A Note on the Robustness of the Disturbance Observer-Based Robust Control Systems

Abstract

This brief shows that the design constraints on the plant-model mismatch and the bandwidth of the disturbance observer (DOb) become more severe when the robust controller is implemented using computers. This brief also shows that continuous-time analysis methods fall-short in explaining the fundamental design constraints of the DOb-based robust digital control systems, therefore leading to unexpected stability and performance problems in practice.