Study on payload stabilization method with the slung-load transportation system using a quad-rotor

This paper introduces the payload stabilization method for safe payload transportation. We assumed that the vehicle and the payload are connected by wires, which is called the slung-load system. For the slung-load system, the wire generates various constraint forces between the vehicle and the payload. Various types of slung-load systems can be defined by various numbers of vehicles and payloads, but in this research, we used the slung-load system that is composed of only one vehicle and one payload. To model the slung-load system, we applied the Udwadia-Kalaba equation (UKE) to account for the slung-load system with various constraint forces. To transport the payload safely to destination point from the starting point, we suggest the payload stabilization method that modifies the structure of position controller of a quad-rotor. Controller gain design processes are also performed. Lastly, using the derived system model based on the UKE, simulation and flight tests are performed to demonstrate the performance of the payload stabilization method we suggested. Additionally, a particular unmanned aerial vehicle of quad-rotor is chosen as the main platforms of the entire system due to its advantages such as simple control logic implementation and maintainability.