An H∞ approach

This chapter describes an H∞ approach to the design of a controller for the Research Civil Aircraft Model (RCAM). The controller produced consists of an inner and outer loop. The inner loop controls the manual flying of the plane and is designed using a multivariable H∞ two degree-of-freedom mixed sensitivity approach. The design incorporates performance and robustness requirements to produce a closed loop decoupled system to meet the flying specifications. The outer loop deals with autopilot tracking and is designed using H∞ normalised coprime factor one degree of freedom loop shaping techniques. Three outer loop controllers are synthesised to track height, heading and to reject lateral deviations. Analysis tests and simulation results look promising. The controllers produced are of a high order, although in principal it should be possible to achieve significant order reduction. For a predefined mission scenario, the performance, robustness, comfort, safety and power results satisfy the specification.