Vehicle Lateral Stability Control Research And Simulation Analysis Based On Differential Braking

Cars in the driving process, due to the load transfer, the decrease of tire cornering stiffness, a sharp turn, change of emergency lane, the road slippery, interference, driver’s improper operation, such as reason. Cars will be loss of lateral stability, that will cause some dangerous conditions of shock, sideslip, spin and so on. Aiming at this problem, This paper designed a kind of vehicle lateral stability control system, to control the critical steady-state conditions of automobile and prevent the cars into the unsteady condition of turn, sideslip and spin uncontrollable. Details are as follows:(1)The seven degrees of freedom vehicle dynamic model and the linear theory of two degrees of freedom vehicle model are firstly established in this paper, and determined the yaw rate and the sideslip angle which can characterize the car stability as the control variable of the control system.(2)Through the deviation of actual yaw rate, actual sideslip angle and its respective expectations, then to determine whether the car is in a state of instability or has the trend of lose the steady through the phase plane method. If instability, then on the basis of the deviation of yaw rate and front wheel angle, apply the brake of differential braking on the corresponding wheel to form the additional yawing moment, to offset the yawing moment which cause the car’s lateral spreads to make the car drive back to a stable state.(3)This paper adopted fuzzy control method which has a good robustness and good adaptability for vehicle lateral stability as the control measures of the control system. And builted combined fuzzy controller which can make up the deficiency of controller which only based on the yaw rate or the side slip angle, let the car can better keep the movement track and good stability.(4)Finally, builded the overall vehicle lateral stability control system through the Matlab/simulink, and verify the effectiveness of the vehicle lateral stability control system respectively under the different steering input conditions. The simulation results show that,the vehicle lateral stability control system make the yaw rate can better tracking its expectations, and greatly reduced the overshoot and amplitude of the yaw rate, sideslip angle and the lateral acceleration. Thus greatly improve the car driving stability, ensured the car in a relatively stable state, The results also show that the control system designed in this paper is feasible and effective.