Design of Repetitive Controller Using Optimization in Frequency Domain with Maximum Gain Constraints

Spacecraft inherently have rotating parts such as the momentum wheels, reaction wheels or CMGs. Slight imbalances can produce vibrations that disturb fine pointing equipment. Repetitive control (RC) can be applied on an active vibration isolation to eliminate the effect of such periodic disturbances. An effective RC design method based on optimization in frequency domain was presented. In situations that a system needs large amount of correction, a compensator with high gains can generate a command that exceeds the capacity of the equipment. The error continues to grow and the system will become unstable. A method to reduce the magnitude of the compensator gains available in literature requires a weighting function that is difficult to design. This paper presents an alternative method to design an RC compensator that can limit the maximum magnitude of compensator gains. Simulation results show that the proposed method is more effective than the existing method.