Performance analysis of a servo system with high-bandwidth torque disturbance observer

The paper analyzes the performance of a servo system with torque disturbance observer when the observer bandwidth is high enough to affect the servo dynamics. The main outcome of the analysis is the under-damped or even unstable behavior of the system. Another outcome is the limited range allowable for the parameter mismatch to keep the system stable. The analysis, carried out in the discrete time, is substantiated by experimental results.