Integrated robust control of path following and lateral stability for autonomous in-wheel-motor-driven electric vehicles

This paper presents an integrated robust H∞ control strategy for improving path following performance and lateral stability of autonomous in-wheel-motor-driven electric vehicles (AIEV) through integration of active front steering (AFS) and direct yaw moment control system (DYC). The AIEV system dynamics and its uncertain vehicle trajectory following system are first modeled, in which parameter uncertainties related to the physical limits of tire are considered and handled via the norm-bounded uncertainties, then the control-oriented vehicle path following augmented system with dynamic errors is developed. The resulting robust H∞ controller with AFS and DYC (RHCAD) of AIEV trajectory-following system is finally designed, and solved utilizing a set of linear matrix inequalities derived from quadratic H∞ performance and Lyapunov stability. Meanwhile, the performance index of H∞ norm from external disturbance to controlled output for AIEV path following is attenuated while other system requirements such as parameter uncertainties, system constraints are also guaranteed in controller design, and then the quadratic D-stability is also utilized to enhance the transient response of the closed-loop AIEV system. Simulations for J-shaped, single lane change and double lane change maneuvers are carried out to verify the effectiveness of the proposed controller with a high-fidelity, CarSim®, full-vehicle model. It can be concluded from the results that the proposed robust H∞ control strategy integrating AFS and DYC can improve the path following performance and lateral stability of AIEV compared with traditional linear quadratic regulator controller with AFS (LQRA) and robust H∞ controller with AFS (RHCA).