The Research On Control Strategy And Design Of Collectivity Scheme Of Commercial Vehicle EPS

Electric Power Steering System (EPS) is a new type steering system, which can save energy, improve vehicle safety, and benefit environment protection. It's a new-high-tech that follows modern vehicle development topic closely. EPS is much superior to hydraulic power steering system. It will be the inevitable developing direction for automobile power steering.The electric power steering system of commercial vehicles has been studied systematically in this Paper by using multi-disciplinary knowledge of automotive engineering, human engineering, automatic control and electromechanical integration. The research selects SX3042GP face-lifting vehicles as the equipped target models of electric power steering system of commercial vehicle, and chooses the solution of cycle- ball electric power steering system in consideration of the steering performance and installation space with target vehicles. This solution combines the motor, worm gear reducer, and cycle-ball steering into a compact system and has many advantages, which are convenient to use, secure, energy saving and pollution-free. The paper adopts the BI torque position sensor of 5-output signals, the permanent magnet brushless DC motor, and the worm gear reducer. It is confirmed that B's curve is the characteristic of EPS power system and its corresponding characteristic parameter.On basis of EPS, the dual degree model of vehicles, the mathematical model of steering system and motor, and mathematical model of PID controller, the simulation model of MATLAB / Simulink are built to analyze yaw angular velocity response under the step input of torque of steering dish. The result shows that the vehicle that loads the PID controller improves dramatically in the following aspects: the torque step input, the overshooting number of yaw angular velocity response and the simulation time. The logic of border conditions of EPS system control strategy were studied, including the power control, aligning control, damping control and the inertia, friction and damping compensation control.