The Fault Tolerant Control Of Vehicle Stability System Based On Sliding Mode Method

As the development of automotive industry, the information, environmental pro-tection and active safety become more and more important. At the same time, various electronic control systems emerge in large numbers, the structures and algorithms of them become more advanced and complex. ESP (Electronic Stability Program) is available to control the stability of vehicles. It considers the yaw stability control of vehicles than prior ABS (Anti-lock Braking System) and TCS (Traction Control System). It ensures vehicles track the desired trails and keep stability while under-steering or over-steering even some vehicle fault occurs, such as sensor or actuator faults.The main reason of missing stability and significance of yaw rate and side slip angle to control vehicles stable are analyzed in this thesis. We assume that one of the four arrester broke down, zero output of brake torque. According to the major method of ESP, a yaw stability and fault tolerant controller is presented based on sliding mode control theory which has strong robust performance. It can well keep vehicles insensitive against the fault and control vehicle track the desired yaw rate and side slip angle while cornering or changing path on the low adhesion coefficient road, then ensures vehicle driving stability.The proposed controller consists two parts. First, a two degree reference mode is provided to calculate the desired yaw rate and side slip angle according to the velocity and the steering wheel angle. An effective yaw moment controller is designed based on sliding mode method to obtain the desired yaw moment for vehicle stability. And then the relationship between the desired yaw moment and slip ratio is established to convert the control of yaw moment into longitudinal tire slip ratio through vehicle dynamics theory and Magic Formula. Then the select strategy of active braking wheel is proposed. Taking the deviation of desired and actual slip ratio as controller input, an active braking controller is designed based on sliding mode method to output braking torque of the four wheel. Finally, the co-simulations based on Simulink/Matlab and AMEsim shows the effectiveness of the presented controller based on sliding mode method.