Hello my team is trying to use a vacuum mechanism for our algae intake, we have never vacuumed anything and would like to hear about your experience and feedback on this idea.
Don’t.
This is one of those things that sounds like a good idea until you have to build and play with it. A vacuum based mechanism for this will always be slower more sensitive and generally less capable.
We used a vacuum for holding the 30 inch diameter exercise balls in 2004 and it lasted 3/4 of a regional before we pulled it off because it was too easy to defend, slow and generally ineffective. And those balls were completely smooth so getting suction on them was easier.
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I don’t recommend, wheels work better and are easy to use. 971 had to go through many (like 20ish) suction revisions to get a grip on 2019 cargo, which is time most teams don’t want to spend on something.
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This has been tried by many teams in many games.
I have never seen a good robot result and most left it at at prototyping.
Getting enough vacuum to hold a ball means a lot of power and ongoing power to maintain it.
Getting a good seal is hard at the best of times and you will likely lose it when hit by another robot.
A good wheel or clamp mech will be as fast or faster and give a more positive hold.
We have a box of suction cups, vacuum pump parts, and vacuum switches from our disastrous 2023 attempt at handling smooth cones and smooth cubes. Free if you want them unless someone already buried them in the parking lot before it was paved over this summer /s. (They were greatly despised.)
I don’t see how you can pull a vacuum on the bumpy algae.
Our team won the official week zero in 2023 charged up with a vac robot that could suck onto cones and cubes. It worked alright, but by our first regional event we had replaced it with a rolly-grabber claw that was faster and more reliable.
The biggest advantage of the the vacuum was how light it was on the end of the arm. All of the motors for it were down in base of the robot. We could wave that arm around and extend as much as we wanted and the robot would never tip, even up on the charging station.
The biggest disadvantage was that it was a long way from “touch it own it”. It often took 10 seconds to grab a game piece with a couple attempts or drops.
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Whatever their 2020 reveal says, 2767 ranked in the top 3 at every in season event and won their states division with vacuum pickup in 2019. Vacuum systems are certainly difficult and rarely the most efficient way to grip something, but they do work.
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Attempted in 2023 because the cones had a smooth surface, did not work. The algae may have more surface area than the cones did, however, the texture on the algae will not play well with suction. Do not recommend.
^Vacuum system ^
Vacuum decision was made by end game climb not for game piece end effector, but once you have end game vacuum, and limited motor slots… (thanks swerve) you take the road least traveled by FRC teams.
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2767 throughly opperates in "no pressure differential " robots XD
I suspect the 2019 bot would have been a fair bit different if we would have had more that 16 PDP slots.
I agree that it is a bad idea, but the similar texture on the 2019 ball was the least of our concerns. Do with that info what you will…
We built one in 2019. We learned a lot.
Your force holding the ball into your gripper is proportional to your surface area times pressure difference, and this can add up to a lot of force. And if you have a good seal it doesn’t take much pressure difference to get lots of force.
Getting a good seal isn’t so much about being perfectly airtight. It’s about compliance. What you really want is something like a conical hood where you have lots of contact area between the hood and the ball, and you need it so that if the ball gets pulled away, the hood is pushed (by air pressure) towards the ball so it stays in contact.
Also it helps to design it such that there’s very little volume inside the low pressure area, but if the ball is pulled away, the volume expands rapidly. That way, if the ball gets knocked, the volume will increase, which will drop the pressure inside the vacuum area, and help pull the ball back into grip position. But again you need to make sure the suction cup or hood stays in contact with the ball. That’s the hard part.
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I made a quick prototype for a vacuum algae grabber. You need SUPER soft contact surface to make this work at all. That also means it takes some time to pump down, and you need either a solid starting push or very good alignment to grab at all.
I would not recommend it.
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So much negativity - you could get the 2023-successful Lady Cans FRC team 2881 opinion. My team couldn’t duplicate their success despite (independently) seemingly duplicating the device. That wasn’t the first time a team claims that they duplicated another team’s robot and how come they ranked highly and we didn’t?
My team erased the 2023 vacuum pump fiasco from our memory except for don’t do it but I’m thinking we used 2 pumps each with a Neo at about half power to suck barely enough for the 2023 smooth game pieces. Evacuating long tubing to the end effector is also problematic.
In 2019 we had some large port (maybe 3/8"?) solenoids near the end effector and some decently large accumulators (a few liters) located in between the pump and solenoid. This helped as most of the tubing was already evacuated and allowed for multiple attempts if suction was not achieved.
The pump was also a lot of work.
Not worth the hassle.
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A critical item with vacuum cups is to have a dedicated pump per cup, and have multiple cups. Its straightforward to couple multiple pumps on a single motor. This is based on looking at the LadyCan’s rockin’ robot 
NOT my direct experience.
You could potentially use a peristaltic pump as a release mechanism/valve. IE, run it forward to help vacuum slightly, run it in reverse to release. I didn’t find that the peristaltic moved enough air to be useful. Piston vacuum pumps are much faster at pull down.
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In 23 we used suction.
We used these vacuum pumps, swapping in AndyMark 550 motors (sanding off the spline) and they fit perfectly. (Thanks to 358 and 810 for providing the motors to the rookies.)
These were the suction cups we used.
Another thing we had to help was running these valves which basically made it viable to only have 1 suction cup touch and not lose pressure.
To help with release we fed a line of air back in through a solenoid to speed up the release. (Something like 5psi.)
While the suction cups and vacuum worked well. It was a bit of a unique complex system that could have been implemented better.
Our bigger issue was when we would try to get cubes they may bounce away. But with 1 suction cup barely on a game piece we still had full control.
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After the success of 971 in 2019, I have to say I am surprised no one is following in their footsteps this year.
To me, it seems like algae is a perfect candidate for a nice vacuum gripper. The variances in batches would not matter to something that just palms the ball. Moving all the pump hardware and electronics off of a manipulator allows it to be as light as physically possible, allowing faster cycles. Imagine how easy it would be to drive up to any of the algae in your reef, and just kind of bumping up against it and it’s yours. The savings in weight will also benefit you for when you want to raise it up to the barge, and just ever so lightly drop it in. No chance of a bounce out like you might get if you shoot it out of rollers!
Please tell me why I am an idiot and what I’m overlooking lol
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Vacuums and PVC don’t work as well would be my first thought but I’m not sure.
algae, not coral