Survey of Active Vibration Isolation Systems for Microgravity Applications

Modeling and Dynamics of a MDOF Isolation System

“…When the excitation is harmonic excitation as xei=eicosωt, the responses could be set as xi=aicos(ωt+ϕ). Then, the displacement transmissibility Ti (dB) could be defined as the ratio between the amplitude of response and the excitation in respective direction as ( ) 10 10 log , , , , ,…”

“…[6][7][8]. In most cases in vibration isolation, better isolation effectiveness can be obtained by using elements with smaller restoring forces which result in smaller natural frequency of the system, especially for microgravity environment in aerospace engineering [9][10][11].…”

“…For the MDOF vibration isolation platform, active controllers are the chief method [9][10][11][21][22][23][24][25][26][27]. The key point of the mechanism of active control in MDOF isolator is to generate anti-vibration forces in different directions by actuators and sensors in the designed system.…”

Dynamics and control of a parallel mechanism for active vibration isolation in space station

“…MIM is damping system for the sub-cabinet level, which utilized eight Lorentz drives that are centralized control to resist vibration disturbances. Thus, a variety of scientific experiments can be performed [1][2][3][4]. ARIS is the damping system for the entire cabinet level, which uses sensors to measure acceleration signals of the experimental cabinet and controls the eight swing-type voice coil motors providing the driving force.…”

“…However, due to the various types of sources producing vibration, various experimental conditions in the space station in terms of the varying acceleration are not ideal for scientific research. Taking the International Space Station (ISS) for example, its vibration sources are divided into three categories according to the frequency [1][2][3][4][5]: (a) low frequency less than 10 −3 Hz, which is caused by gravity and atmospheric drag of orbital space; (b) high frequency larger than 1 Hz produced by continuing sources such as the vibrations of pumps, compressors, motors, and fans, as well as the movement of the crew and propeller, which appears as the transient source; (c) medium frequency between 10 −3 and 1 Hz, which is caused by walking of the crew, propeller movement, etc. Sources producing vibration interference in space station have the features of low frequency, small amplitude, and randomness.…”