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 Chief Delphi Frame Perimeter, and Bumpers Question
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#1
11-11-2017, 01:00 PM
 yagmurm Registered User FRC #6838 Join Date: Nov 2017 Location: Turkey Posts: 1
Frame Perimeter, and Bumpers Question

As long as I understood from the manual, the bumpers have to surround the frame perimeter. Do we determine the frame perimeter according to the base of the robot or do we take the largest part of the robot?

Our robot's base is smaller than its upper part:

Is there a way we can put bumpers around it without violating any rules?

Quote:
 R02. In the STARTING CONFIGURATION (the physical configuration in which a ROBOT starts a MATCH), no part of the ROBOT shall extend outside the vertical projection of the FRAME PERIMETER, with the exception of its BUMPERS and minor protrusions such as bolt heads, fastener ends, rivets, etc.
Quote:
 R31. BUMPERS must be supported by the structure/frame of the ROBOT (see Figure 8-7). To be considered supported, a minimum of ½ in. (~12.7 mm) at each end of each BUMPER wood segment must be backed by the FRAME PERMIETER. “Ends” exclude hard BUMPER parts which extend past the FRAME PERIMETER permitted by R29, part B. Additionally, any gap between the backing material and the frame: A. must not be greater than ¼ in. (~6 mm) deep, or B. not more than 8 in. (~20 cm) wide
#2
11-11-2017, 01:09 PM
 SenorZ Physics Teacher AKA: Tom Zook FRC #4276 (Surf City Vikings) Team Role: Teacher Join Date: Jan 2011 Rookie Year: 2011 Location: Huntington Beach, California Posts: 1,413
Re: Frame Perimeter, and Bumpers Question

Bumpers mounted to frame perimeter.

Frame perimeter determined by holding a piece of string around chassis where bumpers will mount.

So, no, as shown that is illegal. BUT, if the he little angled bit pops out after the start of the match, its all good... provided that the angled bit does not extend beyond the bumper size limits.
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#3
11-11-2017, 01:11 PM
 RoboChair He who fixes with hammers #tsimfd AKA: Devin Castellucci FRC #1678 (Citrus Circuits and 5458 Digital Minds) Team Role: Mentor Join Date: Jan 2007 Rookie Year: 2005 Location: Davis, CA Posts: 1,149
Re: Frame Perimeter, and Bumpers Question

Simply that robot is only legal if that protrusion is included in the perimeter and you have a similar protrusion that your bumpers are mounted to. As drawn it isn't legal.
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#4
11-11-2017, 01:35 PM
 EricH New year, new team FRC #1197 (Torbots) Team Role: Engineer Join Date: Jan 2005 Rookie Year: 2003 Location: SoCal Posts: 22,253
Re: Frame Perimeter, and Bumpers Question

Quote:
 Originally Posted by yagmurm As long as I understood from the manual, the bumpers have to surround the frame perimeter. Do we determine the frame perimeter according to the base of the robot or do we take the largest part of the robot? Our robot's base is smaller than its upper part: Is there a way we can put bumpers around it without violating any rules?
There's one or two rules that you didn't quote that hold the key to unlocking the answer. Here they are, along with a short description.

The bumper zone: This is where the bumpers are mounted, and where the Frame Perimeter is determined. This year, it's 0-7 inches from the floor.
Quote:
 Originally Posted by R23 R23. BUMPERS must be located entirely within the BUMPER ZONE, which is the volume contained between the floor and a virtual horizontal plane 7 in. (~17 cm) above the floor in reference to the ROBOT standing normally on a flat floor. BUMPERS do not have to be parallel to the floor.
On determining the Frame Perimeter:
Quote:
 Originally Posted by R01, emphasis mine R01. The ROBOT (excluding BUMPERS) must have a FRAME PERIMETER, contained within the BUMPER ZONE, that is comprised of fixed, non-articulated structural elements of the ROBOT. Minor protrusions no greater than ¼ in. (~6.3 mm) such as bolt heads, fastener ends, weld beads, and rivets are not considered part of the FRAME PERIMETER. To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT (excluding BUMPERS) at the BUMPER ZONE described in R23 and pull it taut. The string describes this polygon. Example: A ROBOT’s chassis is shaped like the letter ‘V’, with a large gap between chassis elements on the front of the ROBOT. When wrapping a taut string around this chassis, the string extends across the gap and the resulting FRAME PERIMETER is a triangle with three sides. Note: to permit a simplified definition of the FRAME PERIMETER and encourage a tight, robust connection between the BUMPERS and the FRAME PERIMETER, minor protrusions such as bolt heads, fastener ends, rivets, etc. are excluded from the determination of the FRAME PERIMETER.
The question you're asking comes down to one simple question: Is that angle in the Bumper Zone? Given the general shape, I would guess that it probably isn't. If it was in the zone, it would define the Frame Perimeter, and you'd be fine. It isn't, therefore you're going to need to do something.

As to what you do, that would be mechanism-dependent. You could, for example, construct the whole thing on a hinge so that it would be able to be placed inside the Frame Perimeter to start the match, then fall to where you want it as soon as the robot starts moving.

You wouldn't be the only team to discover this little problem...

@SenorZ: Depends on whether their bumpers are at maximum volume or not. If the bumpers aren't at max volume, they can go right ahead and go past them, though that does carry certain other risks related to game rules and contact.

Obligatory disclaimer: As with all other rules, these rules are subject to change for the 2018 game. Therefore, any opinion expressed based on these 2017 game rules is only valid until January 5, 2018.
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#5
11-11-2017, 08:30 PM
 GeeTwo Somebody Else AKA: Gus Michel II no team Team Role: Mentor Join Date: Jan 2014 Rookie Year: 2013 Location: Slidell, LA Posts: 6,043
Re: Frame Perimeter, and Bumpers Question

Quote:
 Originally Posted by EricH There's one or two rules that you didn't quote that hold the key to unlocking the answer. Here they are, along with a short description.
+1, with R01 being the key, but the real story being built up of multiple rules.

Constructively, the rules of the past few years (2015 excepted) have required that the the BUMPERS (except mounting hardware) begin and remain completely outside of the FRAME PERIMETER, and that every non-BUMPER part of the robot begin the match completely inside the vertical prism defined by the FRAME PERIMETER. Consequently, any robot part which extends over, under, or beyond the bumpers must begin each match inside the FRAME PERIMETER and be moved outward during the match.

Quote:
 Originally Posted by EricH Obligatory disclaimer: As with all other rules, these rules are subject to change for the 2018 game. Therefore, any opinion expressed based on these 2017 game rules is only valid until January 5, 2018.
QFT
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