Ben and I made a kinetic sculpture for the assignment “Not Clock” - something that measures anything but time.
Instead of time, we measured how far you could blow. We had a fan on one end, and measured the tiny bit of voltage it made, and used that as a signal to tell our motors how far to wind up our measurement triangle.
Fan blow station:
Designing the system that moved the measure was rather complex. We had to make sure it did not tangle the thread as it wound it up. We had to design a place for the measurement to hit on both ends - small switches that would then tell the Arduino “You’ve wound me up!” or “You’ve returned me to the starting place!”
In the two weeks to do the assignment, we didn’t quite perfect the mouthpiece - that is, the experience of getting up to the fan and blowing as hard as you could - but… people knew what to do, and wanted to compete and try their best to get the measurement farther than the person before them.
We were pleased with the overal aesthetic - clear, metal, a spot of color for the measurement bead - and the software behind making the winding work properly. I coded in a spot of apprehension, of suspense - how far will it go? Before it winds the measurement triangle up - and the same on the way down.
Phototrope is a kinetic canvas that amplifies an obvious but sometimes forgotten part of our daily lives - the way light changes from season to season, throughout the day, whether inside or outside.
Phototrope constantly measures ambient light: the more light there is, the stronger and higher the leaf-like papers arch and curl, as real plants do in the sun; the less light, the gentler and lower they unfurl.
Phototrope moves in a tangible, mesmerizing way - using the material of muscle wire (nitinol) as a mechanism for the curling motion. The muscle wire is silent and responsive in a surprisingly biological way - mimicking animal muscles or the movement of plants (sped up).
It was exhibited in the Winter Show 2012 at NYU’s Interactive Telecommunications Program.
I used an Arduino and a photoresistor to measure the amount of light.
The circuit uses a TIP120 and a heatsink. The Arduino sends a signal mapped to the amount of light the photoresistor receives. This is the “OFF” in the circuit - the muscle wires are always connected to the external power source (2.5 Amps, 6 Volts).
The muscle wire I used is .006HT “Flexinol” brand.
Each leaf has approximately 9.6 inches of muscle wire sewn into place and connected to the Arduino through a copper tape circuit.
The .006HT muscle wire’s data sheet indicates that it requires 400 milliAmps of current or 0.4 Amps. It also indicates that the resistance per length is 1.3 Ohms per inch.
Using Ohm’s Law, I have the following equation:
I = V/R or V = I*R
5V = 0.4A*R
5/.4 = R = 12.5 Ohms
12.5Ohms / 1.3Ohms = target length
total resistance / resistance per length
= 9.6 inches
If you do not calculate the amount you need in this way, you will end up feeding the muscle wire with too much power and you will burn it out.
While you may want to increase the power a little bit (here I increased from 5V to 6V because there was not enough power to make all the leaves really move), don’t increase it too much or the muscle wires will burn.
Follow this tutorial if you are interested in making things with muscle wire:
Hatbox plan for the side / but smaller…
For the general, light feel of it,
for the touchable, recognizable form, for the circular sides that mirror the compass in the center of the design on top.
As many warned me, muscle wire is a tricky material.
It reacts to direct voltage quite happily (if you have the correct equation of resistance per inch etc. in place) - but if you are sending voltage / input from the Arduino, it is not happy as the Arduino does not supply enough current. It only reacts in tiny amounts unless it is getting a huge amount of current (especially with several pieces of M.W.). It also is not happy holding its bended position for a long period of time - the most problematic thing in my last post’s proposed design.
After experimenting a bunch I decided that I want to take more time to explore this material. Instead, I am returning to initial product sketches and tried and true materials.
My goal through this project has been:
- to see where the sun is throughout the day
- throughout the year
- understand its position in terms of cardinal directions
I now have prepared my object and done a mockup using the planned materials:
- sun path in veneer, a material that lets just the right shine of light through and speaks to the concept of understanding things outside while inside -
- mounted on a base with compass rose for orienting the direction of the object / sun path (must point South for proper reading)
- base box size allows for Arduino and Breadboard
- RTC clock working happily on BB
- yellow LEDs strung up from the breadboard through a foam core pre-cut with holes matching the LEDs position in the Arc Veneer top
- sides made with veneer mounted on felt
- top / bottom spacing secured by 4 small poles
- handheld: such that an average person could wrap his or her hands around the sides of the circle while it’s on a desk or table.
I am not representing the full circle of the sun because it is this very location-specific view that I am illustrating.
Further products could explore the addition of the moon and a full circle.
Exploring the compass rose illustration… found some really inspiring drawings:
General idea - leaves curling over, wires contained in light beech wood box - creating a small desktop piece.
Improvements to the reaction of the muscle wire… using multiple “hour” / “month” inputs from the Arduino, filtering through the tip120