Estimation of regions of attraction and ultimate boundedness for multiloop LQ regulatorsClosed-loop stability is investigated for multivariable linear time-invariant systems controlled by optimal full state feedback linear quadratic (LQ) regulators, with nonlinear gains present in the feedback channels. Estimates are obtained for the region of attraction when the nonlinearities escape the (0.5, infinity) sector in regions away from the origin and for the region of ultimate boundedness when the nonlinearities escape the sector near the origin. The expressions for these regions also provide methods for selecting the performance function parameters in order to obtain LQ designs with better tolerance for nonlinearities. The analytical results are illustrated by applying them to the problem of controlling the rigid-body pitch angle and elastic motion of a large, flexible space antenna.
Document ID
19850065589
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Joshi, S. M. (NASA Langley Research Center Hampton, VA, United States)