pic: Team 223 Chassis



Might as well be the first one to say this…

Have you all though about your CG? From what I’m seeing, that sucker is going to be tip-crazy, especially because of the wide-side drivebase.

We had that problem in 06 w/Alice. was crazy top heavy. could score awesome when we weren’t on our backs, but we spent more time over than upright…
Malhon

angled frame + back or side heavy + trackball = oh god, this won’t end well.

Unless you weigh down the opposite side. Which you might not be able to weigh down enough if you can’t make weight normally. If you can, pull a Quixilver and ziptie some rebar to your robot. It seemed to work alright for them…

This paper

http://www.chiefdelphi.com/media/papers/1974

might help explain the situation…

Wow… cut them some slack.

I’m sure a team that’s been around that long knows what CG is, and I bet that’s only 50-60 pounds of what’s going on the robot, you don’t know how the rest is distributed. For all you know that could be all 1/16" wall and be much lighter than you are guessing.

114 of all people should know that being tall doesn’t necessarily mean poor CG.

Tall doesn’t mean high CG, no.

However, tall & offcenter does mean unfavorable CG, typically.

Lets say that there is 60lbs there. Add in the chassis weight, lets say 15lbs, evenly distributed, and the rest of the 120lbs (putting 45lbs) on the other side. Divide that 15lbs for chassis by two and you get 67.5 (woo hoo) lbs on one side and 52.5lbs on the other side. Add in the height, and it gets pretty bad. Then add in the dimensions and it multiplies the problem.

And that’s in the best-case, from what I can see.

I hear you Adam…but how about if you estimate the CG of the proposed design, and think about whether or not you’d recommend your team go with it?

And just because a team has been around a long time does not mean all the people on the team have been. Some teams lose their experienced members and don’t have the depth of knowledge that is available on CD.

I also agree that being tall does not mean having a poor CG. Howerver, having that much extruded aluminum high up, off center, and on a sideways drive base with a very short wheelbase, is an open invitation to disaster. btdt

Guys…its the Pink Team, they can make it work. :]

I stand by my original statements. I highly doubt that 45 pounds is in that structure.

Considering that 1" square 1/16" wall is only .28 pounds per foot, I highly doubt there is any more than 10 pounds (and that’s overestimating) in that structure.

As for it being off center, we have no idea what the rest of the robot is. It could have an arm that extends the other way and brings the CG perfectly in to balance.

And yes, not all old teams are capable, but a team capable of putting together a CAD that nice looking is most likely capable of setting material properties/weight and then going to view> Center of Gravity.

but then again, it’s possible they used entirely heavy materials on the top while discovering some new amazingly light material to use on the base.

Until we get the details from 223, let’s hold off on the immediate criticism shall we?

/they better dont fall…i’ve picked them twice in the Fantasy First :stuck_out_tongue:

Is that by chance 80/20 QuickFrame I see?

Sure, I’ll hold off on the criticism, and only stress the constructive…

Last year we used a single 3" diameter, 1/16" thick round aluminum tube as a mast to support our arm. It worked very well, and allowed us to make a heavy drive base and a virtually untippable robot. Attatching the arm mechanism to the tube was fairly easy, once we figured out that we could make sheet aluminum brackets, and clamp them to the tube.

Making a drive base with the wheels going the long way results in a contact pattern of the wheels on the carpet that is about two feet square.

A pair of arms that are spaced about 26" apart will contact the ball about 4" off the floor. If they are activated as soon as the ball is fully on them, they might be able to lift the ball without the ball bouncing out first.

An amazingly light material is really nice for the upper part of the robot. An amazingly heavy material is really nice for the lower part of the robot.

Wheelie bars are not necessarily part of the chassis, they may be part of a mechanism.

The Pink Team is 233, not 223.

Just so you know, 223 is Xtreme Heat. 233 is the Pink Team.

We are team 223.

Also, the chassis is not complete in the picture. We’re still working on it now.

Why is the chassis cut on an angle at the ends? There are no obstacles to clear and I’d think you wouldn’t want to be riding up over other robots.

Why is the chassis cut on an angle at the ends? There are no obstacles to clear and I’d think you wouldn’t want to be riding up over other robots.

Clearly you’ve never been pushed back far enough to be stuck on an edge of your frame and whatever else is lifting the other end of the robot. The cutback ends allow the wheels to be in contact at any angle. But, with mandatory bumpers now, that point is moot.

Bengineer

From what I can tell from the photo I would be worried that this design (as pictured) would violate <R19> (no wedge bots) thus making it illegal.

<R19> "Wedge” ROBOTS are not be permitted. ROBOTS shall be designed so that interaction with opposing ROBOTS results in pushing rather than tipping or lifting. Neither offensive nor defensive wedges are allowed. All parts of a ROBOT between 0 and 8.5 inches from the ground (the top of the BUMPER ZONE) that are used to push against or interact with an opposing ROBOT must be within 10 degrees of vertical. Devices deployed outside the ROBOT footprint should be designed to avoid wedging. If a mechanism or an appendage (e.g. a harvester for retrieving GAME PIECES) becomes a wedge that interferes with other ROBOTS, penalties, disabling, or disqualification can occur depending on the severity of the infraction.

Note that nowhere in the rule is there any mention of which way the wedge is oriented. Now your bumpers may fix the issue but since you are only required to have the bumpers on 2/3 of your robot it may or may not.

It looks to be 1/8th. However, I don’t know for sure, which is why I asked the team if they had done CG calculations. And we very well know that being tall doesn’t mean bad CG; our 07 bot was 11 feet tall, and could tip to 60 degrees and still stand up.

This drive base looks very solid. Think the poster could take a screenie with Inventor’s CG icon in it, maybe a few views slapped into a post could really clear it up for all of us.