Internal model principle for measurement feedback problem

While the disturbances in actuators are well handled by the output regulation theory (especially, called input disturbance suppression problem), there are rare results to deal with those in sensors. When disturbances enter sensors, the plant states cannot be precisely measured, and the state feedback control laws are not implementable. Instead, the measurement feedback control laws become interesting. This paper gives a new mechanism using the internal model principle for designing measurement feedback control laws to solve the robust regulation problem. The proposed controllers have the robustness with respect to sensor disturbances. The mechanism derives from the output regulation theory, and puts this theory to a new stage.