Research Of Controllers Design For Quadrotor Under Different Working Conditions

Nowadays,quadrotors have entered the public's life from the laboratory,there are a wide rage of applications in aerial photography,resource exploration,short-distance transport and other fields.Although quadrotors have the advantages of simple mechanism,low cost and wide application,because of its high non-linearity,susceptibility to interference,under-actuation and so on,there are some difficulties in controller design,and some problem remains to be solved.There are many researchers studying the control issues of quadrotors from the different viewpoints.Through researching the related literature,we found the following several problems in this field:(1)The Hamiltonian model of the quadrotor has not been given;(2)When the unknown package is dropped from the quadtotor,the model-based controller is difficult to maintain the designed control effect;(3)When the quadrotor experiences the broken of rotor,the stability analysis has not been given for the existing fault protection controller.This thesis is concerned with the problems of modeling and designing controller under different conditions for quadrotors,and gives the corresponding solutions for the above three problems.After many years of development,there are many different forms of mathematical model of the quadrotor,therse models have different state variables and application occasions.This thesis summarizes these models and put forward the Hamiltonian form of mathematical model of the quadrotor first time.First of all,the models of the quadrotor are established under the two frameworks of vector space Rnand Lie groups SE(3).Specially,in vector space Rn,this thesis derives mathematical model by using Newtonian approach,Euler-Lagrangian approach and Hamiltonian approach,respectively.This thesis also gives the corresponding simplified model and discrete model.In particular,this thesis apply symplectic algorithm to the discretization of the quadrotor's hamiltonian model.Then,a novel nonlinear controller is proposed based on the simplified symplectic model.The controller includes two sub-controllers: attitude sub-controller and position sub-controller.Thirdly,we propose a method to update the mathematical model of quadrotor when weight is dropped from it in air.The method mainly contains two estimated regulations: mass and inertia tensor.Besides,we also design a geometric controller in Special Euclidean Group(SE(3)),which can track the given trajectory globally.This controller includes attitude sub-controller and position sub-controller.The attitude sub-controller can track global attitude with the estimated inertia tensor and the position sub-controller can track global position with the estimated mass,respectively.Then,this thesis deals with the problem of a quadrotor experiencing a total failure of one actuator.A nonlinear mathematical model for the broken quadrotor is derived with three control inputs and six outputs,which includes the translational and rotational dynamics.Then,based on the model,a nonlinear controller is proposed by sacrificing the controllability of the yaw state and reallocating the control inputs to the other three healthy rotors.The presented controller includes two sub-controllers: roll angle,pitch angle and altitude sub-controller and horizontal position sub-controller.Furthermore,the stability of the all designed sub-controllers are verified by the Lyapunov stability theorem and simulation results are given to verify the effectiveness of the proposed model and the designed controllers.