H^∞ robust control design for linear feedback systems

This paper deals with the problem of designing, for a linear time-invariant multivariable plant, a feedback controller that minimizes the H^∞ norm of a quadratic combination of the sensitivity and complementary sensitivity functions. With the parameterization of the controller and quadratic cost, a design procedure based on a gain equalization test for computing the optimal controller is described in detail. A design algorithm, which is implementable in computers, is presented. The pitch-axis controller design for a digitized version of the Grumman F-14 aircraft is given. The performance robustness under the external disturbances and large aircraft parameter variations are shown to demonstrate the effectiveness of this approach.