Key Technologies Research Of EPS Controller For Commercial Vehicles Based On CAN Bus

The EPS system is a new-high-tech that follows modern vehicle development topicclosely, which represents the future of automotive steering technology development trend.The application scope of the EPS system is range from the first passenger cars to the largercommercial vehicle direction. With the development of the modern automobile electronicnetwork technology, as well as the CAN bus communication appears, which provides a newrevelation for the development of the EPS system that must support the CAN buscommunication protocols, so as to communicate with other electronic control systems in thecar, which can increase the power performance and improve the vehicle’s active safety.Therefore, development of commercial vehicle EPS controller that supports CAN bus willhave important utility value and practical significance.The thesis selected a medium truck loading4T as the target, through the analysis of thetarget model’s dynamic characteristics, we got the key control parameters of the power curveand then developed MC9S12XDP512processor as the core of the controller, which supportedCAN communications. In terms of the hardware circuits, the author established the controlnodes network of the EPS, mainly developed the power conversion circuit, the input signalregulate circuits, the power drive circuit, the CAN communication circuit, the fault detectioncircuit, then processed the H-bridge drive circuit simulation analysis with Multisim10.1, theresults of which showed that the circuit has a stable and reliable electrical characteristics. TheSoftware was added modular design concept to optimize the power control mode of EPSsystem, then writed the software control program, for the power motor current servo control,the paper proposed an incremental digital PID closed-loop control software design scheme.The thesis added the motor compensation control strategy in the basic control strategy of theEPS, and introduced the actual steering wheel angle signal in the back to control mode,meanwhile, used the measured motor speed as the basis parameters in the damping controlmode. Finally, through the bench performance testing, which the result shows, thecorresponding controller module hardware and software design has been basically to meet thecontrol requirements.