Nine days ago, I woke up completely obsessed with the idea for this, so I built a simple prototype.
And watched in horror as my son destroyed it.
Eight days ago, waking at 2a, well before either my son or the sun, I decided to give it another go, and today I’m reasonably happy with it.
The Mindstorms NXT motor is attached to the Arduino via a standard issue motor shield. The only way I could connect it was using the very special Mindstorms connector wire, which means I had to cut it in half. (Note: I put in a pretty reasonable search for the modules — Micro Center, Fry’s Electronics, etc. — no dice.)
The system knows when the ball is ready using a flex sensor and it determines if the scoop is in starting position using another. When the arm lifts the ball up, the ball moves forward and the flex sensor returns to zero. The arm with the scoop resets to starting position.
Also, since this isn’t particularly mobile, it was useful to power the motor shield using a specially stripped and modified USB cable instead of the usual battery.
Pretty amusing, and a nice little dopamine burst from thinking about something novel. I still have a few //TODO items (do a better job sensing when the ball is ready to move, for example) but I’m mostly satisfied. Big lesson learned: simple timing isn’t a good method for control. Definitely need to use sensors.
Next up: Something substantially taller. Stay tuned!!