Help with change up robot

image this is my robot. The ball is just constantly spinning at the top and I’m out of ideas at this point so any advice would be great. Also I’m at home cuz of 2 week quarantine from school so I have no supplies

Some anti slip on the hood might help, also maybe lowering the compression on it? If you don’t have anti slip, try rubber band.
Edit: also, how fast are your rollers?

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the compression looks good, make sure all motors are spinning the same direction and add antislip matting to the hood. then you may want to adjust your hood from there but antislip on the hood is a must

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you have nothing keeping the ball pressed firmly against the top roller. you need the base of the hood to start much farther forward to maintain compression. also I would suggest a curved hood rather than just a fat piece of metal.

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What do you mean by anti slip

This stuff:

It’s a black sheet that is covered with rubber to provide friction to prevent something from slipping on it.

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You can also use a bunch of rubber bands, if you don’t have the mat. It will work, maybe not quite as well, but it will work.

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If you don’t want to get that, for $11 you can get 18’ in fun colors on amazon.

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basically you have way too much resistive force fighting the torque of the rollers, and the bands on the rollers and the bands pulling the hood down are just absorbing all the energy of your rollers

Add some curvature and rigidity to your hood, and have just a tiny bit of compression with some mesh or foam. You take heavier energy losses due to various resistive factors when the system is as soft and absorptive as you have it, but if it’s entirely rigid you don’t have any room for error and can’t grip the material well (research traction vs rolling resistance if you’re curious, it’s neat stuff). It can’t get past the hood because you’re essentially throwing all the energy into a flimsy structure that doesn’t care if it’s deformed and will just continue to absorb the energy until the bands snap or the rollers overcome it (with heavy losses in the process)

if you want to fix this, i would recommend making a curved hood with a locking mechanism after it flips out, so that you have a set amount of compression that isn’t reliant on the structure’s gravity and the rubber band’s tension, and leave the necessary compressive aspects of the hood to some foam or mesh

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What RPM is your flywheel running at.

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Also, Screenshot_20210111-140928_Chrome
Are these bearings used as stops? Doesn’t seem like a good Idea…

you really don’t need a locking mechanism if you have the hood tensioned upwards enough, it will just stay like that permanently.

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Aluminum is a lot more rigid than any reasonable number of rubber bands you’d put. A lock is more secure and guarantees higher levels of consistency and precision. not necessary by any means but it does help

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I mean the only force that’s going to be pulling the hood down is gravity. you can easily keep a hood consistently kept upwards against a stop with rubber band power alone. I don’t think a lock would help at all with a lightweight tensioned hood tbh. maybe my hood’s just different, but a lock on mine would be effectively useless.

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The difference between it and a well tensioned band would be pretty small, but it’s usually the little things that set teams apart. You can have it tensioned up and then locked for redundancy and very little weight. either way, adding a lock or fixing those bands would probably help some of op’s problems

Are those rubber bands legal? They aren’t dimensionally similar to the ones that vex sells. You’d have a hard time getting those thin wide egg noodles to pass inspection at a restaurant that only serves linguini.

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What about having a ratchet on the hood with a sprocket-not as a power sharing mechanism, but as a lock, so the hood can only open, and not close?

they look like they could be #64 bands to me, which are one of the legal sizes.

@Xenon27 They’re a lot wider than #64. If you look at the hood tensioner, it’s one extremely wide band covering the 1/4” standoff. I primarily use #64
And if you look at where they’re twisted on the rollers, they’re very thin in profile.

rubber stretches

stop

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