The control system of hypersonic missile using state dependent riccati equation

This paper is to apply State Dependent Riccati Equation (SDRE) method, a recently proposed control method for nonlinear dynamical system, in the control system of hypersonic missile. Firstly a SDRE autopilot is designed and used in the control system, which concludes six blocks that are target, kinemics and proportional navigation guidance, BTT logic, SDRE autopilot, actuator and missile dynamics. The SDRE autopilot contains two controllers, one is the slow-loop controller which converts the angle of attack, sideslip and bank angle commands to the body rate commands, and the other is the fast-loop controller to convert the body rates commands to the fin deflections. Soft bounds on the fin deflections are embedded in the fast-loop controller to make sure that the commanded deflections are achievable. The two controllers are based on a six-degrees-of-freedom model which is seriously coupling. The guidance law used here is three-dimensional proportional navigation (PN), its main idea is to decompose the variables in three-dimensional space into two planes and use the conventional PN individually. At last a simulation example is given, the results show that the SDRE autopilot has good performance, and the availability of the control system is demonstrated.