Research On Attitude Control Of Quadrotors Based On Adrc Rejection Methon

The UAV(unmanned aerial vehicle)has the characteristics of a small area occupation,low price,high efficiency and excellent function.So no matter it is applied in the military or the folk,the future of UAV has unlimited possibilities.There into,the most notable is the quadrotor aircraft which is a kind of flying saucer.It can do many other things which numerous fixed-wing aircrafts can not do.Therefore,it is the rotorcraft UAV with the highest appearance rate,the most extensive functions and the most thorough research among the UAVs developed in various countries.The quadrotor is a complex underactuated system.It is an unavoided problem about the resistance to wind disturbance when the UAV is flying outside.The stability of the flight control system is the key to whether the UAV can fly smoothly,has strong adaptive ability and can maneuver quickly and flexibly.So the research on attitude control method of quadrotor aircraft has certain theoretical significance and practical value.The research on attitude control of quadrotor is as follows:Firstly,the theory of flight motion is introduced in detail,the definition of ground coordinate system and airframe coordinate system is given,and the conversion relationship between them is also elaborated.After analyzing the force and moment of the quadrotor by using its conversion relationship,the nonlinear dynamic model is established by applying Newton's law and Euler equation.Secondly,aiming at the quadrotor attitude system,three channels are divided and separately controlled in this paper: roll,pitch and yaw.In consideration of the quadrotor under actuated system,the model cannot be established accurately,and there are external disturbances during flight,so an ADRC(active disturbance rejection controller)is applied.The internal and external disturbances of the quadrotor are considered as the total disturbance of attitude system,and an ESO(extended state controller)is designed to estimate it,and the nonlinear error feedback control rate is used to compensate.For the weak robustness and poor anti-interference ability of single closed loop control,in this paper,a quadrotor attitude double closed-loop controller based on cascade ADRC theory is designed with roll angle as an example.Both internal and external loops are controlled according to primitive ADRC.Finally,the feasibility and effectiveness of the control method are compared by simulation.Thirdly,in view of the fact that the original ADRC controllers are all non-linear functions,with many parameters and complicated adjustments,it is difficult to quickly and easily realize their control requirements in practical applications.Dr.Gao Zhiqiang proposed a linear ADRC controller(LADRC).The frequency domain scales are related,simplifying the tuning parameters to three.This article continues Dr.Gao Zhiqiang's idea.The inner loop of the controller adopts a linear auto-disturbance control method.The linear disturbance state observer is used to estimate the total disturbance amount in real time and compensated by the internal PD controller.The outer loop adopts Model-Free Adaptive Control.This control method can realize the control of the system under only the input and output conditions of the controlled system.The core of the algorithm is to introduce a pseudo partial derivative,which makes the controlled system adopt a tight format dynamic linearity.Time-varying models instead of system models.The cascade control method used in this chapter can also ensure good control results based on the reduction of parameters,and also proves the stability of the designed controller.Finally,the feasibility and effectiveness of the designed controller are proved by simulation experiments and outdoor flight.