Research On System Model And Attitude Control Of Small Unmanned Helicopter In Sandstorm Environment

Compared with fixed-wing UAVs and multi-rotor UAVs,small unmanned helicopters have irreplaceable advantages.Although researchers from all over the world have carried out active and in-depth research and have achieved many phased results in the field of small unmanned helicopters.Due to the complex and highly nonlinear dynamic model of small unmanned helicopters,they have not been widely used in real life.The research content of this paper comes from Jilin Provincial Department of Science and Technology"Research and Application Development of Vertical Take-off and Landing UAV System Equipment for Rapid Response Rescue and Disaster Relief",project number 20190303061SF.The technology has been researched,and at the same time,it has provided ideas for realizing the stable flight of small unmanned helicopters in harsh environments.Aiming at the modeling difficulties of small unmanned helicopters,a more detailed nonlinear flight dynamics model is established.Through the mechanism modeling method,the main rotor,tail rotor,fuselage,horizontal tail and vertical tail aerodynamics of small unmanned helicopters are analyzed.He carried out detailed calculations and derivations,established a detailed nonlinear dynamic model of a small unmanned helicopter,and completed the construction in Matlab-simulink,which laid the foundation for the subsequent in-depth research on the flight control of small unmanned helicopters.Aiming at the nonlinear model of small unmanned helicopter,it is linearized by small disturbance theory,and a low-order parametric loop shaping algorithm attitude controller based on linear matrix inequality is designed for the linear model.The order of the loop shaping controller is 4 lower,and the response performance and stability margin of the controller can be flexibly adjusted by adjusting the parameters.The simulation results verify the effectiveness and flexibility of the control algorithm.In order to further verify the robustness of the attitude controller to the disturbance under complex working conditions,a two-phase flow simulation environment of wind and sand was built in Ansys-fluent,considering the disturbance of wind and sand under different wind speeds,different particle sizes,and different mass concentrations.The wind sand disturbance is introduced into the control algorithm to verify the control effect.Under the wind speed of 18 m/s,the particle size of 100μm,and the mass concentration of 9000μg/m~3,the attitude controller designed in this paper can still converge to stability in about 2s,and then the attitude angle is in the range of±1.15°.The results show that the controller still has a good control effect in the wind and sand environment,which provides a reference for exploring the control performance of small unmanned helicopters in harsh environments.