Attitude Control of Miniature Spacecraft Using MEMS Actuators

The paper examines a novel attitude control method based on MEMS actuators. Each actuator (called pseudo-wheel) comprises of four small beams of electrothermal materials. If these beams undergo the transverse deformation in a clockwise rotation, the spacecraft rotates in counter-clock-wise direction in order to conserve the system angular momentum. However, when the actuator is off, the beams come to their undeformed configurations because of their elastic properties. This problem can be overcome by employing a sequence of large rotations caused by deflecting actuators about two or three orthogonal axes to produce a net attitude change. This paper studies rotation sequences, kinematics analysis of spacecraft, and simulation of attitude motion. Assuming the conservation of system angular momentum and employing inverse kinematics, the time response of attitude motion of the spacecraft is simulated. This approach not only just searches a possible solution based on an open-loop control strategy, but also determines a set of optimal rotating rates of MEMS actuators, which can produce a minimum kinetic energy required for attitude control.