Vehicle Dynamics Control for a 4 Wheel Steering Prototype Car

Transcription

1 15 th USER CONFERENCE ROM, November Vehicle Dynamics Control for a 4 Wheel Steering Prototype Car INSTITUT FÜR KRAFTFAHRWESEN AACHEN Dipl.-Ing. Alfred Pruckner Dipl.-Ing. Sven Fischer Overview - Control Strategy - Development Method - Observation - Control - Outlook

2 4 Wheel Steering Control Strategy Vehicle β Steady State Cornering dry road β -3 icy road Wheel Steering Control Strategy Smaller Wheel Base at low velocity

3 4 Wheel Steering Control Strategy Larger Wheel Base at high velocity 4 Wheel Steering Control Strategy Minimize the vehicle side slip angle β β estimation control

4 Overview - Control Strategy - Development Method - Observation - Control - Outlook Virtual Prototyping Measurement Control information

5 Virtual Prototyping Interface und MATRIXx Full Vehicle Model MATRIXx Control algorithm Subroutine Template FORTRAN-files TIRSUB VARSUB C-Code Control algorithm discrete time interval Overview - Control Strategy - Development Method - Observation - Control - Outlook

6 Observation Linear l F - linear tire characteristics - small angles - centre of gravity on the street l R F R ψ. a y F F δ v v c sv + c sh β = m * v ψ lh * c sh lv * c Jz sv lv * c sv lh * c 1+ m * v lv * c sv lh * c sh Jz * v sh c sv β * + m * v ψ lv * c sv Jz c sh m * v lh * c J z sh δ * δ v h β BM. ψ BM = A + B u Observation Linear u y steering angle B yaw velocity lateral acceleration = A + B u A yaw velocity side slip angle

7 Observation yaw velocity [ /s] Observation yaw velocity [ /s]

8 Observation Linear Observer u y x = Ax+ Bu = A + B u+ L ( y ŷ) B A C ŷ + - ~ x = x = A x+ B u [ A + B u+ L( y ŷ) ] L ( ( ) n det I A LC ) = ( 1 ) ~ x = ( A LC)x ~ i= 1 λ i Observation Non-Linear Observer u y f x ( x,u) x = f(,u ) + (,u ) ( x ) x = f f x~ = x = x (,u ) ( x ) L(,u ) ( y ŷ) ( ) ( )( ) = f,u L,u y ŷ L C ŷ - + β F(,u ) = β ψ β β ψ l ψ l ψ 11 1 l l 1 ay β 1 a λ1 y = ψ λ

9 yaw velocity [ /s] Luenberger Observer Luenberger Observer Observation Luenberger Observer Luenberger Observer Observation Wet Road Luenberger Observer Wet Road Luenberger Observer

10 3 Steady State Cornering Luenberger Observer Steady State Cornering Luenberger Observer Observation Luenberger Observer Overview - Control Strategy - Development Method - Observation - Control - Outlook

11 Control Controller = A + B u u u k β y k δ H β = = kβ _ stat δv 1+ i ω T 1+ i ω T Static Transfer Function D 1 B.4 Steering Ratio r / f characteristic velocity larger wheel base at high velocity A smaller wheel base at low velocity Control State Space Controller x = f( x,u) u y f f x = x + u = A x + B u x u Ricatti Equation ( ) ( )( ) = f,u K L,u y ŷ L + - wanted C ŷ - + T ( k + 1) = A ( k) P ( k) A( k) + Q * P K P T { + R} 1 * T * ( k + 1) = P ( k + 1) B( k) B ( k) P ( k + 1) B( k) * T T * ( k + 1) = P ( k + 1) K ( k + 1) B ( k) P ( k 1) +

12 Steady State Cornering 3.. side slip angle [ ] without 4WS State Space Controller Steady State Cornering Control Without 4WS rear steering angle [ ] without 4WS 3.. State Space Controller Controller State Space Controller Steady State Cornering 3.. side slip angle [ ] without 4WS -3. State Space Controller Control 6. Steady State Cornering Without 4WS rear steering angle [ ] without 4WS 3.. State Space Controller Controller State Space Controller

13 6 4 dry road, icy road icy road, state space model icy road, bicycle model icy road, without 4WS dry road y-path [m] x-path [m] Control dry road, icy road Without 4WS side slip angle [ ] icy road, state space model icy road, bicycle model 15 icy road, without 4WS dry road x-path [m] Controller State Space Controller Overview - Control Strategy - Development Method - Observation - Control - Outlook

14 Outlook Virtual Prototyping Software Rapid Prototyping Measurement Control information C - Code 15 th USER CONFERENCE ROM, November Vehicle Dynamics Control for a 4 Wheel Steering Prototype Car INSTITUT FÜR KRAFTFAHRWESEN AACHEN Dipl.-Ing. Alfred Pruckner Dipl.-Ing. Sven Fischer