Last March, Eric, Sofy and I were invited to present Mental Block at DorkBot NYC.

dorkbot-nyc, 03 March 2010 — Eric Mika, Arturo Vidich, Sofy Yuditskaya: Mental Block from dorkbot on Vimeo.

The code for Beat Feet is massive, and Eric did  a great job of commenting the whole thing. Below is a zipped file ready for download. Or you can copy and paste the code below, but it won’t have tabs for classes.

Happy foot beating.

ZIP!

beat_feet

Below is the code that was uploaded to each Arduino in each headset. Kudos to Eric for the noble task of commenting. It’s easier to read if you copy/paste into the Arduino IDE or another IDE like Eclipse.

Or you can just download the zipped file available right below.

ZIP!

MentalBlockCode

// MENTAL BLOCK
// Parses packets from a Neurosky chip to collect EEG-derrived
// “attention” and “medidation” values.
// Uses these values to set the position of a polarized disk mounted
// on a servo.

#include <SoftwareServo.h>
#include <NewSoftSerial.h>

// Give the headset an ID. Useful for debugging over serial.
int id = 1;

// Set up the polarizer disk servo.
// Using the SoftwareServo library because I suspected the
// built-in library was conflicting with the NewSoftSerial
// library.
SoftwareServo servo;
int currentPos = 45; // Start halfway between the 0 – 90 degrees we care about.
int targetPos = 45; // The target tells the servo where it should move towards.
int servoPin = 9;
unsigned long lastMovement = 0; // Track time so we can move the servo at regular intervals without delay().

// Set up the simulator for brainless testing.
unsigned long lastSimulatedPacket = 0;

// NeuroSky Parser and Serial Communication.
(more…)

(all this and more is available at http://mentalblock.net)

Mental Block system schematic

(Eric Mika has a ton of great documentation for this project on his blog, Frontier Nerds)

Eric came up with a great idea for how to make a variable detent potentiometer using a regular pot and a vibrating motor. When the pot is adjusted to a specific interval, the motor vibrates for a moment letting you know you’ve reached the first, second, third, etc, interval.

Here’s Sofy’s Pure Data patch that mirrors binaural beats– it was really too bad we couldn’t get the radios to work.

Here’s what we came up with, in action:

A fun video of that stuff getting cut out on the laser:

Feel free to copy these images to your computer and use them as you see fit.

A tutorial for making a perfboard solder of the electronic schematic is available here, on Flickr.

All this and more can be found at http://beat-feet.net

Beat Feet system schematic

Beat Feet electronic schematic

(All this and more is available for perusal at http://mentalblock.net)

(This Flickr feed has the A-Z photo documentation for the process)

The project began with an interest in using EEG equipment to control media. There are two consumer level EEG hookups on the market, the MindFlex and the Star Wars Force Trainer. Both use chips from NeuroSky. The MindFlex only let us listen to LED states, whereas the Force Trainer gave us direct serial data. Wonderful. Here’s us playing with the Mindflex, and then hacking the Force Trainer.

After some playing around we settled on listening to people’s brainwaves made audible, and broadcasting your own. It was called Brain Radio. In the original scenario, a wearer would put on a brain-reading headset to start broadcasting brain state over the air. The wearer could tune into sounds generated by other headset-wearers via a dial. Brain Radio sought to create a kind of perceived telekinesis, in which your thoughts — alpha and beta waves reduced to “attention” and “meditation” by the EEG headsets we hacked — supply the source for sounds broadcast to any other headset-wearers who chose to tune in. The sound is designed to reflect and represent on the broadcaster’s state of mind. However, who, exactly, you’ve tuned into is unknown. Instead, it’s left up (more…)

The shoes.

They didn’t make themselves, that’s for sure. The documentation for how we made the perfboards for the wireless modules can be found on a flickr photostream here, and the rest of the documentation (code, etc) can be found at our website here.

The show went really well, with just a couple minor set-backs.  My computer kept crashing when I tried to do more than one layer of looping in MIDI. Closing and restarting the Processing sketch seemed to help for a while. Looking back, I really wish we’d found a way to cycle through the preset MIDI files we created, a way to cycle through using a gesture, or the hat somehow. Switching over to the sound sample files from MIDI would have been great… as it was, I had to stop the sketch, change SYNTH to SAMPLE, and then re-run it.

People seemed to enjoy trying to figure out if the floor was sensing my weight, and what exactly the hat was doing. Tom told me not to talk to people at first, but to simply dance, and people would respond or be intrigued by what was happening. After dancing for 10 hours in the shoes, I finally understood how to use them and the little performative tricks I could play to make it seem like there was more going on than there really was. One of the perks of having a team in this case was that Yin could explain what was happening while I just danced a storm.

The second serial lab. There is a lot to learn when it comes to serial communication between devices and applications. No doubt I will be working hard over the winter break to get serial communication into my blood, to have the handshake method down cold, to master punctuation and prevent binary from byting my ASCII. Sending data serially is a beautiful, complex beast. Most of what’s covered in the two serial labs was key in Beat Feet, the mid-term project that Eric, Yin and I built. We used Zigbees to send data from sensors on a pair of shoes and hat to the computer which played back sound files or MIDI library depending on which sensor was triggered. What we did with that project was more interesting and involved than what I ended up making for the second serial lab, which is basically what was outlined in the examples. The video at the bottom shows an accelerometer and an Arduino used to move a ball around on the screen in Processing. The button makes the ball appear or disappear. (more…)

Finally getting around to some of the labs I neglected.  The servo lab is certainly fun.  I wanted to mount two servos on a welding hat to make the visor go up and down based on some sensory input. Further down the line I might use this as a jaw mechanism for a mask, and have the data controlling the servos come from the jaw of the person wearing it. Classic animatronics. I’m using a light detecting resistor in this video.

I made this system using both the servo library and the “pulse method” outlined on this page. To get the servos to move in opposite directions, I reversed the values of one of the servos in the map() function.  For example, from the pulse method:

pulse1 = map(analogValue,890,660,minPulse,maxPulse);
pulse2 = map(analogValue,660,890,minPulse,maxPulse);

I constrained the values to match the values received by the LDR. Next I will smooth the values so the servos aren’t jumping around as much.

Or maybe we should call it BetaFeta, but that would be cheesy. If we’re in a triumphant vegetative state, BeetFeat.

(more…)