Flight test results for the Microgravity Active Vibration Isolation System employed in the Fluid Physics Research Rack on-board the Chinese Space Station

Abstract

Abstract The Fluid Physics Research Rack (FPR) is a research platform employed on-board the Chinese Space Station for conducting microgravity fluid physics experiments. The research platform includes the Microgravity Active Vibration Isolation System (MAVIS) for isolating the FPR from disturbances arising from the space station itself. In addition, the MAVIS includes a microgravity operating mode that provides an environment with a controllable acceleration on the order of one millionth of the gravitational acceleration of the earth at sea level (i.e., µg0, where g0 = 9.80665 m/s2), and a vibration excitation operating mode that provides an environment with controllable vibrational acceleration signals of specific amplitudes in the frequency range of 0.01–10 Hz. The MAVIS is a structural platform consisting of a stator and floater that are monitored and controlled with non-contact electromagnetic actuators, high-precision accelerometers, and displacement transducers. The stator is fixed to the FPR, while the floater serves as a vibration isolation platform supporting payloads, and is connected with the stator only with umbilicals that mainly comprise power and data cables. However, the umbilicals have some stiffness that provides pathways for the transfer of disturbances from the stator to the floater. Therefore, the controller was designed with a correction for the umbilical stiffness to minimize the effect of the umbilicals on the vibration isolation performance of the MAVIS. In-orbit test results of the FPR demonstrate that the MAVIS was able to achieve a microgravity level of 1–30 µg0 in the frequency range of 0.01–125 Hz under the microgravity mode, and disturbances with a frequency greater than 2 Hz are attenuated by more than 10-fold. Under the vibration excitation mode, the MAVIS generated a minimum vibration acceleration of 0.4091 µg0 at a frequency of 0.00995 Hz and a maximum acceleration of 6253 µg0 at a frequency of 9.999 Hz. Therefore, the MAVIS provides a highly stable environment for conducting microgravity experiments, and promotes the development of microgravity fluid physics.