Research On Modeling And Control Of Variable Rotor Speed Aircraft And Engine System

Variable rotor speed aircrafts are widely used in all fields today.A high-quality flight control system can effectively enhance helicopter maneuverability,at the same time,an engine control system with predictive function can improve the speed of engine's response and immunity.This paper starts with the research working on both flight control and engine control.Firstly,the Component-level model of turbo shaft engine is established.To solve complex nonlinear characteristics of modeling problems in the starting process,stage-stacking method is introduced to obtain the low-speed characteristics data of compressor.Then,on the basis of similarity principle,the low-speed characteristics data of gas turbine and free turbine is calculated.The startup model proposed is a combined calculation for component level cooperated-working and cold working before ignition.Then a complete variable rotor speed aircraft model is established based on blade element analysis and flight dynamics.Finally,a comprehensive rotorcraft propulsion system model is composed of these two parts.Secondly,in order to further improve the accuracy of the variable rotor speed aircraft / engine integrated model,a non-linear dynamic inverse method with strong decoupling ability is used to design the flight control law.At the same time,introduce the reference model and integrator anti-saturation to further improve flight control.In view of the shortcomings of the dynamic inverse method being poor robustness,incremental dynamic inverse method is introduced.At last,according to the principle of time-scale separation,rate controller,attitude controller and navigational controller are designed.The simulation results show that the designed flight control law meets the requirements of flight control.Finally,in order to reduce free turbo overshoot or droop,take the fuel flow and compressor guided vanes as control volumes for predictive control.The dynamic models of torque and dynamic parameters of engine are established by using neural network.Take this as prediction model,and take FSQP optimization algorithm for roll optimization.Finally,compared with the traditional Cascade PID control method,the results show that the predictive control can effectively reduce the overshoot and droop of the free turbine.