Goig "wide" with the chassis
 

I like to know what is the teams opinion on pros(and one
of them is in update #2 drawing) and cons going wide.
We started our frame but debating.

Re: Goig "wide" with the chassis
 

Pro - you get double width to pick up a ball.

Con - you can't squeeze through smaller spaces.

Pro - 4 wheel wide turns itself more easily (fewer wheels, etc) shorter chains.

Con - short front to rear wheelbase on wide means it can rock at times.

Re: Goig "wide" with the chassis
 

Unlikely, this year the 'bots will slide before they tip, unless they're incredibly top-heavy.

A wide body can effect the packaging for a shooter / ball storage, and reduce the amount of useful space for a hopper, depending on how you design all that.

Re: Goig "wide" with the chassis
 

I think the wide is going to be important with control on the slippery surface, but it also means it would be easier to bump into things driving forward. Also if you are planning to bring balls in from front or back or have a wide storing device it gives you space. :cool:

Re: Goig "wide" with the chassis
 

The trailer also helps prevent any back and forth wobble

Re: Goig "wide" with the chassis
 

All I can say is Do It.
You'll enjoy the results.

Re: Goig "wide" with the chassis
 

If your main goal is to pick up balls from the floor, then going wide is the logical choice. Turning with 4 wheel tank drive is better. However, keep in mind just how difficult and time consuming chasing down balls can be.

Re: Goig "wide" with the chassis
 

The only thing I would be worried about with having a wide chassis is, the possibility of being more maneuverable then is necessary.
I haven't run the numbers on this but, the wide wheel base combined with the low friction surface may cause a "widebot" to slide more while performing a turn.
However, I do think it is one of the top chassis designs for this game.
Not necessarily the best, but by no means the worst either.

Re: Goig "wide" with the chassis
 

Also, consider this: the trailer in the back acts as almost an extension to the base of your robot, making sideways a more logical decision because it will take an incredible amount of force (not seen in any first event btw) to knock it clean over.

Re: Goig "wide" with the chassis
 

Be careful how far you take that assumption. While the trailer does give you some down-force at the trailer hitch, and some lateral stability based on which side it might currently be Jack-Knifing ...

The end of the trailer tongue has a circular fitting in the square steel rod. It can rotate along this circular piece and NOT transfer rotational forces to the 'bot.

In other words, when/if the trailer ever tips completely over, the 'bot will not feel the rotational tipping forces at all.

[edit] Take a close look at the trailer drawing (GE-09000), page 3. The Trailer Tongue (Item #5, GE-09009), and the Hitch Swivel (Item #19, GE-09036)

[edit2] Then take a CLOSER look (as I apparently did NOT), and notice Item #50 clearly pinning that Hitch Swivel. ...and then disregard my mis-informed advice above. Sigh. I'm 0 for 2 this weekend. Maybe I'll start lurking instead of posting.

Re: Goig "wide" with the chassis
 

The round stub is pinned to the square tube in the Trailer Hitch. They do not rotate relative to each other.

-dave


.

Re: Goig "wide" with the chassis
 

That's a last minute (12/29) design change?

Re: Going "wide" with the chassis
 

Here is a video of our wide robot test:

http://www.youtube.com/watch?v=6HEE_isM0Uo

Re: Goig "wide" with the chassis
 

I decided that my team should go with a wide base this year the Monday after kick-off and it seems like my decision is paying off. It's main advantage in my opinion is that it'll be less prone to have trouble turning and overturning and should have a wider opening to gather balls. (I've currently designed it to have about a 23-3/4" opening)

Re: Goig "wide" with the chassis
 

We decided to mount our wheels in the wide position

Pro: Even with the wheels and slippery surfaces it is still easy for even rookies to control.

Pro: Ball capture is not difficult

Con: Increases chance of collision and jams.

Re: Going "wide" with the chassis
 

seems like it works quite well...

Tmr i want to get the frame built in wide config, and then compare using 2 toughboxes and having 2 free driving wheels to having a tough box on each of the 4 wheels...

Have you guys tested that?

Re: Going "wide" with the chassis
 

Great to see others getting the same results. Wish you guys the best of luck this year in Chesapeake =)

Hmm, I see your point but not quite. Care to explain further?

Re: Going "wide" with the chassis
 

By the looks of the video, the robot was tested with a tough box on each of the wheels and handles quite well. From my teams experience, have 2 free driving wheels and steering with 2 powered wheels was quite hard and takes a while to turn. This could be because we haven't used software to limit the power output on our motors yet, but it's information nonetheless :D

Re: Going "wide" with the chassis
 

I think the meaning was that with a wide base you wouldn't be able to fit through as narrow of places as you would with a long base. Which is a good point but in this game with the trailer the wide base makes it so that your overall length with the trailer is decreased which I would say is a fair trade off.

Re: Goig "wide" with the chassis
 

DO NOT HAVE NULL WHEELS THIS YEAR.

This has been repeated frequently in many threads. Have all wheels powered otherwise they are useless and add dead weight.

A toughbox on each wheel does work well. Just make sure if you use it on a final robot that your toughboxes have washers keeping the keys in and that they are lightened. Replace the clear backing with Al and add lightening patterns all around. Also the side plates don't need to be there, might want to just add in some delrin standoffs instead. Hope that helps.

Re: Going "wide" with the chassis
 

Glad I started this thread: will help us and other teams
deciding wich way to go. Now, watching 1629 video, from
my calculations, their top speed schould be somewhere
around 10.5 fps. For some reason they going much slower.

Re: Going "wide" with the chassis
 

They're capped.

By our calculations, anywhere from 8-15fps is going to be good for this game. I personally like the 9.5-11.5-13fps range.

Re: Going "wide" with the chassis
 

With the AM box(12.75:1) and 6" wheel direct drive
your top speed is around 10fps. Correct me if I'm wrong.

Re: Goig "wide" with the chassis
 

A trick we used last year was to remove one stage of gear reduction in the Toughbox, changing the ratio to 3.57 or thereabouts. It's pretty easy to do, and not easy to spot in a video of someone else's robot.

Re: Going "wide" with the chassis
 

Many thanks. I plan on using this to talk my team out of a crab drive.:D

Re: Going "wide" with the chassis
 

I doubt that we're going that much slower, although we were playing with the joystick sensitivity througout the day.

Once you try this yourself you'll see that it's not about how fast the wheels can go, but how smoothly you can accelerate and decelerate. Gunning it just makes the wheels spin. It takes a steady hand (and hopefully some good software) to stay controlled. Once the drivers got the hang of steady starts, then the trick was stopping without skidding. There's no letting the stick go, or pulling backwards. The driver needs to allow time and space to slow down under power.

The Trailer actually aided turning by performing a jackknife procedure.

Phil.

Re: Going "wide" with the chassis
 

so assume you use 4 cim motors for each wheel...

say you then wanted to have a belt drive system.. what motors could we use to drive that. My team seems to think that any other motors except the cim motors are too slow...

any ideas?

Re: Going "wide" with the chassis
 

Doubling up on fisher prices should suffice.

Re: Going "wide" with the chassis
 

hmm ok we can look at that

Re: Goig "wide" with the chassis
 

We were thinking of going wide with our chassi, but were concerned that it would be really hard to get out of any tight squeezes, or make any tight turns. However, we are excited to make a mock up of it, and test it. I just wish they had sent a sample of the floor!

Re: Going "wide" with the chassis
 

Impressive mobility. Regarding your floor surface, the seams between RFP panels appears shiny. Is that clear packaging tape or something else? Thanks.