High-Precision Tracking Control Of A Quadrotor Aircraft

The quadrotor has been widely used in military and civilian due to its advantages of simple structure,flexible operation and low cost etc.While the quadrotor brings convenience to the work in various fields,people also have higher requirements for the control accuracy of the quadrotor.Especially in the military field,rapid response and accurate tracking are highly desired for the quadrotor to complete the task.Therefore,the high-precision tracking control of the quadrotor has become a hot topic in current research.Due to the influence of factors such as its own weight,propeller area and span size,the quadrotor will inevitably lead to the difference of model parameters between different quadrotor.It is difficult to achieve high-precision tracking control by the traditional control technology relying on the model.After establishing the model of the quadrotor by the dynamics and kinematics principle,this paper considers the influence of unknown external disturbance on the quadrotor and designs a high-precision trajectory tracking control strategy.Firstly,an adaptive sliding mode backstepping control strategy is designed based on nonlinear disturbance observer.This control strategy combines the sliding mode control method and backstepping control technology in order to improve the robustness of the system.At the same time,the adaptive strategy is adopted in the sliding mode switching term,which avoids the large gain and severe chattering of the system inputs.In addition,the nonlinear disturbance observer is designed to further reduce the weak points of the adaptive terms and achieve accurate estimation of unknown external disturbances.The closed-loop system can achieve asymptotic stability by the Lyapunov stability analysis.Simulation experiments verify that the control strategy can achieve fixed-point hovering of the quadrotor.Furthermore,there is a static error in the trajectory tracking of quadrotor by adaptive sliding mode backstepping control strategy.An adaptive integral sliding mode control strategy based on nonlinear disturbance observer is designed.The control strategy not only ensures the robustness of the system,but also reduces the steady-state error and improves the tracking accuracy of the system.Simulation experiments verify the superior performance of the control strategy.Finally,in order to improve the system’s rapid response capability,a high-precision trajectory tracking control strategy based on finite-time disturbance observer is designed.Specifically,the quadrotor system is divided into a position subsystem and an attitude subsystem.Considering that the attitude subsystem is a fully-actuated subsystem,a non-singular terminal sliding mode control strategy is designed,which ensures the state error can converge to zero in a finite time.The position subsystem is an under-actuated subsystem that still uses an integral sliding mode control strategy.At the same time,the finite-time disturbance observer is used to accurately estimate the unknown external disturbance.Compared with the nonlinear disturbance observer,the disturbance observation error can converge to zero in a finite time.In general,this strategy not only improves the tracking accuracy of the system,but also reduces the time to track the desired value,and achieves the high-precision tracking control of the quadrotor under the influence of external disturbances.Both theoretical and simulation results demonstrate the superiority of this control strategy.