Design and Simulation of a MEMS Control Moment Gyroscope for the Sub-Kilogram Spacecraft

Abstract

A novel design of a microelectromechanical systems (MEMS) control moment gyroscope (MCMG) was proposed in this paper in order to generate a torque output with a magnitude of 10−6 N·m. The MCMG consists of two orthogonal angular vibration systems, i.e., the rotor and gimbal; the coupling between which is based on the Coriolis effect and will cause a torque output in the direction perpendicular to the two vibrations. The angular rotor vibration was excited by the in-plane electrostatic rotary comb actuators, while the angular gimbal vibration was driven by an out-of-plane electrostatic parallel plate actuator. A possible process flow to fabricate the structure was proposed and discussed step by step. Furthermore, an array configuration using four MCMGs as an effective element, in which the torque was generated with a phase difference of 90 degrees between every two MCMGs, was proposed to smooth the inherent fluctuation of the torque output for a vibrational MCMG. The parasitic torque was cancelled by two opposite MCMGs with a phase difference of 180 degrees. The designed MCMG was about 1.1 cm × 1.1 cm × 0.04 cm in size and 0.1 g in weight. The simulation results showed that the maximum torque output of a MCMG, the resonant frequency of which was approximately 1,000 Hz, was about 2.5 × 10−8 N·m. The element with four MCMGs could generate a torque of 5 × 10−8 N·m. The torque output could reach a magnitude of 10−6 N·m when the frequency was improved from 1,000 Hz to 10,000 Hz. Using arrays of 4 × 4 effective elements on a 1 kg spacecraft with a standard form factor of 10 cm × 10 cm × 10 cm, a 10 degrees attitude change could be achieved in 26.96 s.

Study for femto satellites using micro Control Moment Gyroscope

“…This maximum torque occurs during the centre crossing of the synchronized rotational and tilt oscillation. This torque is almost 2 orders of magnitude higher than the value estimated by [17], which can be mainly attributed to the increase in the oscillation frequency for the here proposed design.…”

“…By applying advances in computer aided design tools and electronics technologies, CMG systems have more recently been considered for small satellites [15] and [16]. It also has been considered for femto-satellites [17] and [18]. The main challenges with the creation of a MEMS CMG are the silicon micro machining technology and the control system [23].…”

“…It is more efficient than a reaction wheel in terms of power consumption and slew rate [16]. A MEMS control moment gyroscope for a sub kilogram spacecraft has been studied [17], but no feasibility study for such a MEMS CMG for femto-satellites has been done. The power requirements, thermal design, and performance capabilities of MEMS actuator systems are heavily dependent on environmental variables such as temperature variation, and study of the on-orbit operational requirements for a femtosatellite is a vital part of the design process.…”

Nonlinear MPC for attitude system of miniature satellite using multiple MEMS actuators

“…If these beams undergo the transverse deformation in a clockwise rotation, the miniature satellite rotates in counterclockwise direction in order to conserve the system angular momentum. From reference [12] MEMS control moment gyroscope is designed based on angular vibration instead of angular rotation. It consists of two orthogonal angular vibration systems, named as rotor and gimbals.…”

“…However, the torque magnitude of MEMS actuator was too small, that can not satisfy the requirement of fast atti tude changes of miniature satellite. For example, the best performance of single MEMS control moment gyroscope described in reference [12] was projected to have outputs torque magnitude of lO-6Nm only. For improving the out puts torque magnitude, an array configuration using multiple MEMS actuators as an effective element was proposed.…”