Robust Control of Commercial Vehicle’s Speed Using Disturbance Observer

This paper proposes a speed controller using a disturbance observer to regulate the speed of a commercial vehicles, and presents vehicle test results to evaluate the performance of the proposed controller. Most ADAS (Advanced Driver Assistance System) and automated driving systems need to reliably regulate the vehicle's speed under any circumstances. A conventional PID controller is commonly used to control the vehicle speed, but performance of it varies depending on changes in external conditions. Commercial vehicles are even more susceptible to these changes than passenger cars and more difficult to obtain an accurate plant model. Considering these features, a speed controller using a disturbance observer is designed for commercial vehicles. The proposed controller treats changes in external conditions as disturbances. The modeling uncertainty is also treated as a disturbance. The disturbance observer estimates these disturbances by using the nominal plant model to compensate for the control input. The proposed controller doesn’t depend on the precision of the plant model and is resistant to unexpected disturbances. To evaluate the proposed controller through vehicle testing, it is integrated into the embedded hardware. The test results show that the proposed controller is much more robust and consistent than a mass-produced PID controller when the vehicle is subjected to unexpected disturbances due to road slope. In addition, the proposed controller is robust against vehicle’s weight change, which is required for the commercial vehicles.