2.6 Modeling Assumption 13
2.7 Four Degree of Freedom 4DOF Vehicle Model for Heave and Pitch Motion
13
2.8 Decoupling Transformation 19
CHAPTER 3 METHODOLOGY
21
3.1 Introduction 21
3.2 Mathematical Equation Derivation 21
3.3 MATLAB Simulink Modeling 22
3.3.1 4-DOF Vehicle Model
22 3.3.2
Decoupling Transformation Model 25
3.3.3 PID Control Model
26 3.3.4
PID Control Model 28
CHAPTER 4 RESULTS AND DISCUSSION
34 4.1 Introduction
34 4.2
Vehicle Body’s Vertical Displacement 35
4.3 Vehicle Body’s Pitch Angle
37 4.4 Suspension Deflection
40 4.5 PID Controlled Strategy Response
44 4.6 Fuzzy Logic Controlled Strategy Response
45 4.7 Comparison of the Control Strategies
46
CHAPTER 5 CONCLUSION
47 5.1 Conclusion
47 5.2 Recommendation
47
REFERENCES 48
APPENDICES 51
LIST OF TABLE
NO. TITLE
PAGE
3.1 Parameters used in the MATLAB Simulink model
23 3.2
Values used to tune the PID controller 27
3.3 Rule based used in the Sugeno Fuzzy controller
31
LIST OF FIGURES
NO. TITLE
PAGE
2.1 Vehicle suspension System
5 2.2
The active suspension system 7
2.3 Closed loop control scheme of the time separation method
9 2.4
Active filtered feedback control system 10
2.5 Block of the PID controller
11 2.6
Fuzzy logic structure model 12
2.7 4 DOF pitch plane vehicle model.
14 2.8
The free body diagram of the 4 DOF pitch plane vehicle model
14 2.9
Sprung mass position due to pitching motion 16
2.10 Pitch moment due to vehicle acceleration
18 2.11
The active suspension system 19
3.1 Subsystem of the 4 DOF passive suspension system
22 3.2
Road Bump Profile 24
3.3 Time delay between the front and rear wheel road input
25 3.4
MATLAB Simulink
model of
the decoupling
transformation Equation 25
3.5 The MATLAB Simulink model of 4 DOF active
suspension vehicle model using the PID controller 27
3.6 The MATLAB Simulink model of 4 DOF active
suspension vehicle model using the Fuzzy Logic controller 28
3.7 Fuzzy Logic Control module.
29 3.8
The Fuzzy Inference System editor. 29
3.9 The error and error rate signal of the vertical displacement.
30
3.10 Membership function plot for error signal
30 3.11
Membership function plot of the error rate signal 30
3.12 Fuzzy logic rule base surface
32 3.13
The Passive, PID active and Fuzzy active suspension system control structure.
33
4.1 Vehicle vertical displacement of passive, PID controlled
and Fuzzy Logic controlled suspension system 36
4.2 Comparison of the vehicle vertical displacement of
passive, PID controlled and Fuzzy Logic controlled suspension System
37
4.3 Vehicle pitch angle of passive, PID controlled and Fuzzy
Logic controlled suspension system. 38
4.4 Comparison of vehicle pitch angle of passive, PID
controlled and Fuzzy Logic controlled suspension system 39
4.5 Front suspension deflection of Passive suspension system,
PID controlled active suspension system and Fuzzy controlled active suspension system
41
4.6 Front suspension deflection
42 4.7
Rear suspension deflection of Passive suspension system, PID controlled active suspension system and Fuzzy
controlled active suspension system 43
4.8 Rear suspension deflection.
44
LIST OF SYMBOLS
= Distance if the Front Axle from C.G.
= Distance of the Rear Axle from C.G.
= Front Suspension Damping
= Rear Suspension Damping
= Front Actuator Force
= Front Actuator Force
= Force Exerted by the Front Damper
= Force Exerted by the Rear Damper
= Force Exerted by the Front Spring
= Force Exerted by the Rear Spring
= Force Exerted by the Front Wheel
= Force Exerted by the Rear Wheel
= Vertical Force
= Height of C.G. from the Ground
= Moment of Inertia of Pitch
= Front Suspension Spring Stiffness
= Rear Suspension Spring Stiffness
= Front Tire Spring Stiffness
= Rear Tire Spring Stiffness
= Mass of Vehicle Body
= Pitch Moment
= Mass of the Front Wheel
= Mass of the Rear Wheel
= Negative
= Negative Big
= Negative Small
= Positive
= Positive Big
= Positive Small
= Time
= Settling Time
= Longitudinal Acceleration of the Vehicle
= Zero
= Body Vertical Acceleration
= Front Body Vertical Displacement
= Rear Body Vertical Displacement
= Front Body Vertical Velocity
= Rear Body Vertical Velocity
= Front Wheel Vertical Displacement
= Rear Body Vertical Displacement
= Front Wheel Vertical Velocity
= Rear Wheel Vertical Velocity
= Front Wheel Vertical Acceleration
= Rear Wheel Vertical Acceleration
= Pitch Angle
= Pitch Acceleration
LIST OF APPENDICES
APPENDIX TITLE PAGE
Figure A MATLAB Simulink model of 4 DOF passive
suspension vehicle model 51
Figure B Passive suspension system, PID controlled active
suspension system, Fuzzy logic controlled active suspension system, MATLAB Simulink model
comparison 52
Figure C 4 DOF half car pitch plane passive suspension model
52 Figure D
4 DOF half car pitch plane active suspension model 53
CHAPTER 1
INTRODUCTION
