Robustness and performance tradeoffs in control design for flexible structures

G.J. Balas, J.C. Doyle
1990 29th IEEE Conference on Decision and Control  
Linear control design methodologies for flexible structures require the nominal structural model to be formulated as a linear, time invariant system. Although this model may describe the physical system accurately, any model is only an approxima tion of the physical system. There is always some uncertainty present even when the underlying process is essentially linear. This uncertainty may be due to incomplete knowledge of the physical paramcters, neglected high frequency dynamics or invalid
more » ... umptions made in the model formulation. Descriptions of these uncertainties determine the tradeoff between achievable performance and robustness of the control design. This paper focuses on designing control laws for the Caltech flexible structure experiment using a nominal design model with varying levels of uncertainty. It is shown that an improper selection of nominal and uncertainty models, may lead to unstable or poor performing controllers on the actual system. In contrast, if descriptions of uncertainty are overly conservative, performance of the closed-loop system may be severely limited. Therefore, tight uncertainty bounds are required to provide robust control designs which achieve high performance when implemented on the actual system. Experimental results of control laws synthesized for different uncertainty levels on the Caltech structure are presented. U / Actuator 1 Actuator 2 Actuator 3 36 in. 33 in.
doi:10.1109/cdc.1990.203334 fatcat:7rcqbxjja5h6vnrgly37zalcsy