Studies On Assist Characteristic Of The Automobile's Electric Power Steering By Simulation

Electric power steering system is much superior to traditional steering, and it will also take the place of hydraulic power steering system to be the developing direction for automobile power steering. The assist torque is provided by motor directly in EPS system which resolves the problem of the hydraulic steering system and improves the characteristic of steering control and realizes exactly the request of easy on the low speed and road feel on the high speed.For the assist characteristic of EPS, dynamics model of the system on the base of force analysis is founded. Compared with the P control and the PD control on the system response, the fuzzy PID is chosen as the main control mode.On the studies of three different assist characteristic of EPS, the method of founding curve type assist characteristic is discussed and the curve of assist characteristic is trained offline by neural network. And with the toolbox of MATLAB, the perfect expression of assist characteristic can be obtained. The method of studies on assist characteristic applies to different automobile.In this paper, simulation model of EPS is founded by simulink. With the current control, the closed loop PID control of aim current is finished. The compensate current of damp control can be obtained by the angel rate came from the motor. The result of simulation indicates that the curve assist characteristic can meet the request of both the easy on the low speed and road feel on high speed.