Intake RPM

[jijiglobe]

Originally Posted by IKE

you may want to check your math. I get closer to 8 fps....

(1800 rpm = 30 rev/second, 1" DIA = 3.14159" circumference, this equals about 94 in/sec which is about 8 fps).

I thought I was doing something wrong... minutes != seconds

[Kevin Kolodziej]

We used upper and lower Bag Motors on a 10:1 VP with a 1:1 9mm belt from gearbox to 2.375" Banebot wheels. Theoretical RPM on those wheels is about 1300rpm. Robot ground speed was max 15fps (though I don't think we were ever near full speed when intaking). The belts were fit slightly loosely on 3D printed pulleys to create a "slip-clutch" to prevent motor stalling. The plastic pulleys held up just fine all year, no broken teeth, and even took quite the beating from impacts of robots and walls. Never had a single issue with belts from ratcheting over the pulley teeth either. We've done this a few times for these very low load type of applications - I would NEVER do this setup on our drive (though I know as our wheel axles got bent over the course of the year, we did quite a bit of ratcheting on those belts...but again, no issues).

[Jay O'Donnell]

We ran a 775 at a 7:1 ratio with a 1.75" roller. That's roughly 2600 rpm.

[jman4747]

One 775 pro at 9:1 on 2" diameter rollers. About 17ft/s. The rollers were 1/2" ID polyurethane pressed on to a steel round shaft with a 1/8" key in it. They acted like a clutch when a ball was captured instead of stalling the motor.

[cpiravi]

We started with two 550s, but then we switched to two 775 pros because they kept smoking halfway through a match.

[Hitchhiker 42]

We ran 2 775's through 3:1 gearboxes at 0.4 speed. That comes out to about 2400 RPM.

[aphelps231]

We used a BAG motor on a 9:1 Versa Planetary and switched to a 10:1 for champs. This gave us a wheel speed of about 13fps on our 2" wheels.

I would not run this setup again. The BAG motor tended to stall out when intaking the ball from the side (we ran 2" mecanums on the outer rollers), and the intake was a little slow. A 775pro would have been much more beneficial, as well as faster (speed was the big issue since stalling was fixed by tuning compression).

A handy tip for anyone looking to increase the performance of their mecanum intake: set the intake to have about .75 to 1" of compression, and allow it to be pushed up by the ball when intaking. We achieved this by using an in line pressure regulator to limit the extension side pressure of our pistons on the intake. Although it could be done with code adjusting your Kp value in PID (while intaking == true && the intake position is in a certain range with the lower bound being full extension and upper bound being 0" of compression) if you're using a motor with an encoder to move your intake.

[Cash4587]

I've attached the intake calcs for my teams robot this year. Our robot was geared for 14.5 fps so our intake was geared according. We spent weeks upon weeks testing on what intake was the fastest and best and came out with 6, 4" mecanum wheels (3 on each side) and 2, 4" stealth wheels in the middle. Our intake was very very quick. We took inspiration from 118 and worked with them a bit to understand how theirs worked.

As stated earlier in the thread, 2x your robot's ground speed is a good start for your intake speed. We then also threw power at it. We used 2 versaplanetary each with a 775pro to power our intake. We put about 1.75" of compression on the ball to grab it but when the ball came into the robot it would compress down from about 10" to 4" to get into our catapult. We had no issues with jamming or anything all season.

Here is some video of it in action.

https://www.youtube.com/watch?v=Y13rcqgDcBU