Svalbard UAV: Lessons learned

Here are a few things I learned after ten days of field testing the UAV multispectral data acquisition in Svalbard…

Video showing take off in stabilize mode, switch to loiter mode at about 5 m, quick control test then into automatic mission. 

1. The UAV is surprisingly robust.

The aircraft was transported to the sites on a sled on the back of a snowmobile, hitting sastrugi and general lumps and bumps in the landscape, was hold baggage on three flights, launched and landed in snow, flown in winds and operated at temperatures down to -25 degrees. It is still is perfect working order and flew every mission without issue. I’m now pretty confident in the flight case and arrangement of kit inside, and trust that there won’t be significant flight issues in Greenland in summer.

2. Very low temperatures rapidly deplete the LiPo batteries

One noticeable, and unsurprising, effect of flying in these conditions was that the battry ran down very quickly. The toughest day was about -19 but with strong winds, and we only managed a 2.5 minute automated flight before the battery voltage dropped low enough for me to get twitchy and land the UAV manually.

DSC01424
Taking off on a particularly cold flight, near Telbreen, Svalbard

3. A dGPS and ground control points will be essential for ground truthing the UAV imagery 

It was impossible to accurately pinpoint ground sampling locations using handheld GPS and ground feature ID. This was especially true in Svalbard because of the homogenous snow cover, but will also be an issue in Greenland in the summer. This is not really surprising, but the need for an accurate dGPS location lock has been reinforced by the test flights.

4. The workflow for geotagging multispectral images using Photoscan is not as straightforward as I originally thought. 

The red-edge camera does not output GeoTIFFs – they have to be postprocessed with ground control point data before they can be stacked and aligned. This is not a big problem, but good to know in advance of summer data collection.

5. New landing gear needed

The three-leg solution currently used on the UAV is better than I expected, but there is still the real problem that the legs sink into soft ground (e.g. snow) which risks pushing the camera lenses and the internal electronics into the snow. This could scratch the lenses or soak the electronics when the snow melts. Also, with the current model, a problem with any one of the three legs compromises the whole UAV because it becomes impossible to land flat. I’m going to develop something new before Greenland.

Video showing manual landing on a patch of compacted snow after an auto mission. It would be more stable on soft ground with a skid-type landing gear rather than the three legs. Includes heckling by Tedstone…!

6. Some a priori knowledge of image area can be useful

High resolution imagery is not available for all locations – for some of our field sites there was not sufficient google earth coverage to orient ourselves or draw a polygon by eye in Mission Planner.  It is possible to estimate using the compass and the map scale, but with some existing knowledge of the GPS coordinates of the grid perimeter would help to plan an accurate mission.

7. It’s amazing how small the UAV looks, even when flying quite close by

Even flying the UAV at 30 or 40 m elevation, it quickly becomes difficult to keep track of its orientation when it flies a hundred metres or so on a mission. This does have implications for the length of mission I’d be comfortable flying, since I want to be able to rescue it manually if there are any GPS or autopilot issues – maybe I’m soft but my comfortable range is less than the CAA ‘dronecode’ distance limits- even though these do not currently apply in Svalbard/Greenland. Of course, the conditions (esp. visibility) affect what feels comfortable.

8. The controller is awkward in gloves

At -25 C gloves were pretty essential, but it is also difficult to have fine control over the switches and sticks on the controller. I was flying in a very thin pair of gloves or gloveless, which meant my fingers quickly went numb, especially when there was any wind. This will be less of a problem in Greenland in summer, but I will still get some warmer, thinner gloves with rubber finger pads to help with the UAV control in the cold.

9. Pre-flight checklists are invaluable

It’s so easy to overlook or forget something in harsh conditions or when rushed or excited. The written checklists developed before we went out to Svalbard were extremely useful for making sure everything went smoothly. These are a condition of CAA compliant flights in the UK and our experience in Svalbard demonstrates why! I will probably add a few additional checks or reorder a few things before our Greenland deployment – site specific things like take off and landing zone preparation (in Svalbard it was often a compacted snow platform, in Greenland I intend to use plyboard to avoid melt ponds and cryoconite holes).

DSC01444
One of the field sites at Reiperbreen, Svalbard

2 thoughts on “Svalbard UAV: Lessons learned

  1. Hi, thank you for your interesting post about flying a drone in Svalbard! I’m currently planning some drone surveys in Svalbard for this summer and I was wondering if you encountered any problem with the lack of GPS signal.. Can you still fly the drone (maybe in manual mode only?) when there is no or poor GPS signal?

    1. Hi Hanne,

      I’ll be flying in Svalbard this summer too! It depends on the region. I have not had any issues around the Longyearbyen area; however, the Ny Alesund region is a wifi and radio silent zone and permissions from the Norwegian CAA, Nkom and the local mapping service are required, along with coordination with organizations running radio sensitive experiments (e.g. GFZ). If you are doing repeat surveys over ice, I’d recommend laying down a series of ground control points that will be visible in your images and recording their precise location before each flight using a differential GPS so that you can account for ice flow. If you are competent flying in ATTI mode (not available on the common DJI drones) you can fly without GPS, but the camera trigger will need to be set independently of the GPS (e.g. a timer or manual control) – I imagine it would be tough to get good imagery without GPS support. In summary I suppose it depends on your drone and your field site. I’d be happy to talk more about it – feel free to DM me @tothepoles on twitter or instagram.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s