Distributed Nested PI Slip Control for Longitudinal and Lateral Motion in Four In-Wheel Motor Drive Electric Vehicles

An innovative hierarchical feedback architecture is proposed and simulated to control both the longitudinal and the lateral dynamics of Four In-Wheel Motors (4IWMs) drive electric vehicles. The Motion Planning Layer (MPL) generates the required vehicle longitudinal and lateral speeds and yaw-rate on the basis of the driver commands. The Motion Control Layer (MCL) generates saturated slip references for the 4IWMs so that slip constraints are met. The Actuator Control Layer (ACL) is responsible for distributed motor slip tracking and for online estimation of load torque for each tire. The key innovative feature is to operate a slip distributed control, so that slip tracking instead of torque tracking are implemented for the IWMs, which allows independent on line load torques estimation. An illustrative moose-test simulation is performed using CarSim models.