Elevator vs. Telescope vs. Scissor

[Calvin_1631]

What do you prefer, an elevator, telescoping arm, or a scissor lift?

[Rich Ross]

What if it's none of them? Some teams (Spam for example) use arms with joints.

[brinsy625]

actually... the method i perfer is the one our team used...momentum and gravity

[Calvin_1631]

Dang, thats what I forgot. When adding the choices 3 seemed to little, thanks. OR A JOINTED ARM...

[LordTalps]

Well, we've actually got an elevated arm. With a joint on it.

Sooo... :D

[Kellen Hill]

We have a telescoping arm and while up in the air it sorta goes where it wants to. After attending St. Louis, the Jointed arm seemed to be a nice manipulator but other teams did really well with all of the other types of arm.

[lenergyrlah]

1731 has a jointed arm.

[Gabe]

604 has a jointed arm

[CraigHickman]

We've got a 10 foot elevator that starts in the 4 foot category. It locks up, and has worked very very well for us.

[Guy Davidson]

Jointed arm with a roller based manipulator, with a forklift style arm coming second.

[=Martin=Taylor=]

I recognized early-on that telescoping arms and elevator style lifters would have an advantage this year since the rack is vertical and requires no "reaching." I think these are the best designs.

However, we decided not to use a lifter since they require more parts then an arm and are harder to build.

We have a lot of experience with arms, and we knew how to build one.

[Pavan Dave]

Last year I savaged parts from TeleScorpio and my mentor showed me how it worked. Since then, I have frowned upon telescoping arms, and for this game I do not feel it is efficient enough to use compared to the elevator, which many teams and robots have used including Chanizilla who has completed its tasks beautifully. As for scissor I am unsure of what you mean.

[Andrew Blair]

Scissors are very material instensive for their lifting ability. For a light game piece requiring quick actuation, a scissor is not the ideal way to go.

A telescoping lift is precise, stiff typically, and good for a heavier, more deliberate, reach type game. A good choice, but an elevator is probably the best choice here. In terms of material/fabrication costs, complexity, and speed, this is the winner. Quick, vertical actuation is easy, and cable is light. However, these elevators are typically quite flimsy at full extension. Not a huge deal with a 1lb tube, but still an issue that complicates scoring.

[Joe Johnson]

I have thought about scissor lifts a lot. They seem easy but in fact are quite difficult to implement successfully on FIRST robots. I was toying with the idea of lobbying FIRST to make a rule against them, but I think I have come up with another, better approach.

I think that FIRST should make a rule that explicitly allows scissor lifts but that requires that every scissor lift should have a clown head on top. The size of the clown head is dictated by the following formula:
Min Diameter of Clown Head = {Number of stages in the scissor Lift - (Number of Years Your teams has been involved in FIRST/4) } X 1ft.

Clown heads would be like bumpers in that they can extend beyond the normal limits of the robot, the associated weight is not counted during weigh in, and other robots can bash into it any time they like without pentalty.

While this rule is likely to be controversial, it would be extremely entertaining and I think that it help more people to see the difficulties of actually implementing scissor lift that is not laughable.

Joe J.

P.S. Heavy sarcasm alert.

[MrForbes]

I wonder what the 1726 bot could be described as? it has a motorized joint where the arm attatches to the robot at the "shoulder", and a latching joint at the "wrist", but it isn't really a jointed arm.

We'll see how it does in just a few days! should be fun. In solo practice the students could hang 5-6 ringers pretty easily in a 2 minute session.

[Samuel H.]

We use a 4' elevator that goes to 10'. I believe elevators are the most efficient design for this game. We did fairly well with one at STL.

Sam

[lukevanoort]

We use a two stage elevator that starts at about 3 ft and goes to sevenish, then there is a two jointed arm on top. Works nicely.

[Dan_Karol]

we use an elevator to go from the ground to about 10ft in the air in about 2 seconds, it has a griper on it that can bring the top of the tube about 2 feet higher than the wrest of the arm. It is my team's first attempt at an arm and we are pleased with it's operation.

[Rob]

Would the large tie-dyed bag on top of the scissors lift that Wildstang used in 1996 fulfill this requirement? Does anyone have a picture of that machine?

RAZ

I have thought about scissor lifts a lot. They seem easy but in fact are quite difficult to implement successfully on FIRST robots. I was toying with the idea of lobbying FIRST to make a rule against them, but I think I have come up with another, better approach.

I think that FIRST should make a rule that explicitly allows scissor lifts but that requires that every scissor lift should have a clown head on top. The size of the clown head is dictated by the following formula:
Min Diameter of Clown Head = {Number of stages in the scissor Lift - (Number of Years Your teams has been involved in FIRST/4) } X 1ft.

Clown heads would be like bumpers in that they can extend beyond the normal limits of the robot, the associated weight is not counted during weigh in, and other robots can bash into it any time they like without pentalty.

While this rule is likely to be controversial, it would be extremely entertaining and I think that it help more people to see the difficulties of actually implementing scissor lift that is not laughable.

Joe J.

P.S. Heavy sarcasm alert.

[s_forbes]

I think that elevator robots will dominate the game this year. They are fast and effective, and because the tube isn't on the end of a long arm, it will be easier to score with defense being played.

We went with a jointed arm, though. Simpler, easier to build, and it still works if you bend something.

[Darkforces]

I see elevator, telescope, and scissor but were is the spine arm selection? :D

[meatmanek]

Here on 868 we used an elevator. We love it, aside from the bearing problems it had at St. Louis which would leave it useless for a match.
(We fixed the problem. Turns out you shouldn't mount a track with screws that are smaller than the holes in the track)

What if it's none of them? Some teams (Spam for example) use arms with joints.
More than just some of them. Seems like half the teams at St. Louis used a jointed arm.

[Gene F]

We have a telescoping arm that pivots about the center when retracted. It gives us the ability to rotate to the ground for easy tube pickup. We only extend slightly to reach the middle spider and can easily reach the high spider. Check out pictures on our web site, www.metalinmotion.com.

[dbell]

we have an arm with three joints, but we thought about making an elevator with 2 joints. I think that this pole needs to have a jointed arm option.

[neutrino15]

I think that if you can make a telescoping arm well (like i believe team 25 did this year), it works well. Yet elevators have less moving parts are are much more simple.

[meatmanek]

we have an arm with three joints, but we thought about making an elevator with 2 joints. I think that this pole needs to have a jointed arm option.

Can Elevators really have joints?

[cziggy343]

team 343 (us) has a telescoping arm. it works just as well as most people's. our manipulater is pretty cool too.

[Tom Line]

I think, for any mechanical selection, you need to carefully evaluate the corresponding controls selection.

A forklift style lifting system requires far less powerful motors, has far less momentum, and can be eaily set with switches to stop at given levels.

An arm style lifting system requires extremely power motors / gearing because of the torque of an arm at full extension. It has more momentum that is very difficult to damp and control, and has difficultly stopping at given heights unless you have very powerful motors. I've seen some arm teams using the minibike CIM to power their arms. Any of you forklift styles used a motor that heavy? The benefit is that you can reach "over" other robots for the low positions - if your arm is strong enough to take getting smashed in to.

From a lifting perspective, because the forklift style is easier to stop, it can be made to lift more quickly (again, less momentum).

Don't get me wrong. We've got an arm system. In retrospect, from the controls standpoint, I wish we would have gone with a forklift style utilizing a winch for up and down motion.

To summarize - an arm is for reaching horizontally. A forklift is for reaching vertically.

I can't WAIT to see that spine system work. Where are the videos!!!!????

[Dave Scheck]

Would the large tie-dyed bag on top of the scissors lift that Wildstang used in 1996 fulfill this requirement? Does anyone have a picture of that machine?There are a few in our gallery.
http://www.wildstang.org/gallery2/v/1996/

Here are some close ups
http://www.wildstang.org/gallery2/v/1996/1996_NH/1996_NH_Competition/1996_NH_competition08.jpg.html
http://www.wildstang.org/gallery2/v/1996/1996_NH/1996_NH_Competition/1996_NH_competition09.jpg.html
http://www.wildstang.org/gallery2/v/1996/1996_NH/1996_NH_Competition/1996_NH_competition35.jpg.html

[dbell]

Originally posted by meatmanek
Can Elevators really have joints?
sorry, i guess i didn't make this clear. we considered an arm that had a mast. Then on the top of the mast a joint that can rotate up and down. off that is a beam that can extend, (like an elevator). at the end of that we would have another joint and our gripper.

here's a very rough CAD we did in week 2.
5216
5215

[kaszeta]

None of the above. Team 95's robot has two joints on it's arm, one for side-to-side and one for up-and-down rotation:


http://farm1.static.flickr.com/174/409899947_134391649b_m.jpg (http://www.flickr.com/photos/kaszeta/409899947/)

(well, it has a third joint at the wrist, but that's just for folding the arm on itself when the bot's in starting configuration).

[Samuel H.]

Any of you forklift styles used a motor that heavy?

We use the Big CIM for our winch. Strangely, before we added surgical tubing counterweights to or elevator stages we managed to burn up both the Victor and the CIM. Now that we have the required force decreased, we have not had any problems though.

Good luck,
Sam

[MrForbes]

An arm style lifting system requires extremely power motors / gearing because of the torque of an arm at full extension. It has more momentum that is very difficult to damp and control, and has difficultly stopping at given heights unless you have very powerful motors.

I guess that depends on how you design the arm. With help supporting it, such as a gas spring, it requires relatively little power to move it, and you can get away with a light duty motor/trans (suchs as the small banebots or globe). The control can be handled with two pots, one on the arm and one on the OI, with a bit of programming to conrol the rate of movement. Seems to work real well for 1726 so far.

[ballgame21]

We had an elevator that was powered by a pully to save weight. It seemed to work really well.

It doesn't really matter what type you have when two bots are playing defense on you.

http://youtube.com/watch?v=oepTWtPj5Yk
(Think Pink):cool:

[Dominicano0519]

we have a jointed arm that is also telescopic, The whole thing can pan and tilt. so can the jointed forearm

[1359th Scalawag]

Our robot has a telescoping arm. We have absolutely no motors in the hand (grasping) mechanism. We just scoop up the tube. It's possibly the most simple hand you can have.

I voted telescope arm because we have one but if I had to choose the best kind of arm, i'd say the Elevator (forklift) type did the best. They just come down on top of the spider leg and let gravity put the tube where it belongs. They seemed the most reliable to me.

[artdutra04]

I've never really been much of a fan of telescoping arms: for me it's either an elevator, an arm, or a combination of the two. The biggest problem I have with telescoping arms is that the longer they extend, the harder it becomes to score with them if defense is being played upon you. With a telescoping arm sticking out six feet, a 10degree spin due to defense will offset your manipulator much more than a short two or three foot arm with the same 10degree spin from defense.

This year, 228 has a two-stage elevator (powered by a single big CIM running through an AM single-speed tranny) with a short rotating arm located on the second stage. The arm is designed to pick up tubes (http://www.team228.org/media/pictures/view/2930) from the floor, drive with them almost completely within our robot frame (http://www.team228.org/media/pictures/view/2938) dimensions (which would drastically increase the difficulty of knocking it out of our manipulator). And if you can figure out why we designed the arm to rotate off to the side, then mad props to you. Otherwise, you'll have to wait until UTC. :p

http://team228.org/gallery/61/slideshow/weeksix-125.jpg

[Joe Johnson]

I would have been in the elevator camp until I saw a bit of the Great Lakes Regional competition this weekend.

Proir to this weekend, I was in the elevator camp. Easy control is a key and, while an elevator is not a requirement for easy control, it does make the job much easier.

But, I have now switched my thoughts to say that in many cases a jointed arm is an big advantage (it still has to be well behaved). Specifically, it can enable a robot to reach over an opponent. There were many matches where the HOT Team (#67) or the MechWarriors (#573)* were blocked from getting to the spider leg by another robot, only to reach OVER their opponent and score.

I am convinced. A well behaved jointed arm with the reach to score over an opponent is definitely the way to go this year.

Joe J.
*Full Disclosure. This is my daughters team and they did quite well at the GLR so I am far from unbiased. In my defense, I will say that I had very little to do with their robot design.

[MrForbes]

Jointed arms dominated in Arizona, although that may be because most of the scoring robots had jointed arms.

842 had a simple lower row Swamp Thing type manipulator that worked well until the PVC broke in the finals. 1158 had a turret mounted telescoping arm that was pretty effective, although it's ability to move all around did seem to cause some problems with hanging up in the rack. The jointed arm bots seem to move tubes quickly, and that's really important this year.

Also, the more joints you have in the arm, the more challenging it is to control....and 39 definitely met that challenge!

[obsesswthneesan]

I have thought about scissor lifts a lot. They seem easy but in fact are quite difficult to implement successfully on FIRST robots. I was toying with the idea of lobbying FIRST to make a rule against them, but I think I have come up with another, better approach.

I think that FIRST should make a rule that explicitly allows scissor lifts but that requires that every scissor lift should have a clown head on top. The size of the clown head is dictated by the following formula:
Min Diameter of Clown Head = {Number of stages in the scissor Lift - (Number of Years Your teams has been involved in FIRST/4) } X 1ft.

Clown heads would be like bumpers in that they can extend beyond the normal limits of the robot, the associated weight is not counted during weigh in, and other robots can bash into it any time they like without pentalty.

While this rule is likely to be controversial, it would be extremely entertaining and I think that it help more people to see the difficulties of actually implementing scissor lift that is not laughable.

Joe J.

P.S. Heavy sarcasm alert.

perhaps there could be a big spring with a plate attached to the top and bottom with a wench in between controlling the hight of the spring and retracting it. This would be far better than a scissor lift because it could move far faster and have a nice springy effect when it is impacted by another robot

[hayakuneko]

at the LA regional, I really liked the cheesypoofs/rawc bot design with the hooks and the elevator design, however what I found to be quite helpful was our arm design. With our arm design, we successfully capped mid-level spider legs over a few robots. In quarter-finals, we capped over 1702 (i think) and right as we were trying to cap over them, they even had one of their alliance partners come push us to stop us from scoring, but we still scored. Also in the finals round, we went up against 330/254/4 and with our arm, we were able to squeeze our arm in the little space in between the empty spiderleg and 330's arm. hehe that was a great match.