Hybrid Control-Based Acceleration Slip Regulation for Four-Wheel-Independent-Actuated Electric Vehicles

In this article, an enabling hybrid control-based acceleration slip regulation (ASR) method is proposed for four-wheel-independent-actuated electric vehicles by combining the advantages of the maximum-torque-based and slip-ratio-based ASR methods. Considering the dramatic fluctuation of tire slip ratio at low speeds caused by the poor signal-to-noise ratio (SNR) for the vehicle speed, an adaptive maximum torque search method is employed to ensure the acceleration regulation performance at low speeds. With the increasing vehicle speed, the SNR would have diminishing influence so that the tire slip ratio gradually approaches its true value. Under such scenarios, a robust sliding mode control method is proposed to regulate the real-time slip ratio to its optimal value, so as to maximize the tire-road adhesive force. In order to coordinate the driving torques and guarantee a smooth transition process in between, a finite-state machine-based control scheme is further developed. Hardware-in-Loop test results show that the proposed hybrid control-based ASR scheme exhibits good performance and high reliability under various driving conditions.