Active return control of EPS based on model reference fuzzy adaptive control

Returnability is one of the most important performances of Electric Power Steering system (EPS). In order to have safe driving feel and comfort maneuverability on cornering, the improvement of return-to-center performance of EPS is required. This paper proposed a novel active return-to-center control strategy based on model reference fuzzy adaptive control. The reference mode of return characteristics is a frictional resistance optimized steering system model, while the adjustment mechanism of adaptive controller is designed based on fuzzy logic method. The proposed control strategy can cope with the parameter uncertainty of EPS. Moreover, the EPS return-to-center process can also be easily designed and tuned according to the customer requirements. Off-line simulation confirms the effect of proposed active return control method. By using the dSPACE rapid prototyping bypass tools, the returnability performance at low vehicle speed is verified on a vehicle test.