| EHPS(Electro-hydraulic Power Steering)improves many performances of vehicles such as the fuel economy, handle stability and driving security. Make driving more comfortable. At the same time, EHPS can also protect the environment. Therefore, EHPS is becoming the new researching focus of the power steering technic. EHPS is drived by the power from the hydraulic pump which is controled by the motor. The power is decided by ECU through the state of vehicle and the driver's control. Because of the timely control, vehicle can get better handiness and handle stability.The paper decides the design method based on the structure, working theory and perfirmance characters of the important parts. As the request of the systerm, the paper decides to use the linear assistant power character curve to satisfy the need of EHPS. After analysing the control methods, the paper decides to use both rotated speed and current closed PID method which can satisfy both exlent stable capacity and wonderful dynamic perfirmance. To build the united simulation model with AMESim and Simulink after analysing the dynamics of EHPS. The paper does many simulation experiments such as DC simulation, assistant power hydraulic crock simulation and some steering performances tests. The results indicates that the control methods it gets can make sure of protability and road sence of vehicle. EHPS improves the response speed and the handle stability of vehicle effectively. The results provides many important theory data for empolder EHPS.At the same time, we know that united simulation are advanced and effective for analysing the dynamics of EHPS system. |
