Vacuum Pickup
 

Here's a quick test we did using a cut-down bucket left over from our 2013 Frisbee hopper: http://youtu.be/tPNvIXTAd4s

Obviously we couldn't use a 110VAC shop vac, but we could connect a legal motor to the blower.

Re: Vacuum Pickup
 

That seems possible. Then, you could have a kicker to kick the ball away from the robot.
If you do that, don't forget to place a shoe on the armature, just for the sake of LOLs.

You might want to try it out with a BAG. They will get up to 14,000RPM, so you'd need to see if that'd work, otherwise, 550s, 775s, AMs, etc. Just don't try a window motor :D.

For the kicker, you'd need to relieve the pressure as soon as kicker is about to hit it, to prevent having your vacuum following the ball into the goal, breaking it and getting your robot disabled.

Also, are you going to use the vacuum cleaner or are you going to build your own contraption? I'd like to see how it goes :D

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We used a vacuum in 2010 and it worked well. we cut the guts out of a shop vac like the one in the video and replaced the motor that drove the fan with a Fisher Price motor. It worked well.

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Yeah, having our robot kick itself to death would be entertaining for the spectators, but won't help us win any matches.

A kicker might work. Or swing the ball up & drop it in a catapult.

Re: Vacuum Pickup
 

Just for ha has I ordered the 'snowblower motor' that was on Andymark FIRST Choice. (Was practically the only thing left to order.) Don' know if we'll use it, but wanted to see if it could be used for ball pick-up or perhaps autonomous defense;)

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How far is the effective range on this? I'd like to see a prototype with a miniCIM or something to actually evaluate the effectiveness. Looks way too good to be true.

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The minicim would need to be geared up (increase rpm) to really be effective. Plenty of other motors could be run direct drive with this.

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There really isn't a "range". We have to make contact with the ball to get a seal. Alignment will be a challenge (as with any floor pick-up device). Perhaps v-shaped guides on the front of the bot?

A proper vacuum cup would probably be more forgiving to misalignment, but we had a lot of butchered-up buckets lying around the shop.

Re: Vacuum Pickup
 

I've got a shop vac like that, 2.5hp IIRC. That's about 1800watts of power. For reference, a CIM peaks around 350W and generally all other motors are less.

You might have a rough time given power limitations of FIRST-legal motors and the battery. Prototype, prototype, prototype... and consider contingency plans.

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Pay no attention to the power ratings of shop vacs, they are sales hype. That vac does not produce 2 1/2 HP. They play with inrush current and/or stall current to get the "peak horsepower" rating.

Re: Vacuum Pickup
 

Dont go by what the HP rating is on the vac the manufactures play games with those numbers. Shop vacs dont draw 15 amps. I am looking at ours thats rated for 2.5 HP peak and it draws slightly less than 8 and is rated at 9 amps. Still not close to 350w.

Re: Vacuum Pickup
 

Most multimeters should be able to measure the average current draw.

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Good info, thanks.

Re: Vacuum Pickup
 

We made a suction system for the 2008 game, FRC1771 did also.
You can see a modified version used in our quick video from this year:http://www.youtube.com/watch?v=3FyQQt_3u0Y.

This is a banebots 550 running a shop vac impeller. The seal is not ideal, as we just ripped the weather stripping previously used at the edge to form a seal around a smaller circle in the cone. The cone is also not shaped to this size ball.

Re: Vacuum Pickup
 

Careful. Most multimeters have an internal fuse and are very limited in the amount of current they can measure. You will probably need an ammeter if you're using a 12V motor.

We tried to use a single fisher price for vacuum since the centrifugal fan that came from our 12V shop vac was rated at 16,000 rpm. However, the fan was enough load that the constant motion destroyed the FP. I remember another team that geared up cims and used 2 to create enough suction to hold the soccer ball.

I can't remember which team it was, but they did post the pictures here on Delphi.

Here's a part of the thread where they discuss the model number:

http://www.chiefdelphi.com/forums/sh...cim+impell er

Re: Vacuum Pickup
 

I helped design 190's 2008 suction cup. A neat thing we learned is that current goes down significantly when the ball is captured. This is because there is less air getting in the way of the impeller blades.

Additionally, we learned that rate of removal is more important than the actual vacuum you draw. Those fabric covers are mighty porous.

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You can use a model airplane prop to pull a ball in. Then just turn it off and kick the ball.

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In 2010 we also used a vacuum to hold the soccer ball. It had an excellent grip on the soccer ball (combination of suction force, area applied on ball, and "mechanical advantage" of how wide your grip on the ball is).

We used a two-stage system to pull a stronger vacuum, both stages were identical, using an impeller and impeller housing from a hand-held mini-vac with the stock motor replaced by a Fisher Price. That year we used a large, soft toilet plunger as the suction cup... I'd recommend something comparable in size to the bucket used in this video though.

Some design recommendations:
- Make sure your method of getting the cup to the ball is effective... even if the vacuum works perfectly, it will help you little if your drivers are always fumbling to acquire the ball. Iterate this, and don't underestimate it.

- Use a "suction cup" with a large diameter, but minimize the volume inside it so the vacuums don't have to evacuate as much air to get a good grip

- Find some cheap vacuums (shop vac or hand-held, probably) which you can salvage the impeller and impeller housing from. Carefully disassemble them and press your own motor on (RS550 would be my recommendation, given the high free speed, stall-less application, and excellent power-to-weight ratio).

A vacuum should be pretty low-power... Ours used two Fisher Price motors, but each drew only a few amps if I recall correctly. Don't worry much about the current draw... it won't require hundreds of watts.

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Thanks for all the great tips. We've found large diameter (=>10") vacuum cups online, but they seem to be for flat surfaces.

We have access to a 3D printer. In past years we've made molds with it & cast urethane wheel treads. I suppose we could do the same for a big vacuum cup.

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What does anyone think about using a vacuum for a pick-up this year in Stronghold? My team was discussing it it yesterday, so I am wondering how (or if) we should go about developing a vacuum pick-up for a low goal bot.

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For large game objects on a high visibility field, vacuums could be fine.
For smaller objects on a very limited visibility field, vacuums would require quite a bit of precision.

My team tested it with low results

Re: Vacuum Pickup
 

We had good results in 2014 (https://youtu.be/tPNvIXTAd4s), but decided not to use vacuum because adapting a FIRST-legal motor to a small shop vac was beyond our resources at the time. But another team won our regional with a vacuum pickup. That was Aerial Assist & the game piece was a giant yoga ball with a fabric covering.

I recommend high flow/low vacuum like a small shop vac produces, rather than low flow/high vacuum, as you would get from a venturi-type vacuum generator. Those things are small and light but require a LOT of pressurized air to work.

To prototype just cut a hole in the bottom of a plastic pail or bowl & duct-tape a vacuum hose to it. Even a cheap vacuum can generate ~60" of H20 vacuum (about 2psi). With a 6" diameter bowl: 2 psi x 3 x 3 x pi = 56 lbs lifting force! Even at 50% loss due to leakage, etc. that's still 28 lbs. You might need to vent your system to keep from collapsing the boulder.

Happy prototyping!

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We've included a vacuum in our puncher prototype mechanism. So far using a shop vac we've found that the boulder lends itself well to vacuum suction for maintaining control. Also if you get the vacuum over the pinhole, it sucks all of the air out of it and makes your boulder look like a brain or a raisin. https://youtu.be/f24bk-4sZCo?t=54s So that's fun.

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Vaccuum repair shops are quick to give you their broken motor assemblies if you ask.

I'd agree with Taylor's assessment about the relative size of the game pieces and visibility.

It worked pretty well in 08 for 1741.

http://www.thebluealliance.com/match/2008in_qf2m1