Suspension Control for Full Car Model

Suspension Control for Full Car Model: 

Suspension Control for Full Car Model Presented By : Uzair Khan 1

Presentation layout: 

2 Presentation layout

Suspension systems : 

3 Suspension systems Maximization of the friction between road surface and tyres . To provide the better road handling and ride conditions. Problem is constant suspension parameters. Road Isolation Heave (Vertical) Road Holding Pitch Cornering Roll

Possible suspension control models: 

Possible suspension control models Quarter car model (Only informs about the Heave (vertical motion) of vehicle) Half car model (Information about Heave (vertical motion) and Pitch/Roll motion of the body) Full car model (Information about Heave (vertical motion) , Pitch and Roll motion of the body) 4

Quarter car model: 

Quarter car model 5 Quarter car model (Heave motion) Parameters Notation Suspension stiffness coefficient Suspension damping coefficient Tyre stiffness coefficient Sprung mass Unsprung mass Road disturbance Unsprung mass displacement Sprung mass displacement

Half car model: 

Half car model 6 Half car model (Heave and roll motion) Parameters Notation Suspension stiffness coefficient Suspension damping coefficient Unsprung mass Sprung mass Tyre stiffness Road disturbance Front right tyre displacement Front right tyre displacement Body displacement

8 degree of freedom full car model: 

8 degree of freedom full car model 7

System constant parameters: 

System constant parameters 8 Suspension stiffness coefficients: Suspension damping coefficients: Passenger seat stiffness coefficient: Passenger seat damping coefficient: Tyre stiffness coefficient: Sprung mass (Vehicle body mass): Unsprung masses ( Tyre masses): Road disturbances: Displacement of COG from right body frame: c Displacement of COG from left body frame: d Displacement of COG from front body frame: a Displacement of COG from rear body frame: b

State space representation : 

State space representation 9

State space (Cont’d): 

State space (Cont’d) 10

State space (Cont’d): 

State space (Cont’d) 11

Slide 12: 

System states Front right tyre heave Front left tyre heave Rear right tyre heave Rear left tyre heave Passenger seat heave Vehicle body heave Vehicle pitch Vehicle roll Velocity of front right tyre Velocity of front left tyre Velocity of rear right tyre Velocity of rear left tyre Velocity of passenger seat Velocity of vehicle body Velocity corresponding to pitch Velocity corresponding to roll 12

Model investigation in the presence of road disturbance: 

Model investigation in the presence of road disturbance 13

Road input characteristics: 

Road input characteristics 14

Open loop system: 

Open loop system Road disturbance given to vehicle transmitted from tire to suspension and then to vehicle body. 15

Slide 16: 

Simulation results for open loop system 16

Front right tyre response: 

Front right tyre response 17 Random road profile Road pothole

Front left tyre response: 

Front left tyre response 18 Road pothole Random road profile

Rear right tyre response: 

Rear right tyre response 19 Random road profile Road pothole

Rear left tyre response: 

Rear left tyre response 20 Road pothole Random road profile

Passenger seat heave response: 

Passenger seat heave response Road pothole Random road profile 21

Vehicle body heave response: 

Vehicle body heave response 22 Road pothole Random road profile

Vehicle body pitch response: 

Vehicle body pitch response 23 Random road profile Road pothole

Vehicle roll response: 

Vehicle roll response 24 Road pothole Random road profile

Slide 25: 

Controller implementation 25

Control choices: 

Control choices Semiactive control Active control PD control LQR 26

Slide 27: 

Semiactive controller 27

Semiactive control strategy: 

Semiactive control strategy Its kind of ON/OFF strategy 28

Slide 29: 

Simulation results 29

Passenger seat heave response: 

Passenger seat heave response 30 Road pothole Random road profile

Vehicle body heave response: 

Vehicle body heave response 31 Random road profile Road pothole

Vehicle body pitch response: 

Vehicle body pitch response 32 Road pothole Random road profile

Vehicle body roll response: 

Vehicle body roll response 33 Road pothole Random road profile

Slide 34: 

Active controller 34

Active control strategy: 

Active control strategy 35

Slide 36: 

Proportional Derivative controller 36

PD controller: 

PD controller Using sprung mass error is calculated and then controller works to minimize the error. Where error is computed using vehicle corner displacement. Where 37

Slide 38: 

Simulation results 38

Passenger seat response : 

Passenger seat response Road pothole Random road profi le 39

Vehicle heave response : 

Vehicle heave response Road pothole Random road profile 40

Vehicle pitch response: 

Vehicle pitch response Road pothole Random road profile 41

Vehicle roll response: 

Vehicle roll response Road pothole Random road profile 42

Slide 43: 

LQR based controller 43

LQR controller: 

LQR controller Full state feedback controller, where Gain ‘ ’ is and can be found by satisfying Algebraic Ricatti equation 44

LQR controller (cont’d): 

LQR controller (cont’d) For optimal results the controlled system should have better response for sprung mass so that better road ride (heave response) and holding (roll and pitch) could be achieved . 45

Slide 46: 

Simulation results 46

Passenger seat response: 

Passenger seat response Road pothole Random road profile 47

Vehicle body heave response: 

Vehicle body heave response Road pothole Random road profile 48

Vehicle body pitch response: 

Vehicle body pitch response Road pothole Random road profile 49

Vehicle body roll response: 

Vehicle body roll response Road pothole Random road profile 50

Observer based regulator: 

Observer based regulator Normally all states are not available for measurement, either due to hardware constraint or cost. Thus, the unmeasured states are estimated using state observer 51

Observer based regulator(Cont’d): 

Observer based regulator(Cont’d) 52

Slide 53: 

System response using different control schemes 53

Passenger seat response: 

Passenger seat response 54

Vehicle body response : 

Vehicle body response 55

Vehicle pitch response: 

Vehicle pitch response 56

Vehicle roll response: 

Vehicle roll response 57

Slide 58: 

Performance comparison 58

Conclusions: 

Conclusions For semi active controller, system response has improved by about 36% on average as compared to passive suspension system In case of active controller, system response has significant improvement and disturbance has been reduced more then 90% as compared to passive suspension system. 59

Future suggestions: 

Future suggestions This work could be extended in future so that hardware implementation could be done. Other control strategies could be designed using other control techniques like Sliding Mode Control. Model enhancement can be done by including more degrees in the given Full car model, so that more system characteristics could be found. 60

References : 

References Mouleeswaran Senthil Kumar “Development of active suspension system for automobiles using PID controller” form proceedings of world congress on engineering 2008, Vol 2.2008. UK. “Semi active suspension control” by Emanuele Guglielmino , Tudor Sireteanu Charles W. Stammers , Gheorghe Ghita ,Marius Giuclea . Rahmi GULCU “Active control of seat vibrations of a vehicle model using various suspension alternatives” published in Turkish J. Eng. Env . Sci in 2001. Anil,Prasad.Pravin , Kulkarni “Optimal design of passenger car suspension for ride and road”, published in Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2008 61

Slide 62: 

THANK YOU 62