Broadband positioning control of small payloads mounted on a flexible structure

摘要

This paper considers the problem of high bandwidth positioning and pointing of a small mass mounted on a flexible structure. A potential application would be the positioning of mirrors in a space-based interferometer. For high performance control it is a general rule that a sufficiently accurate model of the plant is needed, particularly in the control bandwidth. Determining an accurate model of a structure over a broad frequency band is a very difficult problem. This paper identifies a bound on the gain and phase of the plant as a function of the ratio of the payload mass to a modal mass of the structure. It is shown that when this ratio is 'small enough' a high performance stable controller can be designed without further consideration of the structural dynamics. Experimental results are presented that quantitatively support this conclusion. Extensions to multi-axis situations are also discussed.