FRC488 Driving Over the Bump

[Madison]

Originally Posted by squirrel

Interesting! Do you have a number for how high the CG is now?

When the robot is climbing the ramp, at a 45 degree angle, the height of the CG affects where the balance point is, relative to the 3rd wheel. Having a higher CG moves the center of mass behind that wheel, so the nose does not want to come down as it tries to crest the bump

Anyways, we're hoping that moving our CG foward (or back and driving over the bump backwards) as well as increasing traction on the center wheels will give us the extra umph we need to get over the bump.

Thanks again for posting this info!

The coordinate system is all messed up in my assembly, so it thinks the CG is -x, -y, -z. The CG ends up being a little bit above the finished frame when the bumpers, kicker, and upper frame are removed.

We're seeing the behavior you describe even now. In the video showing the slower trip over the bump, you can see that it doesn't begin to tip until the third wheel crests. We're using 8WD for this reason, actually -- it slightly lowers the CG over 6WD because the ground clearance can be lower and the 2nd wheel impacts the bump before the 1st impacts the ground. It breaks up the shock into two more manageable chunks.

As things stand now, the robot can climb to just before its tipping point and old that position, though I can't imagine when that'd ever be a good idea. It'll be interesting to see if it changes, though.