Application of linear subspace stabilization and linear adaptive techniques to aircraft flight control problems. II. The outer loop

For pt. I see ibid., p.146-50. Robust flight control laws are developed for a combat aircraft. The control problem is layered into an outer-loop of control, or automatic pilot, controlling motion of the center of gravity of the aircraft and an inner-loop of control that controls the angular motion around the center of gravity. This paper is concerned with application of linear adaptive design techniques to accommodate the nonlinear and uncertain nature of the autopilot control problem. The autopilot controls the flight path and ground track angles. The commands generated by the outer-loop of control are inverted, and the corresponding pitch, roll and yaw rates are calculated. The latter commands are then tracked by the inner loop of control. Linear adaptive control circumvents the use of nonlinear and uncertain terms in the system equations of motion. Those terms are estimated using real-time disturbance accommodation observers. Simulation results for a worked example demonstrate that the proposed autopilot tracks prescribed trajectories accurately