Gain-Scheduled Two-Loop Autopilot for an Aircraft

We present a new method to compute output gain-scheduled controllers for non-linear systems. We use structured H∞-control to pre-compute an optimal controller parametrization as a reference. We then propose three practical methods to implement a control law which has only an acceptable loss of performance with regard to the optimal reference law. Our method is demonstrated in longitudinal flight control, where the dynamics of the aircraft depend on the operational conditions velocity and altitude. We design a structured controller consisting of a PI-block to control vertical acceleration, and another I-block to control the pitch rate.