Final Project Progress¶
Background¶
I (still) play Pokemon GO. In the game, one of the gameplay mechanics to get new Pokemon, is to hatch eggs. Hatching eggs requires you to walk or as of November 2018, get registered kilometers through Adventure Sync. Adventure Sync connects to Google Fit or Apple Health, and registers the distance you walk when your game is closed. Sometimes you need to hatch many eggs fast, or to have an empty egg slot to for a specific reward. Sometimes you accidentally spin a pokestop when you are not supposed to, and get an egg and possibly need to get rid of it fast. Because you can’t delete eggs, you must hatch it. Some people fake walking to hatch eggs while watching tv for example. You just mimic the up-down movement of walking either by hand, or placing your phone into sock and swinging it up and down.
My final project idea¶
For more than a year, I have had an idea of mechanical device where you place your phone and it mimics the up-down movement. However, I don’t want to make a box with a piston sticking out of it for phone attachment, I want a more attractive design. Hence, the Incubator! (Sync-incubator, Syncubator?) A device that looks like a Pokemon GO incubator, but has a door mechanism for you to insert your phone where the egg would be.
I think it should be powered by a usb charger, possibly have a display for elapsed time etc., possibly a timer functionality, possibly a pass-through option to insert charging cable for your phone (would require second usb charger) and more optional functionality waiting to be invented!
I don’t want the first version to have-it-all, I want the first version to work, proof that device like this can exist and so on. In the game there are 3 kind of incubators, so first one will be the infinite incubator with orange accents, future iterations may take form of paid incubator (blue accent) or super incubator (purple accent with more oval shape).
Research¶
Need to research previous work of mimicking walking and fooling Google Fit and Apple Health. My research so far:
I had heard that devices that fake walking have existed before Pokemon GO due to some kind of insurances that require exercising. Searching “phone swing” on google results surprising amount of Pokemon GO related results and products! https://www.amazon.com/JGP-Adjuster-Included-Required-Automatic/dp/B07T3DLBKN/
Note to self: Check also https://youtu.be/cfTv8BxR_hQ
Selecting movement mechanism¶
Initial idea is crank mechanism, but other ideas include “slot” mechanism that Eino told me about.
Crank mechanism is more familiar to me of these two. Slot mechanism could also work, but my concerns are does it wear out itself faster than crank. Crank has rotating parts, while slot has sliding parts. At least some manual lubrication might be beneficial for slot mechanism.
Anyway, I chose crank, since that was my initial idea and it doesn’t have sliding parts.
Actuator (motor) selection¶
Initially, I thought stepper motor could work, as it can be run at suitable speed without gearboxes and I used steppers on our Mechanical & Machine design weeks.
My final project needs an actuator that can lift a phone with protective case.
Options are: - stepper motor: suitable, but requires stepper driver - dc motor: requires gearing - servo motor: requires quite powerful servo with well-made gearing
I found two sizes of stepper motor from FabLab, so I decided to use them. Coincidentally, my output week board would be suitable for running steppers.
I tested these motors using my output week pcb that has stepper motor driver. I was surprised how high currents bigger motor needs for low and zero speed movement. For higher speeds, both motors need a lot less current than lower speeds.
I ended up using smaller of these two motors, due to worrying about high-ish current consumption of bigger motor. Lower current consumption is also good for intents to make this project portable, i.e. to be able to operate from power bank.
Movement guidance / cylinder¶
I thought it would be hard to come up with transparent solution for a cylindrical housing for my final project. I had some ideas about making it out of poly-something (TODO: check name of the plastic) by using vacuum forming. Jani also thought it would be good, but time-consuming idea. Faster solution would be repurpose some plastic, transparent tube that was laying around in Jani’s office and Jani was happy to give it to me.
Crank designs & materials¶
For crank mechanism, I started with designing the simplest crank I could imagine in Fusion360.
I measured motor shaft diameter to be 5.0 mm and the flat part of D-shaped shaft to be 4.5 mm thick.
First version of crank was laser-cut out of 3 mm mdf, but the movement was a bit stiff, so I changed material for 3 mm acrylic.
Joints were tried to be made using plastic spacers and fitting cranks onto them, but later Yrjö had an idea to use aluminum pipe, which also seems to work with less friction than plastic spacers. Aluminum pipe was cut in the workshop next to FabLab, where I also sourced bolts, nuts and spacers for cranks and motor mount.
For first, “quick and dirty” idea of how to mount the motor, I came up with plates that fit tightly around the motor and can be adjusted by tightening nuts to different separation distances. First plate has openings for shaft and motor mount points, second and third plates and openings for motor body and last plate has extra space for motor wires. These plates were laser-cut from 3 mm clear acrylic and were cheap way to find good solution via trial and error. Errors included missing holes and missing space for wires.
Some kind of piston was next thing to be done. I sketched a very simple piston in Fusion360 that consist of two plastic pieces that friction-fit to each other. Later I added indents on top of this piston for easy attachment of piston plate.
Electronics¶
…
Top / 3D design¶
…
Case¶
…
Software¶
…
Presentation¶
…
Video¶
…
Notes for future iteration of this project¶
Ideas postponed to future iterations:
- Making cylinder out of vacuum formed transparent plastic (polystyrene?)