Mutants

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The effects of mutations in one generation of spirographs. Choosing only one graph to survive from the previous generation (not a natural thing to do) results in 36 offspring from the one graph. It is an good way to check the impacts of mutations in the genetic algorithm and has an interesting outcome. The parent graph is below.

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Spirograph

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This Spirograph algorithm is not a strict interpretation of the physical Spirograph device but it generates some very similar and interesting results. The basic algorithm is to blend three circular equations together. Specifically, for values of i from 0 to 2 pi, an x and a y value are generated with :

x = r1 * cos(nr1 * i + o1) + r2 * cos(nr2 * i + o2) + r3 * cos(nr3 * i + o3);
y = r1 * sin(nr1 * i + o1) + r2 * sin(nr2 * i + o2) + r3 * sin(nr3 * i + o3);

In many ways, this is like having three lines of length (set as r1, r2, and r3) being placed end to end with each one rotated a given number of times (set as nr1, nr2, and nr3). Each of the rotations also can be offset (set by o1, o2, o3).

Two different graphs can be drawn in this way and each of those graphs can be duplicated by changing the number of iterations (o iterations would hide graph). Each iteration can be offset by an angle or have its radius scaled.

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Animated Waves

Building on the previous waves study, this sketch creates it’s own image from three dimensional Perlin noise. For each frame, an image is generated and variations in the brightness are used to vertically offset the horizontal lines, forming waves.

The running sketch (below) shows a frame of the noise and the waves below.

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Waves

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This study focuses on the wave algorithms used in this years eggbot drawings. The sketch supports importing an image, scans the brightness value and draws horizontal lines with vertical offsets based on variations in brightness. around any given sample point along the horizontal line.
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2016 Eggs

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This year, I’m using a new drawing app that I’ve been working on to generate files to load into Inkscape and draw using the Eggbot. In general the app processes an image file and creates an SVG based on it. These are several different renderers. The four eggs above are the most abstract. The algorithm draws wandering lines based on the brightness values of pixels in the image.

The image below uses a hatching program that can be quite photo realistic. I have not yet drawn it successfully using the Eggbot and sharpies. I did manage to draw it with pencil, only to have it smear off the eggshell.

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Dad Finder, Map Edition

Three years after making my Dad Finder, I needed to update it to reflect my new commute. Rather than just print a new face for the clock, I decided to make a new version of Dad Finder with a new form factor and updated hardware.

I had picked up a frame from Ikea that is deep enough to conceal some hardware. I originally planned to use it to embed a few LED matrixes behind some artwork to display messages, but decided to use to mark my location on a Cold War era Soviet made map of the Bay Area.

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Dad Finder v1(left) and v2(right)

For the hardware, I chose the Particle Photon which connects with the Paticle.io cloud platform. This was a radical simplification over the first Dad Finder which used five different components to connect to the internet and expose and API for me to hit from my mobile app. Additionally, the Particle platform has the advantage of being supported by IFTTT, so I no longer needed to use my own custom app to trigger updates as I move through different geofences.

Behind the map is a series of bi-color LEDs, one per location that I want to display on the map. On entering a geofence, I light the LED green, on exiting a geofence, I light the LED red.

The code for the Photon is available on GitHub.

Adding Sound

After using the new map for a few days, I received some complaints that it no longer made any sound. In the first version, the clock’s hand is moved by a hobby servo that makes a signature sound when moving the hand to a new position. The LEDs updated soundlessly and it turns out that my family missed having the audio cue that let them know that I was on the move.

To remedy the situation I added a small piezo speaker to the picture frame and added the ability to play melodies as the different zones are activated. We decided that some snippets from classic video games would do the trick. At present it plays the Mario 1-up sound when it starts up and either the first 4 notes or all 12 notes from the Zelda found item tune. Expanding the set of melodies so that each geofence has its own sound is on the todo list.

Using the Photon

I really enjoyed working with the Particle Photon hardware. The whole platform is quite easy to use and it is nice not to have to think about connectivity at all. To pass messages between IFTTT and my Dad Finder, I subscribe two functions in my Photon code (lines 9 and 10 in the source code). To trigger the function, I set up a series of recipes in IFTTT each defines a geofence and publishes to either the updateExisting or updateEntering event with Data that identifies the correct LED to light within the data of the event.

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Screen capture of example recipe from IFTTT

These events automatically trigger the assigned functions within the Photon code (lines 33 and 40 of the source code).

This is radically more simple than working with the Xbee radio which required coding and configuring many more pieces including the Arduino board, the radio module, the hub, the Digi cloud service and an App Engine app to trigger the events reported from my mobile app. What took many weekends to set up on version 1 of Dad Finder took only a couple hours for version 2.

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The components used to connect v1 (top) and v2 (bottom)

However, it did take a bit of time and trial and error to get things stable on the Photon. Originally I was trying to use an LED matrix and backpack from Adafruit, but using that in combination with the cloud platform seemed too much for the Photon. I found myself restarting the board often to reestablish connectivity with the cloud. Even after simplifying the code to its present state, I have had to update the firmware to improve reliability.

The Xbee system may be more complex to set up, but I don’t recall touching the code or the hardware in the three years it was running. Time will tell if the final build of v2 will be as reliable.