Show HN: DIY Position Tracking Using HTC Vive's Lighthouse
github.com
github.com
Let me know if you have any questions!
If I read it right, a way to feed it position data is already integrated in the drone firmware, so you only have to send it the found coordinates and it uses them, correct?
Yep, I'm using Mavlink protocol (specifically ATT_POS_MOCAP message) to feed 3d position to the drone autopilot.
Would it be hard for the drone to be able to seamlessly switch between indoor/lighthouse tracking and outside/GPS tracking? How about the ability for the drone to orchestrate the battery swap autonomously with the charging unit? If you could add those two features you could produce a proof of concept video that would probably blow a lot of minds.
Seamless switching is definitely doable and shouldn't be hard, just need some time to implement. I'm using PX4 autopilot and it's very friendly for adding new functionality.
Orchestration is also close - in current demo both station and drone use Wifi to coordinate, so it's a matter of adding new logic.
Currently the most limiting resource for that project is my time :) I'd be happy if other people would want to join!
P.s. I think the I-term in your pid control loop is too high on your quadcopter, that oscillation isn't really affecting your flight control too badly but it heats the motors more than a stable tune would which reduces the service life of the permanent magnets in them.
Could be the P-term but the oscillation looks too slow for that, I guess one way to check for sure (assuming you don't have a blackbox on there) could be to increase your D-term and see what the response is
Curious what your thoughts are on this vs one of the official SteamVR tracking modules[1] which use the TS3633[2]? For $10 this is an awesome hack for off the shelf components. However, for $70 + Shipping you can pick up 10 of the tracking modules which filter out noise and do accurate envelope calculation.
> The CM1 contains all the circuitry necessary to convert SteamVR Tracking base station infrared light into a digital output that encodes the angle of the sensor from the base station.
That implies that it's not a full location tracking solution by itself (angle only). The data sheet[0] doesn't seem to shed any further (ahem) light. Maybe I'm wrong. And I'm certainly interested in learning more. Do you have more details on the SteamVR tracking system?
What you are getting in this chip is all of the work Valve and Triad have done in improving the accuracy of that envelope signal. Essentially, the accuracy in the timing of that signal == the accuracy of the position. There's a really good talk from Steam Dev Days[1] (that I was fortunate enough to attend) that gives a good overview of all the work that has gone into SteamVR tracking.
There is a huge amount of design that has to go into the sensor layout. Bad sensor layout will cause significant problems in tracking. It's extremely constraining in what you can do.
The system is designed to work with one base station. The second is only for redundancy, covering areas of the play area that are occluded for the master base station by your own body.
In contrast, Oculus uses cameras to detect IR LEDs on the device. It's kind of inside out from SteamVR. They have to them do image processing on the PC to get the angular position with regards to the camera of each LED. SteamVR just has to convert timing values into laser emitter motor positions. Once you get to that point, they are pretty much the same, having to compute position and orientation from that data. It's just a lot cheaper for SteamVR to acquire that data.
It also means that adding more cameras to Oculus adds to the workload, whereas adding base stations to SteamVR does nothing to the PC. Both will increase workload to add more devices, but it's negligible compared to the image processing Oculus has to do. Oculus' system is fundamentally unscalable. SteamVR is fundamentally scalable.
@ashtuchkin maybe link it from your page?
The timing calculation still needs to be done somewhere though, I wish there was a module that would do it internally and just publish the timing numbers - that would be more scalable and then even Arduino would be able to handle several sensors.
Do I understand correctly that a single sensor board as described here will get position, but can't get orientation?
If so, how does the drone handle orienting itself correctly to land on the battery swapping station?
> 3d position accuracy: currently ~10mm; less than 2mm possible with additional work.
Could you outline what is required to take your solution from 10mm to 2mm accuracy? what factors limit maximum accuracy?
Presumably the lighthouse-derived position could be fused with IMU data for better temporal accuracy. Does your drone software do that?
Thanks!
Currently std dev of each position coord in rest is 1.9mm.
Fusion with IMU is the next level and is usually done later down the line because it needs to be tuned for particular model. Yes, the drone does that.
I recently did shop around for motion capture system (cameras tracking markers) and one of the cheapest systems with comparable performance to OP's came out to cost $5-8.5K.
How was the base station visualization[1] done?
[1] https://camo.githubusercontent.com/d9241f231a03d177d215f98bd...
Having been developing with the Vive for most of the last year for Left-Hand Path (http://store.steampowered.com/app/488760), and given I've got a lot of mocap experience before that, I can confirm that Lighthouse's tracking is ridiculously good.
It's not just as good as something like an Optitrack system: it's significantly better.
If this provides comparable tracking to what the Vive offers, it's an absolutely unbeatable price / performance combo.
I have a colleague with some deep technical knowledge in this area - he's the guy who did the heavy lifting when I built an inertial mocap suit a while ago. I've pointed him at your project. If it turns out that it is of interest, perhaps you can get some useful collaboration / suggestions out of that!
There's a whole bunch of indoor positioning methods, having different precision/simplicity/cost profiles, so you might need to shop around. Probably cheapest and closest to my sensor is ultrasound sensors like http://www.marvelmind.com