Intake Issues

My team is using mecannum wheels on our intake and we cannot get them working properly. Instead of strafing the balls towards the center, it pulls the balls over the bumper, no matter how high the bumper is against the intake mechanism. Any suggestions?

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I would try to move the intake closer to the bumpers (i.e. make the gap between the intake and the bumpers smaller).

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Ok, ill mention it to the builders tomorrow! In the video the bumpers are not there but I believe our wheels are almost right up against the bumper.

It’s also possible that you have too much compression. Do you know what the height of your intake is above the ground?

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What kind of mecanum wheels are they? 4 inch vex? If I remember correctly those are some type of silicon which may sound good for grabbing them, it may not help because they may grab too much and act like a fly wheel. It may be worth trying smaller wheels or different wheels with less grippy rollers. We have had good results from 125 3d printed 2 inch mecanums.

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your issue is the grip on the rollers, our team ran into similar issues and solved it by using 3D printed PLA rollers

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In that video it seems you are launching the ball via the hi grip wheels in the center. Doesn’t really illustrate what the mec wheels may do.
Recommend running at a lower speed either way.

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Of course, that’s just an example of what it looks like. That was running via a minicim straight off of a battery with no programming.

For the speed of the intake I generally shoot for the linear speed of the intake roller or wheels to be double the linear top speed of the robot. That way no matter what speed you’re driving, the game peice will be intaked sufficiently quickly without blasting it into space. What it looks like you have with 4" intake rollers at the free speed of a MiniCIM and that is around 100 ft/sec linear speed. Many teams will use a BAG motor or a smaller motor with less power, simply because it’s not necessary, with a gear reduction and this will bring you down to a reasonable value around 20-30 ft/sec.

I recommend the JVN calculator to pick motors and gear ratios, or there are numerous other design calculators that do similar calculations.

Of course I don’t know the specifics of your design but I would guess that the speed is too high for the vectored intake wheels to work properly, or it’s a grip issue like others have said. I highly recommend slowing it down through a gear reduction or through power control and/or checking out some printed wheels from 125 or Thrifty Bot, they’re a really cool product and seem to be really well suited for the power cells.

You have made a launcher, not an intake.

Try driving your intake with a variable speed drill. You may need to use a 1/2" socket on an adapter for your drill.

I would recommend a few things here, first is probably putting a gearbox on that minicim. Second is going to be putting it further out from the bumpers than it currently is, we’ve found that if there is too much compression it likes to pull the ball in more than it strafes. Third would probably be switching to mecanum wheels that aren’t for driving. The thrifty bot is restocking soon and trialanderror3d.com is restocking tonight if you want cheaper wheels or can’t get thrifty bots.

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Mecanums will only center the ball if it can’t go into the robot. If you could put some sort of tubing on the intake across the top with a hole in the middle, it would hold the balls so the mecanums could center it.

We prototyped but did not ultimately use a modification of the “ball magnet” from 2010 to vector the wheels all the way to one side before using more traditional wheels to pull them into the robot.

The idea is to use vectored intake wheels (mecanum) almost all the way back against your bumper, positioned about 2/3 up on the ball. Below and behind that is an idler roller (like just a piece of PVC able to free-spin on a shaft) placed exactly halfway up the ball, so that when the VIWs are spinning the ball, the rear center of the ball is spinning against the roller. This setup kind of worked using the bumpers rather than the idler, but with the idler it worked extremely well.

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We tried it with a drill and the same thing would happen, that was just a example of what it looks like. I’ll post a new picture today.

Did you try running the drill slowly? Usually, drills have speeds much lower than the free speeds of the FRC-legal motors (with no integral gearbox). Larger drills are often are geared to turn slower too.