Integral Sliding Mode for the Yaw Moment Control of Four-Wheel-Drive Fully Electric Vehicles with In-Wheel Motors

Fully electric vehicles with individually controlled motor drives allow the continuous actuation of direct yaw moment control in order to enhance vehicle safety and the handling performance by achieving a set of reference understeer characteristics. For applications on real vehicles, the control structure must provide ease of implementation, robustness and tunability. This paper discusses an integral sliding mode formulation for torque-vectoring control, which fulfils these requirements. The control structure is presented with reference to the vehicle cornering performance objectives, the motivation for integral sliding mode control and the selection of the controller parameters for stability and chattering avoidance. Six different manoeuvres are simulated for an in-wheel electric motor drivetrain layout. The results show that integral sliding mode control has significant benefits over a more conventional control method based on a combined feedforward and proportional-integral-derivative controller. The integral sliding mode controller does not require fine tuning of a feedforward control action and is characterised by superior tracking performance and disturbance rejection properties.