A Consideration of Floor Vibration Feedforward for an Air Type Anti-Vibration Apparatus

Abstract

Anti-vibration apparatuses are widely used to attenuate floor vibration in precision control field. To realize an improved transmissibility from floor to isolated table, the floor vibration feedforward scheme is especially applied. However, tuning method about PI compensator, which is used in feedforward loop, is not clear. Moreover, the influence of position feedback to the transmissibility is also unclear. Then, this paper firstly considers the effect of tuning order of two PI parameters. Next, it is shown that the resonance due to the position feedback occurs in the low frequency region. As usual case, the low frequency resonance is not taken into consideration because its feedback is very weak. However, since some precision machines supported by anti-vibration apparatus are demolished by an earthquake with long time period, we should take care of low frequency resonance caused by the position feedback.