UNCERTAINTY MODELING AND EXPERIMENTS IN H-INFINITY CONTROL OF LARGE FLEXIBLE SPACE STRUCTURES

Approaches to uncertainty modeling for robust control of large flexibl e space structures (LFSS's) such as additive or multiplicative perturb ations in H-infinity do not work very well because of the special prop erties of LFSS dynamics. In this paper, we propose the use of a left-c oprhne factorization (LCF) of LFSS dynamics in modal coordinates in or der to get improved stability margins and performance in robust contro l design. The plant uncertainty is then described as stable perturbati ons of the coprime factors accounting for modal parameter uncertainty and unmodeled dynamics. Two multivariable H-infinity designs based on LCF's of 46th-order collocated and noncollocated models of an LFSS exp erimental testbed are presented together with simulation and experimen tal results to illustrate the technique.