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 !
See you soon in our website !
Comments
@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.
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!
@Kevin, something like Guy indicated :
https://www.sensefly.com/fileadmin/user_upload/sensefly/documents/e...
we can add this one :
http://www.delair-tech.com/wp-content/uploads/2015/09/White-paper.pdf
+ publication of geotagged photos and control points, allowing people tu run their own software.
@Hector : we will publish in our wiki a detailed sequence of tests, including raw data analysis, GCP comparison, stationary/kinematic precision, etc... If you have any ideas of tests, just tell us we will be happy to execute them!
@Darius @Guy
I would say that we are misleading a bit the post.
I see the point of Darius, stating that the main post is more marketing than a rigorous study/results. Indeed I will not need any expensive certification from third parties, but I am the kind of engineer that before spending a cent on whatever equipment, I would like to check a study (detailed "datasheet"?) like the one presented by Guy is his last post.
I completely understand (and support) that the marketing has to be present nowadays. On the other hand it is not incompatible with a nice rigorous study supporting it.
@Darius, do you simply understand the concept of Differential GNSS ? and do you really think RTK started with RTKLIB in 2007 ? How fun ! Have a look there :
I used geodetic and RTK GPS land survey systems from Trimble, Wild (now Leica) and also Sagem if I remember well, since late 90's early 2000's.
For the other issues you raise, I just think it is lost of time to argue, but : "do you know how RTK works ?" (no comment, I am a geodesist), "There is no warranty RTK GPS can offer better accuracy than non-RTK L1/l2 GPS" (in Real Time, no difference really ?), "you need an array of ground based stations geodesy grade geolocalised first" (hum, do ever heard of ITRF or SOPAC ?)
Hi Elios,
I have not tried but I think it could be possible this way :
Base : inject base's raw data into telemetry mavlink
Rover : connect telemetry's TX to Edison, sniff raw data packets for RTK (for example using RTKLIB's str2str, and a buffer file) and route packets back to FC's serial port, leave RX directly connected to FC. Have to try though!
However, RTK's correction data rate is about 10kbits/s, so you can use lower baudrates to increase range, this is why it can be better to use a different data link for it.
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