Hedgy (The Unconventional Teddy)

Vivian Fu, Sydney Pallister, Tania Samokhvalova

Atelier 1 (course code here)

September 28th 2017

Experiment 1: Touch As Interface – Touch Interface Prototype

Hedgy (The Unconventional Teddy)


A colourful stuffed animal that appears ordinary, but plays sounds when its paws, feet, and ears are squeezed.

The piece contains pressure sensitive fabric in its feet, hands, and ears. These parts are connected to the Arduino and breadboard in its body, which are hooked up to a speaker. When these pads are squeezed, the stuffed animal plays a specific sound.




The initial design was a teddy bear wearing stretch sensitive clothes stitched to his body, so that sound (screaming) activates when his limbs are pulled. We also wanted the bear to have LED lights in place of its eyes which would turn different colours depending on the contact, an LED heart that blinked as a heartbeat (which increased when stretched), along with the pressure pads in his feet, hands, and ears.


These ideas changed during the process of creating it. Stretch fabric would not work, as pulling on the bear’s limbs would not stretch the material beneath the stretch fabric. We decided to get rid of the idea of stretching and pulling, and only rely on the pressure pads for sound. First step in this process was testing and altering the resistance of the pressure sensitive fabric. This is essential in making sure Hedgy responds to pressure.


Once the appropriate resistance was determined, we went on to creating the circuit for the speakers. This required an additional resistor (we have 7 1k resistors in series here), a transistor, a speaker, and an SD card adaptor. An issue we had was setting up the pins to the SD card reader properly, but this was resolved easily by messing with the pin positions.


A larger issue was getting the Arduino to properly read the music files. First we attempted to use an MP3 shield, but could not locate any appropriate libraries for it. After converting the sound files to .WAV files, we attempted to construct the WAV shield. Despite parts being soldered in the correct areas, the shield refused to communicate with the Arduino.


After removing solder and moving a piece around that may have been causing the issue, we determined that the circuit was totally unresponsive. This killed our main idea to have the stuffed animal play jarring and creepy sounds, as it isn’t possible without the WAV shield. We decided to scrap the idea and set up the speakers to use the pre-programmed sounds instead. Much less spooky than the initial idea, but the sound is still present.



To up the interest a little bit, we found the feature the Arduino has to play a coded melody of one’s own design. We created our own unique melodies for five of the sensors, the sixth one was inspired by the opening to “The Twilight Zone”.

Hedgy himself was easy to set up. First we cut a slit in his side and removed all the stuffing. Then we hot glued Velcro on the cut to ease in opening up and closing the doll when needed for readjustments (and to retrieve borrowed pieces later).


We then measured and cut out 7 pieces of pressure sensing fabric to fit inside the doll’s hands, feet, ears, and nose (we ended up not using the nose as a button ultimately due to its small size).


We secured these pieces to the doll by sewing them in along a seam to keep them relatively hidden.


Then, copper tape was attached to the pressure sensing fabric in order to connect them to the Arduino. First we attempted to attach wires to the copper tape using solder, but the copper refused to bond to it. Then we tried connecting the two with conductive tape, which ended up not being conductive enough. We decided in the end to attach the copper tape to alligator clips and tape them together (along with taping the other contacts on the breadboard). It took some experimenting to figure out how the copper tape should be connected.


We found two wood boxes to fit the Arduino and the breadboard with all the attached wiring, cutting holes in them so the wires can go between boxes. We adhered the breadboard and the Arduino to their boxes using sticky Velcro.


We recorded the range and values for each pad so we could make them all play a different sound. Ranges we got were as follows:

Right foot: Max – 720

Min – 500

Left foot: Max – 860

Min – 600

Right arm: Max – 950

Min – 500

Left arm: Max -720

Min – 450

Left ear: Max – 940

Min – 600

Right ear: Max – 900

Min – 550

We adjusted each pad to its corresponding range so that the pads would all require the same amount of squeeze to activate.


The hole in his side had to be extended down his bottom to fit the boxes in properly. We were worried about fitting all the wires in along with the rest of the hardware, but it fit perfectly. We added some stuffing back to give him back his plush feel. We did not have the time to incorporate the LEDs, as the sound was much more complicated than we had expected.


We used this tutorial (https://diyhacking.com/arduino-audio-player/) as instruction on how to convert WAV files and have the Arduino play them. We had they idea to use sound and LEDs before reading, but we didn’t have a solid idea on how to. This tutorial only teaches how to play one sound, while we wanted to play multiple sounds from the same speaker when different contacts were pressed. Though we didn’t get the WAV files working, we did accomplish getting each contact to play a unique noise when pressed.

Here is our final code used: https://github.com/sydney4529/Touch-as-interface—Prototype

There are things we attempted to add to this document, but they were not allowed by the site. This includes videos and examples of WAV sound files we were going to use. This will be sent to you separately.

Here’s a link of it (Google Drive):


After stuffing the animal, this is the final result:


It’s fully functional and worked the way we all intended it to at the end.


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