The Robust Autopilot Design Of The BTT Missile

In order to obtain the advantages on the battlefield, it is an effective way to develop high performance missile.Comparing with the traditional STT control technology, the BTT control missile could offers better maneuverability and drag reduction, roll stabilized. The BTT control method determines that BTT missile is a time varying system with strong coupling, and it is hard to design a autopilot for such a complex system. The three independent channels design method is not suitable for BTT missile. So it becomes a hotspot in this field of missile control to find an efficient control method for BTT missile. And the autopilot of BTT missile, designed using the traditional method, has not satisfactory robustness performance. To guarantee the stability of the missile, it is necessary to design a robust autopilot using better method.A high performance robust autopilot has been designed in this paper, using the H∞mixed sensitivity method and LQR method. The autopilot has satisfactory stability, but also a small overshoot, fast speed to track the command signal, and good robust performance.The main research works of this paper includes:1. A mathematical model of BTT missile has been set up on the basis of simplifying the object of study. Considering the scalability of state variables, using the longitudinal and lateral overload as state variables, a mathematic model, which whole state can be measured,was build.2. In order to analys the characteristic of missile, the mathematical model was simulated.Observing the step response curves with different roll angle,it showed that although the pitch-yaw channel was stable when the roll angle was small, but the settling time was too great; and this channel wasn’t stable when the roll angle too big. Compare to no coupling pitch-yaw channel, the step response showed the coupling pitch-yaw channel was affected by the coupling terms. Comparing the step response curves of the nominal model and the model with parameter uncertainty, it was showed that the parameter uncertainty increased the steady-state error.3. On a standard state point, the autopilot of a BTT missile’s is designed using the robust H∞ mixed sensitivity method and LQR method.4. In order to validate the robustness and specifications of the autopilot, this paper sets up the mathematic model of the BTT missile,which is a nonlinear and time varying control system, and does the simulation.5. Though three-channel model simulation, the paper test the autopilot’s robustness. The result shows that the autopilot has good robustness and can track command signal fast when perturbation and parameters perturbation exist.