Ping-Pong Ball Launcher
A flywheel launcher with a servo-fed gate, designed, drawn, built, and tested by a four-person team
Group member: CATIA modeling, the drawing set, the build, and the report
An Arduino-timed flywheel launcher that fed and fired all 20 balls in 26.5 seconds of the 60 allowed without jamming. Height and range consistency were the weak points, and the report sets out what we would change.
Objective
Design and build an automated system that shoots 20 ping-pong balls from a starting square, through a 6 x 6 inch opening in a barrier, and into a bucket in a target square, in under 60 seconds. The system had to fit within 2 ft x 2 ft, stand no more than 1 ft off the ground before starting, run on no more than 12 V, and cost no more than $100.
How it works
A 12 V supply powers an Arduino and a pulse-width-modulation controller in parallel. The Arduino drives a servo that opens a door at the bottom of the ball reservoir for 0.325 seconds, closes it, and waits one second, so balls feed one at a time on a 1.325 second cycle. Each ball rolls down a ramp into two spinning flywheels, which launch it toward the target. A potentiometer on the PWM controller lets us adjust the flywheel speed by hand to tune the exit velocity for the opening height and the range to the bucket.
The frame, ramps, and supports are wood held with hot glue, the reservoir is cardboard, and the flywheels and door are 3D printed in PLA. Rubber bands on the flywheels gave the grip the smooth printed surface did not have.
Outcome
The feed mechanism worked as intended: all 20 balls cycled through in about 26.5 seconds without a jam. The manual speed control made it possible to adjust for the required height and range on the day. The problems were consistency of height and trajectory. The two motors were not perfectly aligned, so the balls did not follow the calculated path, and raising the speed to reach the opening height tended to overshoot the bucket.
If we did it again we would add an adjustable ramp angle so speed and angle could be tuned separately, close in the ramp so the ball path is constrained, and orient the flywheels parallel to the ramp so the ball is not slowed by hitting the ramp after launch.