Re: pic: 1675's REAL IRI Upgrade
 

Its all about what the driver is comfortable with, it doesnt matter what anyone else thinks about it.

Re: pic: 1675's REAL IRI Upgrade
 

Well first off, the treads would probably slide off because they're not secured too well....but ignoring that, i would guess that it would barely strafe, and skip around like popcorn popping. What i want to try is to individually wrap each roller with tread. Nobody steal my idea unless 461 doesn't do that in 2012 :)

Re: pic: 1675's REAL IRI Upgrade
 

Like I said, the kids didn't test it on the practice field like I wanted them to! :P

My guess is that without securing the treads to the mecanum hubs the diagonal force of the rollers would pop the treads off or tangle them in the wheel if it popped off diagonally.

If secured to the wheel it would just act like a lumpy traction wheel.

If secured to the wheel AND strafing was tried, the robot would be trying to pull itself apart and go nowhere.

Re: pic: 1675's REAL IRI Upgrade
 

Nope, not us. 2009 was a Logitech gamepad. The left stick was the crab strick. You could think of it as a top view of the crab modules. Which ever way you deflected the stick, the module would go there. If you let go of the stick, the module would center. The right stick had multiple purposes. When the crab stick was deflected, only the Y axis was used, and it acted as the throttle. When the crab stick was not deflected, the right stick acted as a single stick tank drive. There were also a few gimmicks that we used such as having a button to angle the crab slightly (helped with picking up against the wall) and some special logic to tank turn while the crab wheels were not centered (standard tank turn logic doesn't hold true when the wheels are turned because the robot will try to pull itself apart :p)

Re: pic: 1675's REAL IRI Upgrade
 

Sorry about that. One of our mentors spoke with someone on your team about your crab drive, to get information about building our crab drive. Have you guys ever used, or tested out a 3 axis joystick for your crab drive? He was pretty convinced that a 3 axis joystick was the way to go after talking to you guys. The way he told us, the twist did the function that your left stick on the game pad did. Either he talked to the wrong person, or he confused himself.

Re: pic: 1675's REAL IRI Upgrade
 

I don't think we ever experimented with a 3 axis joystick. We've always gone with the two stick approach. Back in the day, we just used the X-axis of the left stick for crab angle. I think 2008 was the first time that we used both X and Y to use the full circle of the stick for wheel angle.

I would think that the control that you described, where the Z axis of the stick determined the crab angle would be really hard to work with. I feel like you would lose a ton of resolution between the range of motion of the stick, and the physical dexterity required to twist the stick (as opposed to deflecting it). Like I said, I've never tried it, so if someone has had good success with that setup, more power to you.

Re: pic: 1675's REAL IRI Upgrade
 

We have tried 3-axis joysticks to control holonomic/strafing drive trains in the past, but always found that two sticks works much better.

It is simply too easy to twist when you only meant to deflect, and visa versa.

Re: pic: 1675's REAL IRI Upgrade
 

Reported