Bumpers vs Frame which is better

[The Lucas]

Originally Posted by Dzdconfusd

One negative I heard about from the scrimmage is that robots no-longer glance right off each other but can stick because of bumper friction. That means a more sudden stop when hit than without bumpers. Hope your internal components can take the loading.

How can it be a “more sudden stop” when the duration of the collision is longer with the same force? This means less impulse and less sudden stops. However, it may mean more frequent stops as the bots stick together instead of just glancing off.

The added friction is a good point. It may be easier to pin robots this year as the added friction makes escape harder. You may be able to pin a bumper robot sideways against a wall. From a dead stop, a robot may not be able to overcome the static friction of 2 fully compressed nylon bumpers in order to slide out of a sideways pin.

Just think of a rubber stopper or a cork in a bottle. This could factor into corner goal defense.

[Theory6RobotiX]

Question to teams who have competed in the first weekend regionals.
Watching the webcast from the VCU regional, I feel that most but not all teams have bumpers on their robot. Despite the "strong encouragement for having bumpers" from FIRST and the obvious advantages (weight for pushing, protection) what do you think is the reason for teams actually going through matches without bumpers?

[Andrew Blair]

Originally Posted by The Lucas

How can it be a “more sudden stop” when the duration of the collision is longer with the same force? .

Well, I guess, it's not a more sudden stop when you compare a direct collision, but in the case of an indirect hit, where metal on metal would allow more of a glance, resulting in less energy transfer, the bumpers would stick on eachother, causing most of the collision impulse to be transfered. Metal on metal causes a greater impulse, but evidently to a lesser magnitude in some cases.

[Dominicano0519]

Please what is worth more points a blocking robot, or one that can get up on that platform for 15 points. at the jersey regionals i have seen atleast 12 robots bounce off of the platform because of their bumpers



If you ask me a good strong chasis should do u good


And it would sound cool too

[StephLee]

Originally Posted by Dominicano0519

Please what is worth more points a blocking robot, or one that can get up on that platform for 15 points.

What if your robot blocks the third robot on the opposing alliance from getting up the ramp at the end, thereby dropping their bonus from 25 points to 10? That might not be worth points to YOUR alliance, but it shifts the margins, and such a big shift could be enough to swing the match.

It's a matter of trade-offs. You can win both by scoring points and by keeping your opponent from scoring points.

We used bumpers, and we're still fine getting up the ramp. Depends on your design, and your strategy.

[mrmummert]

here is my input on the bumpers from first hand observation....
the bumpers not only (because of the design)have been protecting the frame,covers,wheels,drive and electronics...but also have been an advantage
to help the robot from tipping over if they have been applied to best use.

The tipping issue is most useful on robots with short wheel bases (mostly on four wheel bots)

I think after last years game because of the damage that could be done,
this might be why they suggested the bumpers

[Rick TYler]

We practiced without bumpers, but added them for competition. They probably saved us any number of problems, including one match in which we nearly tipped over, but the bumper provided just enough width to allow us to rock back. We have a pretty low CG (it's one of the few really good things about our bot), but we tipped once in practice and nearly did (thank you, bumper) once in quals. Successful robots competed without them, but a lot of good bots used them.

The smart ticket would have been to use them as a stressed frame element, but we've already gone over that elsewhere...

[Kyle Love]

On the webcast I only noticed teams benefitting from bumpers. I saw some of them stay upright due mostly inpart to their bumpers. Sure, it will make it a bit harder to get up the ramp, but move the bumper up on the frame by a 1/2-3/4 inch and you will be good. (I would guess) Plus, they help keep your frame a little bit more beautiful for the pit and off-season demos.

[Steve Kaneb]

Team 190 chose not to use bumpers, and this turned out to be very advantageous. At the BAE regional, we were consistently able to maneuver around robots and through holes in defensive fronts. During our defensive period, we were often blocking 2 robots, and often kept these periods scoreless. This would not have been possible with bumpers because we relied on short, sharp shocks to robots to get them out of alignment. Despite the 15 pounds of stability advantage that bumpers afford, we never tipped and were frequently pushing bumpered robots around with ease.

Aside from that, we were thankful for not having bumpers because we often needed to check our chains on the driveline, our wheels and our spacers to make sure that it was all in order. Not having bumpers was also really helpful in the pits, because there wasn't extra room, and we keep most of our systems at bumper level.

Important items pertaining to our disuse of bumpers:
Almost all of our weight is wheel level. We're about 2-4 lbs. underweight, with a 6-wheel, one speed driveline.

Matching up against and with robots using bumpers, we noticed that there was a lot of trouble with the ramp and with defense. While the bumpers protected against collision effects, they got in the way of blocking, and often forced robots into misalignment.

[Wayne C.]

Originally Posted by sanddrag

I see bumpers as a failure point. If they rip or fall off or something, they can get caught in your drive system.

The real failure point is where your frame gets mangled and the battery and wiring going with it gets caught in your drive train.....

Pro Bumpers- of course I can relate to anything that adds an extra 15 lbs of padding around the middle....

WC

[Bharat Nain]

I don't know which is better because you have to determine what works best for you. What I can say is that bumpers are more fun in a defensive match. They are great shock absorbers.

[Dan Petrovic]

After the BAE Regional, I saw the Bumbers are far better than no bumpers. Reason being is that the bumpers increase your footprint so it saves you from tipping. We fell over a few times without bumpers and when we did they saved us from countless tips. They also prevent running over balls. Those balls are a pain when you start driving over them and around them.

[Rick TYler]

Originally Posted by Wayne C.

Pro Bumpers- of course I can relate to anything that adds an extra 15 lbs of padding around the middle...

Bumpers are the nachos with extra cheese of FIRST.

[Andrew Y.]

this years game can put some massive beatings on the robot!. we our whole entire frame warrped after a few rounds. This is when bumpers are good.


Only problem with them are when 2 bumpers are put together, they cause alot of friction making it harder to get out of pinned situations.

[Peter Matteson]

Originally Posted by Andrew Blair

Well, I guess, it's not a more sudden stop when you compare a direct collision, but in the case of an indirect hit, where metal on metal would allow more of a glance, resulting in less energy transfer, the bumpers would stick on eachother, causing most of the collision impulse to be transfered. Metal on metal causes a greater impulse, but evidently to a lesser magnitude in some cases.

That's what I was getting at. With the metal on metal/lexan the robots not only slid off each other they could spin each other better so that all the momentum transfer was not just in one direction. The lessen the impact along any given vector.

A couple other things:
If you attached your bumpers correctly they will not effect maintanence.

Bumpers will help the CG of most bots not hurt it based on what I've seen. Most have way to high a CG anyway.