Tethered drone solution

SARA idea has been stimulated starting by a patent filed (July,3th 2015 – #102015000030672 “Aeromobile drone e stazione di cambio batteria per tale aeromobile”) which is based on a proprietary RPAS multirotor tightly coupled to a base station (HANGAR) able to change the RPAS exhaust battery with a charged one. The same system could be modified by substitution of the battery change tool with a winch tool system winding a tethering cable for power supply of the aircraft.

Figure 1‑10  shows some CAD sketches of the design of concept in two configurations

“HEM” (High Endurance Multicopter -on the left
“SAV-TV” (“Sistema Aeromobile Vincolato” registred as “Traliccio VirtualeTM” to Italian Patent office) implementing the Tethered Aircraft solution

The custom battery boarded on RPAS in the “HEM” configuration becomes a DC/DC converter in the “SAV-TV” configuration

The “killer application” for SAV-TV has been identified, by the Italian Coast Guard Stakeholder, inside maritime Search and Rescue applications, especially for night time operations tailor made on shipwrecks survivors rescue. The system will be designed to be tightly coupled inside the vessel, but also easily reusable for other markets. The conceived architecture realizes a deep innovation if compared with the process today used by users (overall Coast Guard Organizations), mainly for drastic reduction of operational time (and its related cost) and for increasing HR safety.

The main functions of the architecture of the tethered RPAS system are hereafter detailed:

RPAS-MPU: Main Processing Unit on board, to supervise aircraft navigation and all the functions generally needed to control the flight; one supplementary function of RPAS-MPU is the synchronization of flight data with the HANGAR-MPU, in order to better control the winch motion and cable torque;
RPAS-PS: Power supply for the aircraft and for its payload, whose main block is represented by the AC/DC converter, which provides the conversion of high voltage electrical energy coming from the base station (Hangar);
RPAS-GNS: GNSS receiver on board and GNSS on the HANGAR-MPU to provide accurate estimation of the baseline (distance) to enhance safety of operations (enhanced monitoring for winch torque and friction parameters of the cable), especially during vessels manoeuvres and movements
HANGAR-MPU: Main Processing Unit of the Base Station (HANGAR), whose main tasks are the control of cable torque and the synchronization with RPAS-MPU;
HANGAR-PS: Power generation to supply RPAS through the cable; it provides the energy conversion from different sources (230Vac, 12Vdc, 24Vdc, 48Vdc) and produces the correct high voltage electrical energy to transfer to RPAS-PS;
HANGAR-GNS: GNSS ground receiver, to get the HANGAR position, dynamically changing during ship journey; it provides the synchronization with RPAS position by data exchange with RPAS-GNS unit;
DATA-XCG: is the TLC media used to exchange data between the RPAS and the base station (HANGAR); in the first step of project a data link based on optical fiber will be tested; should this media have problem (cost or functionality) a “PowerLine” or a WiFi link will be adopted;
HANGAR-SLR: It is the slip-ring inside the HANGAR, whose task is to convert the winch rotation into a fixed connection for both electrical and optical signals.

This project has received funding from the European GNSS Agency (grant agreement No 776099),
under the European Union’s Horizon 2020 research and innovation programme GALILEO-3-2017.