Toward self-reliant control for adaptive structures

Over the past two decades, control technology including a wide spectrum of activities from algorithms to hardware, has made enormous strides in improving pointing and tracking precision and image quality for NASA and DoD space systems. However, the need for qualitative advances toward truly self-reliant control capability are illustrated, in this paper, by results of several highly successful laboratory demonstration programs that were completed within the last five years. We proceed to describe more recent results, both theoretical and experimental, in which various facets of self-reliant capability have been achieved, at least in nascent form. For example, intelligent vibration control built in to actuator hardware is illustrated by the "Frequency Domain LPACT" demonstration for JPL in which an actuator designs and implements its own local loop in situ. Results on the Adaptive Neural Control program for the Air Force using the ASTREX test bed showed the capability to rapidly recover control effectiveness following sudden hardware failures. Further, promising results to-date for the MACE II flight test program show the potential of neural control for autonomous spacecraft control. These and similar developments are used to illustrate the current promise, present limitations and future prospects of self-reliant, intelligent control of adaptive structures. (C) 2002 International Astronautical Federation. Published by Elsevier Science Ltd. All rights reserved.