Category A Crossing?
 

Most of B, C, and D obstacles can be solved with a tank drive, but these two seem a bit annoying. Any suggestions?

Re: Category A Crossing?
 

First: Don't underestimate the "easy" defenses. I guarantee that they will get folks stuck consistently through the season... Spend time prototyping and getting them right.

Second: Some of those others will require simple manipulators to lift/pull/etc.

Re: Category A Crossing?
 

Or, teamwork. Even if your team doesn't have effective manipulators for everything, good driver communication can still breach defenses.

For example, Robot A (which could be the base kitbot) goes under the low bar into the courtyard (incidentally weakening the low bar), then opens either the drawbridge or sally port. Robot B then goes bumper-to-bumper with Robot A and they both drive through to the courtyard. Robot B has crossed the defense and weakened it. Sure, you would have to do it twice, but you don't need a manipulator to cross the sally port and drawbridge. It just might take two robots.

Re: Category A Crossing?
 

What about the portcullis and the Cheval-de-Frise?

Re: Category A Crossing?
 

you just need an arm or two to push the cheval's ramps down and hold them down till you get wheels on them. Depending on how tall you are, you could use the same arm for lifting the portcullis. Main thing on the portcullis is lifting it enough to start going under, then having a smooth surface on top of your robot for it to slide over.

Re: Category A Crossing?
 

Or, if you are sufficiently short, all you need is a wedge to lift the portcullis over your robot as you drive under it.

Re: Category A Crossing?
 

My team is attempting to be able to do all of the defenses because we are concerned about this happening and another robot blocking one of the defenses. I predict that there will be a lot of teams that discover that their robot cannot go over the B and D defenses for the first time at competition.

Re: Category A Crossing?
 

I'm with Kevin. A single arm that moves up and down in front of the robot from near ground level to the height of all the fixed parts of the robot can push down one panel of the CDF, letting you drive over, and push up the Portcullis, letting you drive under. Details are left as an exercise. (We're still working out details!)

Edit: A skid plate may help on the CdF.

Re: Category A Crossing?
 

One of my partners in crime pointed out that pushing down two CdF ramps and driving over those may be better, so you don't have to worry about the skid-plate issue.

Re: Category A Crossing?
 

I suggest using a mechanism that can:
1. Lift the Portcullis
2. Press down one ramp on the Chival de Frise
3. Pull down the Drawbridge
4. Open the Sally Port
5. Scales
This can all be achieved with a mechanical arm that moves up and down from a pivot point on the robots frame, and has two hooks on the end, so that you have a hook facing each way. I would also extend for the portcullis and scale, and with some mechanical genius, it will do all of this. I hope this helped with your robot.

Re: Category A Crossing?
 

Our team just decided that "French" was the better name for the Cheval de Frise. As in, "our robot can handle French pretty easily".

Re: Category A Crossing?
 

My thought for category A was to breach another defense, then come at these the other way and push them open, then you just need to drive back through while your bot is still holding them open. I don't see why this wouldn't work.

Re: Category A Crossing?
 

I do. Take a look at the definition of Crossing, and you'll notice that the first element is that you NOT be in contact with the Defense.

Re: Category A Crossing?
 

Also, you're thinking of the drawbridge and sally port which are category C.

Re: Category A Crossing?
 

"Frenchie" might be better.