Re: pic: GBX-114 swerve with PTO
 

Yea, I figured whenever you sent them to an X configuration you would want to be breaking.

Yes, I wrote up a procedure in that thread. Thats actually what started us doing the testing, we were getting pushed sideways more than we liked.

Re: pic: GBX-114 swerve with PTO
 

Awesome. I will check that out.

Re: pic: GBX-114 swerve with PTO
 

Pushed sideways while in an X? That woule be very hard to do if you set the turning motors in brake as well; they are geared down 1:26 with a secondary of 30:84.

Re: pic: GBX-114 swerve with PTO
 

Sorry, we did the tests last year on our 8 wheel WCD. With a swerve that has straight cut tread it should be just as hard to do as being pushed backwards. (I will have to think about how best to "break" with diagonal tread)

Re: pic: GBX-114 swerve with PTO
 

Thank goodness. I was thinking, "Oh god, did my numbers come out totally wrong!?"
They did, as a matter of fact. This is only geared for 20fps, sadly. I messed up the numbers in the calculator (again). Fortunately, the speed is easy to increase, but hard to decrease.
EDIT: I added a 3-position cylinder to the CAD, but for some reason these cylinders from Bimba are around 6" tall. So you can technically put on one here, but I would probably learn to live with this version.

Re: pic: GBX-114 swerve with PTO
 

I'm confused, what's that have to do with being pushed while in X mode?

Re: pic: GBX-114 swerve with PTO
 

If you get pushed from the side while in x mode, then because the contact patch with the floor (ideally) is a line or thin rectangle, the pusher will torque the wheel sideways a bit like a caster. It seems like it would take a ton of force to shove those wheels back into a straight position, but it is doable. I'm sure that the robot will lift before that though.

Re: pic: GBX-114 swerve with PTO
 

Theoretically it's a line, if your wheels and the floor were both hard and solid, ideally it's as large a rectangle as you can make it because with tread on carpet the physics class friction model goes out the window and surface area is quite important. But 45° wheels pushing from the side should be identical to pushing from the front. You are right though, it's quite hard to turn a (for us) 100:1 braked planetary gearbox. As for lifting, unless your bumpers are higher than your opponents there is no force that is going to lift your robot. Infact, if your bumpers are lower they will be pushing you into the floor a small bit, increasing your normal force and your friction.

Re: pic: GBX-114 swerve with PTO
 

Out of curiosity, how are the side plates of your caster box attached to the turning gear that the robot is resting on?

Re: pic: GBX-114 swerve with PTO
 

Ah, caster box. That's a good name for it.
The turning gear is a modified vexpro 84 tooth gear. A big hole is in the center for clearance, and about 1/8" is cut out of the face of the gear (deburring would have to be done carefully on the teeth). Of the 1/8", there is a small pocket that sticks up which the caster box side plates drop in to.
The pocket is wallled on three sides and has screws on the bottom to connect it properly. The fourth side of the pocket is the big hole in the center of the gear.