Sparkfun’s 9 DOF Razor-IMU


Sparkfun’s 9 Degrees of Freedom (Razor IMU) is essentially a breakout board for a small microcontroller and three separate MEMS sensors: a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetic sensor. While the Razor’s microcontroller ships with sample firmware that demos the output of the three sensors, the full power of the Razor is realized by uploading firmware that utilize the device as a realtime 3D orientation sensor. The Razor’s onboard microcontroller can be programmed directly by an AVR programmer or by a computer-serial connection via a pre-programmed Arduino bootloader.

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Physical Computing Final: The Ferrofluid/Electromagnet Arduino/Servo Motor Disaster

For my final project for Physical Computing, I attempted to create a device that would allow the user to control a sculpture via brain waves.  The device is comprised of a hacked Mindflex (a toy EEG) that,via a processing sketch and an Arduino microcontroller, controls a variable magnetic field, based upon the user’s level of concentration.  This magnetic field, in turn, alters the shape of a highly magnetizable fluid (ferrofluid).

Ferrofluid in a Magnetic Field:
Ferrofluid is a liquid suspension of iron nanoparticles that are small enough to remain suspended by Brownian motion (meaning, the iron does not separate easily from the suspension liquid).  This liquid becomes magnetized  in the presence of a magnetic field and a cone like pattern emerges in the fluid along the lines of the applied magnetic field:

As seen in this experiment performed by scientists at MIT, when confined to two dimensions and subjected to a variable magnetic field, ferrofluid takes on lesser known, otherworldly forms.

Process (What Not to Do):

Disassembled Mindflex

After reading fellow ITP student Eric Mika’s extremely helpful blog entry on his Mindflex hack, I cracked open the case to the Mindflex headset, loaded the Arduino brain library, connected my Arduino, and began reading data packets from the serial monitor.  The Mindflex toy works by sending the EEG readout from the headset to a receiver on the base, which in turn controls a variable DC voltage that regulates the speed of a fan.  I thought that if I could locate the variable DC voltage, I would be able to somehow connect it to an electromagnet to create a variable magnetic field. So, I cracked open the Mindflex base, which required removing many hidden screws and breaking plastic pieces.

I considered creating an electromagnet from scratch by winding magnetic (copper) wire around a soft iron core made of coat hanger pieces.



I scratched this idea when I found a pre-made electromagnet that was run by 2 6V batteries.

2 different Ferrofluid solutions

I had considerable difficulty working with ferrofluid.  Essentially, ferrofluid is both extremely messy and extremely sensitive to magnetic fields.

The combination is disastrous.  Ferrofluid will stain any container that you place it in (glass or acrylic) and find even the smallest of cracks in said container to leap through, when a magnetic field is near.  Placing the ferrofluid in an isopropyl alcohol/deionized water mixture is supposed to reduce the staining power of the ferrofluid.

However, in my experience, the mixture (even in varrying concentrations) alters the consistency of the ferrofluid (transforming it into a chunky metal suspension in water).  Ferrofluid is also very expensive and not so widely available.  Thinking that my first ferrofluid purchase might have been of  inferior quality, I ordered another bottle from a different company.

Unfortunately, the staining/consistency issues where repeated with the second batch.  Finding an airtight container was also an issue.  I sealed a petri dish with a hot glue gun in an attempt to replicate the 2D surface of ferrofluid used in the MIT experiments.  I am still cleaning the resulting mess from this experiment.

Weary of the effect of the strength of the electromagnet on such a unstable substance/contraption, I decided to switch to using a magnetic field created by servomotors and rare earth magnets.  The EEG readout from the headset (via a processing sketch and an arduino) controls the motion of a servo motor, which has a rare earth magnet attached to it.

The Future:
As it stands now, I have created a machine that succeeds in making a massive mess.  Over break, I hope to create some form of my original idea.  I’m hoping to find a way to fashion a leak proof container of ferrofluid made of a material that does not stain.

Physical Computing Final Project Proposal: Telekinetic Magnetic Sculpting

For my PComp final, I plan to work with Ferrofluid. Ferrofluid is a liquid suspension of iron nanoparticles that are small enough to remain suspended by Brownian motion (meaning, the iron does not separate easily from the suspension liquid).  This liquid becomes magnetized  in the presence of a magnetic field.  The effect is beautiful and there are many ferrofluid enthusiasts and artists who have documented their creations online.  Below is a video of some of the works of Sachiko Kodama:

Most of the pieces that I saw online appear to utilize the physical rotation of a permanent magnet to create a varying magnetic field.  However, there are other ways of creating a varying magnetic field.  A simple electromagnet can be made by running a current through a coiled wire. By changing the voltage, the magnetic field is altered. In Tesla’s famous Egg of Columbus experiment (created to show the world that AC was not dangerous) a metal egg magically spins in the rotating magnetic field created by a stator (containing four coils) powered by AC current.  Here is a video of a setup of the experiment:

This device below, created by a high school physics teacher, allows the viewer to mechanically alter the positions of various magnets to alter a magnetic field, and hence the resulting shape of a Ferrofluid sculpture:

I would like to create a device which would allow a user to control the magnetic field and hence the shape of a sculpture based upon their input, and I would like that input to be one of the least tactile of all human inputs: the theta wave output of the brain.

While there are quite a few interesting biographies and documentaries on his fascinating (and tragic) life, this short Funny or Die piece (part of their Drunken History series) sums up some key aspects of the life and trials and tribulations of Nikola Tesla quite succinctly (warning: this biography contains vomit)

Drunk History vol. 6 w/ John C. Reilly & Crispin Glover from John C Reilly

Media Controller Project: Cymatics

For our media controller, our group (Kevin Bleich, Natalie Be’er, Blythe Sheldon, and myself) created a device which allows a user, via 3 FRSs, to control an audio output.  This audio output is delivered via a 10″ speaker which serves as a vessel for a non-Newtonian fluid of the user’s choice.  As the user manipulates the audio output, ie changes the resulting sound waves, the sound is “visualized” in the non-Newtonian fluid.

Non-Newtonian fluids:
A fluid is said to be non-Newtonian if its viscosity changes with force.  A popular non-Newtonian fluid is a simple mixture of cornstarch and water.  If an external force is applied to this mixture, which is what happens when one’s hand reaches into a container of cornstarch and water, the atoms of the non-Newtonian fluid rearrange themselves and the mixture becomes dense (its viscosity increases), acting more like a solid than a liquid.  Just as one’s hand can apply an external force, so can a sound wave.  As the sound waves propagate through the non-Newtonian fluid, the mixture displays the properties of both a solid and a liquid and small, finger-like protrusions emerge.

The Controller:
The media (non-Newtonian fluid) controller consists of an Auduino (an Arduino microcontroller-based sound synthesizer) reading the analog signal of 3 force sensitive resistors, hooked up to an amp and a 10″ speaker, all housed in a wine box.  A black paper plate is placed upon the speaker and serves as the non-Newtonian fluid dance floor.

The Process and Inspiration:
In the brain-storming stages of our project, Kevin suggested cymatics (see below) and shared a link to a Make magazine blog entry which showed the manipulation of a corn starch mixture with sound.  Natalie, Blythe, and I were immediately captivated and so our explorations began.  Kevin created an Audiono (initially using the potentiometers described in the schematics) and found the perfect speaker (neither my tiny 8 Ohm speaker or my old college subwoofer packed enough punch or provided a suitable surface) and amp combo.  At this stage, we were ready to experiment with varying sound frequencies and substances.  The first substance tested was a gel-like children’s slime toy.

Cymatics trial #1 – Silly Sludge from Natalie Rachel on Vimeo.

As expected, the lower frequencies (less frequency = greater force) created larger structures in the gel-like substance. While the patterns formed in the gel were interesting, they were not the finger-like protrusions revealed in the Make magazine video. In order to create these structures, we switched to a cornstarch and water mixture.

Cymatics trial #3 – Corn Starch Monsters! from Natalie Rachel on Vimeo.

Cymatics is a term coined by physician and natural scientist Hans Jenny to describe the study of wave-propagation in matter.

****Photos and video of the media controller provided by the lovely and talented Natalie Be’er****

Stupid Pet Project: The Electron Altar

For my stupid pet project, I wanted to play off of the idea of “believing in electrons” and create a religious experience for the pious (atheist) scientist.  A ring comprised of a photoresistor is connected to an Arduino-controlled LED display which mimics the motion of an electron.  When the user’s hands are clasped in prayer in front of the alter, the LED display is revealed by illumination through a two-way mirror, as the sound of “angels singing” is played through the attached speaker.

Electron Motion:
In 2008, scientists captured, using extremely short laser light pulses, the motion of an electron on film:


The Electron Alter:
The electron alter consists of a photoresistor linked to an arduino, which controls the illumination of a display made of 5 bright blue LEDs and the looping of an audio track on an audio shield.  The lens from a children’s toy prism houses the center LED, while two outer levels (shells) made from metallic posterboard each contain two LEDs.  The LEDs are illuminated from the center out.  As the display is illuminated, the two way mirror (made by an old photo frame and two-way film adhesive from home depot) becomes transparent.  The components are housed in an old shoe-box, which I spray-painted chrome. 

The Electron Altar from Jennifer Shannon on Vimeo.

Fantasy Device

My fantasy device is an interactive ceiling display.  By creating an environment that allows the user to stretch, exercise, relieve eye fatigue, and strengthen the muscles that years of being perpetually hunched over may weaken, this device is a rehabilitation tool for the dreaded “computer slouch”.

Using special gloves with sensors placed on each fingertip, the user may paint his or her own personal Sistine chapel or follow a routine synced with music.

In addition to doodling with an interactive paint menu, combinations of sensors are capable of signaling various output.  Music options accompany these settings, allowing the user to interact on both a visual and auditory level.  Examples:

  • Fire Works:  With all five sensors touching, a launch point is created upon release.  The acceleration of the release is reflected in the firework launch.
  • Shape Bounce:  Enclosed shapes become projectiles.  With thumb sensors in contact, the shapes can be launched across the display.  A bumper along the perimeter responds to “impact”.

For those feeling less creative, a preset routine of stretching exercises is included.

Hokey prototype:

A projector, a hacked Wii sensor, glove, finger tip sensors, and some Processing.