A Robust Lateral Dynamics Control Scheme for a Human-Driven Four-Wheel-Independent-Steering Electric Vehicle

Abstract A four-wheel independent steering (4WIS) electric vehicle (EV) has a separate steering motor for each wheel, for a total of four motors. The existing works on the path-following control of these EVs mainly focus on path-following on level surfaces, neglecting (a) yaw disturbances due to motor faults, side winds, split mu; and (b) uncertainties in tire/road conditions and vehicle mass. A robust lateral dynamics control system (LaDCS) addresses these two items. This paper designs the LaDCS using a nontrivial modification of J. Ackermann's decoupling control, which lets the human driver focus on steering the EV, instead of also attending to items (a) and (b) above. LaDCS uses a structured singular value (SSV) synthesis-based controller to control each of the subsystems arising from the decoupling control. In simulations of path-following by a human-driven 4WIS EV in the presence of items (a) and (b), using the nonlinear model of the EV, the reduced-order versions of these SSV controllers ensure the desired performance within a degradation limit of 5%.