30-01-2006 14:55

Tytus Gerrish

Re: pic: FRC488 - Overview

I Like, Very Elegant. just looking . seems like you drop the hopper down to drop balls into the collector feed to launch. Beautifully skeleton look and the adjustable chassis for chain tension, Id love to see how that works out.

30-01-2006 15:09

Madison

Re: pic: FRC488 - Overview

Yes, that's exactly how the hopper works. We are useless without a working collector along the bottom, so why aggravate ourselves by trying to do something like that in duplicate? Instead, we've opted to reuse the same mechanism to load from the hopper and move balls up to the shooter, should we opt to use it for that purpose. The hopper also will have a method for gravity-feeding the 1-point corner goals that is not displayed. It's way down on the list of things to do.

The chassis isn't adjustable for chain tension in a specific sense, but rather, is completely modular. The modules that hold the transmissions, motors, wheels, chain and sprockets are self-contained and can be removed from the robot after removing four bolts from each side. I'll see if I can't find a picture of the unassembled chassis to show what I mean.

30-01-2006 15:44

Rick TYler

Re: pic: FRC488 - Overview

Cool. So, if you don't mind my asking, what are you using for belts?

30-01-2006 15:49

ChuckDickerson

Re: pic: FRC488 - Overview

I am not trying to nitpick the rules here but rather gain a better understanding of how to interpret them. It is my understanding that the pictured design would not pass rule R4:

<R04> "Wedge” robots are not allowed. Robots must be designed so that interaction with other 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 – see Rule <R35>) that might
push against another robot must be within 10 degrees of vertical. Devices deployed outside the robot's
footprint should be designed to avoid wedging. If a mechanism or an appendage (a ball harvester, for
example) becomes a wedge that interferes with other robots, penalties, disabling, or disqualification can occur
depending on the severity of the infraction.

We were originally thinking of having a "door" that opened to allow balls to exit into the lower goal but have since changed our design specifically because of this rule. While neither your design nor our original design were designed to intentionally flip another robot they both appear to violate this rule. There are parts of the robot between 0 and 8.5 inches from the floor that are not within 10 degrees of vertical and can come into contact with other robots. Your design has a inverted wedge but the rule doesn't specify the direction of any wedges. In your case you are more likely to flip yourself than the other bot but I think FIRST would also frown upon bots driving up on other bots. Please, please, please don't take this as a slam of your bot design. I personally think it is a wonderful design. I am just unclear as to how the inspectors will rule on it. I am intending this to spark a discussion of how strict the R4 rule will be enforced and what is and isn't allowed. By a strict definition of the rule I don't think your design would pass but by a common sense definition I think it is great. I am wondering what other teams are thinking and how they are designing around this R4 rule. Are ALL the bots going to be square boxes from 0 to 8.5" up???

30-01-2006 15:51

Madison

Re: pic: FRC488 - Overview

I'd been planning for 1/4" round urethane belting -- McMaster-Carr part 59725K704 -- but the Senate may overturn my veto of automotive V-belts.

Thanks for the head's up, Chuck. I hadn't interpreted that rule as anything other than a way to discourage teams from engaging in questionable offensive and defensive tactics. It will be easy enough for us to square off the lowest part of the hopper so as to keep it vertical while maintaing the curved profile we need to load balls into the conveyor, however we had no considered that a gravity-fed ramp to the corner goals would also be construed as a wedge.

I'm not certain, even now, that such a ramp would be prohibited by this rule. The last sentence reads, "If a mechanism or an appendage (a ball harvester, for example) becomes a wedge that interferes with other robots, penalties, disabling, or disqualification can occur depending on the severity of the infraction," suggesting that a functional mechanism outside the initial constraints is not considered a wedge (if more than 10 degrees off vertical) by default. Instead, they've used the word "becomes," which implies that it would be okay to use for its intended purpose alone.

I'm interested to read some others' interpretation of how we may be affected by that rule -- particularly anyone who will be an inspector or referee in Portland.

30-01-2006 16:26

Rick TYler

Re: pic: FRC488 - Overview

I was looking at that, too until I saw that the "welding machine" costs $417. Do you suppose that the hollow tubing (which uses 21-cent connectors) would work as well? IAN an industrial engineer...

30-01-2006 16:31

Madison

Re: pic: FRC488 - Overview

[quote=Rick TYler]

Yeah, that'd scared me away initially as well, but as it turns out, the 'welding kit' includes many things beyond what is required to heat up and join the tubing. A simple heat gun should be sufficient and the tubing can be joined in a piece of angle to maintain alignment.

30-01-2006 21:16

techtiger1

Re: pic: FRC488 - Overview

I like Ms.Krass it's very nice, simple and eloquent echoing Dan Quiggle's words. I think our team has a lot of the saem thought process you described about teams not being able to shoot as well as they want to. We too hold a far amunt of balls and from what I can tell are going to proficient about getting rid of them but anyways. Sweet work I really like it looks amazing very beautiful bot seems like it could be a winner.

Good luckwith it,
Drew

30-01-2006 21:43

Alekat

Re: pic: FRC488 - Overview

You'll be at Portland?! Sweet I can't wait to see how it turns out

One question, how do you go from the wide collecting base to the shooter wheels?

31-01-2006 08:27

GaryVoshol

Re: pic: FRC488 - Overview

I interpret "becomes a wedge" in the same manner. Hopefully GLR and Detroit refs/judges will as well.

Beautiful design. How are you aiming the shooter? (If that's not giving too much away)

31-01-2006 10:37

Barry Bonzack

Bravo!

The design looks great, and I share the same belief on your strategy. I mostly want to applaud you on posting a full drawing with no strings attached. I believe this is the true spirit of first and it does not diminish the competitiveness of the competition one bit. Is there really anyone this late in the build season that is going to see someone else's design and change their own to "steal" some other team's idea? Doubtful. Way to be a leader in doing this and having a team that understands these views without questioning it.

31-01-2006 13:16

Madison

Re: pic: FRC488 - Overview

I'm not so certain it'll work. In fact, I know it won't work as shown because the two center rails are missing an endpiece that would keep balls from falling into the gap. I suspect we'll need some larger funnel walls on the sides to coax the balls over to where they need to be.

We're also considering running the conveyor belting on one side on a slightly different pulley size so as to make its speed a bit different. We hope that will aid in relieving any congestion between balls on the way up.

I have some ideas for physically altering the trajectory of the ball but haven't given their implementation anything more than a cursory glance. Essentially, the rails would end at what would be our highest angle of attack -- about 45*. A cowling or shield would rotate about the same shaft as the shooter wheels and extend beyond the rails. By rotating that shield, we'll be able to adjust the exit angle. Of course, we'll also be able to vary the wheel speed -- with some precision, we hope -- so as to vary the trajectory that way. In combination, those two capabilities will probably allow more control over the ball path than is practical, so I doubt we'd use them in tandem.

Thanks, everyone, for the continued compliments. I've grown tired of teasers that aren't that engaging, interesting or revolutionary and am trying to encourage full disclosure in its place. We've had enough trouble trying to design and build in isolation in just six weeks, so I too can't imagine that many teams have the resources or desire to alter their own plans to either copy or make obsolete a strategy or design they see here.