Introduction: 3D Printed Connector for VR Gloves
The Vive Tracker is used to bring real world objects into VR experiences. It tracks physical objects in order to make them part of a VR experience. What is really exciting about the tracker is that there are 6 pins which can be broken out and embedded into circuits to make DIY triggers. We have used the trackers and etextile circuits to make a DIY VR glove. We are using these gloves to do precision work for simulated molecules at the Intangible Realities Lab in Bristol University.
In this Instructable I outline how to make and attach custom 3D printed connectors to the Tracker. These connect the 6 break out pins to gloves, that can be used for pinching or grabbing things in VR in real time. Rachel Freire has made the full glove tutorial (https://www.instructables.com/id/Etextile-VR-Gloves-for-Vive-Tracker/).
3d printed part (this one, see also step 2)
6 x pogo pins (from digi-key)
Silicon wire (for flexibility, can also use regular stranded wire)
Conductive thread (we used Karl Grimm High-Flex 3981 7x1 copper, which you can get in small quantities here)
1/4" d-ring screw (from Jeffie)
Needle nose pliers
Data gloves (use Rachel Freire's corresponding tutorial)
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Step 1: 3d Model Design
The Vive Tracker has 6 pins, each of which connects to a different part of the VR system (such as menu, trigger, track-pad), technical details can be found in the developer guidelines manual.
In this tutorial we use three of the pins - the ground pin, and two of the general purpose input pins. We are only using two finger glove (index and middle finger) to keep the glove design simple. You can modify this tutorial to add more pins.
I created a 3d model using Rhino by remixing a camera fitting design. We use padding and a hard material to as support for tracker, so that its firm and holds the tracker in place. We tested this system with 100+ people and it is it doesn't move around (see Rachel's tutorial for more info on embedding the connector into the gloves).
To make the part, download the .stl file or get it from the thingiverse page, and print on a 3d printer. I used several different printers and a standard MakerBot with PLA works fine, but the higher resolution the better as it is a small part. It uses 1/4" camera mounting screws (designed for tripods) with a D-ring to make it easier to assemble or adjust.
Step 2: Curl and Solder Wires
The wires are used to connect the tracker to the etextile circuit using a hard to soft connection (see Kobakant's extensive research on hard to soft connectors). One end of the wire will be made into a loop so that it can be sewn, and the other end will be soldered to a pogo-pin that fits to the tracker's break-out pins. We used silicone wires because they are flexible.
Cut the wires slightly longer than they need to be. Strip both ends of the wire, careful not to cut any of the stranded wires off. Then curl a loop into one end using round nose pliers. Strengthen the loop by applying a bit of solder to it (this also makes it easier to sew).
If you want to use the tracker for another embedded circuit on the different object then you'll have to work out how long is wires need to be according to your own device.
Step 3: Organizing Wires
Insert the wires into the connector with the loop on the flat side, and the stranded ends on the curved part (these will be attached to pogo-pins). It's really important to keep wires well organized, especially if you are not using all the pins. This is where this is where it starts to get a bit fiddly and if you put the wrong the wire in the wrong hole you will be connecting to the wrong pins on the tracker. We labelled the holes on both sides of the connector using masking tape (label on both sides that way when you turn over your brain doesn't completely flip out trying to understand the mirror version!). If you're using all the pins this is much easier because you just insert 6 wires and you wouldn't need to worry about where they go at this point.
Step 4: Soldering Pogo Pins
Next step is to solder pogo pins to the stranded wire. Soldering the pogo pins is really, really fiddly. To make it easier we constructed a little soldering station with masking tape. Attach sticky-side-up masking tape to the table with two bits of masking tape. The sticky surface is steady the platform for soldering the tiny pogo pins
Then curl loops in the wire with round nose pliers (the same technique as in step 3), but make the loops smaller - so that they fit neatly around the pogo-pin.
Solder in two stages: (1) stick flat side of the pogo to tape, and add some solder to the pin on its own, and (2) put the loop you just curled onto the pin and reheat the solder - this forms a good connection between wire and pin. See the gifs for both stages in action.
Step 5: Fix Wires
To stabilize the wires and keep pogo pins in place add some hot glue. This is a potentially weak joint and the glue helps with this. Make sure that the pogo pins are correctly in place, and the flat side of pogos are flush against the curved part of the connector. Add masking tape to keep them in position (otherwise they could come loose when gluing). Hold wires into direction they will eventually sit when embedded into in the glove and put hot glue into the based of the wire.
Step 6: Prepare Gloves
There are a lot more details on the making and preparation of gloves on Rachel's instructable (https://www.instructables.com/id/Etextile-VR-Gloves-for-Vive-Tracker/), but essentially, the connector sits on top of the glove and slots into the vive tracker. In the inside is a thin plastic spacer, bonded with yellow fabric and Bemis Sewfree glue and another layer of neoprene for comfort.
Step 7: Hard to Soft Connection
Final step is to embed the connector into glove. Draw an outline of the connector with a gel pen onto your fabric so that people can position it correctly if they undo it at a later date. Label the wires with masking tape - again, being organized with wires is really important. We had a spare connector at hand to use for reference, and also labeled the wires to that we connected the wires to the right circuit. Then insert wires into a hole in the glove. Sew the loops onto conductive fabric traces on the gloves with conductive thread, tie off, and add a little bit of clear nail polish to ends to stop fraying. Finally, attach in place with the screw.