Quote:
Originally Posted by GeeTwo
No, I understood, that you never need to lift more than four totes at a time. Perhaps I took your strategy even farther than you meant. Here's what I'm thinking as "making a stack": - Drop two totes through the chute. The first lands on the floor, the second on top of the first.
- Lift those two totes high enough for the next step (about 30-36") (2 totes lifted)
- Drop two more totes through the chute.
- Lower the raised stack onto the stack on the floor, and continue to the low end of the stroke.
- Lift the four totes high enough for the next step (4 totes lifted).
- Drop two more totes through the chute.
- Lower the raised stack onto the stack on the floor, and continue down at least far enough to disengage from any totes.
- Open the release gate for the main robot to score it.
Six totes per stack when doing pairs is 2 for the first lift and 4 for the second lift; 2 + 4 = 6. Fifteen totes on single-stacking is 1 + 2 + 3 + 4 + 5. It doesn't matter where the lift engages the tote; the length of stroke must be as high as the bottom of the tote moves up plus the "engagement distance", that is the amount of motion between the bottom of the stroke and the tote being lifted off the floor. I'm estimating that to clear a 2-stack with a few inches for free entry of the second tote would be about 30-36".
If you were thinking of leaving a tote on the floor the whole time, that would be lifting 10 totes a bit over half as far as the six above. It's probably a wash in terms of air, but two lifts should take less time than four. |
I was thinking of leaving one tote on the ground the whole time and stacking from there. Your way sounds like it could also work very well. Mine would use less air per cycle (shorter throw), but yours would use less cycles (2 vs. 4). I don't have the numbers in front of me to do the exact calculations. For anyone that does, it would be a wash if the height to lift a ground-level tote is double the height to lift a tote stacked 2 high to above the chute. If it's more, your idea uses less air; if less, my idea uses less.
Either way, your idea is almost definitely faster. You have one lift of two and one lift of four. I have that and also a lift of one and three. So either way, yours would have to be faster.
I just wish I thought of all of this during the season instead of now.
Also for the OP, if you do decide to go with pneumatics as GeeTwo suggested, you can move the PCM onto the tethered bot. Then you can decrease the tether to two wires (power and CAN). The power wire has a pretty low amperage when not running a compressor, so if you make it a big-ish wire you shouldn't see too bad of a voltage drop.
EDIT: One more thing for the OP. When totes fall from the chute to ground level, they tend to not land correctly because the front of the tote tips down as it comes out of the chute. Some HPs tried to negate this by pushing on the tote with the chute door as it slid down the chute. I see this as a big source of human error that should be avoided if possible. You may want to experiment with what base height will allow the bottom tote to land properly while still giving clearance for the second tote to fall on top of the first one. This will keep your human player's job down to a minimum, and it will also decrease the height you have to lift, which will decrease air consumption and lift time.