A Linear Parameter-varying Framework for Adaptive Active Microgravity Isolation

Abstract

This paper presents a novel approach to the design of adaptive active vibration isolation systems using linear parameter-varying (LPV) control techniques. The proposed LPV controller is scheduled based on the relative position of the vibrating system, as well as a parameter that characterizes the harshness of the base motion. By scheduling on relative position, the controller is able to shift its focus from a “soft” setting to a “stiff” setting depending on the need for acceleration minimization or relative displacement reduction. An outer loop that is scheduled based on a parameter that quantifies base motion harshness controls the way in which the system transitions between the “soft” and “stiff” settings. Parameter-dependent weighting functions are used to achieve these objectives. A single degree-of-freedom rack-level microgravity vibration isolation model is used to demonstrate the proposed adaptive design framework. The objective is to provide stringent closed-loop isolation characteristics and at the same time restrict the relative motion of the system, so as to prevent it from bumping into its hardstop bumpers. Simulations show that the parameter-varying controller provides excellent isolation with simultaneous position control despite the large variability in the harshness of environmental disturbances.