Intake RPM

[ns3517]

Hello I'm curious around what RPM different teams intakes were spinning and what motor teams were using on their intake. If you chose that speed for a specific reason what was that reason?

[Adam.garcia]

A general rule of thumb is to run the intake such that the speed at the tip of the roller intake is 2x your robot's max speed.

I don't want to speak for most teams, but the motor selection comes down to making sure that you don't stall your motor out when intaking a ball. Consider the worst-case scenario where the ball gets jammed.

These two considerations can help guide you in figuring out a motor/gearing combination that you are comfortable with. But, if in doubt, go with the new 775Pros.

[RoboChair]

775 pro all the things

front intake was 1800 rpm about 11 FPS surface speed

[414cnewq]

50 percent of our shooting speed, theoretically 65 ft/s, but I know its less.
Our intake wheels are the same as our shooting wheels (six inch wheels mounted to to mini-CIMS) with two outrigger wheels to avoid a tangent point. Heres a picture.

[Chris is me]

Two keys to powering a good intake:

1. Throw power at it
2. Make it go fast

We ran a BAG motor at 9:1 on our 1.5" rollers. You can do the surface speed math. It was pretty good. A smidge faster and it would have been able to shoot into the low goal from the bottom of the batter, which is sometimes useful. If possible I would have just left it at 9:1 and put a 775pro on it.

We briefly tried a mini-CIM direct into it, but that was clearly ridiculous, not enough torque.

The 2x robot's max speed rule is also only valid if you are intaking the ball from one side. If you have top and bottom rollers (or left and right), you're pulling in the ball instead of rolling it, so 1x max speed is fine. And as robots gear themselves ridiculously fast, 2x max speed just might not be all that practical.

[jijiglobe]

1800 rpm with a 1" diameter intake roller so we had a surface speed of about 8 fps. We were originally worried about stalling out the intake and burning the motor so we didn't go for the 775pro, opting instead for a bag motor. As it turns out though, the stall torque of a bag is almost the same as a 775pro's optimal power output torque, so going 775pro is almost always the way to go. We switched to the 775pro for champs.

Edit: I failed at math: 8 fps, not 400 fps

[IKE]

Originally Posted by jijiglobe

1800 rpm with a 1" diameter intake roller so we had a surface speed of about 400 fps. We were originally worried about stalling out the intake and burning the motor so we didn't go for the 775pro, opting instead for a bag motor. As it turns out though, the stall torque of a bag is almost the same as a 775pro's optimal power output torque, so going 775pro is almost always the way to go. We switched to the 775pro for champs.

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).

[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.

[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.

[AustinSchuh]

Originally Posted by RoboChair

775 pro all the things

front intake was 1800 rpm about 11 FPS surface speed

Bah, that's slow. We ran closer to 25 FPS, and that was the right answer this year. I've been going for 1.5x-2x the robot speed. (I don't keep track of RPM since it doesn't matter). We actually started running 775 Pro's this year over-geared, and then just running them at 70% PWM to reduce the power draw.

It is always a balance between sinking a bunch of power into the roller on stall or normal operation, and waiting on the intake. You don't want your intake to starve the rest of your robot of power.

[IKE]

Has anyone tried doing smooth belt drive like a Vacuum cleaner beater bar?