Research On Fault-tolerant Control Technology Of A Multi-rotor UAV

In recent years,multi-rotor UAVs have received considerable attention at home and abroad due to their flexibility,because of the characteristic of vertical take-off and landing,hovering in the air,and good concealment.With the development of MEMS,control theory,sensor technology and new materials.Multi-rotor UAVs will be widely used in circuit inspection,military reconnaissance,terrain reconnaissance,express transport and other fields,which puts higher requirements on the endurance and safety of multi-rotor UAVs.In this paper,the hexarotor is used as the experimental object.The design of the hexarotor UAV motor failure was designed.The fault-tolerant control algorithm was built to verify the experimental platform.For the problem of poor endurance of the hexarotor,the power supply scheme with solar energy as the auxiliary energy and Maximum Power Point Tracking(MPPT)algorithm is designed.The main contents of this paper are as follows:(1)Analyze the flight principle of the hexarotor.According to Newton's second law,the dynamic model of the hexarotor is established.The kinematics model of the hexarotor is established according to the Newton's Euler equation.The control distribution of the rotational torque and lift to the six rotor speeds of the hexarotor is studied.(2)According to the mathematical model of the hexarotor,the quad-rotor model of the hexarotor is obtained.Feedback linearization and a sliding mode fault-tolerant control algorithm based on quasi-sliding mode is designed separately for the quasi-quad-rotor model.The solution to the problem of unsolved control allocation of quasi-quad-rotor rotating moment and lift to four-rotor rotating speed are given.The trajectory results of two fault-tolerant control methods are given by simulation in matlab.The results show that the sliding mode fault-tolerant control algorithm based on quasi-sliding mode has better fault-tolerant control performance.(3)The solar power supply scheme of the six-rotor UAV is introduced,including samping circuit,Boost circuit and driving circuit.In order to improve power supply efficiency,the mathematical model of photovoltaic cells and the basic principle of MPPT and the principle of MPPT realized by Boost circuit are studied.Asimulation model of MPPT based on Boost circuit is established.The incremental conductance method in maximum power tracking technology is studied and verified by simulation.(4)The selection of each module of the six-rotor UAV is introduced.Then the composition of open source software ardupilot and the code startup process are analyzed in detail.On the basis of analysis,open source code is modified to realize quasi-sliding mode fault-tolerant control of six-rotor UAV.(5)Introduce the ground control software Mission Planner of the six-rotor UAV and the preparation work needed to start the six-rotor UAV after source code modification.The performance of six-rotor UAV external tachometer sensor for speed acquisition is debugged.Fault-tolerant flight experiment of six-rotor UAV is carried out,and the feasibility of the control algorithm is verified.