[RRLedford]

Since we also balance on the edge of the bridge rail with 20" of our 33" width protruding off the bridge, but in a way that does not grasp grapple or grip the edge rail, I will offer my assessment of why 118' scheme was disallowed.

The device that they engage the bridge with clearly relies on the cantilevered weight of the bot to effectively hook, pinch, grip, squeeze, grasp, and clamp on to the edge rail of the bridge.

Functionally. their device initiates rail contact via multiple opposing points of contact on the mechanism, and the subsequent torque developed, as the cantilevered weight of the bot transfers onto the mechanism causes the mechanism to rotate around the length axis of the rail, so as to twist the device downward and away from the bridge, and this mechanism rotation results in a net pinching effect on the thickness of the rail's aluminum.
The problem with the 118 design results from the way that the multiple opposing points of contact react against the rail to produce a net compression of the opposite sides of the rail. This seems to be exactly what the GDC and their rule wording would not allow.

If I place a C-clamp over the bridge rail, but then I stop tightening it right before it contacts the rail, at which point, I then apply all my weight to the C-clamp, the resulting torque on the C-clamp will make it grip the rail. Just because the C-clamp was not initially squeezing the rail before the weight was applied does nor mean that the C-clamp is not gripping the rail after the weight is applied.

Now if the 118 bot relied on another bot to move the bridge upward in order to lift them off the ground, then I would consider this a possible allowed exception, since the 118 bot is not manipulating any device against the bridge, and the grasping result is just incidental to the motion of the bridge, which they did not cause. Still a stretch though, since grasping engagement was the desired result of how the bot was positioned relative to the bridge.

-Dick Ledford