Elevators/ Forklifts
 

Team 766 is currently designing several ways to lift the innertubes in different ways. We are interrested in several concepts but the elevator/ forklift design seems to be leading the pack. However, our team has no experience in these designs and we are searching for the parts necessary to build the elevator/ forklift. Can anyone can give us a link to a supplier and/or a photo of a robot and its elevator. Also any tips for assembling and powering the elevator (cable, chain or type of rigging) would be very helpful. Thanks!


Edit: It looks like two small CIMs will be powering our elevator or arm

Re: Elevators/ Forklifts
 

Did you look at the parts in the Igus bag? Their track system could provide a possible solution for going up and down in an elevator-like setup. I've seen many teams do this efficiently before.

Re: Elevators/ Forklifts
 

Depending on what you want to do, you'll have different ways of going about these lifting methods; One is the forklift type of lifter. This is usually done with chain, either in continuous paths, or all individual per section. Then there's ideas such as elevator designs, which use scissor-type lifting.. For this you could either use pneumatics, or linear actuators... or possibly have a high-torque motor at the center axis of the sicssors themselves...

just throughing out some ideas :rolleyes:

Re: Elevators/ Forklifts
 

Our team is staying away from scissor lifts because we do not have the tools to machine the parts necessary to make a scissor work. We prefer the forklift style over scissors by a wide margin.
We want someting similar to 1072, 245 or 111's robots (but not as fancy) from 2005

Re: Elevators/ Forklifts
 

Remember, FIRST is very safety intensive. So if you make a scizzors lift it's going to have dangerous pinch points and FIRST is going to expect you to shield off those pinch points from people and if you don't they will make you do so. Just remember to take that into account.

Re: Elevators/ Forklifts
 

Try to plan your forklift off of a real life one. Venture to a sponsors shop and look at it or do some googling. I can suggest 8020 frame work with linear bearings - depending on your budget. We used a forklift in 2005 and was a finalist at GLR :-D .

Re: Elevators/ Forklifts
 

I think the main problem with elevators or forklifts is performance. It will be slow. I am just going from experence of the game 3 years ago with the tetras

Joe Barra

Re: Elevators/ Forklifts
 

as for a scissor lift team 1522 tried it for the games 2 years ago, worked well, it was just heavy and innefective when it came to power consumption...

Re: Elevators/ Forklifts
 

Exactly. If you've only got 15 seconds, the only setup strong enough to dead-lift another robot won't be able to go 12'' in 15 seconds.

Try a screw-type device. They gave us a small black one in the kit. the only problem is that the threads make it extremely slow but very very powerful. There probably isn't anything out there with coarse enough threads to make the lift go faster, and still maintain that same power.

Re: Elevators/ Forklifts
 

I think they were talking on placing the tubes with a elevator lift

Re: Elevators/ Forklifts
 

Our team did the math with alittle help from our mentors but according to our math with a machine 85% efficeint (Geared down by a multistage transmission and 2:1 sprocket ) it would take a round about .0284 horsepower to lift a 150 lb machine 12" in 12 secs with one motor. Our mth might be wrong so dont quote us lol. the question is your bot going to be balanced enough to hold another and is the other robot's weight going to be balanced? If your cant get the solutions for these you risk the chance of tipping urself and damaging your bot and other robots as well. Just my 2 cents of info to keep in mind.:D

Re: Elevators/ Forklifts
 

But the tetras weighed a minimum of 7 lbs and the ringers weight about 1. So with the same power output and proper gearing you should be able to lift tubes the same height at least seven times faster.

Remember Power = Work/Time = Force (weight) * Distance/Time. I'm liking having to worry more about robot to robot interactions than just weight in my designs

Re: Elevators/ Forklifts
 

If anybody has a copy of the 2004 Championship presentation called "Manipulators and Mechanisms" (Or something like that) it has a few good drawings of different ways to cable a forklift. We used a forklift in 2005 and had no problems with the speed, even with the heavy tetras. A three stage lift with all internal cabling powered by (I think) a fisher price motor and a Bosch drill transmission. The only problem we had with it was we had to switch from aluminum axles to steel because the aluminum ones got all warped, and the cable broke once or twice (it was nylon) but it wasn't hard to restring it.

~Allison

PS - If anybody does have a copy of that presentation (it was in powerpoint) it would be splendid if you could send me a copy.

Re: Elevators/ Forklifts
 

Here are pictures of Team 118's elevator that we made for the 2004 competition. Picture 1

Picture 2

Picture 3

Re: Elevators/ Forklifts
 

Extruded aluminum with some of the plastic slides work extremely well for an elevator; we used it in 2005, and it is high on the consideration list for this year as well.

Re: Elevators/ Forklifts
 

Remember that the lifting apparatus can push against the floor directly underneath the robot being raised. There is no need for it to be a completely cantilevered structure. Think "automotive floor jack" instead of "forklift."

Re: Elevators/ Forklifts
 

Yes. That is exactly what i was thinking. It is to have a sicssors lift that is completly self supported from the ground. This means that in will be able to lift the robot relitivly quickly with the right set-up:D .

Re: Elevators/ Forklifts
 

That was actually 2005 ;)


http://www.usfirst.org/community/frc...t.aspx?id=1112
The presentation titled "Designing Competitive Manipulators: The Mechanics & Strategy" offers some details into how to possibly build an elevator.

Re: Elevators/ Forklifts
 

OO sorry about that.. guess i am losing track of time already and it has only been 2 days since kick off:ahh:

Re: Elevators/ Forklifts
 

There are more pics on the robonauts website here if you are interested and there are some videos too.

Pavan.

Re: Elevators/ Forklifts
 

Thaks for everyone's help and especially team 118 for the photos. I looked more into the 2005 robots and saw that wildstang's and team 64's forklifts were the kind we would want to build.

Also this elevator is used excusively for picking up INNERTUBES and not robots.

Re: Elevators/ Forklifts
 

A regular nylon strap is light and can lift quite a bit of weight. We used it to telescope our 15 pound arm. That was back in the days of the Van Door motor...

Re: Elevators/ Forklifts
 

what about using pneumatic pistons how do you think they will work

Re: Elevators/ Forklifts
 

We're looking into it [Team 168]. The only problem is that they weigh so much.:ahh:

Re: Elevators/ Forklifts
 

Our team made an elevator for the 2005 competition. You can see the pictures on our site, www.mckinleyrobotics.org and go to the 2005 website link.

Re: Elevators/ Forklifts
 

One of our off-season projects involved making a lazy boy into a moving robot with pneumatic lifters...lets just say that was the inspiration for our manipulator this year.

Re: Elevators/ Forklifts
 

This Question is referring to the concept of having a component push against the ground and raise the robot.

According to <G56> "Robots score bonus points at the end of the match if they are entirely in their HOME ZONE, not in contact with any element of the field (carpet, alliance station, goal, etc.) and the lowest point of the ROBOT is higher than 4 inches and/or 10 inches above the carpeted field surface."

So my question is, can you have an entity on your robot push against the ground and not qualify as being the lowest point of the robot? Or are there some special circumstances?

Thanks.

Re: Elevators/ Forklifts
 

That rule is referring to a robot that is being lifted by another robot. So the robot that is being lifted can not come in contact with the field and its lowest point must be higher then 4" and/or 12". But the robot that is doing the lifting can and will come in contact with the field, unless your robot has an anti-gravity machine.

-Oris-

Re: Elevators/ Forklifts
 

If you can do that, you will:

a) have a very good chance of winning the Championship
b) have a very good chance of winning a Nobel prize, assuming you manage to get the credit.

Re: Elevators/ Forklifts
 

http://www.chiefdelphi.com/media/papers/1871

try this link for a really quick rundown of folklifts. There's a really nice picture there to get the brain moving. Just trying to figure out where we can get, or produce cheaply, the rails/tracks for something like what's on page 14.

Re: Elevators/ Forklifts
 

I think that fork lifts are a great idea!...but how would it be possible to lift more than 1 robot? what do u guys think?

Re: Elevators/ Forklifts
 

As for team 1675 a scissor lift is becoming a better concept. We have figured out that when it is collapsed it should take up 6"-7" inches, but once opened it could reach upto a height of 88" inches. I personally think this is HUGE payoff. We have the machines to build one and hope to be testing it soon (Within the next week or so...) But we are still talking about drive types. So it might not be done at that point.

Re: Elevators/ Forklifts
 

Does anyone else have quick visual aid of a forklift system?? I think i'll be making a trip to a local Home Depot get acquainted to one.

Re: Elevators/ Forklifts
 

You may want to ask you school Maintenance Shop. Ours has one and let us give it a look over to help with our design.

Re: Elevators/ Forklifts
 

Our team come up with an to your answer your question there is 2 ways to lift 2 robots off the ground at the same time. One have a forklift on each side of ur bot and lift bots at the same team and hope they weigh the same and ur Center Of Gravity is to much to one side or the other. The other way is wat we are going to try. Have a lift strong enough to lift a bot on the front and kind of like a roll back ramp on the back. get one team to drive up on the bak and use them as a counter balance to lifting the other. The only bad things about these ideas is that you are relying on your teammates to be able to finish the round and that they will be strong enough to climb the ramps. If we figure out how to solve these problems or if u guys and gals got any ideas we will be welcome to hear them.:D ;)


~Jester~

Re: Elevators/ Forklifts
 

You are making an assumption here of which you are probably unaware.

FIRST koan: Why must the two robots have the same weight?

Re: Elevators/ Forklifts
 

If your center of mass is outside of the wheels then gravity will apply a torque which will cause your robot to tip over

Re: Elevators/ Forklifts
 

You are making an assumption here of which you are probably unaware.

FIRST koan: Why must the two robots have the same weight?

Second FIRST koan: Does the robot tilt the Earth, or does the Earth tilt the robot?

Re: Elevators/ Forklifts
 

Thanks for all the photos and links for the elevators!

Our team is edging closer to our decsion of whether to use an arm or elevator, but one thing that is limiting the elevator from becoming the design choice is the linear slides. Our team has found some slides, but they are too weak. We want a single tack elevator with a beefy slide that won't weaken if robot to elevator occurs by accident. We like the size of team 64's in 2005 but cannot find a slide of their size. Any help with this would be greatly appreciated.

Re: Elevators/ Forklifts
 

We're at this stage as well, and as I've been home sick I figured I could try to come up with ideas of my own. The consensus is that my plan would be rather heavy, but it's possible I just embellished it too much.

Minimized (click either for a larger version)


Maximized


Anyone have more experience with extruded aluminum? How much does the stuff weigh? Would the sliders breaking be a problem? I don't know enough to make truly informed decisions regarding this plan, so I'm off to research I guess.

Re: Elevators/ Forklifts
 

That looks fantastic but you're right its going to be heavy. One thing to keep in mind this year is that the ringers only weigh about a pound. That device there could probably, based on my wildly inaccurate guess, support about 150 pounds just as a point of context. The first thing to do is think about your material. Aluminum square tube extrusion or 80/20 is probably a good place to start. With 80/20 you can purchase linear slides. I'm not exactly sure what they're rated for, but considering what teams have used them for in the past you can probably get away with a very lightweight design(one 80/20 strut, if properly designed).

As for the weight of a set up a good number to remember is that aluminum weighs .1 pounds per cubic inch. So a foot long piece of square aluminum tube 1" x 1" with a 1/8" wall weighs a little over half a pound. So an elevator that is 8 feet high could easily have about 20 feet of extrusion and weigh about 10 pounds but at the same time that would probably be overkill.

Re: Elevators/ Forklifts
 

The discussion thus far is great, but I have two questions:
-How will these forks grab the bot to be lifted?
-What will prevent the lifted bot from falling off?
Just curious.

On another note, we are planning on using a forklift-inspired tube lifter that will grip the tubes with two sets of froks, one on top and one underneath, with each prong roughly 8" off of vertical center. We plan to be able to get two bots off the ground at the end of the match, but not by sheer force. We intend to make our lift on a pivot where it connects to the bot, and at the end of the match we will be able to rotate it downwards until it is level with the top of our bot. At this point the prongs that hold the tube will be resting on the floor to give the support for that end. A ramp will be deployed out the back, and two robots will be able to run up onto the long track resulting. We also will have a ramp out the side for that occasional bot that has a wide & short configuration rather than narrow & long as ours will be.

Any thoughts, anyone? JH

Re: Elevators/ Forklifts
 

We did elevators in 2005 using Igus drylin linear bearings.. You're welcome to come visit and we'll show you how we did it and such (we always like to talk to other teams)
here's some things I found were good and bad.

Good-
linear tracks are strong.. we cheeseholed the heck out of ours and we didnt have a problem. It did sway a little at the top but then again, we did go extremely high.

Much less programming involved, we could get the thing up and running with just dead reckon code.. good arms require good control code, dunno if thats a problem with you guys.

The things are robust.. theres not much that can go wrong with a good pulley system.

Bad-
Binding.. binding binding binding, makes it pretty hard to drag up the linear bearings (even with no load) we used 2 fisher-price motors in their plastic gearboxes attached to a spool.

Cables are annoying.. I can't stress this enough. cables have to be tensioned, there has to be a return cable.. its just annoying and unless you think it thorugh its full of surprises.

Good luck with whatever you choose

Re: Elevators/ Forklifts
 

Here is a basic scissor style fork lift which is quite doable.

Re: Elevators/ Forklifts
 

We have had lots of success with forklift style elevators, we used a system with cables, pulleys and bearings on our 2005 robot and it worked really well. It was pretty fast too. We have some pictures on our website, cooneyrobotics.com under the media part if you want to take a look.

Re: Elevators/ Forklifts
 

The forklift we used in 2005 worked reasonably well, the only problem was we had issues with the cable not spooling right. We found out that the cause of our spooling issues came from powering it with the van door motor which would stall out as we got higher. When the van door motor stalled the whole lift would come crashing down to its starting position without spooling the cable.

Re: Elevators/ Forklifts
 

My team also used a cable lift and a van door motor in 2005. It work fairly well (gravity is much slower than we would have liked), but we had no trouble with our motor stalling. We did, however, have to limit motor speed so it couldn't come unspooled.

Re: Elevators/ Forklifts
 

Anyone have pics or CAD representations of a forklift system?

Re: Elevators/ Forklifts
 

does the picture I uploaded help?