Dynamics Modeling And Control System Synthesis Of Compound Coaxial Unmanned Helicopter

The compound high-speed coaxial unmanned helicopter can not only has the characteristics of helicopter vertical take-off and landing,hover,and low-altitude flight,but also has the characteristics of high speed,long range and endurance of fixed wing aircraft.It has very important practical value in both military and civil fields,and is one of the important development directions of high-speed helicopter in the future.This paper focuses on the dynamic modeling and flight control technology of the compound high-speed coaxial helicopter with the configuration of"coaxial helicopter&propulsion propeller".The research contents of this paper are as follows:Firstly,the basic configuration and parameters of the compound high-speed coaxial unmanned helicopter are introduced,and the control characteristics of different flight modes.Based on the aerodynamic analysis of the rotors and other aerodynamic components of the composite coaxial helicopter by modular design and mechanism modeling,and the full nonlinear mathematical model of the compound high-speed coaxial helicopter is established.The linearization model is obtained by simplifies the full nonlinear model with small perturbation linearization.Secondly,According to the control characteristics of the compound high-speed coaxial helicopter,the flight modes include helicopter mode,transition mode,and aircraft mode.The relationship between control variables and control in different flight modes is analyzed,as well as the analysis of switching strategy of transition modes.Finally,The classical PID control theory,H_?control theory and three classic H_?mixed sensitivity design methods are introduced.According to the obtained linearized mathematical model,the control law of the compound coaxial helicopter is designed.In helicopter mode,the control law architecture is designed with the inner and outer loop structure.The attitude loop and the velocity loop in the outer loop are designed with the H_?mixed sensitivity GS/T,and the position loop in the outer loop is designed with PI controller.In airplane mode,H_?mixed sensitivity GS/T is used to design the control law for longitudinal motion,and H_?mixed sensitivity S/KS/T method is used to design the control law for lateral motion.The control strategy of the conversion mode is also analyzed.