Drotek releases first L1 RTK GNSS compatible with PixHawk (ArduPilot/PX4)

Dear Community,

Drotek, French tech start-up is proud to release its L1 RTK GNSS ! RTK technology allows to enhance GNSS positioning and to go down to centimeter level precision.

We have seen a lot of RTK boards coming up. However we have witnessed no good integration for the UAV segment and no performance enhancement in difficult environments.

This is why we decided to develop a solution to cope with these issues. Drotek is specialized in electronic design for UAVs and has put all its expertise in designing this board, jointly with French National Center for Space Studies (CNES) and French Institute for Aeronautics and Space (ISAE).

What is RTK for?

RTK technology uses corrections from a second GNSS receiver (called “base”, the other mobile receiver is called “rover”) in order to correct errors that lead to meter level precision. It has been used for a long time by surveyors, but at a very high cost. Today we want to trivialize this technology.

Our two years spent on developing this product have led us to focus on several points, such as connectivity, signal quality, EMI, real-time, etc...

We have compared our system’s performance with dual frequency receivers (in blue, Rover : Septentrio AsteRx 3 L1/L2 + Novatel geodesic antenna in RTK with base Trimble NetR9 + TRM59800), and it is pretty astonishing!

RTK works well in clean open-sky environments, but we like to test our device in difficult scenarios. Urban canyon is stil a pipe dream, but some route on ground robot in medium-hard environment (buildings, trees…) gives pretty good results :

Comparison between single GPS (red) and RTK : have a look at the left side under the tree. Single position gets highly contaminated by multipath, whereas the big ground plane and the Tallysman antennas filter it quite well :

Comparison between RTK Drotek (orange) and another open-source RTK solution (yellow) :

Base correction data can be sent through serial port with 3DR Radio types but also through cabled or wireless Internet for those want to get rid of range limitations. All drivers and server programs are already in the board. The following table sums up the different possible ways of communication between rover and base.


We are currently developing LoRa based transmitters, hoping that these will fulfill our expectations (we are quite excited about them!). Coming soon.

We truly believe in open-source community, but this board has also been designed to work “as is”. All boards will be delivered flashed and ready-to-use, with really little configuration, mainly for non-advanced users who would wish to get to precision without spending too much time on understanding how it works. Our wiki will explain everything step-by-step, but will also provide support on using RTKLIB graphical tools for post-processing and analyzing data. Do not forget to check our Github, we will publish in it really soon!

All our boards are stamped “Made in France”, we pay a lot of attention to the devices we manufacture in our French factory. Our motto is open source and open hardware, we work this way and we will stay this way. We want sell the atoms not the bits.

The package will be available in our site for pre-ordering. The expected release date is in one month, with a price of 699 € excluding VAT.

Our website is currently being redesigned, hope you will appreciate the new one! There will be plenty of content on how to use all the devices we manufacture, from little sensors to big boards!

Some additional exciting results :

This picture depicts the precision you can expect with good conditions, amazing!

 

A little demonstration (shot yesterday!) :

We modified an Iris+ drone, removed its GPS and replaced it by our board. Take-off is manual, and as soon as the drone lifted we triggered Return To Launch mode. The drone succeeded in landing on the table approximately 1 out of 2 times. It touched the table with at least two feet each time we tried the procedure.  Wind conditions were quite gentle but with a fair amount of gusts. Even if the board provides precision, there has been a lot of work on the controller’s PIDs to achieve this result!

We used a Netgear WiFi router to transmit raw data from the base to the rover, using Edison's WiFi. Base was connected in Ethernet to the router, everything powered by a 4S LiPo and a 12V power module.


We will offer a board to the person who comes up with the coolest name for the device !

10% off on pre-order !

http://drotek.io/1PodT25

See you soon in our website !

www.drotek.com

Views: 14163

Comment by Hector Garcia de Marina on February 8, 2016 at 3:45am

Exactly, it does not need to be a "mathematical scientific paper". On the other hand, it is always nice to check "exhaustive" experiments where if a follow the same systematic steps under very similar conditions then I would expect X results, as the ones that @Pascal or @Guy posted. Then I can judge whether I need your product or not, and if I need it and I meet the requirements, I know what I should expect from it. In my opinion, one of the the worst thing that you can have is a bad image from your costumers because of miscommunication/misunderstanding.

For example, I would say that the video posted in the main post would not be a good idea (I remark that this is just my opinion). Why? because it does not have anything to do with your RTK, the performance is more about the implemented controllers in the quadcopter, the quadcopter itself, etc. Just do not complicate your system more than it is, e.g. windy conditions, which in theory does not affect (?) too much your position estimations.

On the other hand, the plots in a urban environment are very awesome and they are 100% related with the performance of your RTK. So actual data in a separated report is always welcome!

Comment by Marc Dornan on February 8, 2016 at 7:45am
Yes. But drones landing on a table is a very effective demonstration of Pixhawk integration and that is a big selling point. Leave it in!! Even if it not scientific.
Comment by Darius Jack on February 8, 2016 at 8:01am

@Kevin,

live tests work the best.

Just connect 5 of your RTK GPS units to web server, placed at different geolocations

and let them plot GPS 3Dfix points cloud on-line, exactly as Ublox and other did.

And let live tests to be run for a week, month, always.

Comment by Darius Jack on February 8, 2016 at 8:19am

@Guy,

did you ever study RTKLib code, wire frames, algorithms implemented ?

You should be aware, RTK corrections have been already implemented into GPS satellite data feed.

So some known and unknown reasons Ublox still offers high-accuracy 5-10 metres GPS units.

Geodetic grade RTK GPS described by you to work since late 90's is not the implementation of RTKLib.

Do you have access to ITRF or SOPAC as a drone operator, hobbyist and your RTK GPS can read corrections on-line from them ?

Use of geodesic grade RTK GPS is by inked contract.

What is offered and called as RTK GPS is for public use and subject to long-term live tests, since flying a drone you can claim high-precision landing but you are accountable

to FAA or alike agencies world-wide, every time your high-precision landing fails.

"

 "do you know how RTK works ?" (no comment, I am a geodesist), "

In case of geodesy, you risk nothing, since you operate geodesy grade equipment purchased or renteed under contract.

In case of flying a drone, you risk everything, your money in third party personal injuries

if any.

Ok, you are a geodesist, you didn't study RTKLib implemented algorithms.

Could you read one day, 200-page long GPS M8 manual by Ublox and give us your comments ?

Comment by Pascal P. on February 8, 2016 at 9:08am

Getting a good absolute position for base station is the main problem for me. What we can't do with the Drotek system alone. Dual frequency receiver is needed to have a good PPP solution in a place with few geodetic point like where I live.

I remember a "UAV ground control kit" with one dual frequency receiver + 4 single frequency ones.

Comment by Kevin Lopez Alvarez on February 8, 2016 at 9:39am

Actually there are some tips to get a correct position (cannot be as good as dual frequency obviously)  for the base if you cannot afford dual-frequency receivers. For instance in France the IGN (French National Geographical Institute) has stations all around the territory.

If you are not too far from a station, typically less than 10 km, you can download raw data from the station. They are usually equipped with dual-frequency Trimble type receivers. You can then compute RTK algorithm in pots-processing. Otherwise algorithms like NRCAN PPP can also give sub-metric solutions if you upload large raw data files. Better than nothing in my opinion :)

Comment by Paul Meier on February 8, 2016 at 10:01am

@ Pascal, sorry my ignorance, so does a dual freq system give better ground station absolute position ?

and is google earth position not good enough ?

thank you

Comment by Darius Jack on February 8, 2016 at 10:17am

Thank you @Guy,

"

The RTKLIB in PPP‐static mode fixes the location with relatively high stability. Analysis of the accuracy of this fix results in the 2 m horizontal error when the vertical inaccuracy is at a level of 3 meters.:"

Did you read these papers ?

Comment by Pascal P. on February 8, 2016 at 10:20am

Paul, due to ionospheric effects which cannot be eliminated with single frequency data, you need dual frequency system if your baseline is above, let say 20 km. Remember that precise GPS is always a minimum of two receivers, one being on a known point. We determine vectors. Several vectors for one point will give you the possibility to assess the accuracy.

As we are talking here about 5 cm accuracy, Google Earth does not offer this level of confidence.

Comment by Darius Jack on February 8, 2016 at 11:01am
@Guy,

did you read these papers first ?
Could you extract one sentence, one drawing in support of claimed RTK GPS higher GPS accuracy ?

@Kevin

"
For instance in France the IGN (French National Geographical Institute) has stations all around the territory.
"

Access to state owned and supervised ground control stations is restricted, subject to registration, fees and more complicated terms, so individual modellers, hobbyists are excluded this access.

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