10.2514/6.2016-0675">
 

Optimal Attitude Control of Agile Spacecraft Using Combined Reaction Wheel and Control Moment Gyroscope Arrays

Document Type

Conference Proceeding

Publication Date

1-4-2016

Abstract

This paper explores the benefits of combined control moment gyroscope (CMG) and reaction wheel array (RWA) actuation for agile spacecraft that are capable of slewing to multiple targets in minimum time. The combined RWA and CMG (RWCMG) system is evaluated using both analytical simulations and hardware experiments. A closed-loop control scheme is developed which takes advantage of the strengths of each actuator set. The CMGs perform slews for a representative target field. The RWA assumes control of the spacecraft when desired pointing tolerance is met for a given target to keep the spacecraft on target. During collection, the benefit of allowing the CMG gimbals to travel along null motion trajectories toward preferred angles to prepare for the next slew is evaluated. Preferred gimbal angles are either pre-computed off-line using optimization techniques or set based on look-up tables. Logic is developed to ensure CMG gimbal angles travel the shortest path to the preferred values. Next, proportional-integral-derivative, quaternion feedback, and nonlinear Lyapunov-based controllers are assessed for the RWCMG system. Extended and unscented Kalman filter techniques are also explored for improved accuracy in analytical simulation. Results of RWCMG hardware experiments show improvements in slew capability, pointing accuracy, and singularity avoidance compared to traditional CMG-only systems.

Source Publication

AIAA Modeling and Simulation Technologies Conference

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