Intake Motors...

[silverD]

Originally Posted by charby611

We are running into difficulties with the speed the motors are running on our intake arms. What gear ratio are you running your intake wheels at? 5 to 1, etc......???

Maybe a BAG motor with a gearbox from VEX? I appreciate any ideas and references to a specific set up that will work!

I have seen a wide range of ratios for intake wheels for this year. The amount of compression and wheel diameter will also factor in. From Andymark, have you tried the PG27 (27:1)? If you were to purchase items now, I'd recommend the VersaPlanetary due to it's flexibility in ratios, motors, and mounting. The weight looks to be a wash between the 2 options. We have a mix of ratios on hand for the VersaPlanetary too. I think we have the PG27, but would need to check. Let us know if we can help.
Nate

[Steven Smith]

Also worth noting (edit: Silver did), as I'm personally looking at options to integrate an active intake for swap in at next competition...

Shouldn't the discussion shouldn't be more along the lines of linear speed?
A faster RPM on a smaller BB wheel or a slower RPM on a larger BB wheel would likely have similar results (not accounting for rotating mass and wear effects).

So if a given team is running their intake rollers at X RPM, I think noting the type of wheel and diameter would be pertinent.

[silverD]

Originally Posted by Steven Smith

Shouldn't the discussion shouldn't be more along the lines of linear speed?
A faster RPM on a smaller BB wheel or a slower RPM on a larger BB wheel would likely have similar results (not accounting for rotating mass and wear effects).

So if a given team is running their intake rollers at X RPM, I think noting the type of wheel and diameter would be pertinent.

We prototyped intake wheels and came to the conclusion that the max linear speed we'd need to pull in the tote (assuming no slip) was around 5 ft/s. To achieve this we had selected 2-7/8" banebots wheels paired to VersaPlanetary geared to 30:1 and powered by a bag motor. We would then be able to slow down the intake from there if needed. I want to note that currently our bot doesn't make use of intake wheels so this is where our data ends.

[electroken]

We're using RS-550 motors on Banebots P60 64:1 planetaries. The wheels are home-grown and 4" in diameter. This setup is working well for us.

[Ether]

Originally Posted by electroken

We're using RS-550 motors on Banebots P60 64:1 planetaries. The wheels are home-grown and 4" in diameter. This setup is working well for us.

How do you prevent the motors from stalling as the intake completes?

[ice.berg]

We have window motors geared up through belt and sprocket about 1:2 with bane bots 4 7/8" wheels on the end.
Seems to be working great so far. No issues with stalling or going to fast/slow

[electroken]

Originally Posted by Ether

How do you prevent the motors from stalling as the intake completes?

A limit switch on a digital input tells the control system when a tote is within its last inch of travel.

[Ether]

Originally Posted by electroken

A limit switch on a digital input tells the control system when a tote is within its last inch of travel.

Do you have a picture of that you could post? So many rookie teams ask for advice how to mount limit switches. It would make a good reference link. Thx.

[electroken]

Originally Posted by Ether

Do you have a picture of that you could post? So many rookie teams ask for advice how to mount limit switches. It would make a good reference link. Thx.

If it wasn't for that big ol' bag on the robot...
Now I have a reason to get that switch onto the practice robot.

Our frame serves as the mechanical stop for the totes, extending the life of the switch to beyond one cycle.

[Ether]

Originally Posted by electroken

Our frame serves as the mechanical stop for the totes, extending the life of the switch to beyond one cycle.

Yeah, that's what I'm talkin' about

[GeeTwo]

Originally Posted by Ether

How do you prevent the motors from stalling as the intake completes?

Two other techniques we considered for our ball pickup last year are:

1. Make the frictional force low enough that when the game piece is fully in place, the wheel slips. Problems with this method include possibly reduced intake force and rapid wear on your rollers.
2. Monitor the current draw on the motor and cut it off quickly when it spikes. This used to require custom current sensors, which we had purchased from pololu, but now they're built into the power distribution panel.

Last year we used our solution number one, as the balls were compliant and not much force was needed to pull them in; it may not be a good solution this year.