Study Of Formation Control For Multiple Quadrotors Based On Consensus Theory

Due to its small size,light weight,adaptability,high concealment and low hazard coefficient,the small quadrotor UAVs are of great practical value in military and civil fields and are favored by many scientific research institutions and commercial companies.Quadrotor has a wide range of applications,including disaster monitoring,topographic reconnaissance,rescue and short-distance transport.However,the payload of single-quadrotor is limited,which causes limited task complexity and limited fault tolerance.Then the cooperative task of multiple quadrotors becomes more and more significant in quadrotor research.In this thesis,a distributed formation control method based on the consensus theory and sliding mode control is designed for multiple quadrotors to realize the coordinated flight of the entire formation.The effectiveness of the designed control algorithm is verified and analyzed by numerical simulation.The content of this thesis can be summarized as follows:First,we consider the quadrotor as a rigid body and establish the kinematics and dynamics equations of the quadrotor.The established quadrotor model is divided into position subsystem and attitude subsystem.In view of the super-twisting and terminal sliding mode method,a finite time controller based on disturbance observation is designed for the two subsystems to achieve stable tracking for the desired trajectory.Meanwhile,it also reduces the influence of external disturbances and uncertain parameters on the stability of the control systems.Secondly,a distributed formation controller is designed for multiple quadrotors.We assume that each quadrotor can only get the position information of the neighbors.Only a few individuals in the formation can get the flight trajectory of the leader.In this case,we design a distributed formation controller based on the consensus theory and the sliding mode control method.The formation controller generates the desired velocity information for each quadrotor,and the velocity tracking controller drives each quadrotor to track the desired velocity in finite time,which means that the desired formation is achieved.Finally,a distributed formation controller with collision avoidance effect is designed for formation and reconfiguration control of a team of quadrotors in this section.In order to avoid collision between quadrotors,we add a potential energy function into the controller to achieve this goal.In the flight space of the quadrotors,we introduce the potential field and design a spherical collision avoidance zone for each quadrotor and treat the other aircrafts in the space as obstacles.When the distance between the obstacle and the quadrotor is greater than the radius of the collision avoidance zone,the potential energy function does not work.When the distance between the obstacle and the quadrotor is less than the radius of the collision avoidance zone,the potential energy function can generate repulsive force so that the quadrotor can bypass the obstacle.Moreover,the size of the repulsive force increases as the distance decreases,so the collision between the aircrafts can be avoided effectively.