The EC-SAFEMOBIL project, initiative that belongs to the VII Framework Programme for R&D of the European Commission led and coordinated by CATEC and the University of Seville in the field of unmanned aerial systems (UAVs) and robotics, continues advancing its research and has achieved another milestone in this field. The project team has developed in recent days a pilot project which has led to the first landing of an unmanned aircraft on a three dimensions moving platform using a cable and without GPS. This experience paves the way for the implementation of this kind of landing UAS on vehicles such as boats or land vehicles.
Landing tests have been performed on the facilities of ATLAS Flight Test Center for testing unmanned aircraft, ascribed to FADA-CATEC and located in Villacarrillo (Jaén). These are the only facilities in Spain that have been designed specifically to test light unmanned aircrafts.
The EC-SAFEMOBIL project seeks to develop new technologies of multivehicle cooperation using unmanned aerial systems (UAS), specifically new methods of accurate position estimation and motion control that will make UAS and ground autonomous systems more secure and reliable for a wide range of applications such as disaster management, search and rescue (especially under extreme conditions), security and other missions that involve human risk.
Besides landing an UAV on moving surfaces, the project is developing other new technological demonstrators, such as the launch of an unmanned aerial vehicle from a manned one or tracking several ground vehicles using multiple unmanned aerial systems with the ability to avoid collisions.
Comments
Hello Eli,
The big advantage with this system with respect to a computer vision system it is the robustness. Using a visual pattern you will probably have problems in bad visibility conditions, like fog, rain, etc. Also, in the last meters of the maneuver, it is possible that you will lose the visibility of the visual pattern or you need to put several of these visual markers depending on your distance to the landing pad.
This system with the tether is very robust and all the required sensors are on-board, so you do not need GPS!
Hello Rob, you are totally right about the sling load. We actually did this some years ago, in a project called AWARE, where we used a two angle sensor (you need the two angles) to stabilize a load at the end of a cable.
Yes, the operation that we have in mind it is like the one you commented.
Thanks Juan Carlos for your comments. Yes, the helicopter is a logo but we integrated our own avionics to transform it into an UAV.
We use a winch that automatically keeps the tension of the cable constant so we do not have the effect that you mentioned. We tested up to 50 meters of height and it was working perfectly.
A landing pad on a ship is`nt gonna change i`ts shape or pattern, so you just could use some visual pattern on the pad like chess pattern, and use an optical flow algorithm with one camera, that`s all.
Guys it`s a total waste of your money and time.
I don`t understand why you call it autonomous.
It`s a cable being stretched between the helicopter and the pad !!
Of course you could read correction values with a cable,I have no words.
Interesting. I bet that sling angle sensor could also be used for controlling flight with a sling load.
So the intention is that the helicopter could fly around untethered, then come in to land, drop a tether line, which is hooked up, and then it's winched in? Just like full-size. Very interesting.
Very interesting.
What happens when there is heavy wind and forces that are detected through the cable are distorted? The typical situation when the cable draws a parabola, especially with very long cable lengths. Is it feasible in this situations?
The helicopter it's a logo?
Thanks Rob for your comments.
You are right, we have a winch under the platform that maintains the tension but the helicopter is not just applying full collective. We have modified the control algorithms to take into account the whole system, including te tether forces. But as you mentioned, we plan to use this system to land UAVs on rough weather conditions at sea.
You are also right. We use two angle sensors on the wire connection, so we know the relative orientation of the tether with respect to the UAV.
Yes, the idea is that the helicopter is always tethered. In a complete landing maneuver, there will be a moment that the UAV has to deploy the tether and an operator should connect it to the winch. However, this technology could be also used to make the UAV follow a ground vehicle without using any type of GPS or external sensor.
Nice to see more helicopters!
I see the winch under platform, is the helicopter being winched down similarly to how they land helicopters on Frigates and Destroyers today? The helicopter applies full up collective, and the boat winches it down, to solve the problem of landing on a heavily heaving deck in rough seas. I suspect not, but it could be used on rolling seas.
I imagine there's an angle sensor on the wire connector under the helicopter which tells the controller what the angle of the wire is so it knows where the platform is.
Is the plan that the helicopter is always tethered? So this is just a method of landing a tethered UAV on a moving platform?