An Analysis and Synthesis of Internal Model Principle Type Controllers

This paper presents a method to synthesize internal model principle type controllers for rejection of sinusoidal disturbances. The frequencies of the disturbance are not required to be of rational ratios of the sampling interval or each other, thus addressing both periodic and aperiodic signals. The control synthesis utilizes positive feedback around notch filters to create the internal model and employs stable inversion of the plant dynamics to achieve closed loop stability. An example and simulation on a general electromechanical motion control system are presented to demonstrate the effectiveness of the proposed method.