As we have written before we are working on a DWM100-based ultra-wide-band local positioning system, we are making good progress and are getting ready to ship alpha systems. We hope to be able to ship in the following weeks. We aim at shipping these alpha system to anyone interested to test it early.
The alpha anchors and DWM deck will be very close to our expected final system. We are in the process of pushing the source code for it on GitHub, it will have open-source public code before we ship the first system.
We have now stocked enough DWM1000 modules and we are ordering the final PCB design for the anchor. This would allow early access to the technology and for us we would be able to get feedback. We are planning on selling the anchors around 100USD each and the DWM decks 70USD. The price is taking into account that we are manually soldering, testing and shipping ourselves. If you are interested to get access early please contact us (you can find the contact email on the contact page).
We have just made a quick and dirty video tour of our basement/autonomour flight lab. This was shot in one take so it is a bit messy, but our goal was to show our current state. We are using the Crazyflie python client training mode with the automatic controller as a student. This is why I keep the gamepad in my hand most of the time: the first flight is done with me controlling thrust and yaw, the controller controls roll and pitch. The second flight is fully autonomous but I still could take-over control by pressing a button. On a side note these tests are showing how good it is to have a lightweight and robust quadcopter like the crazyflie: the Crazyflie you see in the video has crashed countless time this last mount in the basement, I have not yet changed the motor mounts nor any other part on it.
7 comments on “Local positioning system alpha program launch”
This looks awesome! :)
I have a few questions:
-What is the minimal number of anchors that you need for stable positioning?
-What is the range of the anchors?
-Why did you put all anchors on the ceiling? Would triangulation be better if you had an anchor on the ground?
-Do the anchors need any connection besides power? Can they be powered with batteries/LiPos?
– 4 anchors is the minimum to get a 3D estimate. In theory 3 should be enough but I have not tried
– The theoretical range is up to 100 meters. I would assume about 30m indoor (again not tested).
– The anchors are on the ceiling because it started to work like that. I have 2 in the floor planed but then the ranging do not fit anymore in one LOG packet. So even if having anchors on the floor would in theory make the system more accurate in Z I have been mostly working on integration so far.
– The anchors are standalone. They just run a very simple state machine, waits for packet from Crazyflie and answer with timer values to allow Crazyflie to calculate the ranges.
Thanks for the questions, I need to update the wiki with more information like that.
I am going at FOSDEM at the end of the month and I plan to bring the system: if it is dry outside I could try a longer range autonomous flight ;-).
Will the anchors require a clear line of site to the CF2?
As far as our experimentation goes, it works great as long as the Crazyflie has direct line of sight contact with at least 4 anchors. We get ranging measurement while communication non-line of sight but so far these measurement have been then very inaccurate.
Sorry, I am getting too excited about the technology and asking questions too quickly :)
I researched the Decawave and found that they advertise 300m distance with line of sight, and 40m with non line-of-sight.
Here is a link: http://www.decawave.com/products/overview
For the DWM1000 module integrating the small antenna, the max range we have been able to get outdoors is about 60 or 70m, with line of sight. It would be interesting to know if others could get a better range. I would not count on NLOS with this module, and in any case even if it worked it will bias your range measurements in ways that can be quite unpredictable if you just use Time-of-Flight based distance estimation.
When do you think the source code will be available on GitHub?