Design and Performance Test of Hexapod Micro-vibration isolator for High Torque CMG

Abstract

Control Moment Gyro (CMG), which can produce higher torque than Reaction Wheel Assemblies (RWA), is used as a key component for agile satellite attitude control. However, micro-vibration generated from static and dynamic imbalance of flywheel and bearing inside the CMG degrades the pointing stability of the optical payload. In order to reduce the influence of micro-vibration generated from the CMG, vibration isolator must be installed at the interface between CMG and satellite bus. Among many types of isolators to isolate 6 DOF micro-vibration, Stewart platform based hexapod isolator has been widely used because it has advantages such as high stiffness, symmetry, and low mode coupling. This paper deals with the design and performance test of hexapod vibration isolator for high torque CMG for medium-large satellite. Vibration characteristics of CMG was analyzed using a 6 DOF vibration test system, and hexapod micro-vibration isolator and its key parameters was designed based on the vibration characteristics of the CMG. Single-axis isolator was built using welded bellows, then expanded to the hexapod configuration. This hexapod micro-vibration isolator was connected to the target CMG to experimentally evaluate its microvibration isolation performance. As a result, it was shown that the proposed hexapod micro-vibration isolator effectively isolated (over 95%) microvibration that contained harmonic forces generated during the operation of CMG.