| A quadrotor is a rotorcraft UAV capable of vertical take-off and landing.With its widespread use around the world,the amount of research being done to achieve autonomous tasks is increasing.Because the quadrotor is small and portable,low cost,high mobility and other characteristics,the quadrotor suspension system is more and more popular in military detection,emergency rescue,intelligent transportation and other tasks,especially in the complex terrain,the quadrotor suspension load transportation has obvious advantages.In this paper,the quadrotor suspension system is taken as the research object,aiming at the safety problems caused by excessive load swing in the transport process of the quadrotor suspension by rope,and how to reduce the adverse impact of environmental disturbance on the quadrotor transport,the specific research content is as follows:(1)The 2-D mathematical model of the quadrotor suspension system is established by Euler-Lagrange method.In order to improve the transportation efficiency of the quadrotor slung system,inspired by the bridge crane structure,a 2-D mathematical model of the quadrotor suspension system with variable rope length at non-equal speed is further established.The model can transport goods to the target location without the quadrotor landing operation.Due to the influence of various environmental factors on the transportation of the quadrotor suspension system,the3-D mathematical model of the quadrotor suspension system including the environmental disturbance is established by considering the influence of environmental factors on the transportation of the quadrotor suspension system.(2)It can be seen from the quadrotor suspension system dynamics model that the dynamics model is established by combining the energy of the system with Lagrange equation.Therefore,energy based passive swing reduction controller is selected.The controller takes advantage of energy dissipation and passivity to transform the control of each state quantity of the system into the control of energy.Through the control of the system energy,the pendulum angle of the load is limited within the safe swing range.(3)A partial linear feedback controller with strong robustness to a wide range of model parameters is designed to solve the problem that the rope length of a 2-D mathematical model of a quadrotor system with non-constant speed varies during flight.The nonlinear feedback technique is applied to linearize the direct drive system dynamics.Without changing the complexity of the model,the 2-D mathematical model of the quadrotor suspension system with variable rope length at non-equal speed is controlled in this way,and three control objectives are achieved: restraining the swing amplitude of the load,ensuring the stable flight of the quadrotor to the target position,and controlling the length of the rope for stable variable speed change.(4)Aiming at the problem that the environmental factors reduce the transportation efficiency of the quadrotor suspension system,the environmental disturbance is added to the quadrotor suspension system model as the disturbance model,and the 3-D mathematical model of the quadrotor suspension system including the environmental factors is designed.A sliding mode cascade robust controller suitable for the model is designed.The controller takes exponential reaching law as sliding mode function,which makes the model converge quickly and can precisely weaken the influence of environmental disturbance on the quadrotor suspension transport.(5)For the above three control schemes,the numerical simulation is carried out in the SIMULINK toolbox of MATLAB platform,and the simulation results show the effectiveness of the three control schemes. |
