Design and application of a tire slip energy control scheme based on optimal guaranteed cost theory for four-in-wheel drive electric vehicles

In this paper, vehicle stability with time-varying tire cornering stiffness and tire slip energy torque distribution is investigated for four-in-wheel motor drive electric vehicles thanks to the control flexibility. On the issue of tire slip energy, a scheme of "semi-empirical tire slip energy model" is proposed and analyzed. In this scheme, the hierarchical control method is used to reduce tire slip energy and improve vehicle stability. In the outer loop controller, cost control is designed based on optimal guaranteed cost theory, which is compared with the traditional linear quadratic regulator. The integrated control method of active front steering and direct yaw moment control is evaluated and studied from the cost perspective by norm-bounded uncertainty. Finally, the simulation results verify that the control framework considering time-varying uncertainty has significant advantages under the condition of high-friction coefficient single-lane change and low-friction coefficient slalom change. Compared with the linear quadratic regulator and the minimization of tire slip energy control, the control framework with optimal guaranteed cost can achieve smaller sideslip angle; meanwhile, it can save more tire slip energy.