FabLab@School

Digital Fabrication for Education

BBA Final Project: Papert Tronics (Anna, Adam, Joy & Jeff)

Group

Joy Wong Daniels (LDT MA student, School of Education) [www.joywongdaniels.com]
Anna Ly (LDT MA student, School of Education) [www.stanford.edu/~akly]
Adam Selzer (LDT MA student, School of Education) [www.veryverysilly.com]
Jeff Kessler (MS student, Mechanical Engineering) [www.jkcreations.carbonmade.com]

Summary

Papert Tronics is an educational toolkit that allows 9-13 year olds to give lifelike movement to paper constructions by using simple electronics and sensors. With Papert Tronics, students can design and fold their own creatures that move at the press of a button, test the boundaries of material strength, or link their creations together to demonstrate the cause and effect of systems. Papert Tronics is an educational tool deeply rooted in constructivist and constructionist learning theories: students using Papert Tronics have personalized, hands-on opportunities to explore their own interests, design with their own intuitions, and test out their own ideas. Papert Tronics transforms the simple sheet of paper into a memorable experience that inspires curiosity and ignites student engagement.

Project Media

Slideshow (48 images): http://bit.ly/KWY8mu

 

Motivation

This project began with inspiration drawn from an online video (from the High-Low Tech group at the MIT Media Lab) of an origami paper crane that was made to flap its wings with the addition of nitinol wire. Watching this video led our group to a conversation about different qualities that paper could take on when we added embedded electronics. We found examples online of electronic paper that made sounds and lit up, but it was movement that we found most exciting. We conducted a brainstorm to try and conceive new possibilities about ways that paper could move, like walking, dancing, and jumping. Our thought was: if our team could build an amazing paper object with life-like properties to engage students, then we could deconstruct it into more accessible pieces through a toolkit with a set of curricular activities to help those captivated students explore big ideas.

 

The System

For our BBA presentation, we built a sample finished student project (rather than the finished product) to communicate the promise of Papert Tronics.

The Papert Tronics starter kit will contain:
(1) Extra long Papert Tronics wire
(1) Long Papert Tronics wire
(2) Medium Papert Tronics wires
(2) Short Papert Tronics wires
(2) Papert Tronics IR sensors
(2) Papert Tronics touch sensors
(1) Papert Tronics power base with IR emitters
(1) Papert Tronics mini base
(1) A starter kit guide (see the PDF attached in the media section)

The Papert Tronics wires will be similar to the ones we built – a length of Nitinol wire crimped and soldered to a twisted pair of jumpers – but the kit versions will be integrated with female Molex-style connectors. They’ll also incorporate in-line resistors so that each Papert Tronics wire can be plugged in to any male Molex port on the power base, mini base, or into a sensor and generate the correct amount of current based on a 9V power source.

The Papert Tronics sensors will also be similar the ones we built, but each sensor will have a 5-pin female Molex connector. The sensor itself will use 3 pins (this is necessary as some sensors are transistors, which must wire to +5V, and others are switches, which must wire to ground), and the other two pins will be pass -through pins to an attached Papert Tronics wire loop. The circuitry inside the Papert Tronics base will use the sensor’s output to switch any Papert Tronics wire attached through that sensor.

The Papert Tronics power base will be a low-cost electronics enclosure (ideally, laser-cut acrylic with an open-source file). Unlike our prototype, it will be powered by an off-the-shelf wall adapter that sources 9V and > 3A. The power base will have (4) 2-pin male Molex plugs for attaching Papert Tronics wires and (4) 5-pin male Molex plugs for attaching Papert Tronics sensors. Each 2-pin plug will have a push-button for manually triggering the Papert Tronics wire. All (8) plugs will have a nearby indicator LED to show whether the attached Papert Tronics wire was bing triggered. This will help students easily test their sensor setups.

The Papert Tronics mini base will be a much-lower-cost enclosure with battery power. It will have (1) 2-pin male molex plug with a push-button trigger and an indicator LED. Students will be able to build more portable, show-and-tell projects.

In our vision, Papert Tronics.com will also incorporate instructions for folding and sewing some of the mechanisms in our demo, as well as downloadable files for either printing and cutting out or laser-cutting.

Future Expansion

We could expand Papert Tronics to incorporate other kinds of sensors, such as sound sensors, or other actuators, such as tiny cell phone vibration motors.

We also hope to host user-created content (videos and folding patterns) in addition to our starter content on Papert Tronics.com.

How it Works

Papert Tronics in action is probably best explained through the Starter Kit guide, which contains three sample activities that allow kids to explore:

  • The effects of heat on Nitinol
  • Creative paper project design
  • Cause and effect in created systems


Download the Starter Kit Guide here:


You can also check out our BBA Expo demo video here:  http://bit.ly/KeFyWi

 

How it was made

We build an Environment Stand for the BBA expo to demonstrate what Papert Tronics could do. We integrated nitinol circuits into paper objects and designed a prototype version of the Papert Tronics power base circuitry to make objects move via infrared sensors and buttons.

Environment Stand:


For the environment stand, we bought a sheet of MDF pegboard and laser cut 1” high press-fit walls out of lab MDF. We used gorilla wood glue and reinforced it with hot glue while it was drying. After we built all of the paper creations and tested them with the circuitry, we covered the environment stand with craft-store moss using hot glue.

Papert TronicsWire:

Papert Tronics relies on .375mm Nitinol (nickel-titanium) wire, also known as muscle wire, available from Jameco Electronics: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001...  Nitinol is a shape memory alloy, or SMA, and it has the unique property of contracting when it heats up. It also acts as an electrical resistor, so all you need to do to heat it up is run a recommended amount of current through it. Whenever  a complete circuit is made, the Nitinol contracts to about 95% of its length. When the circuit is broken, the current running through the wire stops and the Nitinol cools to room temperature, extending back to its original length. Once the circuit is built, the Nitinol is easily controlled by completing and breaking the circuit.


We prepared the nitinol using a propane blowtorch so we could get the desired shape that the nitinol will mold into when it gets reheated via the current of the battery. Most of the nitinol we used to make Papert Tronics wire was straight, but for some pieces (such as on the snake), we trained the nitinol to ‘remember’ a coiled state.

SAFETY NOTE: If you’re doing at this at home, be careful!  First of all, don’t burn yourself. Second, make sure to clamp the nitinol down and only heat it until it turns red – this takes about 1-2 second with a blowtorch at 6 inches – otherwise it will burn out and lose its SMA properties.

Finally, wires had to be attached to the nitinol to get it to conduct electricity. We did this with the jumpers included in the nitinol from Jameco, but we recommend doing this:

  • after giving the nitinol memory
  • with robust stranded wire, not with breadboard jumpers
  • using 1/16″ – 1/8″ crimp beads available from a craft store

 

Paper Creations:

For each of the objects, we used paper as the primary medium. All of the paper objects except for the butterfly and leaves were origami (i.e. folded rather than cut).

Youtube Videos Tutorials:

In order to create the flapping motion of the butterfly wing, we carefully sewed the nitinol (using small stitches) along the perimeter of the top wings of the butterfly paper cutout. One of the key things to note is that in order to ensure that the paper has a dramatic lift, the nitinol must be sewn taut to create the necessary tension to make the paper move without any slack whatsoever. Electrical and masking tape was also used securely laid down on top of the jumper wire to keep the tension constant.




When the current runs through the nitinol (when the circuit is closed), the wire heats up and contracts, which causes the wings to flap forward. Once the circuit is re-opened the wings relax, flap backwards, and return to their original shape.


We used a little hot glue to attach some tissue paper for decorative purposes. For each of the moving objects, we attached .375mm nitinol using sewing thread (as shown above for the butterfly), color masking tape or a little hot glue. The snake was the primary object that needed the masking tape and hot glue because it was such a long structure. We also attached the nitinol on the outside of the snake on its side (see below image) so people would be able to see the nitinol coil up as it heated. We used two long pieces of nitinol attached together via a jumper wire but we suggest using a single long piece so there could be less chance of breakage during movement.




The sewing technique used for the butterfly was also done for the leaves and the curling and uncurling of the frog tongue. The nitinol was sewn in a curved shape inside of the origami paper and taped down at two ends of the curve to create the necessary tension to lift the paper. In order to get the desired tongue “roll” look, we wrapped it around the body of a Sharpie marker to curl the tongue.
   

Papert Tronics Circuitry:

To get the nitinol to respond to sensors, we built a circuit on a breadboard using a 5V battery source (really 6V of older batteries), an LM324N op amp, a 74HC04 inverter, and several IRZL34N power mosfets with a kit of jumper wires and a prototype breadboard.

Since the nitinol wires ran high currents (the .375mm nitinol needs over 2A of current to activate!), we got some power MOSFETs to use as electronic switches.  These allow current to flow only when the gate voltage is substantially higher than ground.

We triggered the MOSFETS with an op-amp circuit (using an LM324) that amplified the signal from an IR phototransistor, but this signal was active low: When the IR phototransistor detects IR light, it pulls the op-amp output down to ~0V. If we hooked the output up to the MOSFET gate, it would let current flow by default.

So, we ran it this output through an inverter (a 74HC04) before sending it to the MOSFET gate. That way, the circuit would turn on the nitinol only when the phototransistor detected light from an IR LED.

For the touch sensor circuits, we used momentary switches in series with the nitinol and the appropriate resistor.

The IR LEDs (1.2V Vf) ran on 5V in series with 150 ohm resistors, for a running current of 25 mA.

We mounted the breadboard, with a switched ~5V power supply, to the bottom of the environment stand and threaded all the Papert Tronics wires, sensors, and IR LEDs through the pegboard as necessary for their function:

 

One surprising thing we learned

We formed a team around the idea that working with paper would lend itself to designing a simple and elegant project. We reasoned that a paper project would be easier since paper is inherently limited in strength, size, and versatility. Throughout the course of many long and intense work sessions we were surprised to learn how complicated a simple idea could be.

Nitinol wire was a completely unfamiliar material with unfamiliar qualities. We learned to use nitinol wire by scouring the internet to learn how others had used it. We followed some of the directions for using nitinol that we found on the internet, but some of the directions that we followed turned out to be incorrect and unknowingly skipped over others. A lot of what we learned was a result of trial and error, which was both a rich experience and a time intensive process. We sometimes reflected on how much further we could have gotten if we had worked on a project that relied on a more familiar process, such as laser cutting.

In our development process we were often confronted with a challenge that required us to zoom in closely to solve. For example, attaching the nitinol wire to a power source required affixing jumper wires using crimp beads.  We ran into a number of problems trying get the crimp beads to keep the wires enclosed so we tried attaching them with copper tape, solder, prayers, hot glue, crossed fingers, and tape. Because we were so consumed with solving the problem of attaching the wires to crimps we lost perspective of the actual challenge which was about conducting electricity to the nitinol wire. Also, the jumper wires kept breaking. The nitinol we bought was packaged with super-thin (super-fragile!) solid-core jumper wires intended for wire wrapping, not anything that moved. We decided to stop using the thin wire and move over to thicker jumper wire provided by the TLT Lab. With the new jumper wire, a crimp bead and a dab of hot glue, we got a stronger connection that was easy to put into the breadboard without breaking. For the other wires attached to the LEDs, IR sensors, and switches, we discovered the amazing properties of heat shrink, which really helped with preventing wires from breaking.

Simplicity was a great goal to shoot for but the guidelines of our design project required us to uphold many complex qualities each with their own tradeoffs: safe, durable, versatile, intuitive to use, easy to construct, expandable, educational, relevant to a wide variety of educational settings, and appealing to a wide variety of student users.

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Tags: adam, anna, daniels, jeff, joy, kessler, ly, selzer, wong

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