Direct yaw-moment control design for in-wheel electric vehicle with composite terminal sliding mode

In this paper, a direct yaw-moment control strategy based on the adaptive terminal sliding mode (TSM) control technique and disturbance observer (DOB) is developed to promote the safety driving under extreme situations for in-wheel electric vehicles. First of all, the ideal yaw rate is calculated through a two-degree-of-freedom vehicle model. A traditional TSM control scheme is designed to ensure that the yaw rate can approximate the ideal value as closely as possible. Since a large gain is always needed in the TSM controller to overcome the unknown disturbance, an adaptive TSM controller is constructed to attenuate the chattering. The key merit of the proposed adaptive TSM controller lies in that it can automatically search the minimum gain satisfying the reaching condition of sliding mode. To further facilitate the performance improvement, a new nonlinear DOB is constructed to estimate the disturbance and a composite adaptive TSM control framework is designed by combining the proposed adaptive TSM controller and the given DOB. Simulation results under a professional software verify the presented methods.