An altitude hold autopilot design to work with an observer-based stability augmentation control law

A study about an altitude-hold autopilot designed by the optimal control method, LQR, has been carried out and the possibility of this design to working not only with the sensor based inner loop stability augmentation system but also with a redundant observer-based inner loop stability augmentation system has been evaluated. The possible simplifications in the autopilot design have also been studied. The main objective of the study is to show that the redundancy obtained for the inner loop flight control system can be extended to the autopilot system. The example aircraft used was the Boeing 747 and a comparison with another design was also performed