Study on mixed H/H output feedback control of maglev actuator for microgravity vibration isolation system

Abstract

Aiming at how to specify the fundamental trade-off between robust stability and nominal performance of mixed H 2 /H ∞ control as well as lack of experimental studies on vibration control for the maglev actuator in microgravity vibration isolation system, a mixed H 2 /H ∞ output feedback controller based on the linear matrix inequality method is designed and analyzed. This article establishes a state–space realization for a one-dimensional vibration isolation system and the H-norm performance indices are identified and calculated. Furthermore, the curves of threshold values and true values of H ∞ and H 2 norms are plotted to specify the relationship between the system’s robust stability and nominal performance. Therefore, the threshold value of system’s H ∞ norm is identified through repeated simulations, and the state–space realization of optimal controller with minimum H 2 norm under the constraints of H ∞ norm threshold value is obtained. The vibration control experimental apparatus of one-dimensional control system is designed and manufactured to test the actual application of mixed H 2 /H ∞ controller for the maglev actuator. The result presents that the designed mixed H 2 /H ∞ control has a better performance in suppressing acceleration vibration and has a higher attenuation amplitude than cascade proportional–integral–derivative control at each corresponding frequency, which proves the practicability and effectiveness of the design method.