Nonlinear Design of Three Axes Autopilot for a Tactical Aerospace Vehicle

Abstract- The nonlinearity and coupling of the aerospace vehicle dynamics can be linearized and decoupled by well known feedback linearization techniques. The fundamental problem of feedback linearization technique is that it is not able to handle the model uncertainty. Significant research works have been carried out in order to overcome the above aspect. In this paper, a new robust nonlinear controller structure using feedback linearization technique is proposed. The design is carried out in two time scale separation. The fast dynamics (inner body rate loop) and slow dynamics (outer latax loop) are controlled separately by two nonlinear controllers. The performances of the design in terms of robustness, minor coupling between the longitudinal motion and lateral motion, stability and guaranteed tracking are shown in a realistic 6-DOF simulation. I