Robust Nonlinear Design of Three Axes Missile Autopilot via Feedback Linearization

The nonlinearity and coupling of the missile dynamics can be linearized and decoupled by well known feedback linearization techniques. The fundamental problem of feedback linearization technique is not able to cater the model uncertainty. In accordance to this, a new robust nonlinear controller structure using feedback linearization technique is presented here. It linearizes the nonlinear dynamics, decouples the longitudinal and lateral motions and caters the model uncertainty. The design is carried out in two steps. The first one is to design a robust feedback linearization controller. It linearizes the fast dynamics of missile and decouples the axes using input output feedback linearization technique. In the next step a robust linear controller has been proposed almost similar to a model reference controller which gives the desired tracking performances. The performances of the design in terms of stability, robustness, minor coupling between the longitudinal motion and lateral motion and guaranteed tracking are shown in a realistic 6-DOF simulation.