Robust vehicle longitudinal motion control subject to in-wheel-motor driving torque variations

Driving torque variation which introduces external yaw moment greatly impacts vehicle motion particularly for distributed powertrain vehicles such as in-wheel motor electric vehicles. This paper proposes a weighted gain-scheduling H_∞ controller to compensate for torque variation and track desired vehicle motions. The weighted H_∞ performance is adopted to attenuate the effect of torque variation. A weighting factor is designed to tune the relative importance of external input and torque variation. An eigenvalue placement technique is used to confine the feedback control gain in certain region. The state feedback control gain is calculated by solving a minimization problem. Furthermore, a gain-scheduling scheme is used to incorporate time-varying signals in the system. Simulation studies were conducted on a high-fidelity vehicle model developed in CarSim^®. Results indicate that the designed controller is able to compensate for driving torque variation and track the desired vehicle trajectory simultaneously.