Returnability control algorithm for EPS system of electric bus

In order to enhance the returnability of electric power steering(EPS) system of electric bus, the fuzzy PID control algorithm is developed. According to the angle and speed of rotation detected by related sensors, the aligning voltage is controlled as system output by fuzzy PID theory in order to make the steering wheel reset to the mid-position. The fuzzy PID controller for the system is designed, which combines the advantages of fuzzy control and PID control, and can amend the parameters of PID controller on-line. Using the designed algorithm, the returnability of EPS system is improved. The simulation and test show that the control strategy can improve the wheel returnability at low speed and restrain the aligning overshoot at high speed without any adverse effect on driver's steering feeling.