Arm Designs

[wojahoitz]

I really like the forklift idea, I can see a robot driving over the flat side of the base of a goal tetra to the point where the scoring tetra is over the point of the goal tetra. Then just lower the forklift onto the top of the goal tetra. You may also be able to articulate the "tower" the the forklift is attached to to lean the tower forward, enabling the bot to be further away from the tower. This would raise the center of gravity, but I see it as a last ditch effort.. I also see the scoring tetra hanging from a hook or something like it on the bottom of the forklift. I think this would be easier to place on the goal. Thoughts? Opinions?

[greencactus3]

Originally Posted by Max Lobovsky

reaching over a 38" long robot and then reaching 10-14" into the goal (assuming you hold the tetra from about the end) is going to put your CD pretty far forward. Don't expect to be safely reaching over an entire robot without something to stabilize you.

cd? cog? or am i mistaking sumthing?
but who said it had to be one joint.

[Tom Bottiglieri]

Hey, how about that arm on the blue robot in the new game animation? You know, the one that extends about 20 feet?

I'm glad Dave and I share a common sense of humor.

[Alaina]

My team doesn't have a favorite idea yet for an arm, but I'm looking forward to go to competitions and see all the different designs people come up with.

Double-jointed is looking good for us, though.

[Ssbfalcon]

We were discussing a forklift today, but we found out that it would require a long prong to reach the top end of the goals, causing massive balance issues... A forklift elevator combined with an arm of some sort... hmm...

[Ianworld]

Yeah, for anything short of a verticle lift you're going to have some massive torques on the arm. The tetras are heavier than the big ball last year and heavier than the boxes from stack attack. You also need to reach rather far into the goal which can add two to three feet of extra torque on any type of arm, verticle(forklift), extending or swinging. Getting the tetras on top of the center goal is proving to be much trickier than at first glance.

[team66t-money]

undefinedundefinedundefined I know i am new at all of this but would somebody please tell me how to start a thread i have no idea and spent 2 hours trying to find it . Thanks

[team66t-money]

Originally Posted by Ssbfalcon

We were discussing a forklift today, but we found out that it would require a long prong to reach the top end of the goals, causing massive balance issues... A forklift elevator combined with an arm of some sort... hmm...

You would not necessarily need a long heavy forklift we discussed that a couple of days ago but a forklift elevator combined with some sort of arm would be ideal

[Ductapemaster05]

so how about instead of an arm, you do a escaltor type deallie, have a concave tetra style figure at the base of your bot and then with like a couple of belts drive it up and deposite on top, we had something like that last year except it went the opposit way. i dont see why that wouldnt work

^/|
/ |
^/__| kinda sorta
you get the idea, im trying to think outside the box

[Parker]

Originally Posted by Cyberguy34000

I know there is a very similar thread already out there, I just wanted to get some input specifically related to the arm design. What kind of design would work better, fork lift or a bending arm? Ideas? Post away.

I think a "bending arm" would accomplish the task better because it has more ranges of movement vs. a forklift. Forklifts simply move up and down. Although simple is sometimes good, this year I think the more complex arm designs will win.

A "bending arm" also allows the robot to stack tetras on a goal at a greater distance than forklift, due to the fact that forklifts have to be under the goal and be perfectly aligned the properly stack a tetra.

As far as CG is concerned, simply change where you mount your arm in relation to the robot.

[Pshyco]

But you have to reach 7 feet and up ( if you wanted to stack more tetraes on)!!

Won't height be the biggest problem for every team????

[Jake177]

In 2001 when I was on 177 we made a 14-foot telescoping arm to put the big balls on top of the goals. Granted we didn't need to worry about reaching very far from the base of the robot, and I don't think the balls were as heavy as the tetras are, but a long arm can be done.

[ShadowKnight]

It's not so much height that is the concern, it's that the robot has to bend that arm over a greater horizontal distance than before with a heavier weight on the end. Again, height isn't the problem, tipping is, and not from jerking the robot too much. I think some teams will be using the edges of the goals as rests, to help aleviate the problem of tipping, or at least approach the goal from that angle as a safeguard in case they do in fact tip over. (that way they rest up against the goal with a lot less damage done to their bot and the possibility to right themselves)

[Cyberguy34000]

The general consensus among the team leaders is that less is more... Less joints with more strength will give us a bit of an edge over some weak arms that can move everywhere in sight, but barely lift the Tetra. And let me tell you, we just finished constructing one of those things tonight, 9 pounds doesn't sound that heavy until you try picking on of these things up. Then thinking about moving it 8-9 feet away from the base of the robot... You get the idea. If you can, try building one of those Tetras as soon as you can.

[ShadowKnight]

Well, I mean that's kinda the point. I think that some people aren't quite realizing how far they are gonna have to lean out to cap. I would not be using a pnuematic piston to actuate the arm for that very reason. I just don't feel that it would respond quick enough under that kind of load (we use pnuematics last year to actuate our arm that capped and it was not incredibly responsive). We should be using motors to actuate the arm this year. (The new Fisher Price ,otors are looking promising for this application).

It's around 2 and a half feet horizontally that you have to lean out, assuming that your right there in front of it. In reality, it's gonna be a bit more, nearly as large as a bot footprint. Yes, the motor or pnuematic piston actuating that arm would have to mighty powerful to have any kind of dexterity when stacking.