Constrained H∞ Control of an Experimental Flexible Link

Abstract

A new approach is presented to design robust controllers for an experimental flexible beam with noncolocated sensors-actuator. The objective is to position the free end of the beam in the specified time under tight bounds on the trajectory of the tip and control action. We derive a transfer function nominal model for the beam and a quantitative description of model uncertainties based on experimentally obtained frequency response data. Robust controllers are designed by applying the recently developed Constrained H∞ control approach (Sideris and Rotstein, 1993, 1994), in which time-domain constraints are treated directly without translation to the frequency-domain. Constrained H∞ controllers are compared with standard H∞ and μ-synthesis designs in terms of both simulation and experimental results and are found to be superior in the considered case of stringent time-domain specifications.