Modeling of the Cooperative Slung-Load Transportation System with Multiple Quad-Rotor Unmanned Aerial Vehicles

Abstract

This research concerns the modeling of the cooperative transportation system using multiple quad-rotor UAVs. Due to the advantages of the quad-rotor UAVs, such as the capability of hovering and the simpler control logic implementation, they are selected as the main platforms for the transportation system. This paper first describes the modeling and control strategies of the quad-rotor UAVs in order to give a brief explanation of the main platform. Among the existing methodologies on the UAV cooperative transportation, the technique used in this research to model the system is the slung-load system using Udwadia-Kalaba equation (UKE). UKE is applied in order to deal with various constraint forces existing in the system, since the slung-load system is equipped with a number of inelastic cables to carry a payload. Since the modeling of movements of the cable is also important when the constrained forces are not present, the logic of tightening and slackening of the wires is also included in the system model. Stability analysis and controller design of such model are also performed. Finally, with the finally derived system model based on UKE, a number of numerical simulations are carried out in order to verify the slung-load transportation system model.