World Atlas


Developer:

Richard Johnson

Co-conspirator:

Joshua Bradley

Source code:

https://github.com/OrwellsGhost/WorldAtlas



Introduction

The world is not flat and I can prove it with my 3D globe of light! This project attempts to harness the geothermal power of mother earth, the torrent of legendary hurricanes, and a persistence of vision in an effort to produce a spherical world map that can be rotated by simple hand gestures from afar. In fact really, really far and preferably from behind something! At high speeds this thing is down right scary!

How does should it work?

Using a vertical strip of 32 green LEDs to represent a column in a 32 pixel height monochrome bitmap encoded as an arbitrary length array of 32-bit unsigned longs, masking operations are applied to turn each LED on or off for a given horizontal index. Timestamps of the last eight instances where a mounted reed switch passes a magnet are captured and their inter-arrival times used to calculate the RPM for regulating the horizontal cycle rate through the bitmap as the motor turns the device. Once auto-calibrated, the globe will appear stationary regardless of variance.
Additionally, a Wifi Shield is employed to auto discover and establish a channel of communication between the device and laptop. A Kinect is used to capture left or right waving gestures for processing by the laptop and a signal is transmitted to the globe device. The received values further augment the horizontal cycle rate to simulate left or right spin, which persists but attenuates relatively quickly over time.
The entire frame of the globe was custom designed in TinkerCAD and 3D printed using Makerbot.

Parts List

  • A drill (0-3000 rpm)
  • 32x Green LEDs
  • Arduino (Mega 2560)
  • Wifi Shield
  • Reed switch
  • 2x Magnets
  • 2x Quad AA battery holders
  • 8x AA batteries
  • Metal rod (1/8")
  • Laptop and Kinect
  • 2x 1"x6"x10' boards
  • 1x 1"x3"x10' board
  • 75x #8x1-1/2" wood screws

Challenges

This project encountered a number of problems. Prototype version 1, constructed with Josh, turned out to be too large and unbalanced to turn at high enough speeds. The design and craftsmanship of prototype version 2 is greatly improved over its predecessor. However, it turns out that the device requires a fairly high current (12V @ 2A continuous) to avoid brown outs and chaining together small lithium ion batteries just wasn't enough. AA batteries had to be used, in fact 8 of them, which notably added to the overall weight and shifted the center of mass away from the center. Then things got really complicated when research priorities diminished the time I had available to complete this project, but I continued working on it even after the deadline. And just in case that's not bad enough, the damn thing blew up on me! (totally my fault)

Inspirations

  1. The LED Ball
    http://www.youtube.com/watch?v=SEvToQ9jMXs
    http://www.youtube.com/watch?v=sO2-tqoyGik
    http://www.youtube.com/watch?v=79WzI-v1qJk
  2. RGB LED Globe
    http://www.youtube.com/watch?v=cQhBm_EgB0w