Research On Attitude Control Of Quadrotor Craft

Quadrotor craft is a four input and six output underactuated system,which is sensitive to the change of uncertain factors,because of the multivariable nature of the system,the strong coupling between the attitude angles,and the uncertainty existing in the internal and external environment.Therefore,the system can easily change the parameters of the system because of the influence of external interference factors,thus breaking the stability of the system.Quadrotor system has complex features and some in the flight of unknown factors,the mathematical model of the original building is difficult to meet the requirements of flight,so we need to design a better control mode to make up for Quadrotor attitude control is not enough.The specific work of this article includes:(1)A large number of literatures about the development of Quadrotor in the field of attitude control and the related control technology are often consulted.According to their structural characteristics,Newton’s theorem and Euler equation are used to establish a nonlinear mathematical model.(2)A simplified mathematical model and linearization of nonlinear system by using the LVP method,proposed the PID attitude control scheme based on the adaptive control law,but the model reference adaptive control(MRAC)with two different control structure,in order to design a performance more excellent attitude controller,therefore,designed two different the structure of the attitude controller,and the experimental data were compared and analyzed.The experimental results show that,although the system has a certain amount of overshoot,the adjustment time is faster,and it is suitable for the larger environment.(3)To solve the problem of small range flight or narrow space,we propose a nonlinear active disturbance rejection control(ADRC)scheme,the experimental results show that the system has small overshoot,for uncertain factors,has a strong anti-jamming capability,and using the Lyapnov theorem on the stability of the closed-loop system are demonstrated.But because of ADRC,adjustable parameter number,need to spend a lot of time to adjust.(4)Aiming at the problem that many control parameters are difficult to set up in ADRC,a linear active disturbance rejection control(LADRC)scheme is proposed.The scheme is mainly composed of PD control algorithm and extended state observer(LESO).The control scheme can realize the estimation and real-time compensation of internal disturbances and external disturbances,which can overcome the coupling of the system and the uncertainties of the internal and external systems,and use the frequency domain method to determine the stability of the closed loop system.Finally,the real time control experiment is carried out by using 3DOF Hover as an experimental platform to verify the feasibility and practicability of the designed controller.The experimental results show that compared to the improved model reference adaptive control(MRAC)and ADRC,LADRC not only has strong anti-interference ability,and has strong robustness to the system uncertainties,greatly enhance the compensation ability and estimation online system capacity,and the system has small overshoot the system can be subjected to uncertain factors in case of interference,can still ensure the speed regulation of aircraft system stability and attitude control,suitable for small space flight environment.