Collector Roller Questions
 

We are building a collector system with the front roller wrapped in a grippy material, OD about 2.5". I was wondering what would optimal speed of the roller would be, and which motor/gearbox we should use to drive it. Is there a simple/general answer to this (I know there are different motors I can use, my main question is about the speed).

Re: Collector Roller Questions
 

The linear speed of the outer edge of the roller should be at least as fast as the maximum linear speed of your robot's drive train in order to pick up balls while you are moving.

For example, let's say a robot drivetrain is geared for a maximum speed of 10 ft/sec and it has a 2" diameter intake roller. In order for the edge of this roller to travel at 10 ft/sec, it needs to spin at at least 1146 rpm. The math:

10 ft/sec * 12 in/ft * 60 sec/min = 7200 in/min

7200 in/min / (2in * 3.14159) = 1146 rpm

You'll need to substitute in different values into the equations above based upon your robot's maximum drive train speed and your 2.5" roller diameter.

Re: Collector Roller Questions
 

Yes and no. That speed is really only necessary when you are backing up full speed and trying to suck a ball in. Realistically, that should not be the case - you'll be driving forward to pick up balls. Even if you intend to back up right away, with your roller at half the 1146 rpm speed you'd still be moving the ball along at 2.5 feet per second - meaning it will be up into your shooter in well under a second.

Also, keep in mind that you actually need to double that RPM if you're trying to pick up while driving full speed backwards. The center of the ball will only move half as fast as the outer edge you are rolling (since you can only roll one side of the ball while the other is against the ground).