Nonlinear vehicle stability control using disturbance observer

A disturbance observer-based nonlinear vehicle stability controller is proposed in this paper. The lumped disturbance to the vehicle yaw rate dynamics has been estimated using the disturbance observer. The disturbance is due to the uncertain factors such as tire forces, vehicle parameters and hydraulic actuator parameters. The estimated disturbance has been used to stabilize the lateral dynamics of the vehicle. The dynamics of the hydraulic actuator is incorporated in the vehicle stability controller design procedure using the model reduction technique. Modular control design methodology is adopted to effectively deal with the mismatched uncertainty. Simulation results indicate that the proposed disturbance observer-based vehicle stability controller can achieve the desired reference tracking performance as well as sufficient level of robustness.