Lateral Control of a Commercial Vehicle Using Feedback Augmented Disturbance Observer 2022-01-0093

In the path following problem, a commercial vehicle has a delay of a hydraulic steering actuator and slow steering response accordingly. In addition, there are disturbances due to the harsh driving conditions of commercial vehicles. These disturbances may include uncertainties about actuator dynamic delay, modeling error and steering angle sensor offset. Designing a lateral controller with good performance that can overcome this problem is the key to successfully carrying out autonomous driving of commercial vehicles. Usually, it is difficult to consider disturbances with uncertainties in the geometric based control methods. Therefore, this paper proposed a lateral controller using feedback augmented disturbance observer for the commercial vehicle. First, a dynamics was modeled which can describe delay of the hydraulic actuator of the commercial vehicle. After that, a lateral controller was designed based on this dynamics model. The designed controller consists of three types of controllers such as feedforward control, curvature feedback control and disturbance observer. The feedforward controller has a form of conventional Pure Pursuit with additional differentiator controller. It has a role of lead compensator for the actuator delay. The feedback controller is designed to compensate turning radius error of the vehicle when the vehicle does not behave according to the kinematic model predicted. The disturbance observer has a role to compensate the steering wheel angle disturbance and modeling errors. The autonomous commercial vehicle experiments were conducted to evaluate proposed controller. The results confirmed that path following performance is much more improved when the lateral controller is designed considering the characteristics of commercial vehicles.