victor brake/coast setting
 

According to the manual, the jumper to set brake/coast on the Victor can be replaced with a limit switch - not particularly useful. According to the custom ciruits rules, we can't make something to replace the jumper. I'm also assuming that a relay or transistor would fall under the category of custom circuit. I just wanted to make sure that I'm interpreting the rules correctly. It just doesn't seem like that great of an idea to actuate a limit switch with a servo or soleniod or something to dynamically change the setting.

Re: victor brake/coast setting
 

Last year there was a thread about this. The way to do it completely within the rules, is to use a servo to act on the "limit switch." This year there is no rule limit on how many servos you use on your bot, there will be a point where you run out of places to plug them in.

Re: victor brake/coast setting
 

I'm not certain of any of the rules and I don't make any claims on the legality of this but look at it this way, what is a jumper? What is it's purpose? It bridges the gap between two pins. A physical electrical conection. What if instead of that little bar of metal, you had a wire connecting those two pins? What if this wire became an inch long? Then why not a foot long? And what if cut this wire right in the middle and install a switch. Opening and closing this switch would have the same effect as placing and removing the jumper.

Re: victor brake/coast setting
 

Well, my goal was to use a relay or something so that it can be controlled in software. Useing a servo to actuate a switch doesn't seem very efficient - or fast - to me.

Re: victor brake/coast setting
 

You might surprise yourself. Use a switch that is easy to "open" and "close" like a limit switch with one of those long metal strips.

Re: victor brake/coast setting
 

We have done this with an array of relays for the last two years and had no problems with inspection. I havn't read the rules carefully enough to see if it is legal this year though.


------------------- Edit --------------------------
It Looks to me like Rule R51 prohibits this sort of thing. There may be a loophole however. I believe that all the jumper does is pull a pin either high or low. there is no rule that i can see that prevents you from directly connecting this pin to a digital output. I wouldn't consider this a "custom circuit". This may be a loophole but i feel it does not go against the spirit of any rules. You are not providing a PWM outpur, not directly controlling movement and not posing a safety rist. BTW I believe the signal pin is the middle one.

Re: victor brake/coast setting
 

This method (direct connection to the controller) was addressed last year in Q and A on the first site, and as I recall was not allowed, The relay method would seem logical even if you have to drive it with a spike. I would suggest spell out exactly how, including a wiring example and submit it to the Q and A process.
Thanks in advance -Biff

Re: victor brake/coast setting
 

Sci,
Please keep in mind that many rules are made to prevent damage to IFI hardware or to prevent bodily harm. (It's expensive to replace.) Using a limit switch prevents any team from connecting power supply to one of the pins. It is also to prevent a team from using underrated electrical components from supplying power to the motors. A fire on the field could rain on everyone's parade.

Re: victor brake/coast setting
 

If anyone posts a Q&A on this, please post it here. It doesn't seem like there should be anything wrong with driving it with a digital output.

Re: victor brake/coast setting
 

Max,

The digital outputs are powered from the controller. The brake/coast jumper is powered from the Victor. Directly connecting two power sources is what they are trying to avoid here. A dry contact switch is what is required to replace the brake/coast jumper.

Re: victor brake/coast setting
 

Don't make these kind of assumptions. A closing (dry, no voltage) contact is what is required.

Re: victor brake/coast setting
 

Q&A says that the relay is fine as long as it's allowed by the part use flow chart. Pretty much, if you can get a relay from the approved vendors, it'll be fine.

question #1189

Victor Braking
 

I know that the vics can go into break mode when the jumper is in one position, anyone know which that is (left or right). The help file doesn't show it. Thanks!

Re: Vic Breaking
 

If I remember right, when the jumper is in position A-B, the Victor is in brake (not break) mode. When it is position B-C, the Victor is in coast mode. I also searched and found it in an old thread. I'm assuming things haven't changed since then...

It should be pretty obvious if you have it in the wrong position when you test it out.

Re: Vic Breaking
 

from the ifi manual



if the pin is set to the left it is set to break
if the pin is set to the right it is set to coast

Re: Vic Breaking
 

Thanks!

Re: Victor Braking
 

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

Re: Victor Braking
 

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

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.

Brake or coast on drive train Victors
 

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.

Re: Brake or coast on drive train Victors
 

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?

Re: Brake or coast on drive train Victors
 

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.

Re: Brake or coast on drive train Victors
 

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).

Re: Brake or coast on drive train Victors
 

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.

Re: Brake or coast on drive train Victors
 

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