A project log for HTC vive lighthouse custom tracking

3d position tracking using our own design of the sensors, an altera fpga for decoding the signals and custom code for triangulation and poseestimation

Simon TrendelSimon Trendel 05/14/2018 at 23:180 Comments

So eventually we have moved to the much more integrated TS4231 from Triad. The reasons are size, price and assembly time. While Luis chip works like a charm, the time to assemble the two-sided PCB with 30+ components has been very annoying. The TS4231 only requires 2 caps, a resistor and the photo-diode. We assembled  63 of the new sensors in approx 2 hours.  You can find our kicad layout here.

The sensors are cheaper now aswell, like 1.50 euro per sensor. If you make more it will get even cheaper.

The size of new sensor is approx 10x9 mm, so it is smaller aswell. If you are crazy enough to go for double sided assembly, you might be able to half that size.

One downside of the TS4231 is, that it needs to be configured via its two cables. On power-up it goes into a state, where the envelope signal is output on the data line (which caused major confusion, when we started using them). It does that for about a minute or so, then goes to SLEEP. We have written a small verilog module called ts4231.v, that automatically configures a connected sensor to go to WATCH state, in whatever state it is. This module essentially does the same as the arduino sample uploaded by Triad. I dont know, why Triad decided to design the sensors like this. It would have been cool, if the sensor would just output the envelope signal on whatever single line, without going to SLEEP state. But the way it is designed you will need two wires for sure for each sensor. Which sucks of course, but I guess thats the price for this pretty little fellow, that also gives you the modulated infrared signal on the data line (lighthouse v2 we are coming).

So far, we are very happy with the new sensors. They seem to be a lot more robust against shallow incident of light and to be in general less noisy than Luis design. 

Currently, we are designing tracking sleeves, with an integrated fpga+esp8266 solution, so stay tuned...