FRC T-bone-ing and Hexagonal drive

[nuclearnerd]

Originally Posted by Lil' Lavery

Only if they hit it right on.

If I understand it correctly, one of the effective things about T-Bone pins is that they are "self-engaging". Check out the attached sketch (in stunning powerpoint CAD!) When the defensive robot on the left (yellow) hits the offensive robot on the side (blue), the contact force is angled to the right of the Blue robot's turning center. This creates a torque (green arrow) that turns the blue robot into the front bumper of the yellow robot. Since the other corner of the yellow robot is on the left side of the turning center, contact there will try to turn the blue robot back the other way. The result is as long as the yellow bot pushes, the blue robot can't exert a turning torque greater than the one caused by the contact, so the two robots become locked together at a 90 degree T (not shown).

A hexagonal robot (shown in blue on the right) changes the contact location and angle in an attempt to move that contact force closer towards (or completely across) the blue robot's turning center, reducing the leverage and producing less "T-Bone torque". But this can be subverted by notching the front bumper of the defensive robot (shown in yellow on the right). The notched bumper contacts the blue robot at almost exactly the same place, and with as much T-Bone torque as the scenario on the left. (although it might be a little reduced if the hex angle is sharp enough).

An easier way to reduce the chance of getting T-boned is to move the turning center closer to the front or back of the offensive robot. If you moved the turning center on the blue robot all the way to the right of the diagram for instance, the yellow robot would produce almost no T-Bone torque (or even reverse or helpful) T-Bone torque. The turning center can be repositioned using permanent or drop-down omni wheels (as suggested earlier), or with swerve drives. Those features allow an offensive robot to "pick and roll" off a T-Bone pin.

That's my understanding of things anyway. I'd be interested to hear if other people of different theories or data.