bumpers, a problem? [Archive]

65_Xero_Huskie

13-01-2006, 22:05

problem with bumpers..
i saw that the center of the bumper is higher than the center of the ball, and that makes it possible that the bumpers will cuse the robot to roll over the ball and get it stuck underneath, if someone can explain this differently, i would appreciate it, cuz thats a big thing i see wrong

JBotAlan

13-01-2006, 22:14

I don't really see this as a problem.
From R35, last bullet point at bottom:
Bumpers must be positioned on the robot so that they remain between 2-1/2 inches and 8-1/2 inches above the floor
Even though what you said was right, the overlap is big enough, I think.

The bottom of the bumper, covered with smooth material (required in the bumper rule) should not catch the balls. I think it'll be low enough to not cause problems.

Just my take on it.
JBotAlan

Donut

13-01-2006, 22:15

The center is higher than the center of the ball, but the bumpers can extend all the way down to 2 & 1/2", so there shouldn't really be problems rolling over balls unless a team doesn't extend all the way down to that level, I would think.

prettyyinpinkk9

13-01-2006, 22:17

You're correct...if the center of the bumper is higher than the center of the ball, the ball will roll under the robot, causing 2 different scenarios...1)the ball will cause the wheels to come off the ground, hendering any type of movement 2) the ball will cause only the front wheels to come off the ground, but as the robot moves forward, the ball forces the back wheels off the ground, but at the same time the front wheels are lowered back onto the ground

Henry_Mareck

14-01-2006, 01:24

the bumpers are designed so that balls will not go under, as well as impact reduction.
FIRST does not want ball around wheels or in chain and sprockets.
I can imagine a balls going under a robot, and a spray of foam pieces coming out the other side. oops.

Schneidie

14-01-2006, 13:06

I seriously doubt the fact that FIRST would overlook a problem that could destroy their equipment for all the competitions.

adam

14-01-2006, 14:07

If bumpers can be 2.5 inches off the ground, and the center of the ball is at 3.5 inches (7 inch diameter i believe)........I don't see there being any problems.

Besides, i'm pretty sure that you can have other non-bumper material below 2.5 inches.

Nuttyman54

14-01-2006, 14:15

Besides, i'm pretty sure that you can have other non-bumper material below 2.5 inches.

yes you can (otherwise we'd need hovercraft robots), but any non-bumper material must be within the original 28"x38" footprint

adam

14-01-2006, 14:32

yes you can (otherwise we'd need hovercraft robots), but any non-bumper material must be within the original 28"x38" footprint

we were just thinking of going for the hovercraft design...

Nuttyman54

14-01-2006, 14:35

we were just thinking of going for the hovercraft design... you know...i never checked to see if that was legal...good luck getting it to run off of the Exide! :p

SenseiSkins

14-01-2006, 14:57

I like bumpers

Eria4044

14-01-2006, 14:58

If you had a hovercraft, could you fly above 5 feet? :p

pez1959

14-01-2006, 22:55

If you had a hovercraft, could you fly above 5 feet? :p

Ok I'll bite, <R08> states "The robot may not exceed the 60-inch height restriction at any time during the match."

And on a non-rule point, getting a hovercraft more than a few inches off the ground is hard...5 feet is nearly impossible.

Nuttyman54

14-01-2006, 22:59

And on a non-rule point, getting a hovercraft more than a few inches off the ground is hard...5 feet is nearly impossible.

I think he's asking (jokingly of course) if you could make a 60" robot and then raise it a few inches with the hover-drive, thus breaking the limit...and the answer would be no, you can't

robotoby35138

15-01-2006, 10:15

about the hover craft it would be almost impossible to steer. and when you are even bumped by another robot you would just start bouncing around the arena. you would not have the acceleration to stop you from bouncing around the arena :p

Nuttyman54

15-01-2006, 13:41

psycho7

15-01-2006, 13:55

yes you can (otherwise we'd need hovercraft robots), but any non-bumper material must be within the original 28"x38" footprint

or just steal some star wars repulsor lift coils :D

adam

15-01-2006, 15:28

I'd say that a hovercraft above 5 feet could be legal.....I'm pretty sure that the rule is that you cannot exceed 5 feet while in a STABLE POSITION (flat on the ground?)

pez1959

15-01-2006, 15:36

I'd say that a hovercraft above 5 feet could be legal.....I'm pretty sure that the rule is that you cannot exceed 5 feet while in a STABLE POSITION (flat on the ground?)

<R08> states "The robot may not exceed the 60-inch height restriction at any time during the match."

That is a direct quote from the manual

adam

15-01-2006, 17:14

<R08> states "The robot may not exceed the 60-inch height restriction at any time during the match."

That is a direct quote from the manual

hmmm, in that case i'm not sure what i was thinking of. I seem to remember some mention of the height requirement only applying to robots in a stable position (so if another robot tips you over, one of your corners raising above five feet won't count against you).

pez1959

15-01-2006, 18:50

Well, not to beat a dead horse, but I think if your robot is within the 60in cube during gameplay, unless you have a diagonal piece, tipping over would not put you outside of the limit. Lifting you up could, which is something you may want to look into if you're a tall robot and you're concerned of being lifted.

Hmm I assume the 60in is 60in from the ground? Ie...when you're on a ramp, its 60in from the top of the ramp instead of original playing field?

Arkorobotics

15-01-2006, 18:56

Call me dumb but what is the bumper "zone"?

cleonavicius

15-01-2006, 19:21

I'm kind of curious, if bumpers are 2.5" off the ground, will they clear when the bot is going up the ramp? (assuming standard 4 wheels)

pez1959

15-01-2006, 19:41

I'm kind of curious, if bumpers are 2.5" off the ground, will they clear when the bot is going up the ramp? (assuming standard 4 wheels)

Well that's something to take into account when designing your bot...think trig. :-)

Doug G

15-01-2006, 22:18

For those who think that if your bumpers are at 2.5" off the ground and come in contact with a ball, they ball won't go under them - YOU'RE WRONG!!

We have already tested this with our practice robot and the balls go under the robot a lot, luckily we have enough driving wheels still on the ground for it not to be a big deal, but I guarantee there will be plenty of balls ran over this year and FIRST will be prepared for it. In 2004, they stocked 3x as many balls as needed for any one competition. That year we had a robot with about 3-4 inches of clearance, and we ran over dozens of 13" balls and sadly popped a fair share of them. Luckily this year they don't pop, but I suspect they'll be fairly chewed up after a day of matches.

pez1959

15-01-2006, 23:35

Question, when you were testing this, was the robot weighted a full 120 pounds or was it a light frame. If it was a light frame it would make a little more sense.

Evilfrog87

16-01-2006, 10:27

I was under the impression that bumpers had to start 2.5 inches above the ground. No more, no less.

As to the problem with running over the balls, the Manual says:
“Bumper height has been specified so that robots will make contact bumper-to-bumper and so that the balls will be pushed rather than pulled under the robots.”

The biggest problem I see with the bumpers is going up the ramp. If you use 6” wheels, and have the bumper placed an inch behind them, you cannot make it up the ramp without bottoming out. (that is of course if the bottom of the bumper cannot be higher than 2.5” off the ground)

pez1959

16-01-2006, 11:09

R35 is the bumper rule. It basically says the bumpers must stay between 2.5 and 8.5 inches. But if you use two pool "noodles" as suggested, that only gives you an inch or so of leeway. So 2.5 to about 3.5 inches from the ground. The mounting your bumpers so that you can go up the ramp is obviously something that needs to be kept in mind during your design and build stage. I won't give away our robot, but perhaps you could mount the bumpers on the sides perpedicular to the ramp instead of parrallel?

Another option, if you have drive wheels in the back and you hit the ramp, even if you're front wheels dont make the ground, the back wheels could push you up?

Just some things to think about ;)