Design of localizer capture and track hold for a transport airplane: an H∞/LTR approach

The authors describe the design of a lateral track-hold control law in a localizer capture and track autopilot using a procedure based on H^∞-optimization and loop transfer recovery. The recovery of the achievable performance using output feedback from a satisfactory track-hold design obtained in an H^∞ -optimization is demonstrated. Simulation for a lateral track command is presented along with robustness properties of the output feedback design. Results indicate that the recovery of achievable performance must be carefully traded-off against control bandwidth limitation