Using Art and Tech to Communicate Concepts in Information Theory

Information Theory (Winter 2020)

Team Members: Sarah Woodard, Meera Radhakrishnan, Natalie Gable, Andrea Ramirez

Introduction

For our final project, we developed an interactive LED-based art installation to communicate concepts in information theory, with the goal of presenting it to students at Ravenswood Middle School at the end of the quarter. In creating this project, we hoped to combine our interests in electrical engineering and art to design a project that would both intuitively communicate the underlying concepts in information theory while being visually engaging and interesting for the students at the outreach event.

Although we initially intended this art installation to be an interactive setup at the end-of quarter outreach event, given the cancellation of the event we instead demonstrated our project via a video to be shared with the students who would have attended the event. We appreciated the opportunity to leverage our engineering skills, explore our artistic sides, and develop a project with the intention of reaching out to students who may still be deciding whether they find engineering exciting.

Our interactive installation consists of the following two components:

1. An art piece inspired by bits traveling across multiple cascaded binary symmetric channels.
2. Two instructive mini-displays that students can play with to learn how a binary symmetric channel and binary erasure channel work, so that they can better understand the concepts underlying the art piece.

Art Piece

In developing the concept for our main art installation, we wanted to come up with a design that would be both educational and visually exciting. We decided to build an LED light sculpture that displays patterns inspired by the behavior of multiple cascaded binary symmetric channels.

Concept

Our initial concept is pictured above. The sculpture would consist of a twisted cylinder of 10 vertical lines of LEDs. (The picture only shows 3 for clarity.) Each LED strip represents a series of cascaded binary symmetric channels across which a bit is communicated.

First, an Arduino controlling the installation would generate a random sequence of 10 bits. 0s would be represented by one color, and 1s by another. These bits would light up along the top ring of the sculpture.

Then, each bit would be “communicated” downwards to the LED below it. With a small probability of error, the color of the next LED below may flip, indicating that an error in that BSC has occurred. This occurs down each line of LEDs, with the LED color flipping at each step with a small probability representing the probability of error.

Finally, when the bits reach the bottom ring, the program controlling the sculpture will check if the communicated sequence of bits matches the originally generated bit sequence. The columns representing any bits that were communicated incorrectly will then light up red, and columns representing bits that were communicated correctly will light up green.

Construction

To build the sculpture, we decided to use a cylindrical lampshade as a mechanical scaffold for our LEDs. The lampshade would mechanically support the LEDs and provide the cylindrical shape we were looking for.

While prototyping the design, we also decided to modify the “twisted cylinder” design and instead have the LED strips run straight vertically down the sculpture. This would both be easier to construct given the LED strings we had, and would more clearly communicate the underlying concepts to viewers of the art piece.

We debated several ways to mount the LEDs onto the scaffold. Since the LED strings came with significant wiring, we wanted the wiring to be neatly tucked inside the sculpture.

One option we considered was to poke holes through the lampshade, push the LEDs through from the inside of the sculpture, and glue them in place. However, we realized that the paper of the lampshade might be too fragile, and that it would be difficult to make this design look neat. Instead we chose to glue the LEDs to the inside of the cylinder, allowing the light to filter out through the lampshade. We used hot glue to attach a total of 200 LEDs to the inside of our sculpture.

Programming and Control

Our sculpture is controlled by an Arduino and a potentiometer. The potentiometer sets the probability of error that the sculpture uses to display the binary symmetric channels.’

Interactive Mini-Displays

In addition to our larger display, we created two interactive hand-held mini displays. The goal of these displays was to teach students at the outreach event how different types of channels work, so that they could better understand the concepts underlying our art installation.

Binary Symmetric Channel (BSC) Display

The display pictured below represents a BSC. The switch on the left can be toggled to change the input bit, which is displayed at the leftmost LEDs, from a 1 to a 0 or vice versa. In the image below, a 1 has been selected as the input and so the leftmost green LED lights up. The probability of error is encoded on the Arduino, and is used to generate a random number which determines whether or not an error has occurred.

If no error occurs, the light will travel in a horizontal line to the output, which is represented by the rightmost column of LEDs. If an error does occur, then this is represented by the light travelling down one of the diagonal strings of LEDs to the opposite output. This process is illustrated in our outreach video, which is linked to below.

Binary Erasure Channel (BEC) Display

The other display, shown below, models a BEC. The BEC display is similar to the BSC display, except now instead of error causing the light to travel to the opposite value, it will now travel to the center-right blue LED. See the outreach video below to watch the BEC display in action.

How They Work

Each mini display was made using an assortment of LEDs, an arduino, and a switch. The boards were hand soldered, and the cathodes and anodes of the LEDs were wired based on what row and column the LED belonged to, and resistors were added to each column. The input of each row and column went to the output pin of an arduino using the longer grey wires in the image below.

The serial input of the Arduino can be used to alter the probability of error, which is then used to randomly determine if an error has occurred. Once this is determined, the appropriate cathodes and anodes are activated to create the desired LED lighting pattern.

Outreach

Here’s the video presenting our project, as well as a flyer that we would have distributed at our installation if the event had occurred in person. We hope you enjoy!

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