How are you picking up the tetras?
 

Are you picking it up from the top (crane)

Bottom (forklift)

Other...?

Re: How are you picking up the tetras?
 

We are picking up from the top and then sort of swinging it out so we are grabbing it from the bottom corner. It works well, and it saved us some major arm height.

Re: How are you picking up the tetras?
 

We're picking it up from the top with a cross-like structure, positioning it over the goal, and lowering the tetra while driving backwards.

Re: How are you picking up the tetras?
 

Levitation is definitely the way to go.

I'm telling you.

Re: How are you picking up the tetras?
 

we're picking it up from the top.

:)

Re: How are you picking up the tetras?
 

We're picking it up from the top, and then rotating it back so that it effictivly grabs it as if we grabbed at the bottom. I think thats the easiest way to explain it.

Re: How are you picking up the tetras?
 

We grab it at the bottom, which saves us a lot of time and adds extra length to our arm. We can cap about8 tetras on center goal without needing any extension. However our grabber is not a forklift. It just grabs the bottom corner.

Re: How are you picking up the tetras?
 

I'd start by moving my eyebrows and asking it "How are YOU doin?"

:)

As Daniel describes, his team's robot seizes the Tetra from the apex. The result is a tetra that is unitized with the arm.

Re: How are you picking up the tetras?
 

Our team picks it up eathier at the top, or in the middle of it. Eathier way works well, but holding it in the middle gives us more height.

Re: How are you picking up the tetras?
 

This is basically our grabber from a top view:
_________________________________
\---------------------------/
\------------------------/
\---------------------/
\------------------/
\---------------/
\-------------/ edit: the spaces didnt show up
|------------| it is a triangle at the end of
|------------| a bar, this forum doesnt like
|------------| text art very much, oh well
|------------|
|------------|

It slides under the top and nestles in the endcaps where all the sides meet. This also centers the tetra automatically on the gripper.
We cut it out of solid 1" thich aluminum, it took about 30 min of straight cutting, and a ton of cutting grease also.

Re: How are you picking up the tetras?
 

http://www.chiefdelphi.com/forums/sh...ad.php?t=34995From inside (but top corner)

Re: How are you picking up the tetras?
 

The claw
The claw decides our fate.

Re: How are you picking up the tetras?
 

Other :D
But then again you may say it fits in one of these catagories Elgin since you saw it Saturday.

Re: How are you picking up the tetras?
 

We get into the apex and as the arm goes up the tetra rolls back and nests on a brace that touches the tetra in five places including an eight inch span across the bottom. The first one we built used a tennis ball in the apex and worked well but we redesigned and built a better and stronger one. We don't know if we want to use a ball on then new one or not.

Re: How are you picking up the tetras?
 

We use a simple hook to grap the tetra by the apex.

We decided against the use of a complicated, actuating mechanism because we would figure that it would take more time and precision, as well as having to lift more weight on the end of a cantilevered arm.

The drawback to this type of tetra grabber is that we have less control over the tetra, and it tends to swing around a little bit. We are planning on adding a horizontal beam to the hook that will keep it from sliding down the arm too easily, and to hopefully steady it a bit.

Non-actuating hooks work well, but only if you design them right.

Re: How are you picking up the tetras?
 

but how many can pick off the floor, auto loader or dependent on the human station????

we have an arm type thing as seen...

Re: How are you picking up the tetras?
 

our team was going to go for the simple hook method, but since we thought of it so quickly, we figured everyone else did too ...which turns out to be true...
so we decided to spice things up. our gripper holds all 3 sides facing you off of the auto loader. first we line up by touching the bottom, then we grasp onto the two sides, this gives us much more control of the tetra so we wont lose it while running around the field and getting hit by other bots.
also, it has a certain coolness effect to it, maybe the movie Tremors will stir up your imagination ;) .. we'll post pics later

Re: How are you picking up the tetras?
 

We can...

Re: How are you picking up the tetras?
 

The most efficient tetra manipulator we developed in mock-up used a skewer with a cross bar behind and slightly below the arm beam. We also found that the skewer worked better when tilted 5-10 degrees upward. So far, I've seen lots of skewers with crossbars -- some powered at the wrist and some fixed -- but only a couple that include that tilt.

Ironically, our team voted on a different manipulator in part because the fixed skewer was too simple. Some teammates wanted to be able to flip the tetra over and carry it over the body of our 'bot, others thought it the skewer would require too much reduction in the arm lifter, and, more importantly, it would have made the pneumatics team unemployed.

Re: How are you picking up the tetras?
 

We can also pick it up from anywhere. Our first claw was a simple ball with a shovel at the bottom, but we tried it and it wasn't as easy as we wanted it to be, so we designed a new claw. Here's a pic of it (after we painted it).

Re: How are you picking up the tetras?
 

Just as shown here: http://www.chiefdelphi.com/forums/pictures.php?s=&action=single&picid=10034&directio n=DESC&sort=date&perrow=4&trows=3&quiet=Verbose

Upside, we don't have to lift our arm high to put one on - Also, tetra is secure onece it is in the position shown.

Downside, we may have to come up with an unusual way to load at the human players station. ;)

Re: How are you picking up the tetras?
 

We can as well, although the most efficiant way is the human player. Here's a picture of our claw.

-Daniel

Re: How are you picking up the tetras?
 

We had this idea too. We figured it'd be quite difficult to line up the grabber in the xy plane to pick up tetras from the floor and to score them, so we ultimately went with something different.

How well does your grabber work in terms of lining itself up right? We had a triangular guide in our mock up to help guide the three fingers into the right places.

Re: How are you picking up the tetras?
 

We are using a claw, it looks a little different now that we had to lose some weight but the idea is the same. It uses a 6 inch pneumatic cylinder to rotate it up or down to pick up and release the tetra. This makes it easy to pick up a tetra from the ground, manual loading station or the human player.

Re: How are you picking up the tetras?
 

We use two plates: 1 that is stationary and one that moves. The moving one goes inside the tetra and lifts it into the other plate like this:
Buzz X

Re: How are you picking up the tetras?
 

We haven't actually tried picking it up from the ground, but theoretically (the p-word that the drivers hate) we can do it. The cone helps to center the tetra, and ultimately, if we can get it over the tetra, we can grab it about nine times out of ten. Again, it's much more efficiant to have our H.P. do it, but s/he needs to be tall (I'm 6 feet tall and I need to lift the tetra over my head to get it where it needs to go)

-Daniel

Re: How are you picking up the tetras?
 

This year 88 decided to go very simple... Nothing complexed about it... Though for those of you who have seen us you know how slick we can be... Though I must say the coolest thing about our robot is the 4 foot lead screw we have in it... tehehe... can't wait till the competition!

Re: How are you picking up the tetras?
 

We grab the tetras on the sides when using the autoloader, or have the human player hang it on two bolts in the arm. We do not have the ability to pick tetras off of the ground, or grab vision tetras, but the lack of those abilities hasn't appeared to be of any handicap.

Re: How are you picking up the tetras?
 

We originally went with a forklift design for our grabber. But when we got to competition, we found it was to hard to line up to the auto loader and it was not compatible with the human player. :(

So on Thursday of SAC we came up with a pneumatic that pushes out to hook the tetra, then retracts to let the tetra slide off. But the pneumatic shaft got bent. So down goes design numero dos.

Our third (and luckily final) design is a simple hook with rods coming out either side to stabilize the tetra. It works reasonbly well, but it isn't as good as a well thought out grabber would be. Everything turned out ok though, we played defense for our alliance and got to the finals for the first time in our team's ten year history. :D

Re: How are you picking up the tetras?
 

Our robot has the ability to pick up tetras off the ground but we barely use it. For any of you who have seen our robot you'll know that we depend on our human player to load us up with up to 3 tetras and cap like a maniac.

-Crash

Re: How are you picking up the tetras?
 

We have a somewhat similar claw. In function anyway.
http://www.anderson4.k12.sc.us/schoo...cs/index.2.jpg

We also have a hook used for extra height. Our robot was the only robot at UCF with a claw. Most all of our parts were hand cut/fabricated by us. I actually cut out the claws my self. Well 2 out of 3. I fixed the third one though. ;p

Edit: That picture was taken before the robot was finished. If you were at UCF you saw it with all the graphics and such. There's not a lot that's different. It's just prettier. Oh and a few parts on the claw ended up changing after this picture was taken. Just some brackets. Nothing major.

Re: How are you picking up the tetras?
 

We pick up the tetra inside and lifting up with a chain/forklift design. Very simple. We can load from the human player station as well as the Auto load very efficiently. Whichever one is more conveniant... we go to... We can pick them up off the ground as well...

Re: How are you picking up the tetras?
 

Extendable pneumatic arm with claw.

The Claw

Re: How are you picking up the tetras?
 

We spear it with a piece of pvc, then lift it with a forklift like lift mechanism. It is easy to aim for anywhere inside a tetra and then lift.

Re: How are you picking up the tetras?
 

We use two servos to extend an arm with 3 fingers that can pick tetras up off of the ground, auto loading station, or human loading station. The entire mechanism can be extended up to 17 feet in the air with a 4-stage telescope with self-contained pulleys.

See: http://www.chiefdelphi.com/forums/sh...ad.php?t=36329

Re: How are you picking up the tetras?
 

ur machine kicks serious bot (when its not leaving its lampshade on one of your home goals)

I would love to see an exploded diagram of your lifter.

Re: How are you picking up the tetras?
 

Team 1370 can pick up the tetra from the bottom or from the top we have to different grippers we find that it is much faster to pick it up from the top but you sacrofes how high you can go.