Research On Closed-loop Identification Modeling For Control-oriented Flight Robot

The flying robot based on four-rotor is a kind of unmanned vehicle which can vertical take-off and landing,hover and rapidly change course,it has the advantages of simple structure,flexibility and concealment,and has important military and civil value,which is one of the research hotspots in the world at present.Meanwhile,as an unstable system with nonlinear,underactuated and strong coupling characteristics,it is necessary to establish an accurate mathematical model for the stability control of small quadtotor.However,it is difficult for the quadrotor to obtain accurate mathematical models due to the complex aerodynamic characteristics.In this paper,a quadrotor assembled by themselves as the object of study,respectively,in the mathematical modeling and flight control and other aspects of a series of research work.First,the basic structure of small quadrotor is introduced,and several common flight modes are analyzed.In the geodetic coordinate system and the body coordinate system,based on the Newton-Euler theorem and the coordinate transformation principle,the kinematics and dynamics modeling analysis of the 6-DOF rigid body is carried out,and the gyro effect and the coupling characteristic in the flight process are fully considered,and the full state nonlinear theory model of the four-rotor aircraft is deduced and established in detail.The closed-loop control simulation experiment of the model was carried out by PID control method in Matlab/simulink,and the nonlinear,strong coupling and underactuated characteristics of the quadrotor were fully understood,and the flight principle and motion law of the four rotary-wing aircraft were fully appreciated.Then,according to the basic structure of the quadrotor,the whole hardware scheme is designed,and the selection and purchase of the components are completed in the economic and practical principle,and a small quadrotor vehicle is assembled to meet the requirements of the experiment.Based on the algorithm of four-number algorithm and multi-sensor data fusion,a software scheme of attitude solution is designed,and the actual flight posture of quadrotor is obtained.According to the classical PID control strategy,the flight control system is designed for the quadrotor,which realizes the cascade PID control of the inner loop angular velocity and the outer ring attitude angle.The data acquisition system and flight condition monitoring platform of quadrotor are designed,and the actual flight test and flight data collection of the quadrotor are completed,which provides data support for the next identification modeling.Next,for the quadrotor,the open-loop unstable system,starting from the basic principle and general steps of system identification,the recursive least squares identification algorithm is chosen as the method of parameter estimation for closed-loop system based on the classical least squares algorithm,which has a fast iterative speed and has definite physical meaning.Based on the small perturbation principle,the nonlinear model of the quadrotor is simplified and decoupled,the model of the drive motor is simplified,and the discrete identification model set of the attitude channel is constructed.The closed-loop identification experiment is designed,and the remote control is used to carry out manual sweep signal,and the input and output data of three attitude angle channels are collected respectively.Based on the selected identification algorithm and experimental data,three attitude angle channels are identified,and the discrete transfer function model of the attitude channel of the quadrotor is obtained,and the accuracy of the identification model is validated by the test data under the same conditions.Finally,under the conventional controller,the model reference adaptive controller is designed based on the Lyapunov stability theory,aiming at the drift and vibration of the quadrotor in the outdoor flight experiment.According to the theory model of the quadtotor,the control problem is divided into two subtasks,the model reference adaptive control method is used to control the two subtasks,the stability of the system is proved by the Lyapunov function,and the adaptive control law is obtained.In matlab/Simulink,the model reference adaptive control method is simulated and compared with the third chapter PID control method.The simulation results show that under the same flight environment and flight instruction,the adaptive controller can suppress the drift and vibration of the quadrotor,and the attitude stability and tracking performance of the spacecraft are better than PID control.Thus,the theoretical basis is laid for the application of adaptive control in the engineering practice of quadrotor.