H-Infinity gain scheduling design for the meridian UAS for a broader range of operation and for fault tolerant applications

This paper describes the design of a MIMO H-infinity gain schedule for the Meridian UAS and illustrates its application for an extended operational range and for a moderate fault tolerant capability. The gain scheduling concept is based on smooth interpolation between two H-infinity controllers, covering a broad range of trim conditions. This interpolation is provided by the homogeneous design of the controllers by using the same augmented model structure within the H-infinity algorithm. The scheduling variable is defined as the commanded airspeed, acting as an exogenous variable, driving a smooth transition between the current and the next controller. The utilization of an exogenous signal avoids the occurrence of hidden coupling effects, typical in gain scheduling applications. Also, a new procedure is defined to adapt the controller when a failure or a significant dynamic change in the UAS takes place. Using the best knowledge of the failure the H-infinity controller is calculated. This controller is computed with a predefined gamma value, avoiding iterations, generating the new controller instantaneously.