Dynamic Research Of Vehicle Electric Power Steering System Based On Virtual Prototyping Technology

The steering system is used to control vehicle driving direction, its performance affects the comfort and safety of vehicle directly, so the research on steering system is one focus of the vehicle dynamics research. Electric Power steering system is a dynamic steering control system which can supply assist torque according to the state of motion and driver's steering requirements on different road conditions. Vehicle equipped with EPS can meet the requirements of the higher maneuverability for low-speed steering and the better stability for high-speed steering. Electric Power Steering Systems have advantages over conventional mechanical steering systems or hydraulic assist systems by improving fault-tolerant, anti-jamming performance, fuel economy, low-temperature startup performance, safety and environment protection, which makes EPS the key point of current steering system research and vehicle technology development.Virtual Prototype Technology(VP) is based on kinematics, dynamics and theory of control. Three-dimension computer graphical technology, net-work technology, informatics and other modern technologies are used to make VP more advantageous and easier for modeling and simulation of mechanical systems. It's the future trends of modeling and simulating full vehicle system with VP.Vehicle dynamic model, which contains suspension, steering, chassis, tire, brake and road subsystems, is built in ADAMS. EPS control model is also built in MATLAB/Simulink, whicl includes steering model, assist character, current PID closed loop controller, PWM module and motor model. Co-simulation technology is used in this paper to link the control model established in MATLAB to the mechanical model established in ADAMS. Rack assis force is the input of mechanical model, and it is also the output of control model. The outputs of mechanical model, wheel steering torque, wheel steering angle and signal of vehicle speed, are used as the inputs of control model. Co-simulation results verify the control strategy is effective in improving maneuverability and stability.The method of co-simulation is a feasible way to study the kinematics and dynamics of EPS, it can provide guidance and reference for EPS or other mechanism product research and development.