol.10,No.1 , February 2005 , pp 118-122

14. T.Asami and O.Nishihara, “Analytical and Experimental Evaluation of an Air Damped Dynamic Vibration Absorber : Design Optimizations of the Three-Element Type Model”, Transactions of the ASME, Vol. 121, July 1999, pp 344-3425.

15. V.Gavriloski, D.Danev & K.Angushev, “Mechtronic Approach in Vehicle Suspension System Design ”, 12th IFToMM World Congress, Besancon (France), June 18-21, 2007,

16. C.Lauwerys, J.Swevers and P.Sas , “A Model Free Control Design Approach for a Semi-Active Suspension of a Passenger Car ”, American Control Conference , June 8-10 , 2005 , Portland, OR, USA, pp 2206-2211

17. R.D.Cavanaugh , “Air Suspension and Servo Controlled Isolation Systems”, American Control Conference,Hand Book of Sound and Vibration,1970,Chapter 33, pp.33-1 to 33-25

18. S.S.Rao , “Mechanical Vibrations ”, Fourth Edition , Pesrson Education ,Chapter 9 , Vibration Control , pp 657-740

19. Ruzicka Jerome E. and Cavanaugh Richard D. , 1958, “Elastically Supported Damper System Provides a New Method for Vibratiojn Isolation ” , Machine Design , pp 114-121

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( R.G.Todkar ) (Dr. S. G. Joshi )

Research Student Research Guide

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8.0 FIGURES

Fig. 1 SDOF Quarter Car Suspension System with Air Damper (Air Tank System not shown)

01 Sprung Mass 05 Suspension Spring 02 Air Cylinder 06 Slider Plate 03 Piston Rod 07 Slider Guide Bars 04 Spring Positioning Lock Nut 08 Cylinder Locking Nut

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Fig. 2 2DOF Quarter Car Suspension System with Air Damper (Air Tank System not shown)

01 Sprung Mass 02 Air Cylinder 03 Piston 04 Spring Positioning Lock Nut 05 Suspension Spring 06 Slider Plate 07 Slider Guide Bars 08 Cylinder Locking Nut 09 Tyre Spring

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Fig. 4. Experimental Setup for 2DOF Pneumatic (Air Damped) Semi-Active Road Vehicle Suspension System Model (µ<< 1 )

Air supply (2 kg/cm2) Controlled air pressure

(0 to 5 v) (4 to 20 m A) ( (1- 2 kg/sq.cm.)

A/D 1 . Computer D/A 2. V/I converter 3. I / P Converter

4. P / V Converter 7. LVDT1 u(t)

6. LVDT 2 x1(t)

Fig. 3. Block Diagram of the Air Pressure Control System

* The system represents developed air damper system to be connected the vibrating

system of Case I or Case II or Case III depending on the case taken for experimental analysis

G1 (s) *5. Air Damper

Attached to the System taken for Analysis

G2 (s)

G3 (s)

x1 (t) Variable Volume Air Tank No.2

Volume = vt

vc dpipe

LVDT1 for x1 (t) k1, c1 ka , ca

x2 (t) vc lpipe

k2 Variable Volume Air Tank No.1 Pressure Feed Back Signal Volume = vt

u (t) Pressure Transducer

LVDT2 for u (t)

Air Supply at Constant Pressure

A/D computer D/A V/ I Converter I/ P Converter

m2

m1

Model for Experimental Analysis

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9.0 PLATES

Plate 1. Air Damper Cylinder and Slider Assembly

Plate 2 SDOF System with Cylinder-Piston and Air Tank

Cylinder Assembly

Slider Assembly

Suspension Mass m1

Mounting Frame

Suspension Spring

Piston

Cylinder Assembly

Capillary pipes Air Tank System

Instrumentation

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Plate 3. Experimental Setup

1 Speed controlled d. c. motor drive 6 Instrumentation 2 Model mounting plate 7 Pressure Sensor 3 Air Damper 8 Unsprung mass m2 with LVDT 2 4 Sprung Mass with LVDT 1 9 Air tank system with capillary 5 Computer System pipes

Plate 4 Air Tank and Capillary Pipe System.

4

Air Tank System with Capillary Pipes

Pressure Sensor

1

2

3

8

9 een

5 6 7

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Plate 5 Instrumentation

1 Computer System 5 P / V Converter 2 V / I Converter 6 I / P Converter 3 Air Damper 7 LVDT 2 for u(t) with Signal

conditioner 4 LVDT 1 for x1(t) with Signal

conditioner

4 5

3 2

1 7

Sprung mass

Excitation Drive system Sprung mass

6

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