Nonlinear Compensation of Zero Power Magnetic Suspension for High-Performance Vibration Isolation Systems

The treated vibration isolation system uses zero-power magnetic suspension for realizing negative stiffness and combines it with a spring that has positive stiffness (positive spring). Infinite stiffness against direct disturbance is achieved by setting the amplitude of negative stiffness to equal the positive stiffness. One of the problems of this system is that the amplitude of negative stiffness varies from the nominal value when disturabance force is applied to the isolation table. This paper presents two approaches to overcoming this problem. One is to apply a nonlinear feedback control to zero-power magnetic suspension. The other is to use a magnetic spring as a positive spring. The carried out experiment demonstrated the efficacy of both the methods.