Active Disturbance Rejection Control Of Quadrotors

A quadrotor is an aircraft with four propellers.Compared with a manned aircraft,a quadrotor has the advantages of small size,low cost,low environmental requirements,and strong survivability on the battlefield.It is used worldwide,and the great charm and development prospects of quadrotors have attracted much attention.A lot of energy has been invested in both industries and academics to promote the development of quadrotors.Since a quadrotor is a nonlinear multivariable system with strong coupling,there are many challenges in the control design,and it is an ideal platform for practical control applications.Many control methods have been applied to quadrotors.PID is one of the most common methods.However,it is difficult to achieve the desired performance using a conventional PID controller.Therefore,this paper proposes a PD-LADRC two-loop control system to improve the tracking performance and disturbance rejection performance of the system.First,the structure and flight principle of a quadrotor are analyzed;the state variables of the quadrotor model are expressed on the basis of aerodynamics,and the dynamic model of the quadrotor is established using the Newton-Euler equation.Then linear active disturbance rejection controller(LADRC)is studied,and a parameter tuning method based on an existing PID controller is proposed.The method can provide useful initial values for LADRC parameters,in that the LADRC with the obtained parameters achieves the same stability and disturbance rejection performance as the existing PID controller.For the nonlinear,under-actuated quadrotor with strong coupling and uncertainty,a two-loop control system is proposed to control the attitude and the position of the quadrotor separately.PID controllers are first tuned for the two loops,and LADRC controllers are obtained from the tuned PID controllers.Simulation results show that the LADRC-controlled system has the same disturbance rejection performance as the PID-controlled system,and a better regulating performance in attitude.Finally,a PD-LADRC control system is tuned for an experiment quadrotor,crazyfile2.0.Simulation results show that the proposed control method can estimate the internal and external disturbances of the system and compensate them quickly,which can meet the control requirements of quadrotors.