Robust Autopilot Design For Bank-to-Turn Missile

Bank-To-Turn (BTT) and Skid-To-Turn (STT) control techniques are widely used in current missile control systems. The BTT control technique has significant advantages to accomplish such tasks as high maneuver, high velocity, and long-range etc, which plays an important role in improving the performance of tactical missile and will be one of the main control approaches in tactical missile flight control systems. The key technology for BTT missile autopilot design is how to maintain effectively and efficiently the robustness in large fight envelope.The characteristics, such as the missile kinematical coupling, aero-dynamical coupling and inertial coupling existing in BTT missile control systems are first analyzed. Based on some simplification and assumptions, the BTT missile roll channel and pitch/yaw channel mathematical model are established by choosing the easily measurable variables.Because the coupling between the pitch/yaw channels is very severe, a double loop control method for BTT missile control systems is presented. The linear quadratic regular (LQR) method is used in inner loop controller design, which bounds the error between actual model and nominal model. In the outer loop controller design, structure singular value theory is used. The outer loop controller can make the tracking precision of load command in the pitch/yaw channel meet the requirements against uncertainties. This design method can decouple the coupling of pitch/yaw channel effectively, ensure the stability and fulfill the performance without changing the controller in large flight envelope. The simulation results in the different flight conditions show the validity of the developed method.Considering the uncertainties in controller gains practically, which may lead to the deterioration of control system performance and even instability, An approach for non-fragile controller design is proposed based on linear matrix inequality(LMI) theory. The analysis and comparison between non-fragile controller and regular robust controller testify the validity of the proposed method.