1Download and View the Material Carefully
Building and assembling the prototype entails considerable effort. But generally it should be feasable to hobbyists and makers as well as to professionals in electronics and hardware development. There is no doubt that many steps will differ from build to build as the used materials and the tools may differ. This guide therefore tries so give you an overview over decisions I made and the strategy I followed, when I build my unit. As I am very interested in your way and also in your questions and proposals for improvement: Comment here or drop me a line, when you start to work on this!
Have fun with this guide, I hope it will help!
2COMPUTING UNIT: Finf, Buy and Print Components
Plenty of stuff is needed and some parts may need some improvisation as you maybe can't purchase them all over the world.
We're starting with the casing for the computing unit. Therefore you need:
The Armband and the Adapter
There are many offers out there for detachable sport armbands. You can find them in different variants. This one and this one should come closest to the one I used. You can also find the parts separate, like this adapter
TNTOR Power Bank
Might be difficult to find outside of Europe – at least I couldn't do so. It is a very thin (8.8mm) power bank which in general keeps it promises.
Raspberry Pi 3b+
You will best know where to purchase. I didn't test many other versions, but performance should be best on the newest... Raspi ZERO DOESN'T WORK! As is doesn't know NEON commands, used by the camera's library.
The 3D printed Case itself
You can find the 3D files in the files section. Hope you have access to a printer. Double check the measurements if your components fit!
3COMPUTING UNIT: Slim Down the Raspberry
To slim the computing unit down, I removed the USB ports, the Ethernet port and the "Display" socket and cut the end of the Raspberry Pi 3b+. Have a look at this and this tutorial!
First the tricky part: unsolder and clean up the soldering joints. When the parts are removed, cut the raspberry along the green line:
4COMPUTING UNIT: Put Everything Together
The Assembly is pretty self-explaining. Glue the armband adapter into the printed casing, put the cables in the wholes and solder them to the Raspberry as described in the schematics (files section). Then you can mount the raspi in the case, close it and stick the power bank in the slot (I used some fabic tape to protect it from scratches).
Did everything work out well so far? Comment or write if not!
In the next step we will continue with the PCB
5MOTOR BOARD (PCB): Buy Parts and Reflow!
This motor board will later be sewed to the glove. As I use LRA vibration motors I need 9 seperate DRV2605L drivers to power them. As they all have the same i2c address that can't be changed, I used two TC5948A i2c multiplexer to communicate with them. A few capacitors and pull-down / pull-up resitors and that is basically it.
First check my PCB Design. I uploaded the Gerber file and the Eagle file (which I used to create the design). Furthermore I added a link to a Dutch producer of prototype boards. Use this, if you're from Europe. They are fast and deliver good quality and the best thing is: they order and pack all the parts you need from digikey – which would take extra time and costs if you order from Europe...
Can't add a lot to the process. This is my first PCB design, there might be plenty of improvements... I was also new to the reflow technique and asked a friend for help. It is definitely worth to learn! This is, how my PCB looked after reflowing:
6GLOVE: Find and Buy Components
For this last step a bit of improvisation is needed: The glove I used is already out of stock and so could be the next I select.
The final glove is made out of two layer, covering and holding the motors, the cables and the PCB. The vibration motors need to have good skin contact. So for the inner layer you should test some models and choose one that is fitting properly. The outer layer has to be a bit bigger, that it fits around the inner. Of course you can sew your own glove completely, I just used ready made ones to save time whilst prototyping.
Furthermore you need to purchase a right-angle camera cable and the LRA vibration motors of the components list: G0832012. Keep in mind to buy some spare parts, sometimes they break.
7GLOVE: Assembly and Sewing of the Inner Layer
This is the general layout of the glove (without its shell):
The motors have adhesive on the bottom which helps to stick them onto the fabric until you can sew them in fix "pockets" with the outer layer. Position the PCB and start with routing and sewing the cables of the motors towards the PCB. Here it is important to sew them in a sinuous line to relief tension off the cables, especially the soldering joints at the motors. I put some extra glue on them to fix them additionally.
Next solder the cables to a free port of the motor board. The order doesn't matter, you can change it in the code. Also the polarity is not so important, as LRAs need alternating current. Furthermore solder 4 free wires of the connection cable to the board. As described in the logs I couldn't find a cable fulfilling the requirements yet, I keep you updated.
Last but not least you have to sew a Magnet onto the glove which later keeps the camera in place. I used some nylon as a base plate, but you have to see what you have there...
8GLOVE: Assembly and Sewing of the Inner Layer
Now comes the finishing work: put the bigger, outer layer over the inner and start sewing around the motors in the fingers, so that they are in pocket-like fixtures and can't move out of them anymore. Apply this method for every motor and periodically do some stitches to fix the outer on the inner layer. In the end you need to cut a small whole for the camera cable put the open end through and solder it to 4 wires of the described connection cable, to connect it to the USB port of the Raspberry. The mounting of the camera with the magnet is provisional, I will update this post, when I found a better solution.
9COMING SOON: Installing and Using Code
I have to end the instructions here. Soon I will write more about the software side and how to install and use the code. Stay tuned!