pic: Effective Aperture of Low Bar Defense

[Lil' Lavery]

It's in the picture, but it's worth highlighting that the bar is not centered on the ramp. As a result, the maximum height will vary depending on which side you're approaching it from.

[Madison]

Originally Posted by Lil' Lavery

It's in the picture, but it's worth highlighting that the bar is not centered on the ramp. As a result, the maximum height will vary depending on which side you're approaching it from.

...and also that the neutral zone would be on its left side in this picture.

[bEdhEd]

Glad this was brought up and shared with a picture. This was a factor we were considering with our short bot idea yesterday.

[Kevin Sevcik]

Originally Posted by Lil' Lavery

It's in the picture, but it's worth highlighting that the bar is not centered on the ramp. As a result, the maximum height will vary depending on which side you're approaching it from.

That's fun. You'll need to have a CG that's something like 14" from one end of your robot to make it backwards through the low bar, in that case....

[MrForbes]

Or keep the ends of the robot a little bit shorter than the middle.

[Nebster]

Originally Posted by MrForbes

Or keep the ends of the robot a little bit shorter than the middle.

I was thinking about this too. Something where the front end of the robot is less than the ~14" limit for when the robot is on the ramp, but the rest of the robot can go up to 15.9" or so and be fine.

Warning- MS Paint incoming:

[wilsonmw04]

Originally Posted by Nebster

I was thinking about this too. Something where the front end of the robot is less than the ~14" limit for when the robot is on the ramp, but the rest of the robot can go up to 15.9" or so and be fine.

Warning- MS Paint incoming:

something like this would tackle the low goal well, but it would have significant issues with the overhang of the frame. The approach and departure angles make some defenses impassible.

[Nebster]

Originally Posted by wilsonmw04

something like this would tackle the low goal well, but it would have significant issues with the overhang of the frame. The approach and departure angles make some defenses impassible.

True. My wheel placements weren't accurate to a real robot, i just kind of drew them on in 10 seconds to show that this was a robot. The wheels would definitely be closer to the outside edge of the frame.

[bt20304]

hey, looking at measurements in solidworks, you seem to be off.
in reality the field elements are 13.73" measured the same way
https://drive.google.com/open?id=0B4...G5rM1Q0YlNCYmc

[Madison]

Originally Posted by bt20304

hey, looking at measurements in solidworks, you seem to be off.
in reality the field elements are 13.73" measured the same way
https://drive.google.com/open?id=0B4...G5rM1Q0YlNCYmc

When I measure against the field model provided by Autodesk, I get 13.86". Did you model those elements yourself or were they taken from elsewhere?

In any case, that discrepancy is why I added a disclaimer in this thread saying that y'all shouldn't take my word for it and should check things out yourselves.

[pHolmgren]

Thanks for this! It really helped us visualize what's needed for a low bar robot.

[pHolmgren]

I know it must be do-able but the challenge is fitting a firing mechanism in that space, to shoot in the high goal.

[EricLeifermann]

Unless your drive base is the exact length of the defense ramps your robot isn't going to be on a 13.5 degree angle.

I suggest all teams put in their robot in a sketch and run it through like it was actually driving through the low bar. The height of that bar isn't as low as people are making it out to be if your drive is designed correctly.

[Kevin Sevcik]

Originally Posted by EricLeifermann

Unless your drive base is the exact length of the defense ramps your robot isn't going to be on a 13.5 degree angle.

I suggest all teams put in their robot in a sketch and run it through like it was actually driving through the low bar. The height of that bar isn't as low as people are making it out to be if your drive is designed correctly.

This depends somewhat on your CoM. If you have a CoM near the back, you might not fall down horizontal until you're well into the low bar. At which point you'd start pushing against the low bar. Just CAD isn't going to give you those details.

[pfreivald]

I realized this problem right away, but appear to have gotten the orientation of the low bar backward--I thought the bar was closer to the Courtyard, rather than to the Neutral Zone. Thanks, Madison!