Optimal Nonlinear Tracking Control for Bank-to-Turn Asymmetric Missiles using Polynomial Feedback

For a highly maneuverable bank-to-turn missile, the dynamics of the pitch, roll, and yaw axes are not only cross-coupled but also nonlinear especially when high roll rates are involved. However, most BTT autopilots proposed to date rely on linear methods, whether the classical SISO techniques or the state-space methods of modern control theory. These linear approaches restrict their applicability to either small or slowly varying roll rates. The unmodelled effects of severe nonlinearities inherent in the missile dynamics, particularly for asymmetric airframes, still remain one of the most critical issue for BTT autopilot design. In this paper an optimal nonlinear tracking control using polynomial feedback is developed for BTT autopilots A comparison of performance between LQ tracker and optimal quadratic-feedback is presented for an asymmetric missile through numerical simulations.