pic: FRC488 Lift Mechanism Deployed

[ChuckDickerson]

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".

<R34> ROBOT wheels, tracks, and other parts intended to provide traction on the playing field may
be purchased or fabricated (“traction devices” include all parts of the ROBOT that are
designed to transmit any propulsive and/or braking forces between the ROBOT and the
playing field). In no case will traction devices that damage the carpet or other playing
surfaces be permitted. Traction devices can not have surface features such as metal,
sandpaper, hard plastic studs, cleats, or other attachments. Anchors (i.e. devices that are
deployed/used to keep one’s ROBOT in one place and prevent if from being moved by
another ROBOT) can not use metal in contact with the carpet or other playing surfaces to
“stay put.” Gaining traction by using adhesives or Velcro-like fastener material is not
allowed.

[Madison]

Originally Posted by DeepWater

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".

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.

[Fred Sayre]

Originally Posted by DeepWater

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".

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.

[T3_1565]

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*

[Manoel]

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! )

[NMR]

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

[Ericgehrken]

Great system, nice model.

[Madison]

Originally Posted by Manoel

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! )

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.

Originally Posted by firstbots195

Great system, nice model.

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