This device was inspired by John Edmark’s kinetic spiral art and the Fin Ray Effect, a structure used in robotic soft grippers.

When given this assignment, I immediately wanted to experiment with a curling movement. My first prototype involved the Fin Ray Effect structure. I fashioned a crank on the servo and attached it to the base of a “fin”. However, the movement was not as graceful as I had envisioned.

I searched online to see anyone else’s attempts at a similar vision and discovered John Edmark. I found this CAD file of his rolling spiral design. After examining the file, I designed a much simpler version of an arm made of small oval-shaped joints. After I assembled the arm and made a spool to mount on the servo motor, I connected the tip of the arm to the spool with a piece of string and the movement I desired was created. Unfortunately, I did not have enough time to figure out how to unravel the spiral reliably.

The code that I used was very simple. The servo motor spins from 0 to 180 degrees then back to 0 and waits 15 seconds before restarting the cycle. The long time delay is necessary for manually unwinding the arm and ensuring it starts unraveled in the correct position.

#include <Servo.h&gt;
Servo doug;

void setup() {
   doug.attach(9);
}
void loop() {
   doug.write(160);
   delay(15000);
   doug.write(0);
   delay(1000);
}