Cannot pick up more than 4-5 cubes

My team has been having compression(?) issues on our intakes for months now. We don’t have much time to troubleshoot, as our Robotics club is an hour-long class every school day, including set up and cleanup. Since our bot has been built, we have struggled to pick up more than 4 cubes, despite rebuilding our intakes countless times and recently doing an almost complete rebuild. I have been taking our robot home each night to troubleshoot and have tried moving our intakes closer together, putting more rubber bands on the hinges to keep the intakes closer together, changing tray angle and position, and changing the gearboxes on the motors to no avail. We have our final competition coming up next week. Help! See attached

Google Drive Folder

It seems like your intakes are simply not grabbing the cubes once you have 4-5 in your tray. If you have tank tread upgrade kits (the ones with the grippy tread), try adding some of that - the extra grip might help you grip the cubes better. Also, your intakes are moving too far out on their joint - have you tried making it a static joint so that the intakes can’t bounce as much (as they do in the video)?

1 Like

When you intake a cube, look and see how much the cube is spreading your arms apart. If its spreading them apart alot then you should try bracing your arms at the base of the arms to stop them from spreading apart too much. That should hopefully fix your problem.

How could I make this a static joint? The arms move so we can place cubes in towers and the intakes have to move out of the way to allow us to stack cubes. I’ve been struggling coming up with a solution that allows the arm to still freely move but not move too much as to not grip the cubes. My last resort before the competition is to remove this entirely and just direct mount the intakes, removing the ability to put cubes in towers.

@vrc Interesting. I’m not sure how I’d implement this into my design, but I’ll take my bot home and try it out tonight.

Hmmm. I think, if you don’t want to rebuild your intakes again, you should lessen the sitting angle of your tray. Less resistance to gravity. Also, get the rubber tank treads, and brace your arms.

We have rubber tank treads which I will definitely put on my robot tonight. I might be able to move the pivot of our tray forward a little bit so that should lessen the angle by a few degrees and possibly make it exactly parallel to the intakes. By bracing the arms, is it what VRC mentioned above or some other method?

Can your arms lift? If so, then create barriers on the outside of the arms, as near as you can to the intake, but don’t screw them to the arms. A plate or standoffs would work.
Alternatively, if your arms don’t lift, screw them to a mount, again, as close as you can to the intake.

Our arms do lift. What I’m mostly worried about is when I move the arms down, it will hit or be outside of the barrier

Could I have images of the entire robot?

20200211_160701 20200211_160655 20200211_160644 20200211_160631 20200211_160625

I was pinged? That is my video, yes.


Plates and standoffs.

Thanks, but not really understanding what the picture is trying to show me: here’s a better angle

Your tray is way too steep. They’re literally lifting the cubes straight up.



Blue - plate
Yellow - standoff
Mirror onto the other side
Remember to lessen resting angle of the tray. Reduce gravitational resistance.

1 Like

Planning on changing this now. Is the angle of my intakes still too steep or should I go shallower than that?

Intakes should be parallel with tray, if not a bit shallower. So if I’m looking at the image correctly, yes, it’s too steep.


Better angle?1581481072941974821382526111627