Hardware-in-loop Simulation And Research For Automobile Electric Power Steering System

As the number of FF car is increased and there is more loading on the front suspension, people widely pay more attention to the steering handiness of automobile. The power steering system can not only solve the conflict between steering handiness and steering agility, but also improve the safety and comfort of driving. Therefore it had been widely used nowadays.Traditional hydraulic power steering system has to consume energy, whether or not it works. So it will increase the additional consumption of gasoline. The electric power steering system (hereafter call it EPS) totally abolishes the hydraulic instruments and uses electric power to substitute the hydraulic power. As a result, it decreases the consumption of gasoline. It is in coincidence with the titles of safety, environment protection and energy saving to research and develop EPS. Thereby it really means a lot for today and tomorrow.One hardware in the loop simulation (HILS) system of automotive electric power steering is designed and set up, which can use the MATLAB/Simlink to improve the efficiency and effect of developing EPS control strategy. In this system two kinds of control strategy, controlled by proportion and controlled by proportion&differential (PD), have been tested and evaluated.Control on the assistant power is one basic control strategy. The controller determines the goal current of electromotor in accordance with the signals from steering wheel torque sensor and car speed sensor. Then the current controller will dominate the current for electromotor to give the needed assistant torque. There are two primary problems for EPS control. One is to determine the goal current of electromotor, the other is to trace and adjust it. The goal current of electromotor is determined by assistant torque curve map. The current for electromotor is modulated by means of PWM.Via the experiments on hardware-in-loop simulation EPS platform, not only the possibility of EPS system is confirmed, but also the influence of EPS for automobile feather and the difference between two kinds of control strategy are found out. Furthermore, hardware -in-loop simulation experiment is better than traditional real object experiment in many ways, such as safety, economy, convenience, repetition, etc.