Attitude Stability Control Of Multi Rotor Unmanned Aerial Vehicle With Variable Loads

In recent decades,the unmanned aerial vehicles(UAV)have been widely used in military and civilian fields.Its related research has received more and more attention from engineers and technicians.The multi-rotor UAV has become the focus of UAV research because of its simple structure and flexible maneuverability.Multi-rotor UAVs need to carry various mission loads when performing different tasks,The attitude stability of UAV which will be affected by the shape and quality of the payloads is the basis for the safe completion of the mission.Therefore,it is of great theoretical significance to design a proper attitude controller so that the UAV can achieve attitude stability under different loads.This paper focuses on the attitude control problems of a coaxial twelve-rotor Unmanned Aerial Vehicle with different loads,and mainly research on the following several aspects:(1)The establishment of the mathematical model: To study the attitude control of UAV,the dynamics model of UAV must be established first.Firstly,the appropriate reference frames are selected and the transformation matrices between the coordinate systems are given.Then,the dynamics and kinematics equations of the multi rotor UAV are established by using the Newton kinematics correlation formulas.Finally,the situation of UAV carrying different types of loads has been concerned,and the dynamic equations of the multi rotor UAV carrying different loads are introduced.(2)The design of attitude controller: Two different controllers are designed for comparison in this paper.Firstly,the attitude controller of multi rotor UAV based on PID control was designed.Considering the influence of different loads on the attitude of UAVs,multiple groups of simulation experiments were designed to verify that the controller is effective.Due to the limitations of the PID control,the attitude controller of UAV based on Auto Disturbance Rejection Control(ADRC)was designed to improve the control effect,and the same experiments were designed to test the controller.Then several groups of comparison experiments of two kinds of controllers were designed to compare the control.Finally,the conclusion was drawn.(3)The design of track controller: The double closed loop control system for position controller and attitude controller of multi rotor UAV was designed.The attitude controller based on ADRC with better performance was used in the inner loop,PD control was used in the outer loop to design a position controller.Then the trajectory tracking simulation experiments were carried out and the results were analyzed.The results show that the controller designed in this paper can achieve stable trajectory tracking requirements when UAV carried different loads.