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Final Project Proposals

I initially considered two possible final projects. Ideally I would have liked to to do both, but reality got in the way. I ended up doing only the first one, Bonobo Lights.

What follows are my original ideas, research and project planning for both Bonobo Lights and The Contraption.

Bonobo Lights

Bonobo lights are a tool for fun, safety and personal expression when riding bicycles at night.

This is the version I delivered (v0.9):

Summary slide

POV Displays

Persistence of Vision displays seem to be a whole category of DIY project. I wasn't able to find one that is both A) open-soure and B) meant for bicycle use until Guillem Camprodon pointed me in the direction of [LadyAda's SpokePOV] during the local review session.

See the references section for some examples and research.

Platform

Thoughts on choosing an MCU for the project.

ATtiny: can't program it (see week 08)

After reading a bit, I've decided to go with a SAMD21. The ESP32 and RP2040 chips seem to be a bit overkill for my initial requirements. I can always change it later. SAMD21 seems plenty powerful and simple enought. I can keep the Adafruit M0 Express feather as a reference.

Features that I want, in order of importance

  1. Ability to drive at least 12 monocolor LEDs and a hall effect sensor at the same time.
    • Eventually that should rise to RGB LEDs, and more of them.
  2. Ease of programming
  3. Wireless connectivity
    • This can be added later, after prototype 2
  4. Ability to output images (much later feature)

Project planning

Spirals:

Prototype 1 (POC)

Prototype 1 is a Proof of Concept. It isn't useful by itself but demonstrates the essential capabilities required.

Features:

  • Attaches on a bicycle's spoke.
  • Can detect and keep track of wheel turns.
  • Can turn LEDs on and off in the exact same position in each turn.
  • Compromises:
    • Powered by a powerbank rather than an internal battery.
    • Uses a commercial protoboard rather than a custom board (?).

Internal deadline: 2024-04-23

Prototype 2 (MVP)

Prototype 2 is a Minimum Viable Prototype (MVP), a 1.0 version. It is, just barely, useful.

Features: on top of prototype 1:

  • Can display a preset RGB static image.
    • Requirement: polar to xy.
  • Integrated battery.
  • Splash proof.

Internal deadline: 2024-05-21

Further spirals

TBD. Some features that might go into a v2.0+ prototype:

Non-essential features:

  • Bluetooth control
  • Programmable with custom images
  • Dynamic display: video / gif
  • Self-powered (with the bike's movement)
  • Sound
  • PC or phone interface
  • Configurable for different wheel sizes
  • Speed measurement / display
  • Multiple units working in concert

Each of these might become a spiral by itself.

Internal Deadline: TBD (updating the plan scheduled for the week 2024-04-03)

First version of project plan

Refs

POV projects

Capacitive Touch

Addressable LEDs

Other

The Contraption

The Contraption is a miniature mechanism without a purpose. It's a collection of linkages and structures that only exist. It is made of brass tubes and plate.

As it moves and turns it might move some paper signs or pepakura.

Inspiration:

Spirals

Rather than spirals, I've divided the development of The Contraption into elements that might go into it and that I want to learn to make:

  1. Right-angle structures with predefined dimensions and shapes, with the appropriate tolerances, dimensional and angular. Will probably need to print some jigs for this
  2. Flat shapes in brass: gears, latches.
  3. Motor mounts.
  4. Curved structures.
  5. Ferris wheel and belt.
  6. Wooden case.

Diameter of wire: AWG22(0.6440) - AWG24(0.5110) Source) * 0.6mm

First version of project plan

Gears

I made some gears!

1.6mm brass rods came in at 1.55±.02mm.

I designed some 1.6mm holes in Rhino and milled them in the Roland and they came out at 1.48±0.01.

I'm making a calibrating run with holes in different sizes.

  • On the left Roland, I got holes .2mm smaller than nominal and out shapes .1mm bigger than nominal.

Fits: * Press fit: 1.75mm nominal * Rolling fit: 1.8mm nominal * Sliding fit: 1.825mm nominal

Refs

Material sources

Tiene que ser de 0.64mm (AWG22) max. Los diámetros que valen son AWG22 y AWG24 (más pequeño).

Brass in Amazon

It's quite expensive.