WEEK 17 / APPLICATIONS AND IMPLICATIONS
Document a final project masterpiece that integrates the range of units covered, answering:
What does it do?
A device that registers lines in 2D surfaces or in the air and stores them in the cloud for posterior access. Like Harold and the Purple Crayon, but in the digital world.
Who's done what beforehand?
Several digital pens already exist, but rely on tablets or pads. The first sort of object were probably the PDAs, which since then have been gradually evolving.
There is a similar project from the Fab Acadamy network: Roberto Gallo.
What did you design?
The electronic system to interact with an IMU and packaging in the shape of a pen.
What materials and components were used? Where did they come from? How much did they cost?
Bill of materials
| Description | Manufacturer | Part Number | Quantity | Price (USD) |
|---|---|---|---|---|
| Adafruit 9-DOF Orientation IMU Fusion Breakout - BNO085 (BNO080) | Adafruit | 4754 | 1 | 24.95 |
| Seeed Studio XIAO ESP32C3 - RISC-V tiny MCU board with Wi-Fi and Bluetooth5.0, battery charge supported, power efficiency and rich Interface | Seeed Studio | SKU 113991054 | 1 | 4.99 |
| Double sided copper PCB | 1 | 2.64 | ||
| TPU filament | Bambu Lab | 60103 | 0.027 | 39.99 |
| Aluminum sheet | JS102011SAQN | 0.25 | 16.90 | |
| Small tactile switch | C&K | PTS636 SM43 SMTR LFS | 2 | 0.19 |
| Small slide switch AYZ | C&K | 1431 | 1 | 0.71 |
| Capacitor 1206 0.1uf | 4 | 0.1 | ||
| Resistor 1206 500 Ohm | 3 | 0.1 | ||
| Resistor 1206 10k Ohm | 3 | 0.1 | ||
| Resistor 1206 0 Ohm | 1 | 0.1 | ||
| Mini neopixel | Worldsemi | WS2812B-2020 | 3 | 0.41 |
| Regulator linear 3.3V 1A | Diodes Incorporated | AZ1117 | 1 | 0.24 |
| Battery LR41 1.5V | 4 | 1.99 |
What parts and systems were made?
Electronics: PCB to interact with an Adafruit BNO085 IMU using a XIAO ESP32C3 microcontroller
Casing: front and back parts that hold the PCB and battery slot together
Front and back screens: front and back layers made of aluminum sheets
What processes were used?
CNC milling for the PCB and aluminum sheet
3D printing for the casing
What questions were answered?
Is it possible to create an independent digital pen that doesn't require a pad? Yes!
Is it as complicated as it seems? It depends! The required hardware is much simpler than I thought it would have to be. Programming it, however, was a huge challenge. Not only the movement tracking, but make a proper interface that would make the device provide a seamless experience.
What kind of hardware is it needed? The least is a microncontroller, an accelerometer, a button and power supply. A gyroscope and magnetomer IMU for more comples movement detection.
How to track movement accurately? Interpreting hand gestures is a complex task. The hand doesn't guide a pen in a literall 2D movement of the shapes it is intending to write.People hold the pencil in different ways.
What worked? What didn't?
Worked: sketching on a horizontal surface worked, with large gestures, using a power cable.
Didn't: sketching on any surface, BLE transmission, cloud saving. Although these could be further spirals.
How was it evaluated?
The ability to draw on a canvas using an IMU.
What are the implications?
It is possible to develop such device using an IMU. However, more development is needed to achieve the accurate recording and interpretation it would require to record natural handrwriting and sketching gestures.
The hardware can evolve to provide a slimmer device.
The digital interface can evolve to provide a seamless experience to the user.
Wireless and offline capbilities should be implement to experience the device at its fullest.