This section will demonstrate the mechanical design of the system, highlighting the interesting choices.

Tot System

To make the TOT system user friendly we created a bucket to catch the TOT once it is released.

The TOT is held in place by a servo arm. It is held in position such that it can also be pulled out from the top if needed.

Timer System

We mounted the timer system to the back panel. The mount method combined two standoffs whose distance could be adjusted to locate the servo arm in the desired position.

Interactions

Lever

The handle of the PingPong ball interaction was 3D printed. We designed the mechanism to connect the arm and the potentiometer to make sure that the shaft of the potentiometer did not carry any of the weight. We 3D printed mounts and attached the lever to a shaft. We then coupled the shaft to a the potentiometer shaft with a coupler.

Spinner

We used a real fidget spinner to make the spinning interaction more fun. We attached magnets at the bottom of the spinner and used a hall effect sensor to detect the spinning motion.

Upon assembly, we realized the thickness of the duron board uses (0.25in) added enough material to interfere with the sensor operation. We drilled a little into the duron to decrease the separation between the spinning magnets and the sensor and the system worked perfectly.

Blower

The blower was a mic enclosed in a plastic cone with a hole on the cover. The hole focused the breathe onto the mic.

Responses

PingPong Tube

We attached the ping pong tube onto the fan on the bottom end and supported it to the response panel at the top with a laser cut piece. This made it easy to mount and unmount but hold a fixed location when testing.

Attaching the IR emitters and receivers needed supports because they could not protrude into the tube. This is because the size of the tube was only sightly larger than the ball and anything else would prevent the ball from smoothly rising and falling in the tube

We faced an inconsistent pressure imbalance in the tube during repeated tests which made it harder to calibrate the centrifugal fan. We covered the top of the tube with tape and put holes to have consistent results with the centrifugal fan.