Research on active suppression resonant peak of pneumatic vibration isolators at optical instrument platform

Abstract

This article introduced the active control to suppress resonant peak at pneumatic isolation optical platform with Multi-degree of freedom. In the field of optics, microbiology, precision weapon and solid material etc. pneumatic isolation platform is the key basic equipment, which is supported with several pneumatic isolators to cancel floor vibration disturbance and make the isolated precision optical instruments on it working stably. Pneumatic isolation technique is passive isolation and exists in its system frequency characteristic resonance phenomena in low frequency region, ranged from 1Hz to 6Hz, due to its limited physic parameters. Therefore, pneumatic isolation technique is unsatisfied with the need of high stability optical instruments. The active control to suppress resonant peak at pneumatic isolation has been developed in resent years, in which digital active suppression controller is attached to the original pneumatic vibration isolation system and resonance phenomena mentioned above is suppressed effectively. In essence the resonant peak suppression is system damping problem with each degree of freedom. This article gives the mechanical drawing, mathematics' model described in Lagrange's second equation and analysis of pneumatic isolation platform system, , and lists the conditions of decoupling active suppression (or damping) and the form of velocity feedback on the basis of math model analysis above mentioned. Further more the article puts forward a new algorithm of independent active suppression (or damping) control with 3-degree of freedom for the pneumatic isolation optical platform system, and presents its actual application and its frequency characteristic curves obtained by active suppression and without. Last the article come to conclusions that a. Compared with modals feedback suppression control, this new algorithm of active resonance suppression (or damping) is easy to be realized and real-time b. The active suppression with 3-degree of freedom above mentioned is not complete and it is necessary active resonance suppression with 6-degree of freedom under some circumstances.