Control of Micro-Satellite Orientation Using Bounded-Input, Fully-Reversed MEMS Actuators

Abstract

We present a novel technique for controlling the attitude of micro-satellites using MEMS-based microactuators. In addition to being restricted in the magnitudes of inputs, most microactuators need to be returned to their original inactive state at the end of the attitude control maneuver in order to reduce energy consumption. This type of bounded and fully-reversed actuation on a free rigid body leads to a special type of system in which nonholonomic effects have been incorporated by design . We discuss issues of controllability and develop motion planning algorithms for such a system considering the nonintegrable nature of rigid body rotations. We use approximate methods to develop two algorithms for controlling satellite orientation. The first method uses a series of pair-wise actuation steps and is guaranteed to converge to the desired orientation; the second uses fewer steps, and in certain cases uses less input power. We also present preliminary results of a practical implementation using electro-thermal microactuation.