Abstract: Based on establishing the mathematical model of electric power steering system (EPS)，a method for estimating the state of steering wheel by the combination of the moment signal measured by steering wheel moment sensor and the estimated steering angle, then the fuzzy proportion derivative (PD) control strategy is applied for conventional power-assited or self-aligning control. The simulation results show the steering moment decreases apparently under in-situ and low speed condition, the returnability is improved remarkably. Moreover, the electronic control unit (ECU) is designed on the basis of control strategy. For verifying the feasibility of software and reliability of ECU, the comparison vehicle test is carried out on the vehicle equipped with the self-developed EPS and without EPS respectively according to the relative national standards. The test results indicate that the practical effectiveness of self-developed EPS system is consistent with the simulation results.

Key words: Control strategy, Electric power steering system, Mathematical model, Vehicle test