Indoor Formation System Implementation And Research On Control Strategy For Quad-Rotor UAV Based On Navigation Of VICON

Multi-unmanned aerial vehicles(Multi-UAVs)formation control has been a hot research topic at home and abroad for the reason that certain task requirements have been getting too complicated to meet for single UAV.In order to cope with the indoor formation control problems for the quad-rotor UAV,a formation control system is developed based on the VICON motion capture system.Then,decentralized formation control,distributed formation control,and formation communication reconfiguration have been investigated on the basis of the designed formation control system.The main contributions of this thesis are listed as follows:Firstly,the indoor formation system platform is developed.The quad-rotor UAV platform is built by using the Pixhawk mini flight controllers,and the secondary development is conducted for the ArduPilot flight control firmware.The host computer is developed based on the VICON system and MATLAB software,and the point-to-multipoint formation communication network is constructed via the XBEE.Such a formation system platform,which is of good compatibility,stability,and human-computer interaction,lays a solid foundation for the algorithm verification in attitude control,trajectory tracking control,formation control,and formation reconfiguration.Secondly,the mechanical structure and flight principle of the quad-rotor UAV are analyzed,and then the dynamic model of the quad-rotor UAV is established based on the analysis results.By using the proposed model of the quad-rotor UAV,attitude-angular velocity cascade controllers are designed concerning that attitude control is the basic control in the quad-rotor UAV flight control systems.Then,the proposed quad-rotor UAV model and attitude controllers are built in Simulink,and the software simulations and flight experiments are carried out to show the effeteness of the designed controllers.Thirdly,the design of the decentralized formation controller is completed.The two key points of the formation control are the trajectory generation and the trajectory tracking.As for the trajectory generation,a trajectory planning method is proposed based on the artificial potential field method.To deal with the trajectory tracking control problem,a position-attitude double-closed-loop control structure is designed according to the semi-coupling property of translational and rotation of the quad-rotor UAV.The flight experiment results are given to show the validity of the proposed algorithms.Finally,three different distributed formation control strategies are investigated.To solve the following problem in the distributed case,a formation holding controller is designed by adding an error mixer device.As such,the actual speed of the leader is added to the formation keeping controller,which can improve the speed responses of the followers.With the purpose of dealing with the formation failure caused by leader failure,a reconfiguration strategy of formation communication is proposed based on the graph theory depth-first search.By using the proposed reconfiguration strategy,the connectivity of formation communication information flow can be checked whether it is destroyed by the failure quad-rotor UAV.Then,the communication can be reconnected according to the hierarchical relationship of UAV.The experimental results show the effectiveness and correctness of formation maintenance controller and reconfiguration strategy.