Final Project: Bobble Game

Intention

The objective of this project was to create a simple soft electronic device, which presents to the user a comfortable interaction with technology. My first idea was to make a glove or bracelet with a set of LEDs. These LEDs would light a random number, upon being activated with shake of the wrist, such as the motion of rolling dice. I expanded the function to be a self contained game that would only take a jiffy to play.  I changed the shape of the device, so that rather than wearing it, the user could merely pick it up and shake or toss it to play. As a result, the object could be available for anyone to approach and be entertained for a moment, without any setup.

Process

I set out to used an ATtiny85 microprocessor, the same one found in an Arduino Gemma. However, my project required use of seven of the ATtiny's eight pins, and a Gemma only offers access to six. I sought to use a Piezo element to measure vibrations, and detect the user shaking the device. Basic game play can be seen on the breadboard prototype in the video below. Each light has a fifty percent chance of being lit on its respective shake; four lights wins full points and one of each color wins half points.

Given the number of LEDs, I decided to create a tetrahedral shape for my object so one light could be on each corner. The shape was stuffed to create a small pillow, with a pocket inside of the electronics. The edges of the shape were machine sewn; the fortuitous presence of green thread on a bobbin gave me the idea of using green and red thread together, one being on each side of the fabric, to match the colors of the LEDs.

Product

The final product was a small tetrahedral pillow with LEDs on the four corners. The battery is stored on the pillow's pouch, while the electronics are stitched to the outside. Conductive thread connects the LEDs back to the micro-controller, and a snap acts as switch, closing the circuit between the battery and the MCU. When this switch is closed a boot sequence on the object occurs, flashing all the lights, which can be seen below.

Reflection

The prototype turned out well, and most issues were with the rigid elements of the electronics. Organizing the Piezo element and the MCU on a generic perf circuit board did not allow for a very compact package. Furthermore, connecting the conductive thread to the small solder pads would have been easier on typical wearable platforms such the Gemma, which have larger pads. Ultimately, a custom PCB would be essential to making this object function in the ideal manner. A PCB would also allow for the MCU and battery to be connected with solid metal leads. This would not only make the package more compact, but would also mean less resistance between the MCU and battery, and thus brighter LEDs and more consistent behavior. Resistance in conductive thread is useful for limiting LED current, but on a power source line, the voltage drop can have unexpected consequences on the computer's functioning. 

In a future iteration I would look for a different material to create the object. The muslin used is simple to work with, but easily frays at the ends and it not ideal for small pieces. A non-woven fabric such as felt may have produced smoother edges, as well as provided a more firm structure. In this case, it would be easier to stitch the conductive leads before the object is stuffed. This would allow the electronics to be connected in the pouch with leads not only on the outer surface of the object; this would lead to much easier and more reliable wire routing. Creating a slightly larger structure would have also made construction easier, as the conductive traces could have been machine sewn. Thicker traces would lead to lower resistance and better performance

Sample Book

Include some photos of your sample book.