Looking for clarification on <R4>. Part of the rule says:
“A Robot may not expand beyond its 13” x 20” starting area constraint at any time during the match”.
Inspectors and judges at some events have used a wooden box with inner dimensions of 13x20 to enforce this rule. Using the box they can easily verify that a robot designed to tip a basket full of balls into the high goal never extends forward past 20" as it begins its dumping motion and arcs forward, and never extends backwards past 20" as it dumps a load of balls into the goal. This is a useful technique for validating most robot designs.
However, robots that can expand in width and at other times expand in length come into question because they cannot change their dimensions within the confines of a rigid box, without rotating the box. Here is an example:
A robot (gray & black in the illustration) starts the match in a configuration where it is wide enough to collect two rows of balls simultaneously. The red dashed line is a 13x20 rectangle that the robot fits within.
The robot is reconfigured after collecting the balls so that it is only 13x13.
It then drives into position to dump the balls.
It extends forward as the lift makes its arc. At this point the robot still fits within a 13x20 rectangle, but note that the orientation of the rectangle has changed.
Now the robot extends backwards to dump the balls into the goal. The orientation of the rectangle stays the same, but it must be move backwards relative to the robot’s drivetrain.
The example shows that the robot is never larger than 13x20. However when inspected within a box, the robot cannot transition from configuration #2 to configuration #3 without either lifting and rotating the box, or lifting and rotating the robot. The robot cannot rotate within the box.
Is the intent of <R4> to restrict robots so that they must function with an rigid 13x20 box, or are they free to expand in any direction, so long as they are never more than 13x20?