So, we don’t actually “pluck” the apples. We sort of bash them instead. Lacks a bit in finesse or elegance, but it’s simple, and pretty effective.
Basically, we have a “knocker” at the height of each branch. The knockers have fingers positioned at the location where the apple stems are on the branch (pretty handy that these trees have such consistently placed apples…).
The apples are attached to the tree with small magnets. When the robot approaches the tree, the fingers restrain the apples so they don’t “pivot” upwards too much, and the back knocker panels push them off the tree.
They fall into a “scoop” container at the front of the robot, and at the end of the run the robot returns to the barn, raises the scoop and dumps the apples.
So after our earlier discovery that rice is indeed heavy, we re-thought our strategy for delivery. We now use 3 bins that rotate on a turntable. This way the mass is concentrated over the wheels instead of in front of the wheels.
Each bin is filled with enough rice to fill a bin half-way, plus 20%. Each bin has a servo-operated trap door at the bottom that allows the rice to be delivered all in one big “gush”. The turntable is driven by a small stepper motor, geared down by 4x so it can handle the necessary torque (did i mention that rice is heavy???).
We did it !!! BrattyPi was able to successfully feed the Hungry Cattle and pluck the Nature’s Bounty apple tree. We didn’t do quite as perfectly as we had initially hoped (and we didn’t play with any sheep), but we made a very respectable effort, learned a lot, and had a LOT of fun doing it. Can’t wait for you all to see the videos in July.
We haven’t been very attentive to this blog in quite a while (life happens…), but we expect to start updating it to show technical documentation for the various parts of our project now that the pressure to “get it working” is past.