Dynamic modeling and control of quadrotor slung-load system using pid and nonlinear backstepping controller

Unmanned Aerial Vehicles (UAV) have proven their utility, robustness, and adaptability across a diverse range of applications and industries. Multi-rotor UAV have successfully replaced helicopters for a lot of applications, especially related to load transportation, successfully in recent times. Load transportation using quadrotors is being researched extensively. This work aims to contribute to the ongoing literature by addressing the problem of load transportation using quadrotors by developing a PID and Nonlinear Backstepping controller for a quadrotor slung-load system. The proposed controller works on controlling the quadrotor’s position and attitude which in turn damps the swing of the slung load. The control objective is achieved by having a cascaded double-loop architecture. The outer loop controls the horizontal translational position of the quadrotor slung-load system and commands the desired values of and by small angles as inputs to the inner loop. The inner loop then achieves the desired attitude by controlling the roll and pitch angles of the quadrotor. The controller stabilizes the quadrotor and simultaneously damps load swing. The performance of the proposed controllers is tested on the nonlinear model of the quadrotor slung-load system using MATLAB/Simulink simulation environment. The physical parameters used for the simulation are based on the quadrotor designed and fabricated by the Aerospace Engineering Department at King Fahd University of Petroleum and Minerals. Finally, a comparative study of the performance of the two controllers is presented based on the peak value of the load swing and settling time of the quadrotor’s translational and rotational parameters. The proposed controllers damp the load swing within acceptable time by controlling the position of the quadrotor.