Research On Integrated And Coordinate Traction Control System For 4×4 Light-duty Vehicle

Traction Control System is a new active safety control system which can enhance the handling stability, steering and acceleration performance of vehicle by preventing the driving wheels from spinning.As Traction Control System controls the slip ratio of driving wheels to the optimal slip ratio, it can ensure great acceleration as well as lateral stability.TCS control unit computes vehicle speed and the target slip ratios of driving wheels using the collected wheel speeds and accelerations, then keep the wheel actual slip ratio to the target value by adjusting the engine torque and braking at spinning wheels.TCS has been studied in abroad for decades and already in manufacturing but it is still in studying phase in china. So it is of great importance to develop mature technology of TCS control unit and TCS control algorithm.Based on the theory and practical experience of the lab, the paper presented a hardware design process for a light off-road vehicle at frist. the process including: selection of microprocesser, design of the minimum system of singlechip , the structure study and hardware design of actuators.Then the control algorithm is studied,which comprises engine throttle control based on PID, logic threshold contorl of braking and the logic for shifting control when TCS is active.After validation of the TCS control algorithm under diferent road condition in Matlab/Simulink,the structure of the hardware in the loop test bench platform is proposed and the platform is built,and the hardware in the loop simulation of TCS control algorithm is carried out. The content of this paper includes:1. TCS hardware design After analyzed the structure of TCS control unit and input/output signals, the control unit is designed based on the 32 bits microprocessor MPC565 which is one of Freescale production.The minimum system includes: power supply circuit, clock circuit and reset circuit. The peripheral circuit includes: the wheel speed collection circuit which is designed based on the characteric of the wheel speed signal and can collect the wheel speed preciseness; The analog signals and switch signals collection circuits which can collect the signals such as acceleration padel signal, longitudinal and lateral acceleration signals, yaw rate signal and all kinds swith signals used in TCS control. The driving circuit for the solenoid valve including fault self-diagnose function is designed so that hydraulic regulation unit can increase, hold and decrease wheel cylinder pressure according to the PWM signals generated by MPC565. The structure of electronic throttle is studied and hardware circuits for electronic throttle control unit are designed. The RS232 serial communication circuit is designed so that the microprocessor can communicate with PC.CAN communitation circuit is desined for multi-ECT communication amoung TCS ECU, electronic throttle ECU and transmission ECU.2. TCS software designAn in-depth study about TCS control algorithm is carried out and throttle control algorithm based on PID and logic threshold braking congrol algorithm driving wheels braking control based on analyse of the threshold calculation principle are proposed. TCS oriented AMT control logic is proposed based on the analyse of influence of shifting when TCS active.the general scheme for modelized TCS control algorithm and the realization of the sub-routines including wheel speeds calcution ,vehicle speed calculation and target wheel speeds compution,TCS control algorithm and muti-ECU communication are proposed.3.TCS software and hardware in the loop simulationThe TCS off-line simulation plantform including vehicle model, engine model, AMT model,final drive and deferential modle,tyre model, dirver model is built based on the vehicle dynamic modle and TCS control algorithm prototype under Matlab/Simulink. software in the loop simulation of TCS algorithm for homogeneous low mue road,split-mue road and mue-jump road is carried out.the simulation results show that the off-line plantform can fulfil the development of TCS algorithm;TCS control algorithm can provent the driving wheel from spinning and keep the slip ratio to the target slip ratio effectively.The down-shift caused by throttle control and braking control may impair the acceleration and stability of v(?)hicle, this can be eliminated by the TCS oriented AMT control logic.TCS hardware in the loop test bench is built according to the TCS hardware in the loop test bench blue print. The test bench comprises system software, test bed, sensor and actuator, real time plantform and signal-collection system. The TCS ECU and electronic ECU are tested and hardware in the loop simulation of TCS based on control algorithm prototype under multi-conditions are carried out.the simulation results show that TCS control algorithm proposed in this thesis can prevent the driving wheels from spinning and enhance the acceleration performance of vehcile effectively. The AMT conrol logic can stabilize the shiftand ensure the stability of vehicle when TCS active.