Disturbance analysis and feed-forward compensation for the flexible solar array sun-tracking drive

Abstract

This paper analyzes primary disturbance-causing factors inside the flexible solar array drive system based on an electromechanical model. Two feed-forward input compensation drive strategies, derived by decomposing moment component and hypothesizing motion trajectory, respectively, are proposed to weaken the effect of disturbances. Analytic results indicate that the cogging effect of the hybrid stepper motor is a significant factor affecting angular velocity fluctuation, thus generating disturbances. Both of the proposed disturbance-mitigation drive strategies improve angular velocity stability and disturbance torque stability without degrading the pointing accuracy of solar array or altering the original design state of drive assemblies. The effectiveness of disturbance mitigation, however, gradually degrades as cogging torque amplitude errors increase in number. Drive strategy which utilizes the hypothetical motion trajectory method is slightly preferable in terms of disturbance mitigation performance.