Formulation of an improved set of weighting functions for H∞ control of flexible beam-like systems

This paper prsents a practical approach to frequency weighted H_∞ control design. The advantages of an ´additive unstructured uncertainty´ model, compared to a ´multiplicative unsuctured uncenainty model´ are investigated, and the ´additive uncertainty´ is found to be very useful in developing controllers which are insensive to unmodelled struicual dynamics, or uncertain sructural parameters. The performance objective is described in terms of output response to both commads and disturbances on the input side of the plant (ie torque disturbances, friction). A example using a SIMO linear model of a single-link flexible beam is used to motivate and illusae the design ap proach. The resulting controller is discretized and implemented on the flexible beam hardware testbed.