Multi-rotor UAVs have been applied for load transportation, such as package delivery, and even flying taxis in the future. However, attaching load, especially those with large sizes, directly underneath the UAV can disturb the airflow detrimentally and consequently reduce the aerodynamic efficiency.
The sling load operation is a solution to tackle this issue, in which the load is connected to the UAV through a tether. Existing controllers typically neglect the elasticity of the cable, treating it as a rigid link, hence lacking accuracy.
In order to know more about how the elasticity of the cable affects the system behavior, we consider the system consists of a single quadrotor UAV, a point-mass load, and an elastic cable.