Study on DOB based Control Systems with Saturating Actuators and Measurement Noise

Abstract

In chapter 1, we consider effect of measurement noise of DOB based control system with saturating actuators. Augmenting feedback control systems with disturbance ob-server (DOB) is a widely used technique in system design to compensate for the effect of exogenous disturbances as well as plant model uncertainties. In practice, DOB implementation has to take actuator saturation into account in order to avoid poor transient response or instability occurring due to saturating control input. In such systems, we have observed that a tracking loss may occur due to zero mean measurement noise. This phenomenon has never been reported in DOB literature. This paper reports the phenomenon, analyzes the conditions under which the tracking loss occurs, and also presents design guideline to avoid it based on the analysis. Experimental verification is also provided using a BLDC motor drive testbed. In chapter 2, we consider heavy-duty vehicle platooning. Heavy-duty vehicle platooning has received much attention as method to reduce fuel consumption by keeping the distance between vehicles short enough to decrease aerodynamic drag. Major disturbances in the platooning are the slope in the road and uncertain mass of the vehicle. Existing method to reduce the effect of slope is to combine the vehicle position obtained from GPS and the slope database to calculate the amount of feed-forward type compensation. However, slope database is costly to acquire, and GPS signal is unreliable in some locations. We present vehicle controller based on disturbance observer (DOB) to compensate the effect of slope and mass without relying on the GPS and the slope database. Actual measurement of the road slope taken in highways of Sweden is used and simulation is conducted. ⓒ 2017 DGIST