Erik Pettersson’s interactive sculpture, Roball, is a gripping take on the classic rolling marble kinetic sculpture. Roball uses a robotic arm to pick up a small ball and randomly place it on one of five tracks, where it twists and turns as it rolls down the track, eventually coming to rest at a holding station. The input to the system is a single pushbutton, and when the user presses the button, the arm picks the ball up wherever it stopped. Then, the device randomly selects another path, moves the marble to the start of that track, and releases it. A 12-channel Maestro controls the whole system and analog sensors (which might be our QTR-1A) at each holding station at the end of each track help not only detect the ball, but help the Maestro randomize its next move. Because of the ball’s non-uniform surface, the analog sensor will read different values depending on how the ball is positioned. That reading is then used in a calculation to determine what track to roll the ball on next.
You can learn more about this project on its Thingiverse page.