Simulation And Optimization Of Vehicle Dynamic Control System

Following the development of automotive industry, vehicle handling and stability gain more attention and dynamic control has been widely studied now. ABS (Anti-lock brake system) and TCS (Traction control system) prevent the wheel lockup and the vehicle spins during the vehicle traction and braking operations, but do nothing in vehicle turning. With the development of science and technology, VDC(Vehicle Dynamic Control) system came out. It is compatible superior functions of ABS and TRC, which can enhance the vehicle stability and handling in the emergency situations through the control of traction and braking forces at the individual wheels, greatly reducing the occurrence of accidents and injuries.Vehicle turns to nonlinear behaviour of limiting condition when taking high-speed-turning, lane-change or brake-in-turn. Individual wheel's lateral stiffness rapidly decline then. Vehicle loses control response of driver and deviates from the desired trajectory, which easily leads to oversteering or understeering, especialy in low attachment icy road conditions. VDC's ECU(Electronic Control Unit) can infer the driver's intention based on sensor signals and control logic works out stable yaw moment based on the difference between actual and nominal vehicle states. Then, ECU adjusts vehicle's lateral force by controlling individual wheel's slip ratio, making vehicle running as driver's intent.For stability control is complicated, based on theoretical studies of the basic principle of vehicle stability this paper discusses stability control strategy, including handling and stability characteristics of tire's lateral characteristic, road condition, steering angle, and velocity.A multi-body dynamic model was built with MSC.ADAMS which was used widely in vehicle simulation field. Several kinds of control methods were designed for the VDC model based on the feedback of side slip angle and yaw rate, including threshold control, PID control and fuzzy control. Dynamic model and control model were co-simulated by MATLAB and ADAMS/Control through TCP/IP connection. Control parameters were analyzed and optimized by DOE, GA(Genetic Algorithm) and SA(Simulated Annealing) with iSIGHT platform. The research indicated that the lateral stability of vehicle and handling could be enhanced by any VDC control method which could adapt all kinds of road and driving condition.