Method of Pipe Resonance Suppression for an Air Type Anti-Vibration Apparatus

This paper addresses an air-type active anti-vibration apparatus. An important development issue is to reduce the natural frequency. However, it is known that the high frequency dynamics of its apparatus influence on the positioning and measurement accuracy of mounted precision instrument. In order to suppress the dynamics, i.e. the pipe resonance of anti-vibration apparatus, the influence of both the piping material and the pipe length on the high frequency response is experimentally investigated.Firstly, the electrical methods to suppress the resonance are shown. In detail, both the notch filter technique and the differential pressure feedback are described. Secondly, the resonant characteristics due to the pipe length and the pipe material are experimentally shown in order to develope the mechanical suppression means. Through these experiments, noteworthy phenomenon, namely the disappearance of pipe resonance in case of special pipe length, is found out. Though the pipe resonance has been recognized as Helmholtz-type, it becomes clear that this understanding is slightly mistaken. Finally, a mathematical model for control is presented. Some experimental results can be explained using this model. However, the above-mentioned phenomenon cannot be successfully explained.