Trackable Lasertag sensor

As a partner piece to the PDT Tracker I needed to make some 'wearables' to go with it.

My original plan had been to take some of the PCBs made for the PDT Tracker and jury rig them into that wearable.

I did this in May but in the end the software wasn't ready for the event I needed them at and even had it been the game overran and we didn't get to the point where they were necessary.

So I've had a couple of months to come up with a wearable beacon and I decided to go for an MVP of my Lasertag 'holy grail' idea: a  Lasertag sensor that is remotely trackable and sends status updates.

I consider it a 'minimum viable product' because not only is the software a first attempt it relies on external modules for some of its features.

All the PCB has on it is an ESP32-C3 WROOM module, RFM95W LoRa module, LDO voltage regulator, a few passive components and solder headers for various things.

The GPS will always be a bought in module but relying on an external USB breakout, LiPo charger and sounder makes it bulkier than it otherwise might have been. I also put the components all on one side for easy soldering which gives it a fairly large 'footprint'.

Initial desk based testing with the board you can see above showed everything to work so I designed a quite utilitarian 3D printed enclosure and assembled four headband style sensors to test.

Convention in UKLTA is that sensors are worn on the head and this prototype ended up slightly bulkier than the commonly used sensors but with a LiPo inside rather than 3x AAA batteries it was no heavier.

Getting everything inside the case was fairly easy but construction of the headband which includes four IR sensors and four 3mm LEDs was quite tiresome. I'd opted to make little 3D printed enclosures for these and this really exacerbated struggles with getting the wiring done tidily.

In the end this all worked so I'm going to improve on the software between now and our next event in May 2024. I might do a second revision of the PCB with more functionality on-board but without a clear requirement for the system yet the four prototypes I have work and can be used to further test the concept.

One of the things that didn't get tested is haptic feedback, mostly because I was rushing and I didn't have a nice compact vibration motor to use. It's planned though as one of our members is hard-of-hearing and also I really like the haptic feedback in the Laserwar equipment I use at another LARP.

So far this post has been all about the process and the componentry but here's the concept I'm trying to realise.

  • Every participant in a LARP is location tracked, players, crew and 'monsters'
  • The 'health' of every participant in the LARP is tracked
Obviously this only makes sense in an outdoor LARP with an element of tactical combat but that's what I play.

The purpose of this is essentially to allow us to replicate the sort of thing you see in action sci-fi media where there are one or both or some combo of the following two things.
  • A 'tracker' that shows the relative location of friends/foes to players eg. the Alien/Aliens motion tracker
  • A 'squad status' system for squad leaders eg. the 'command desk' in the APC in Aliens that shows the 'health' of the squad.

This is all very mil-sim industrial sci-fi stuff but that's what I want from my games. In principle it should also be able to link the sensor to my prototype Lasertag weapon board using Bluetooth and show when a participant is firing, out of ammo etc.

I would also love to partner it with my HelmetCam prototype for the full Colonial Marines experience but the challenges of WiFi outdoors may make that impractical.

These ideas are taking a long time to come to fruition but I am slowly edging towards them. I bought the GPS modules used in this back in 2020.