Active Vibration Isolation of Multiple Degree-of-Freedom System Based on the Minimization of the Output Force Control Strategy

Vibration isolation technology has been widely used to reduce the vibration transmission from the machinery to the foundation in many different engineering systems. Magnetic suspension vibration isolation technology is an excellent active isolation technology, which has some useful characteristics, such as non-contact, high response frequency, high reliability and long life-span. Hence, the magnetic suspension isolator is designed. The electromagnetic force of the magnetic suspension active isolator is measured in advance by experiment. Multiple degrees of freedom (DOFs) vibration isolation system supported by magnetic suspension isolators and springs is established. The dynamical and state equations of the system are formulated. A control algorithm and the value function of active vibration isolation based on force transmissibility are proposed. The control model based on the control algorithm is established. Output force responses of the active vibration isolation system and passive one under same excitation are simulated. The simulation results indicate the active system possessed much better effect on vibration isolation. Comparing with passive system, the force transmissibility is reduced by 2dB-3dB in low-frequency stage, especially around resonance frequency, the transmissibility is reduced by 10dB-18dB. In order to test the reliability of the active system and control algorithm, an experimental platform is carried out. Experiment results show that the force transmissibility is reduced by 10dB-15dB around resonance frequency. The research indicates that experimental results are found to be in good agreement with simulated results.