Research Of Unpowered Emergency Landing Control Technologies For UAV

The engine is the power source of the normal flight of unmanned aerial vehicle(UAV),and once the engine fails,the UAV will no longer be powered.The study of emergency landing flight control technology for UAV after the engine failure can guarantee the safety of UAV and aviod realizing huge losses.The sample high aspect ratio UAV was chosen as the object in this paper,and the guidance and control problems in the process of UAV flight and landing after the engine failure was studied.The main contents include:According to the uncertainty of the initial position and the heading,the process of emergency landing is divided into four stages: heading adjustment section,flight return section,energy management section and landing section.And then analyzes the influencing factors of the energy consumption during the emergency landing process,and works out the flight strategy of each stage according to the energy.The problem of energy allocation after the engine failure was solved.Considering the constraint relationship between UAV heading and position relative to the landing airport,the two-dimensional horizontal trajectory during the unpowered landing process was designed by using the plane analytical geometry method,which solves the guiding problem of the UAV’s horizontal direction.Aiming at the problem that the trajectory tracking and velocity control are seriously coupled during the unpowered emergency landing process,the height trajectory was designed by taking the principle of balanced glide which bases on the unpowered glide performance of the sample UAV.This design method can not only ensure the accuracy of height trajectory tracking but also guarantee the safety of UAV flight.Based on the principle of energy conservation,the ability for UAV to return to the airport was analyzed,and the guidance strategy of trajectory tracking was established.By using the robust servo and root trajectory control theory,the height trajectory tracking and horizontal trajectory tracking control law were designed which solved the problem of three-dimensional trajectory tracking during the unpowered landing process.Finally,the flight of unpowered emergency landing is simulated in MATLAB,and the simulation results verify the emergency landing control scheme designed in this paper.The results show that the trajectory,guidance and control law can guide UAV to return to the airport and land safely in the case of uncertainty of initial state and wind disturbance.