pic: Small CIM in wheel swerve

[Spoam]

Originally Posted by GeeTwo

Does anyone have any insight on what 254 (or any other more "fluidly" driving team) uses to control their swerves or holonomic drives?

254 does not use holonomic drives. They do, however, scale inputs and use motion profiles to control their skid-steers.

[Richard Wallace]

Originally Posted by Spoam

254 does not use holonomic drives.

I think that is because they don't need to.

[Andrew Schreiber]

Originally Posted by GeeTwo

Does anyone have any insight on what 254 (or any other more "fluidly" driving team) uses to control their swerves or holonomic drives?

254 doesn't swerve. But they DO use Cheezy Drive. It's designed to make driving in long sweeping arcs easier.

I know 16's controls encourage their drivers to drive in the long arcs you often see them do. I don't have nearly enough stick time with a bomb squad robot to explain it, hopefully I can get Jefferson to explain it a bit.

[AdamHeard]

Originally Posted by GeeTwo

I strongly suspect than many teams program both holonomic and redundant (e.g. swerve) drive controllers like tank, and if so, then of course they're driven that way. By "like tank", I mean that the primary drive is either two-tread style or arcade style, with options like strafing, translating in odd directions, translating odd directions while rotating, and rotating around a fixed point being either special cases or left for the driver to figure out.

When 3946 did mecanum (Aerial Assist, not our best tactical call), we had all of the translation in a single joystick, and rotation on the left and right "triggers" of the xBox controller. This did encourage a bit of combination maneuver - you could move towards the ball or goal while simultaneously rotating. Even I was able to do both at the same time within a couple of minutes when I did a demo at my office department's spring picnic. I'd personally like to have done a joystick with a long (+/- 60 to 90 degrees) proportional twist axis, but I wasn't mentoring programming that year, and I understand that we didn't have any joysticks up to the task, in any event.

Does anyone have any insight on what 254 (or any other more "fluidly" driving team) uses to control their swerves or holonomic drives?

Their swerve code is in the block below.

[sanddrag]

Originally Posted by AdamHeard

Their swerve code is in the block below.

Gosh, that's the lightest-weight code I've ever seen.

[Dunngeon]

Originally Posted by Andrew Schreiber

30A breakers don't pop immediately. (http://www.snapaction.net/pdf/MX5%20Spec%20Sheet.pdf) So, a 30A breaker pulling 80A (which according to tests I've heard about is about the max you can get to a CIM given other loads on the system and the battery) will last 0.8 - 1.8 seconds. A 40A breaker will give you about twice that time. But that's assuming you're practically stalling the CIM. And it completely ignores the fact that, more than likely, the RoboRio will cut your motor power due to voltage drop.

Acceleration is also a function of code/driving/operator interface. All too often I see swerves driven like tanks. Go to point, pivot wheels, go sideways, pivot wheels again, go back to going forward. If you watch how teams who have mastered swerve (ok, I'm a 16 fan boy, I'll admit it) they tend to be much more fluid and rely less on raw power to accelerate from 0 in that direction. 254 does similar things when it comes to tank drives, it's why they seem to get away with gearing so much higher than other people.

Basically, while being able to pour more power for longer may seem like a good solution to the acceleration problem there's a fair bit more to it and utilizing it will mean your motors run cooler, your batteries last longer, and you can STILL out swerve most people.

That all being said, if I could easily find a 40A rated slip ring for comparable weight/cost of the 30A I'd choose it every time. But if I given the choice between a more complicated module (bevel), more complicated code (limit rotations), and limited continuous current (30A breaker) I'd choose limited current every time. But I'm a software engineer, I have a certain set of criteria I apply to decisions. Other folks with different backgrounds might make different decisions.

Yeah, I was looking at the breaker specs today and realized that for most scenarios the 30A will have nearly the same functionality as the 40A (as you said). That was the part of our power system that I wasn't sure about and I mentioned in my post. I definitely agree with you on the control code, that is incredibly important to any drivebase.