The rule for the bumper says that a corner must have a least 8in to each side covered by the bumpers, it also says that a side smaller than 8in must mi entirely protected.
Here is the rule:
ROBOTS are required to use BUMPERS to protect all outside corners of the FRAME PERIMETER. For adequate protection, at least 8 in. of BUMPER must be placed on each side of each outside corner (see Figure 4-3). If a side is shorter than 8 in., the entire side must be protected by BUMPER (see Figure 4-4). A round or circular FRAME PERIMETER, or segment of the frame perimeter, is considered to have an infinite number of corners.
With this in consideration: Would a robot with a front size of 25in and an opening of 13in thus leaving 2 small sides of 6in, be legal? As the one shown in the image.
Not legal. The Frame Perimeter happens to cross the gap. You’ll need 2 more inches on each side.
I uploaded an attachment in http://www.chiefdelphi.com/forums/showthread.php?p=1526439#post1526439 that should explain what the Frame Perimeter is in this situation. The bottom right side is your situation, or very close; the top right is a legal configuration.
Short answer is no. This question has been asked several different ways on this forum. Search is your friend.
Your ROBOT as shown does not have 5 sides. It has 4. The FRAME PERIMETER is defined by the 4 corners of your ROBOT. The front side happens to have a gap in it, but the side still runs from corner to corner.
But are the rules talking about the sides of the frame perimeter or sides of the corner. (Typically 4 sides on a robot, but 2 on a corner of it.)
They’re still the same sides. Each side is between two corners and each corner is adjacent to two sides.
Bumpers are evaluated with respect to the corners of the FRAME PERIMETER. In the drawing above, there are four corners and each corner must have 8" of bumper on each side of the corner. If the side of the robot was less than 8" long, the entire side must be covered in bumper. The bumper is evaluated for length by measuring the backing board from the corner of the frame.
Please see the lower left drawing in Fig. 4-3 of the robot rules.