IFPC system design and simulation for HALE UAV

The propulsion system impacts the performance of High Altitude Long Endurance Unmanned Vehicle (HALE UAV) greatly, so in the stage of design and simulation of the integrated flight and propulsion control ( IFPC) system, it is necessary to build high fidelity models of the flight dynamics of UAV in consideration of the engine. At first, a nonlinear model of engine was established, which is calculated by variable specific heat aerothermodynamics method, and power extraction is considered also in the model, then the linearized equation of the rotor torque is derived, thirdly, the S-function of Matlab is employed to convert the engine model written by Fortran program to a module, which is useful in Simulink simulation platform. Compared to the results of engine ground test, the max relative error of thrust of calculation is 6. 5% only, this shows that the engine model utilized in this paper has reflected the exact properties of the real engine accurately. The IFPC model is derived by augmenting the model of longitudinal equation of motion of the UAV and the linear model of the engine together, and a mixed sensitivity H_∞ method is employed to design the IFPC controller, the simulation results show that, the dynamic respond performance of the velocity of the UAV can be met by using the controller, and when large power is extracted from the engine, which will vary the properties of the engine greatly, the vary of the dynamics of the aircraft slightly, and the robustness of the IFPC controller is proved.