Sketching with Hardware 3/5: FrettyFlytrap

In March, we celebrated the 5th anniversary of our workshop “Sketching with Hardware”. In 7 days, 12 students learnt to use electronic components, to create new creative user interactions and realized their own physical computing projects. The overarching topic for this course was ”Bionics”. Again, at the final presentation the crowd had the chance to experience five extraordinary experience prototypes. During the following days, all projects will be presented on this blog. Today: Part 3, FrettyFlytrap!

by Michael Konrad and Clara Lüling

lueling@cip.ifi.lmu.de

What is FrettyFlytrap?

Natural model for FrettyFlytrap is the venus flytrap, a carnivorous plant that is domiciled in a narrowly restricted spread-area in the USA. It catches and digests animal prey – mostly insects. Its trapping structure is formed by the terminal portion of each of the plant’s leaves and is triggered by tiny hairs on their inner surfaces. When an insect or spider crawling along the leaves contacts a hair, the trap closes if a different hair is contacted within twenty seconds of the first strike.
[Source: Wikipedia]

Natural model: Venus Flytrap
(Source: stock.xchng)

In contrast to the real flytrap, FrettyFlytrap isn’t just a plant that has primitive needs like food, but also has some human-like feelings: it seeks for love and fondness, and if it gets no food or if it is provoked, it probably shows its angry side.

How can FrettyFlytrap express its feelings? For the one thing, LEDs on the top of the plant’s head show its mood. Red LEDs signalize a critical state, green LEDs show that the plant is satisfied. A further indication is given by the plant’s mouth: If it is open, the plant is hungry and thus impatient or was recently provoked by being touched at its teeth. If you want to treat FrettyFlytrap well, you can tickle it under the chin, and you will see that FrettyFlytrap rotates its leaf, which is a sure sign that it enjoys your treatment.

How does FrettyFlytrap work?

The most important question was how to let the plant’s mouth snap. After having tested two different kinds of mechanical construction, it was decided to install a power servo motor inside the plant’s pot (see figure). The motor rotates an arm by 180 degrees. At the end of this arm, a robust but flexible stick is fixed and moved up and down. This movement is transferred to the plant’s upper jaw. A further motor was fixed at the stem of the plant to rotate a lightweight paper-leaf.

Mechanical construction: power servo motor

After the mechanical issues had been solved, the plant needed to get some senses for the users’ inputs. In this case capacitive sensors were most convenient. The plant’s teeth were painted with an electrically conductive silver-containing coat. For making the plant’s chin sensitive, graphite spray was used because its brown color is more suitable for the plant’s look.

For getting informed that a user had fed the plant, a push-button was installed at the bottom of the plant’s stem. If some food is thrown into the mouth, it falls down the stem and pushes the button which gives a signal to the arduino.

To breath life into the prototype, the last step was to deal with the program logic. Heart of our prototype is an Arduino Uno board, which contains the program code and controls the prototype. The program code declares an interval for the points when the plant gets hungry, for example every three minutes. If the Arduino board is informed by the capacitive senses about some user input, it introduces appropriate outputs (LEDs blinking/lighting or motor rotation).

Values and Potentials

The intension of FrettyFlytrap was mainly to create an entertaining toy. But it can be more. Despite it is just a simple electronic device, it seems for the user that it has a human or animal character. Thus it is imaginable that the prototype could serve as an amusing electronic pet the user has to care about. The use is easy and needs no explanation. The users have to find out how to treat the plant and are excited about its reactions. They can enjoy if the plant shows its nice side, and are maybe frightened if it bites them. Besides, in situations of no current interaction, FrettyFlytrap is just a normal plant – a decorative object.

Next steps

The current version of FrettyFlytrap allows a very limited interaction yet. But there are much more in- and output possibilities, for example sound. Extending the plant’s interaction possibilities would give it a more complex character and thus would make it more interesting.

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