Reactive spaces kinetic sculpture 2.0

Reacting to Tweets

This kinetic sculpture integrated into its environment subtly communicates awareness of the on-going global refugee crisis (#refugeecrisis). It offers viewers a chance to participate in this important geo-political issue on social media by physically responding to messages posted to #flighttofreedom.

The full-scale model, installed ouside the entryway to an apartment building in a Pittsburgh neighborhood with many international residents.

The journey from conceptualization to installation...

…was long and circuitous, but I learned the importance of model-making for experimentation and the importance or rapid prototyping in order to communicate my ideas.

Sketches from our first brainstorming session, in which we imagined diferent ways which we could present a kinetic sculpture around the concept of paper birds...
The first Yupo paper cranes I've ever successfully folded!
We also experimented with using other materials for our birds, each with their own unique advantages. Seen here are three different acrylics and a cardboard model (made using a laser cutter).

Bringing the birds to life...

...involved inspiration from several sources, including the classic weighted bird mobile. I constructed a large cardboard model in our lab to express the kind of motion we should strive for. We were then able to experiment on this model various ways of controlling the motion of flapping wings.

In order to help us visualize the potential motion of our sculpture, I built this large 'mobile' that balances and uses kinetic energy to flap.
Coroplast is the type of material used for political yard signs. Its longitudinal flutes turned out to be perfect for our intended use.

Selecting a material...

...was difficult, given that various materials had different attractive properties (acrylic would glow when lit at night but is heavy, cardboard is lightweight but fragile, Yupo(R) is weatherproof but difficult to fold and not rigid). Then we stubled upon corrugated plastic, which can be used for yard signs and other outdoor uses.

Using this material Coroplast(R) as a constraint, we were able to channel (literally) our creativity to address our two biggest challenges: motion and stability of each bird. By threading fishing line horizontally through the flutes in the corrugated plastic wings, the bodies of the birds were able to move freely along the vertical axis while any twisting motion was eliminated. Each column of birds was then attached to a vertical loop of fishing line wrapped around a pair of pulleys at the top and bottom of the structure. This eliminated unwanted horizontal shift of each bird while their vertical position was maintained by the horizontal hinge points on each wing.

Building a scale model...

...of the final installation was important so that we could experiment with various mechanical controls and iterate through various patterns of motions for the array of birds. At this point, our team split into two sub-groups: one worked on the mechanical and electrical implementation of the motion control (using DC motors and a micro-controller) and the other group worked with the static model to determine what kind of motion could be created and would have the greatest visual impact on the observer.

As you can see in these two stop-motion animations of our model, the "wave" pattern is not nearly as impactful as having all of the models flap in unison with one another.

On the mechanical implementation side...

...the biggest challenge was reversing the current of each motor so that the pulleys could spin in BOTH directions, pulling the bodies of each column of birds up AND down, alternately. This was accomplished by building an "H bridge" on each motor's circuit.

"H bridge" circuits on a breadboard.
The electronic schematic of the motors driving the sculpture.
Three of our full-scale birds installed in the lab to test the load (torque) of our motors.

From scale model to full-scale

Being the beginning of December in Pittsburgh, we wanted to construct as much of the full-scale version inside the lab as we could, in order to minimize assembly outside in cold weather. Using part of the structure of room as the upper support (which had an analog at the installation site, and using a long two-by-four for the bottom support, we tested our pulley system on three full-size Corroplast raptors, before fabricating the full set.

Installing the sculpture

...was more than a little challenging given the extreme cold, but all of us working on it were grateful we had done so much of the work beforehand. We chose a location that would get quite a bit of foot traffic and could just be seen from the road and bus stop. Our hope was that the light and some small motion would invite pedestrians to engage with it more directly.

The full-scale sculpture installed on-site.

Our sculpture reacts to tweets... using Twitter's API and connecting to a Node.js server that ultimately served as an input on the Arduino. When an observer sends a message on Twitter using the tag #FlightToFreedom, they are rewarded with bird wings flapping in unison, plus a message of one refugee's story as a response to their original tweet.

Thanks to my teammates:

group photo on site
  • Sriram Venkiteswaran
  • Neeraj Talukdar
  • Neeraj Veerma
  • Javier Argota
  • Gyuri Han
  • Arnita Saini