Drop Center Bumpers

This might be one for the Q&A, but maybe somebody here already knows:

When interpreting bumper zone rule R402 (…a virtual horizontal plane 7½ in. (~19 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), does “normally” mean “resting configuration” or “geometrically normal”? We have a drop center 6 wheel drivetrain, and want the bumpers as high as possible (to assist with getting on the Charge Station). If the frame is parallel to the ground (front and rear wheels both slightly off the ground), the bumpers can be a little bit higher than if they have to be under 7.5" whenever the robot is tilted onto the forward or back wheels.

Before giving you my opinion I will recommend Q&A.

That said when I designed drop center drive robots I made sure which ever way we tipped the bumpers stayed in the allowed bumper zone no matter what so we couldn’t get called on a rule violation.


The bumper zone is much more than 5 inches wide… If you mount your bumpers so the top is at 7 inches or even 7.25 inches, then the normal oscillation of a drop center will not affect you.


If the robot is at rest, that’s a normal configuration. If you are stable at rest when tilted the other way, that’s also a normal configuration. You need to meet both of these conditions (and perhaps others). If you’re planning anything else, I definitely second @Peter_Matteson’s Q&A suggestion.
If the height of the bottom of the bumper is that critical to you, you can get further by squeezing the bumper tolerances than gaming the drop center.


Posted in Q&A #179

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