Victor 884 Brake/Coast Issues

[patTeam241]

Thanks!

[dez250]

You can also directly access the Victor 884 User Manual to find other answers.

[Greg Ross]

Originally Posted by dez250

You can also directly access the Victor 884 User Manual to find other answers.

(I suspect you didn't mean that he could find different answers. )

Interesting. The diagram in the manual only shows "B" and "C" (no "A".) This is the way the Victors were the first year or two we received them.

Here's your mnemonic*: Ignore the "A", and remember that "B" stands for "Brake", and "C" stands for "Coast". Set the jumper nearest the "B" for "Brake" mode, and toward the "C" side for "Coast".

*Mnemonic: n. A device, such as a formula or rhyme, used as an aid in remembering.

[jgannon]

I'm curious to see which setting teams use for the Victors on their drive train. We used Coast last year, but while I was testing my new drive code, I set them all to Brake, and I felt like I had much more control. I'll probably leave them on Brake when we build the real robot.

[sanddrag]

We're just going to have to try it once we have something to drive. I have one question though. Are there any downsides/problems with braking only one motor in a dual motor gearbox?

[jgannon]

Originally Posted by sanddrag

We're just going to have to try it once we have something to drive. I have one question though. Are there any downsides/problems with braking only one motor in a dual motor gearbox?

Why would you want to? I don't know if there are any problems with doing so, but I don't see any advantages, either.

[russell]

That would be interesting to try. Does the braking option just connect the leads of the motor, or does it actually sense any electricity coming from the motor and counter act it? If it just connects the leads then the motor will still turn, just not as well. You could use this to slow the robot without it skidding to a halt and other unwanted side effects of braking both motors.... I will have to try that tomorrow. We tried out brakes last year using the drill motors with their transmissions and the provided gear boxes (which were plastic and no good, and broke in competition) , and we concluded that it was horribly abusive to everything involved, including the rest of the robot which would decelerate at like 3+ gs (i just pulled that number out of nowhere actually but you know what I mean).

[Ian W.]

Originally Posted by jgannon

I'm curious to see which setting teams use for the Victors on their drive train. We used Coast last year, but while I was testing my new drive code, I set them all to Brake, and I felt like I had much more control. I'll probably leave them on Brake when we build the real robot.

I've used both, it depends on your goals.

My first FIRST robot, in 2002, I had the Victors set to Coast. The reason being, there was a scoring feature similar to this year's game where any (not all) robot back in the zone right in front of the driver station got you 10 points. By putting the Victors on Coast, it allowed me as a driver to wait until about two seconds left before just hitting the joysticks on full and zoom up to full speed, and then the match would end and power would be cut. But with all the momentum my robot had, it would fly across the line and one time hit the diamond plate so hard I actually scared a few of my teammates.

However, you may also want it to be on Brake, especially this year, because if you plan on stacking any tetras, as you are sitting in front of the goal, you don't want to be pushed around. Brake mode doesn't eliminate pushing, but it definitely makes a big difference in how hard it is to push you.

Lastly, you may want to figure out a way to alternate, if your strategy depends on getting back in the last few seconds. I've never tried to switch them during a match, but it is possible, the Victor polls those pins something like 100 times a second.

[jgannon]

Originally Posted by russell

Does the braking option just connect the leads of the motor, or does it actually sense any electricity coming from the motor and counter act it?

It just connects the leads. It stops CIM motors running at full speed pretty quickly, though.