Development of Ultra-quiet Gravity Unloading for Micro-vibration Testing of Space Precision Payloads

To ensure the performance and reliability of ultra-quiet payloads in orbit, the ground test are usually carried out before launch. However, the gravity unloading system with suspension introduces redundant disturbances into ultra-quiet payloads. The gravity unloading system may affect the vibration isolation performance of the ultra-quiet payloads. To solve the problem of introducing disturbances, a gravity unloading system with high stiffness shelf and ultra-low frequency spring is designed in this paper. Testing results show that the gravity unloading system reduce the redundant disturbances to less than $2\mu\mathrm{g}$ within the frequency range of 0.6-100Hz, which can simultaneously guarantee the gravity unloading function and ultra-quiet environment.