Internal Stacker Ideas

I know many teams have decided on some sort of a robot where they internally stack. I would be interested in different ideas teams are using for internal stackers.

The consensus on the forum is to use a chain bar or four bar to hold your stack. You can see many examples of this in the forum. As for your cone manipulator, you will probably want either a rd4b, linear lift, or some similar type of lift to move your cones, but all those lifts are linear, and thus you have to have some sort of mechanism to transfer the cone to the chain bar. For this, I’m using a chain bar. Hope this was helpful

Our team is actually using a small elevator lift to manipulate the mobile goals. Video link to our Instagram can be seen here:

That emall elevator lift seems pretty good!

Interesting…that’s not something I’ve thought of. However, the problem with elevators like that is that they require greater torque to manipulator heavier and heavier loads. So, when you start to get stacks of more than a few cones, your going to likely find your motors stalling out

Isn’t that consistent with all lifts?

Nah, with my inverted qualdruple reverse 8 bar, more weight=less torque to lift


I’m saying that in general, Elevators require more torque to lift the same weight as an RD4B or something else

Because we’re using 6 tooth sprockets to drive the chain, there is barely any leverage relative to the rotational axis to move the chain. And, because we’re using 2 motors, it stays up simply due to the resistance in 393 torque motors (no power required), even with high stacks. We’ve found it works really well.

For a mobile goal manipulator, efficiency isn’t a huge concern, and if the motion is a little slower, that’s ok. The mobile goal only needs to be lifted a few inches off the ground, and there are only 4 mobile goals per alliance. However, space efficiency and a linear, vertical motion are extremely important, meaning an elevator lift is a good choice.

Conversely, for cones, you need a fast, efficient motion with as little friction as possible. Thus, an elevator lift is a very bad choice relative to a DR4B or something similar. Skyrise proved that scissor lifts and DR4Bs are far superior to elevator lifts in lifting speed for large extension.

@noahiszipin, it looks like your elevator lift takes a little longer than most other 2 motor mechanisms to lift the mobile goal without bringing it into the robot. However, it seems like a great design choice because it’s so compact and perfectly linear.

Thanks for sharing your mechanism!

I might have to disagree with the lift system here. Skyrise was a game that required robust expansion that needed to be capable of lifting loads of about 3 pounds or more. I completely agree that for the cones you need a fast, efficient motion with as little friction as possible. However, a double reverse bar hardly fits that description. We actually used a double reverse 4 at worlds for Starstruck, and, while it had its advantages over the 8 bar we once had, it is far too rough and unpredictable for In the Zone. But this year, because cones only weigh like 1.18 grams or something, an elevator lift can be made to minimize friction and maximize speed. Our original design, which we are still pursuing, is actually quite similar to the ALBA robot, except the chain bar is elevated by a single stage elevator. It is fast and reliable, requires almost no metal, and reaches a height of about 50 inches when the chain bar stands upright. But, we’ll see how the season plays out.

Not to derail the thread but I just wanted to mention this for anyone that is going to look at this thread. Just because you can build a lift that is fast doesn’t mean you should go that fast. Doesn’t matter what that lift is, but I’ll mention dr4b’s since that’s what’s been getting hyped up. Making a dr4b that can lift a cone in less than a second on paper is great except that you still need to be able to safely control that in the real world and going fast is not always the awnser. Slow can be better if it means you can control it. Sorry for the mini rant.

1 pid is your freind
2 automation is your freind
3 going slower than the competition will make you lose
4 ???
5 profit

I’m not really sure what you mean about DR4Bs being rough and unpredictable to be honest. It looks like your lift was quite fast and smooth.

Your robot was quite impressive in this match.

You’ll notice basically every other lift design had trouble reaching the speed your lift reached. However, 134D, another DR4B, also had an extremely fast lifting motion.

And the fastest skyrise lifts tended to largely be DR4Bs as well.

If a DR4B is too jerky, it can simply be made slower, or the PID control can be optimized. It seems like having high efficiency and low friction is always a good thing.

Conversely, elevator lifts tend to be much higher friction because of their linear sliders. I’ve never seen an elevator lift reach the speed of these DR4Bs.

Anyhow, you’re right that time will tell. Good luck with your design!

And the same to you. You can never really tell so early in the season.