Research On Formation Control Of Quadcopter UAV

With the development of new materials,mechanical electronics,inertial navigation systems and control technology,coupled with the miniature rotorcraft's low price,flexible operation,stable control performance,the ability to adapt to the environment and the characteristics of avoid casualties,rotorcraft has been widely used in military and civilian fields over the recent years.However,there are problems such as lack of energy,limited load and low efficiency in the face of complex environments when a single aircraft is performing a task.To solve the problems,the simplest and most effective way is to use the coordination of multiple aircraft.Therefore,based on the study of quadcopter UAV control algorithms,this dissertation focuses on the formation flight control method of quadcopter UAV.The main work and contributions of this dissertation are stated as follows:1)In order to better deal with the system uncertainties of aircraft and external disturbances in the real world,the position control technology of the aircraft is studied.Based on the analysis of the equations of motion of quadcopter UAV,two kinds of controllers,which are sliding mode variable structure controller(SMC)and separated saturations controller,are designed for the position control of quadcopter UAV.In this paper,different trajectories are designed and simulated.By comparison and analysis,we know that the two control algorithms have better control effect in handling the system uncertainties of aircraft and external disturbances,and the separated saturation nonlinear control algorithm can offer a more smoother UAV behavior.In addition,the quadcopter UAV attitude control system is developed by the model-based design,and the validity of this idea is verified by simulation and experimental.2)As the adjacent cross-coupled synchronization control strategy makes the complexity of the aircraft formation control system increase with the increasing number of aircrafts,a ring coupling synchronization control strategy based on the ring network communication topology is designed and a new mean deviation coupling synchronous control strategy with better synchronization performance is proposed to solve this problem,which can guarantee the synchronization performance of the aircraft formation control systems and not increase complexity of the control system with the increasing number of aircrafts.In addition,those synchronization control strategies combining SMC approach can be better able to deal with the system uncertainties and external disturbances of quadcopter UAV formation flight control system.Finally,the simulation results are given for system uncertainties,different external disturbances and different synchronization control strategies.Extensive comparative results show that the ring coupling synchronization control strategy and mean deviation coupling synchronization control strategy are effective in synchronizing the position of quacopter UAV and ensuring the stability of the formation of UAV.The proposed mean deviation coupling sliding mode control scheme has high control precision in position tracking and synchronization of quadcopter UAV,which achieves the better formation effect of UAV formation flight.3)In order to achieve more accurate formation control,the second-order integral model of the aircraft is considered instead of the first-order integral model,which can not reflect the position and velocity of the aircraft,the formation control problem of quadcopter UAV is studied through combining the nonlinear separated saturations control and second-order consensus protocol.Firstly,the dynamics is decoupled into x,y position and z height dynamical subsystems and the controller are designed,respectively.Secondly,based on the horizontal position of UAV and its second-order integral model,the second-order consensus protocol is used to develop the aircraft's consensus algorithm and formation control algorithm.Finally,the simulation results show that the formation control system composed of three quadcopter can converge to the desired trajectory and achieve the consensus control as well as formation flight control with the proposed nonlinear formation control scheme.4)Based on the second-order kinematics equation of quadcopter UAV with system uncertainties and external perturbations,the second-order sliding formation controller(SOSFC)combining the concepts of graph theory and second-order SMC is presented for leader-follower formation control.Then,the formation control system composed of one leader and three followers,which can achieve a square formation pattern,is utilized to verify the feasibility of the proposed formation controller.The experimental results show that the proposed SOSFC has better control performance and formation performance than PD formation control and sliding formation control(SFC),and which indicate the high robustness of the proposed control approach against parameters change and external disturbance,while can alleviate the chattering phenomena.