Uncertainty modeling and experiments in H∞ control of large flexible space structures

Approaches to uncertainty modeling for robust control of large flexible space structures (LFSS) such as additive or multiplicative perturbations in H_∞ do not work very well because of the special properties of LFSS dynamics. In this paper we propose the use of a left coprime factorization (LCF) of LFSS dynamics in modal coordinates for robust control design. The plant uncertainty is then described as stable perturbations of the coprime factors accounting for modal parameter uncertainty and unmodeled dynamics. Two multivariable H _∞ designs based on LCFs of 46th-order colocated and noncolocated models of an LFSS experimental testbed are presented together with simulation and experimental results to illustrate the technique