On active acceleration control of vibration isolation systems

Vibration isolation systems (VIS) have appeared in applications ranging from space shuttle applications to ground vehicle suspensions. In this paper, the significant advantage of using I (integral) and II (double integral) type flotor acceleration feedback control together with feedforward compensation of the umbilical dynamics is analyzed theoretically and is also demonstrated experimentally with respect to a typical system, namely a microgravity isolation mount (MIM) operated in the ground environment. The lowest isolation frequency is reduced by about 40 times with a sufficiently improved vibration isolation performance up to 10 Hz, compared to a conventional PID controller. A unique frequency selective filter (FSF) is proposed to suppress the peak frequency responses caused by umbilical resonant modes. The effectiveness of the FSF is demonstrated experimentally with a 20 dB attenuation at 22.2 Hz.