(A) study on microvibration isolator for cmg based on the stewart platform

Abstract

In the satellites carrying sensitive payloads, microvibration is a significant factor in performance degradation. The Control Moment Gyroscope(CMG), used for attitude control in agile satellites, is a well-known source of microvibration, stemming from imbalances and irregularities in its high-speed flywheel. The satellite's structure, characterized by low damping properties, transmits these microvibration to the sensitive payloads, making it crucial to isolate these vibrations at their source. This study introduces a novel hexapod microvibration isolator based on the Stewart platform for CMG. A single-axis microvibration isolator was designed and tested using welded bellows and silicone oil, aiming to achieve a low resonance peak and a high roll-off rate. Additionally, a single-axis HSLDS microvibration isolator incorporating a PM NS unit was developed and evaluated to exhibit strong hardening behavior for low-frequency inputs, facilitating smooth torque transmission of the CMG. The effects of various configurations on the force transmissibility of the Stewart platform were subsequently analyzed under fixed strut length and mass-limited conditions to identify an optimized configuration for Stewart platform-based microvibration isolators compared to the commonly employed cubic configuration. Building on this, a hexapod microvibration isolator was fabricated and tested with both cubic and alternative configurations, including an analysis of CMG-induced microvibration. Performance tests revealed that the hexapod isolator with an alternative configuration exhibited more stable performance, avoiding the severe degradation observed in the cubic configuration. Finally, HSLDS hexapod microvibration isolator was analyzed using an MBD model to investigate the hardening behavior of the HSLDS single-axis microvibration isolator and to assess the effects of configuration under mass-limited conditions on CMG torque transmission and the microvibration problem.