Vehicle stability enhancement by using an active differential

Abstract

The paper investigates the improvement of vehicle dynamic performance by the use of a rear, electronically controlled, limited slip differential. This control is based on the vehicle yaw rate, rear wheel slip values, and braking subsystem on the front wheels. An optimal linear quadratic regulator (LQR) controller is employed together with an elaborate six-degree-of-freedom linear vehicle model. The objective is to include the important effects of roll and steering dynamics into the controller design. For simulation purposes, the optimal controller is included in a nine-degree-of-freedom, non-linear vehicle-handling model developed for the study. Simulation results are obtained using MATLAB/Simulink for different vehicle manoeuvres. Results indicate that use of the active differential improves the handling qualities and driver perception especially at cornering situations while accelerating, at which other control methods based on braking decelerate the vehicle not in favour of the driver’s desires.