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Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 1/28/2000 5:35 PM MST


In Reply to: Team Update #6 is Out! posted by Eric Rasmussen on 1/28/2000 4:12 PM MST:



How many other folks out there were under the wrong impression about bumpers prior to Update #6?

We were very much so.

Under our interpretation, we thought that we had essential an ENVELOPE that was vertically centered about 6.5 inches above the floor.

Now, we learn that the BUMPERS must be vertically centered at 6.5 inches above the floor.

This is a very different thing indeed!

Now I begin to wonder what other rules on bumpers did we miss. My first thought was that the bumpers were perhaps required to have the wood backing (sink-o). But, thanks to a later Q&A:

Q175. Does the hard backing for the bumper have to be made out of wood?
A175. No, the hard backing does not need to be made out of wood.

But questions still abound:

1) Is 'hard backing' required? If so how hard is hard?

2) A bumper the is 'vertically centered' at a given height may be interpreted to imply some rough symmetric shape that is 'center-able.' So, my next question is, is there a requirement that the bumpers have some sort of symmetry about the centerline?

3) This, of course, leads to another question, is it the whole bumper that must be 'vertically centered' or is it the outermost edge of the bumper that must be 'vertically centered'?

4) Yet another question, does each cross-section of the bumper have to be 'vertically centered' or can the entire bumper be 'vertically centered'? The difference is VERY important. If all I have to do is have the highest and lowest point of the entire bumper be equal distances from 6.5, then this is an easy met condition. However, if EVERY section of the bumper must have its highest and lowest point equal distances for 6.5 inches, this is a Very tough rule to follow.

Rereading the rule in question (M6), I now wonder about many other things that I may have gotten wrong.

5) Does the bumper have to be fastened with 'bolts with recessed heads' or are other fastening methods acceptable?

6) Does the mounting surface of the robot have to be PRECISELY at the edge of the robot as shown in the figure or may we mount to our robot frame somewhere a bit inboard?

7) My last question involves the definition of 'energy absorbing material.' I have heard of strength of materials Profs, who started each lecture with the question, 'What happens when a fly lands on an anvil?' The answer that the class was required to recite was, 'It deflects' ('It' in this case referring to the anvil.) The point was that regardless of how strong a beam seems, it bends when loaded without regard to the magnitude of the load. Ah well, I have gone far afield, my point is that, one man's energy absorbing material is another man's anvil! So… Would a 'hoop skirt' type affair made from thin walled aluminum tubing qualify as an 'energy absorbing material' or not? How about sheet of 0.020 thick aluminum formed into some (hopefully legal) shape?

Finally, I think that this is going to be VERY hard to judge fairly & consistently what is legal and what is not.

So… I beg that FIRST reconsider the interpretation of the rule that is has currently proposed in favor of a rule that basically allows teams to put whatever they want in the envelope defined (not material limits on stuff inside the bumper zone) but the bumper must be rigidly fixed to the robot (no moving bumpers) and a team must be able to remove & re-install it in less than XXX minutes.

What do you think?

Joe J.