Simultaneous vibration isolation and pointing control of flexure jointed hexapods

Vibration isolation and precision pointing problems using hexapods have been separately investigated by several groups of researchers. Since many applications require simultaneous vibration isolation and precision pointing (e.g., telescopes, laser communication. and laser weapons), it is particularly useful to do both with a single device. A simultaneous control scheme is developed in this paper using acceleration feedback to provide high-frequency vibration isolation, while Cartesian pointing feedback provides low-frequency pointing. The compensation is divided by frequency because pointing sensors often have a low bandwidth, while acceleration sensors often have a poor low-frequency response. Methods for unifying these finite bandwidth joint and Cartesian controls to perform simultaneous pointing and vibration isolation on a single platform are developed and verified. Experiments on the University of Wyoming hexapods show that this scheme provides a viable control bandwidth.