01-02-2007 14:12

dtengineering

Re: pic: FRC488 Lift Mechanism Deployed

Brilliant... I know where I want to park when we get to Portland!

Jason

01-02-2007 14:18

Guy Davidson

Re: pic: FRC488 Lift Mechanism Deployed

I call this parking lot in SVR.

Looks pretty sweet.

-Guy

01-02-2007 14:22

Dantvman27

Re: pic: FRC488 Lift Mechanism Deployed

One Word









DANG!


(in a good sense)

01-02-2007 14:26

s_forbes

Re: pic: FRC488 Lift Mechanism Deployed

Great looking cad model! Out of curiosity, is the material that the platform is made out of going to be transparent? I can imagine that it would be difficult to see what was going on on the field with those things folded up.

01-02-2007 15:01

Rich Wong

Re: pic: FRC488 Lift Mechanism Deployed

Why didn't I think of that!!

01-02-2007 15:10

Dan Petrovic

Re: pic: FRC488 Lift Mechanism Deployed

We had this idea earlier on but it was scrapped because we decided not to lift.

It's a very nice, easy, and safe way to lift. I like it.

01-02-2007 15:50

fluffy

Re: pic: FRC488 Lift Mechanism Deployed

we also tought of doing it at one time, I even drew it up in inventor, but since then, our team has decided on a lighter design

01-02-2007 16:45

Re: pic: FRC488 Lift Mechanism Deployed

114 looks forward to working with you guys at both PNW and SVR! Looks very good! How long does it take to lift up a 120 pound robot to full height? Also, are there any dimensions on the total size of this platform? I'm very curious as to how easy it will be to drive onto this platform.

01-02-2007 16:56

Madison

Re: pic: FRC488 Lift Mechanism Deployed

The material we're currently planning on using is semi-transparent. You can see shadows through it, but no fine detail. When folded, these lifts form something near a triangle atop our robot, so the profile along the long axis is pretty small. Looking at the side of the robot, though, is a lot like staring at a wall.

The gas springs haven't been attached yet, but under no load, they extend their full length in about two seconds. It ought not take much longer than that to lift a robot since the gas springs operate at a pretty constant force.

The overall dimensions of the flat part of the platform are about 37 x 45". When collapsed, the top is 2.25" from the floor. There will be ramps leading up to the flat portion that ought to be about 9" long.

01-02-2007 17:11

ChuckDickerson

Re: pic: FRC488 Lift Mechanism Deployed

Madison,

The lift looks really nice. We have been mocking up a couple of different similar designs using gas shocks and I have a couple of questions. First, in your design what keeps the two tall pieces of channel from just bending over? Second, (this is more of a rules interpretation question) are you placing any material between the bottom two pieces of metal (channel? Box tube?) and the carpet? I ask only because we are wondering if we need to so ast to not violate <R34> (the no metal touching carpet rule). I guess it depends on what is meant by a "traction device".

01-02-2007 18:07

Madison

Re: pic: FRC488 Lift Mechanism Deployed

The force of the gas springs at the start of the lift is exerted entirely vertically. As the lift extends, some force is exerted horizontally. It's about 25% of the total force, or 30 lbs. per gas spring. I should have done elaborate amounts of FEA on the linkages to determine their behavior given that they're seeing unprecedented loads for FIRST robots, but I honestly didn't have the time. Instead, we're taking a wait and see approach.

The linkages themselves buckled under the load in our first iteration. This was redesigned to accomodate that experience -- if something similar happens to the vertical pieces, we'll just make it stronger.

I'm pretty confident that the bottom of the lift will not be considered a traction surface, but I've been trying to also plan for nearly all eventualities and we hope to have something available to us to coat the bottom should the inspectors require it.

01-02-2007 18:51

Fred Sayre

Re: pic: FRC488 Lift Mechanism Deployed

Not on 488, but on my old team 824 we used all metal ball casters and they allowed it despite the metal contact with the ground. So it seems that normal forces against the ground should be okay, at least by that inspection.

01-02-2007 19:39

T3_1565

Re: pic: FRC488 Lift Mechanism Deployed

our design for lifting is fairly similar to that, but I must say your picture is better than ours lol very nice! Hope to see you guys at atlanta! *crosses fingers*

01-02-2007 19:52

Manoel

Re: pic: FRC488 Lift Mechanism Deployed

Looks great, as well as the rest of the robot, but I have a few questions - not sure if I completely understood your system.

Are the gas shocks preloaded, and then released to lift (launch? ) another robot? If that's the case, how hard is it to load them? Lifting a 150 pound robot 14" up in two seconds sure requires a lot of force.

Also, does the entire system pivot around that huge C-bracket?
Anyway, your robot sure looks great. It seems like we are using the same material on our ramps (does it, by any chance, weigh 1,5 kg per square meter? Incredibly strong stuff! )

03-02-2007 22:14

NMR

Re: pic: FRC488 Lift Mechanism Deployed

http://www.tommygate.com/downloads.asp

03-02-2007 22:18

Ericgehrken

Re: pic: FRC488 Lift Mechanism Deployed

Great system, nice model.

03-02-2007 23:17

Madison

Re: pic: FRC488 Lift Mechanism Deployed

The gas springs are compressed before the match by some method which has yet to be determined. It'll likely involve students sitting on it or something similar while we lock things down. When we lift, the lock holding the springs closed will be released and they will extend and raise the platform.

We're using 2 125 lbf. gas springs, so it take 250 lbf. to lower the platform. We are considering switching to 100 lbf. or 75 lbf. springs to make it easier to reset the system -- but that switch is predicated upon their ability to lift a robot. They exert pretty near constant force, so it doesn't take more than a few seconds for them to fully extend.

The lifts do rotate around the large 'C-bracket'. The platform is made from 16 mm Polygal (www.polygal.com) and weighs .55 lbs./sq. in. -- about 11 pounds for both sides.

Thanks There'll be some pictures of our progress on the lifts uploaded sometime very soon.