Robust H-infinity Controller for a Single-axis Spacecraft Rotation

Abstract

This paper focuses on the problem of robust H-infinity control design for a linear uncertain SISO system represented as a single-axis spacecraft rotation. The parametric uncertainty and disturbance input make this control problem a challenge. The paper presents an H-infinity control design which stabilizes all possible perturbed plants within the system and guarantees disturbance attenuation and meeting the tracking specifications while maintaining practical controller gains for all admissible uncertainties. The paper includes a design of a PD controller on the single-axis spacecraft plant and a comparison between the two controllers under the effect of disturbance and uncertainty. The robust H-infinity control problem is formulated into the General control problem formulation then solved via DK-iterations which is based on the concepts of H-infinityoptimization and μ-synthesis. The synthesized robust H-infinity controller is verified by nominal stability analysis, nominal performance analysis, robust stability analysis, robust performance analysis and worst case gain analysis, in addition to, testing the controller’s performance specifications.