Research On Transportation UAV Tracking Robust Control

Unmanned Aerial Vehicles（UAVs）have attracted a great deal of interest from researchers due to their simple structure,their powerful manoeuvrability and their great value for commercial and military applications.Especially in the last decade,a significant increase of research interest in lightweight,short-range air transport technology.Lightweight,short-range air transportation technology are important for express delivery,intercity transportation and emergency rescue.Therefore,as the simplest structured UAV,the quadrotor UAV with a suspended-load is an important transportation tool for material transfer in complex and hazardous environments.Since the quadrotor transportation system is an eight-degree of freedom system with only four control input,it is difficult to achieve rapid stabilization under the external disturbances.For the quadrotor suspension payload system with unknown load mass,this thesis designs the anti-disturbance controller of the quadrotor transportation system to improve the stability and robustness.The details of this study are as follows.1.Constructing the kinematic and dynamic models of the tethered quadrotor system by Newton-Euler method,and establishing the dynamic model of the quadrotor suspended load system based on Lagrange’s equation,which provides a model basis for the design of the control system.2.The tension model of the tethered UAV is derived by Newton’s second law and the law of centripetal force.A differential trajectory-based control method is proposed for the stable and high-speed flight of the tethered UAV.By the differential trajectory,the velocity at any point in space converge to the desired trajectory in order to improve the robustness of the quadrotor in high-speed flight.Also,a nonlinear controller based on the rotation matrix is designed to avoid the singularity of the Euler angles.Numerical simulations are performed by MATLAB to verify the robustness of the proposed control method.By comparing the PID controller and the geometric tracking controller under different perturbations,it can be concluded that the differential trajectory-based controller outperforms the other two controllers and has good robustness for stable flight at high speed.And the trajectory tracking controller guarantees a stable flight speed of 10.5m/s under aerodynamic disturbances and mass changes.3.For a quadrotor suspended load system with unknown load mass,this thesis designs a parameter adaptive control algorithm to achieve stable trajectory tracking and load oscillation suppression.A nonlinear controller based on a rotation matrix is designed to achieve fast attitude stabilization.By analysing the effect of load mass on trajectory tracking control,a parameter adaptive controller incorporating a load mass estimation algorithm is proposed for position control.The control method maximizes the load carrying capacity within the thrust range of the quadrotor.An analysis of the system stability based on Lyapunov stability theory shows that the attitude error converges exponentially and the whole system can remain stable.Comparative simulations show that: 1)the mass estimation algorithm can accurately estimate the mass of the load in the air; 2)the controller outperforms a sliding-mode controller with input shaping in terms of mass estimation,trajectory tracking and immunity to disturbances,and can increase the maximum payload capacity.