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.

Attitude control for the rigid spacecraft with the improved extended state observer

“…Where θ A is the rotation angle of the solar array. The driving system is an independent and complete control system, which consists of the drive controller, the stepper motor with two-phase (A and B) and the motor [33][34][35]. Considering Eq.…”

“…The estimation of the rotating velocity z 21 is transformed into a motor current signal i real by the winding current modules. The error between the current signals i real with reference current i re f is the input for the control torque modules, where the is as follows [33,34]:…”

Multi-degree-of-freedom vibration reduction strategy of the solar array drive system

“…However, the motion of solar array induces unremitting disturbance to the body of the spacecraft, affecting the pointing accuracy of the high-precision spacecraft and the dynamic environment of the sensitive equipment. 1–4…”

Analytical Kinematics and Coupled Vibrations Analysis of Mechanical System Operated by Solar Array Drive Assembly

“…The problem geometry for analytical model consists of SADA operating rigid rectangular plate of 600*500*90 mm 3 attached to transmission shaft, of length 300 mm and diameter of 100 mm, fixed to top of motor rotor figure (1). SADA ideally provides a step wave excitation torque to mounted assembly along spin axis.…”

“…Over the course of suntracking drive process vibration disturbances caused by low-and-dense natural frequencies of SA, attached to SADA, simultaneously react on spacecraft body thus influencing its dynamic environment [1]. These must be mitigated effectively to achieve high pointing accuracy [1].…”