Comparative study of H∞ robust control methods in missile autopilot design

Several controller synthesis techniques in the H-infinity methodology in an application to missile autopilot designs are investigated. The designs investigate performance and robustness characteristics of the controllers in the range Mach 1.6-2.6 covering the sustained phase of a missile with non minimum phase characteristics. The first synthesis concerns the use of a mixed-sensitivity approach at different flight conditions. Adaptation of the performance and robustness filters leads to a single satisfactory controller for the entire range. The second and third approaches focus on pole-zero cancellation problem and also improve the design objectives. Further approaches are concerned with third and four terms in the optimization in order to account for uncertainty in the controller and-or to account specifically for output measurements uncertainties.