Missile autopilot design and analysis based on backstepping

The tactical missile autopilot design process is detailed from a backstepping control perspective. Wherein, two autopilot topologies are proposed, i.e. the angle of attack (AOA) autopilot and acceleration autopilot. A set of new parameters is presented to simplify the expression of AOA control law and show that the positive real requirement on control parameters during step by step design has an unfavorable effect on closed loop system performance. An acceleration autopilot as a tracking problem is then set up and developed. Two control gains, i.e. k₁ and k₂, are determined on the basis of step and sine command tracking. The results show that k₁ affects mainly system steady state error, and k₂ affects mainly response speed. Moreover, k₁ is bounded and its upper bound has less relevance with k₂. The nonlinear acceleration autopilot based on a backstepping approach exhibits excellent tracking performance and robustness. In spite of good performance, the application of nonlinear autopilot is limited owing to a lack of physical meaning and complex engineering implementation.