Re: Bumpers: why not?
 

There are several robots that are designed to shoot from atop the ramp. They must get off the ramp to not score points for their opponents and to collect more balls.

Re: Bumpers: why not?
 

or they could just build some thing that dips down to touch the floor . . .

Re: Bumpers: why not?
 

we had this problem since we didnt have a bumper on our front where we have the ball loader/corner goal scorer and we almost had problems but then we cut the bumpers back so they dont extend past the end of the chassis problem=solved

btw ramming is still a penality regardless of bumpers or not bumpers may allow you to increase you speed doing it but not much we got a penality for ramming with our unprotected side during autonomous but they still would've given us the penality even if we had done it backward where we have bumpers---- just a warning

Re: Bumpers: why not?
 

We had to remove our "front" bumpers for this reason. :(


Bill Pease
Aces High Team 176
2006 UTC New England Champions with 177 and 1124
2006 BAE Granite State Finalists with 319 and 562
2005 UTC New England Engineering Inspiration Award

Re: Bumpers: why not?
 

Yes, your bumpers can extend past that limit. the solution? we got the idea from a few other teams to put a guard up so that our robot would stop before its bumpers could get too far into the goal.
The 'guard' was just a peice of metal placed at each corner of the robot, just inside the bumpers. this allowed for us to stop before we reached the sensor, and therefore wouldnt get a penalty.

Re: Bumpers: why not?
 

Well, we had bumpers, and on the wood ramp we had no problems.

When we got to competition however, the extra 1/4 inch of diamond plate caused us not to be able to go up the ramp.

Re: Bumpers: why not?
 

I was thinking about this the other day coming from a physics perspective.

One of the most important and fundamental equations in physics is F = ma (Force equals mass times acceleration). Now think about this equation while imagining an impact between two robots.

In a collision, a robot with bumpers will have a smaller acceleration upon impact than a robot without them. Because acceleration is the change in velocity divided by the change in time, the acceleration is small because a bumper gives the robot more time to stop. The smaller the acceleration, the smaller the resulting force. In the same way, there is smaller acceleration when a car comes to a gradual stop, as opposed to when a car crashes head on into a tree. There is more force exerted on the person in the car that crashes into the tree, than there is on the person who comes to a gradual stop.

The force imparted by a bumpered robot is smaller than a non-bumpered robot. This fact can be taken into account when deciding whether or not to use bumpers. If you are planning on being an offensive shooter-bot, the use of bumpers would help you because it would make the force of impacts smaller. This would make it harder for your opponents to knock you out of scoring position. However, if you are planning on playing defensively, bumpers might not be as advantageous because they will cushion the impact you will have when playing defense against another robot. They will reduce the force with which you strike.

My team's robot is primarily a defensive/corner goal scoring robot. We chose not to use bumpers this year. Because of F = ma, it appears that this was a good decision. If we had used bumpers, our impact against other robots would have been smaller.

Now the question is, would the weight advantage of the bumpers have overcome the loss of acceleration due to the padding?

-- Jaine

Re: Bumpers: why not?
 

While there is much to be said for the impusle of hitting another robot in pushing them that is a dangerous manuver to rely heavily on. Refs are more leniant with bumper rots and ramming but penalties still do occure. In my case 1549's bot was able to push just about anyone sideways in addition to the impulse of initial contact. The bumpers do very little to decrease the a in F=ma. They offer enough shock absorbancy, however, to prevent robot damage.

Re: Bumpers: why not?
 

While your concept is worrect, I find it hard to believe that bumpers slow a robot down at all at impact. Unlike braking a car, bumpers are like putting a big, well...bumper, in front of the car. The bumpers are really to protect the frame of the robot from damage, not to make less force.

In fact, bumpers will actually increase force, as they add more mass (15 pounds) to the robot. Comparing a 120 lb robot to a 135 lb robot, the 135 lb robot has 12.5% more mass, and thus 12.5% more force. Even if bumpers did make accelleration slower, the added inertia of the 135 lb robot would cancel this out.

I encourage every robot to put bumpers on if they can, because without them, more penalties will be called on you, and your robot will get more damaged.

Re: Bumpers: why not?
 

update 15 states

so if your robot doesn't go into the corner goal normally but another robot pushes you into it, it is penalty for the other team. not you.

So were the referees calling this penalty wrong at a lot of places? This update may become handy to carry around in your manual binder if you think a referee ruled incorrectly at regionals.

Re: Bumpers: why not?
 

The big fault i'm seeing with this argument that more weight equals more force is that everyone's talking about ramming other robots, which is where this would apply.

For various reason's, my teams robot was (one regional, and that's all :( ) a rather good pusher. We did not however go racing across the field to ram the opponent. We generally had to maneuver to push the side of the opponents too. Our toughest opponents, if pushed from behind, would end up on the ramp and still able to shoot. Not to mention we did spend most of our time in the "personal" space of our opponents (so less distance ramming).

When going to the side to push, your weight affects the force of collision much less because of less speed. What matters is your pushing power, torque. The weight will and does increase torque.

Our robot had bumpers on 3 sides (ball collector, rarely used, on the front). My innate logic thinking says that this made us a more effective pusher when it came to getting that initial push from the side. We never sustained any damage (well a few dents in the shooter which was flush with the front of our robot) or penalties.

None the less, we couldn't push everyone (especially treads, which rather dominated the finals...). And I'm not doing so well in AP Physics this semester, so I could very well be wrong with some of the physics :confused:

Re: Bumpers: why not?
 

Well Our bot doesnt have bumpers for one simple reason. We ran outta time.

Re: Bumpers: why not?
 

Ours does because, well, why not? On one side we didn't have any, for ramp purposes. (Although I think it wouldn't have changed it much, it seems like it'd be sort of hard for a couple of pool noodles covered in smooth cloth to keep a high power, high traction, 6 wheel drive with good ground clearance off the ramp.) The other sides had them, except a small opening for ball collection. And, believe you me, we'd have been in sorry shape after the elims without them. However, Sparky didn't have them, and from what I saw, their frame still seemed to be in fine shape at the end of VCU. (I could be wrong, it's not like I examined it) As for them reducing defensive ability, If you were at VCU and watched us play, you might have noticed that we played almost entirely defense (yet at the beginning of Saturday we had the 4th highest avg match score, go figure :confused: ) we never felt that they were hurting us. Collision physics aside, that 15 lbs (Ours were about 10) gives you a good bit more traction, and in a pushing match against a similar drivetrain, this'll make the difference, not how hard your (illegal) high speed ramming is.

Re: Bumpers: why not?
 

The penalty is applicable to both robots. The bot attempting to score in the corner goal still is expected to have been built so it will not enter the goal.

Re: Bumpers: why not?
 

I think we had an instance of this in St. Louis during the eliminations. Both robots were DQ'd so the effect was a replay (tie). See my post in an earlier thread.