Modeling for solar array drive assembly system and compensating for the rotating speed fluctuation

Abstract

A dynamic model of the solar array drive assembly (SADA) system consisting of a stepper motor and two flexible solar arrays is investigated. The fluctuation compensation of the rotating speed and vibration suppression is studied by integrating the sliding mode control (SMC) method and input shaping (IS) technique. The dynamic equations of the system are derived by the Hamiltonian Principle. The linearized form of the nonlinear dynamic equations with boundaries conditions is adopted to obtain the natural frequencies and global modes of the solar arrays. Based on the electromechanical dynamics model of the stepper motor, a cooperative compensation scheme is designed to achieve the stability of solar arrays and the suppression of system vibration. Numerical results show that the driving speed is significantly influenced by the harmonic torque and the structural vibration of payload. The SMC method compensates for the rotating speed fluctuation much better than the pure feed-forward operation used in the traditional stepper motor. The system with SMC method and IS technique performs much better than the case without vibration suppression.