Modeling And Control Scheme Research Of Quadrotor Variable Mass Load System Under Wind Disturbance

With its hovering and vertical take-off and landing capabilities,the quadrotor can complete various tasks in limited areas and indoor environments.Therefore,it is widely used in military,civilian and entertainment.Currently,popular applications include unmanned aerial vehicles(UAVs)for delivery,forest fire rescue,environmental monitoring,etc.Most of these applications require ropes to hang loads to complete various tasks.However,the external wind disturbance and the change of load quality will affect the stability of the quadrotor and cause the swing of load when the quadrotor is hoisted.Therefore,it is necessary to suppress the load swing while ensuring the quadrotor track the preset trajectory stably.This paper introduces in detail the design of the modeling controller for the quadrotor suspension variable mass load and the research design of the swing angle suppression.The main research contents and methods are as follows:(1)This paper investigates the quadrotor suspension system,and expounds its development history,research status,hot spots and difficulties.(2)The hardware structure and flight principle of quadrotor aircraft are introduced.The position and attitude dynamics models of the quadrotor without hanging load are established by Newton-Euler method,Lagrangian method and quaternion method,respectively,and the three methods are compared.(3)The research status and types of mathematical models of quadrotor suspension system are analyzed.In order to be easy to understand and combine with practical application,considering the effect of mass gradient or mutation and external disturbance on the quadrotor during load suspension transportation,according to Newton-Euler method,the mathematical model of this kind of quadrotor suspension system is established.The dynamic model of the suspension system is simplified to facilitate the controller design in the later stage.(4)Combining the characteristics of the Newton-Euler mathematical model of the four-rotor hanging variable mass load,a control scheme based on the combination of the extended state observer(ESO)and the backstepping control method with an inner and outer loop structure is designed.And introduce error integral and saturation function to improve the backstepping control method.In the position loop,ESO is used to estimate the complex disturbance caused by load mass change and external environment disturbance in real time,and realizes the control of horizontal position by compensating in the control loop.A stable and robust attitude and height control law is designed for the inner loop of the control scheme using improved backstepping control method.In terms of load swing suppression,a combination of active control and passive control is used to suppress load swing.In passive control,the pendulum Angle controller is designed.Online trajectory planning is carried out in the aspect of active control,and the proposed trajectory generation method can achieve the goal of load swing suppression without adding a tracking control.In addition,the anti-pendulum term in the target trajectory does not affect the positioning performance of the quadrotor.In addition,the anti-swing item in the target trajectory does not affect the positioning performance of the quadrotor.(5)The proposed control scheme is simulated by MATLAB/SIMULINK and Rflysim platform is used to download the algorithm to the flight control for hardware in-loop simulation experiment.Compared with the traditional cascade PID control,the effectiveness of the proposed controller scheme and swing angle suppression strategy are verified.