The Controller Development 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 direction for automobile power steering.The dissertation selected SX3042GP face-lifting vehicles as the equipped target models of electric power steering system of commercial vehicle, and developed MC9S12DG128 processor as the core of the controller. In this dissertation, the principle of the EPS, hardware circuit and software design are described in detail.Besides detailedly researched the controller on both hardware and software, the dissertation also did the matching of the system according to the characters of the vehicle and the circumstances the vehicle was in. On the frame of hardware, we devided the resources of the ECU, and designed the circuits of motor driving and the voltage-lifting, and we design the reactive circuit of the motor's rotating speed and suitably arranged the module power, in addition to these, we also design the circuits for the signal capture and part of self-diagnosis circuit. On the software, the control methods have been lead into the research, and the PID controller was used to carry on the control to this system.We confirmed the parameters of proportion and differential. Force aiding, damping and returns of the three control mode has been analyzed.combined with the demand of driving and the characteristic of the driving condition,the three methods of control were held according to different instance on the programme.Based on these functions, the identity of stability and maneuverability of the vehicle can be changed and the easement of the driver can also be promoted .The software of the controller was accomplished.The software of EPS system is structured by modules, and every module is responsible for a group of related functions, while the interfaces between the modules are realized through the global variables or global functions. The system has the elementary function of self-diagnosis, and it ensured the safety of driving. The intention can be basically fulfilled by debugging both the hardware and software.