Research on control strategy of vehicle electric power steering system.docVIP

Research on control strategy of vehicle electric power steering system 　　Abstract：The structure and working principle of steering column-power type electricpower steering（EPS）system were introduced.The control strategy and assist characteristics of EPS system were designed.Torque control strategy of power steering motor was designed based on the research of structure and control method.Power steering tests were completed in the EPS system test bench.The test results showed that the designed control strategy is effective. 　　Keywords：electric power steering（EPS）；control strategy；assist characteristics；steering test. 　　Introduction 　　Electric power steering system（EPS）is a new type of automobile power steering system which has many advantages such as saving energy，environment protection and assist characteristic，etc.The research about EPS system is mainly focused on the selection of the booster motor，the optimization design of controller and control strategies[1，2]. 　　When the driver operates the steering wheel，the sensors detect a variety of signals such as steering torque signal，vehicle speed signal，engine speed signal processing and other types of signals and send it to the ECU.Based on the respective signals sending to the ECU in which the working conditions of vehicle can be determined，power-assisted was controlled through the torque signals，road feeling was controlled by the speed signal，then power-assisted motor output the torque of the working conditions，the reduction mechanism reduce speed and increase torque，then amplified the torque again on a rack and pinion steering gear to achieve the power-assisted steering role.When the torque of steering wheel amplifies，the motor increases torque to ensure the portability of steering.At higher speeds，the torque is reduced in order to obtain a better road feel[3，4]. 　　System overall control strategy 　　The EPS system is based on the traditional mechanical steering system and increased of the electronic control