DESIGN AND EXPERIMENTATION OF A PAYLOAD CONTROL SYSTEM FOR VERTICAL LIFTING OPERATIONS VIA A TETHERED SINGLE-AIRPLANE

Abstract

Some unconventional vertical lifting techniques making use of tethered airplanes combine the high efficiency of airplanes with the vertical lifting ability of helicopters. The main challenge consists of accurately controlling the position of the centralized payload. Kilometre-long tether configurations, subject to aerodynamic damping, were studied to reduce the orbit radius of the payload, but they are sensitive to wind and flight path deviations. This article presents the mechanical architecture, numerical model, and control strategy of a payload control system (PCS) for a circling single-airplane tethered lifting system. The PCS is mounted onto the payload, and it compensates for external perturbations and the horizontal force acting on the payload from the tether due to the single-airplane configuration. Experimental flights were conducted using a DJI Matrice 600 drone equipped with a 31m long tether to mimic the trajectory of a circling airplane. During these flights, the PCS maintained payloads ranging from 1.6 kg to 4.8 kg at ∼10 cm from the target position. The PCS is a key component of this novel vertical lifting method, which can provide an alternative to helicopters and multi-rotor drones for cargo delivery or aerial work operations.