Robust Adaptive Control of a Weakly Minimum Phase General Aviation Aircraft

Loss of control is the leading cause of accidents in General Aviation aircraft. Installation of autopilots on every airplane would significantly reduce this type of accident. Adaptive controls could offer an affordable autopilot for a wide variety of aircraft, by allowing the gains to automatically adapt. This investigation presents the design and test of an adaptive autopilot. The autopilot was designed to control the altitude and bank angle of a small airplane at a specific trim condition. The airplane was then moved to extreme points in its flight envelope, and the autopilot successfully adapted to maintain controller performance, except at airspeeds near stall. Since the aircraft is weakly minimum phase, a zero filter was used in the adaptive autopilot, which required a nominal model of the linearized plant at the design condition. Turbulence was added to test robustness, and the autopilot was able to maintain its performance.