Spazing Robot

[Matthew_H]

We had a problem with our robot spazing after only 30 sec of driving. We went thru our robot and found that we had wired the small fans on the Victors directly to the power side of the Victors. When we rewired the fans to go to thier own circuit the spazing stopped. Can anyone else confirm this or has any other team had this problem?

[Tom Bottiglieri]

i dont see why wiring them to the voltage in of the victors would make any difference at all. They draw so little power, and it should not affect The actual ouput of the speed controller.

[pi_guy578]

Originally Posted by Matthew_H

When we rewired the fans to go to thier own circuit the spazing stopped.

Interesting. On our robot we also wired it to the power side of the victor and had no problems. I think that possibly your fans we're incorrectly polarized and after thirty seconds of ineffective cooling the triacs stopped working properly and started "spazing".

[Ian W.]

Originally Posted by Matthew_H

We had a problem with our robot spazing after only 30 sec of driving. We went thru our robot and found that we had wired the small fans on the Victors directly to the power side of the Victors. When we rewired the fans to go to thier own circuit the spazing stopped. Can anyone else confirm this or has any other team had this problem?

Could be that you're pulling too much current through the speed controllers' circuit breakers, and tripping the fans in the process. That leads to ineffective cooling, which could make the speed controllers unhappy, leading to what I've affectionately named the "Robot-Not-So-Happy" Dance. We had problems like that last year, we tried rewiring the fans, and no problems so far (unless someone knocks the fan cable out...).

[Greg McCoy]

The Victor fans should be wired to the left terminals (GND and +12V, not M-/M+ on the right hand side) on the Victor, right along with the connection to the appropiate fuse block.

This way, the fan operates whenever the Victor is powered. There's really no need to wire all the fans together and power them through a breaker or something (which sounds like what you did); it sounds like a good way to smoke your Victors if that circuit disconnects for some freak reason too

The fans should have absoultely no effect on robot operation in terms of driving, motor movement, etc. They only keep the Victors from overheating. If your robot is having control problems, I would suspect that there is faulty wiring elsewhere, bad code, or possibly radio interference. Can you post more details on the nature of the robot's behavior when it's spazzing out??

EDIT: A diagram of the correct wiring is on the first page of the Innovation First User's Manual for the Victor 884.

[Andy A.]

I've asked around about just how important cooling is for the victors.

Every responese I've heard so far is: In 2 minutes, at the loads we opperate, no one should ever be able to smoke a healthy victor with our with out the fan running.

All the same, the strong recomendation is to wire the fans to the 12v+ and negitive terminals. Make sure that the fans' red lead is on 12v+. They will either not function or not function well if hooked to reverse polarity. There is no good reason to wire the fans to a seperate circuit, and plenty of reasons not to.

I suspect that in the process of rewiring the fans, you fixed the real problem. My guess would be a loose terminal screw that was causing intermentint contact and possibly overheating.

-Andy A.

[Greg McCoy]

Originally Posted by Andy A.

I've asked around about just how important cooling is for the victors.Every responese I've heard so far is: In 2 minutes, at the loads we opperate, no one should ever be able to smoke a healthy victor with our with out the fan running.

Maybe, but what about the finals where you can be in up to 9 quick matches? That's 18 minutes

You should just wire them the way the user manual tells you to. I would recommend also checking for frame grounding, make sure that all of your connections are well-insulated and wired the way the FIRST diagram shows.

[Matthew_H]

The only evidence that I have is that once we rewired the fans on the Victors then the spazing stopped. I ran into another team st the Palmetto regional that was wired the same way and they too were spazing after a few seconds. I am not sure if they rewired but I fairly sure that the rewiring of the fans got rid of the spazing problem.
By the way this was the only thing that we rewired because we were going one by one to find were the problem really was. During the St Louis regional we were pretty much undrivable but in Palmetto at least we could drive the entire match. We did not end up so well overall but at least we now have a drivable robot to take to demonstrations.

[Ian W.]

Originally Posted by Greg McCoy

The Victor fans should be wired to the left terminals (GND and +12V, not M-/M+ on the right hand side) on the Victor, right along with the connection to the appropiate fuse block.

This way, the fan operates whenever the Victor is powered. There's really no need to wire all the fans together and power them through a breaker or something (which sounds like what you did); it sounds like a good way to smoke your Victors if that circuit disconnects for some freak reason too

The fans should have absoultely no effect on robot operation in terms of driving, motor movement, etc. They only keep the Victors from overheating. If your robot is having control problems, I would suspect that there is faulty wiring elsewhere, bad code, or possibly radio interference. Can you post more details on the nature of the robot's behavior when it's spazzing out??

EDIT: A diagram of the correct wiring is on the first page of the Innovation First User's Manual for the Victor 884.

The reason wiring the fans seperately is if you do blow the Victor's breaker, the fan will keep running to ensure, without a doubt, the Victor stays cool. Sure, it's more work, but I'd rather be stupidly safe than sorry.

The only advantage I've seen to having the fan wired through the Victor's terminals is that you can see when the Victor is off, but they have the nifty LED anyways.

Remember, it can't ever hurt to be extremely careful, it just takes a bit of extra planning to make it all work.

[Venkatesh]

There is no good reason to wire the fans to a seperate circuit, and plenty of reasons not to.

When I had first heard about a team (i forgot which) connecting their fans to an independent circuit, I thought that it was such an ingenious idea. When the Victors trip their breakers, they can still be cooled. I thought that it should have been obvious to me.

I can't think of any problems that could be caused by connecting them in a separate circuit. Could you please explain?

[Al Skierkiewicz]

Matthew,
Let me chill one post above, there are no triacs in the speed controllers, the power devices are all power hexfets. They are able to be turned on and off better than triacs in DC circuits and have a lower "on" resistance. What you describe as the problem may have in fact been only related to your wiring, not that you moved the fans and corrected the problem. If the fans were wired to the supply side of the Victors (+12 and Gnd)) then you likely had a high resistance connection due to the addition of the fan wires/terminals. High resistance connections heat up with time and usually produce intermittant contact as they heat. It is a dominoe kind of effect. It is unlikely that the fans were drawing enough current to trip the breaker feeding each speed controller if you had wired the robot according to the manual. (You should not have been able to pass inspection if there was a problem with wiring.) I think what happened is you tightened the connections when you rewired the fan supply and that corrected the original problem. The fans provide some cooling to the power devices but they already are pretty efficient little beasties. Remember that the speed controllers are operating in an "H" configuration so only two of the four banks are on at one time. If you are using a tank tread drive the speed contollers could get warm after a two minute match but if the fans are wired as speced in the manual, the fans should be running the minute you turn the robot on. Since there is not a lot of thermal mass in the contoller, the fans ought to do a good job of cooling before you retrieve your robot at the end of a match.

[kmcclary]

Another issue is HOW you wire the primary power leads on the Victor.

If for example you have any wires wound around the screw instead of using ring tongue lugs, you can easily jam the screw. A piece of stranded wire can "lock up" the screw, making it FEEL like it has bottomed out, when it has NOT. This is especially true of the thin fan wiring. This causes a loose primary wire, creating erratic operation as the robot wiring vibrates from accelerations. This condition may be evidenced by watching the lights on the Victor. If the light glitches out as you're driving around, you most likely have a bad primary power connection somewhere.

You should NEVER have a wire wound around the screw. ALWAYS use RING TONGUE LUGS. In addition, they need BOTH the proper hole size for the screw, AND the proper wire gauge size for the crimp end. Attempting to use an oversized hole lug can also create a dancing robot situation.

The way WE wire them, that has NEVER had a "dancing robot" problem, consists of the following procedure:

1) CLEAN THE SURFACES OF ALL LUGS, to remove any oxidation from storage. Sometimes, lugs have been sitting on the store shelves for years or even DECADES due to bad stock rotation rituals. It may LOOK clean, but often there is a slight, nearly invisible oxide coating that can interfere with good metal to metal contact. I use a few strokes of 600-1200 grit sandpaper to "polish the flats", and a stroke or two with a piece rolled up in a tube to "polish the wire hole". This action removes the oxides. It is important NOT to remove the coating, though. Just a SLIGHT cleaning action is all that is needed. In bad cases, I've used a TINY touch with a Dremel ultrafine sanding disk, but you risk coating removal with that method. (I've also used the paper peeled off of the "ultrafine" side of a cheap two sided fingernail sanding stick.) Now clean off the contact with some alcohol or contact cleaner/degreaser to remove any grit and oil (or you may be WORSE off than doing nothing at all!)

2) Trim the fan wires to length to get rid of the excess. Attach the appropriate sized ring tongue lugs to them. Since the fan wiring is SO thin, and the most common "small" ring lug is only 20-24 gauge ("red" coded insulator) we double up the bare end (strip to double bare length, then fold the end back), to thicken it slightly. This insures a GOOD crimp contact.

3) Crimp on the appropriate gauge wiring ring tongue lugs to the primary power wiring.

4) Remove the left (raw power) screws from the Victor. Inspect the Victor's case clips. They're normally NEW, but if you're reusing old Victors from previous years, be sure THEY are clean as well. If there is any oxide coating, remove it as well. Ditto with the screws. Hold the screw with a pair of lock jaw pliers, and use a small wire wheel to clean off the threads and the underside of the head. Don't put chemicals into the Victor, though. Use a clean cloth moistened slightly with your alcohol or contact cleaner/degreaser and wipe it instead of spraying it. I also hold the Victor "upside down" while polishing their bare contacts, then vacuum, to insure metal flakes don't drop into the screw holes and get into the internal works. (Make sure Gravity is your FRIEND...)

5) Stacking order: Place the FAN wires on the screw FIRST, THEN an "internal star lock washer", THEN the power wiring. All Reds go on the "+" screw, All Blacks go on the "-" screw. Reattach the screws. From the BOTTOM UP, your stack should now be: Frame contact on Victor, POWER lead wiring, internal star lock washer, FAN lead wiring, screw head.

(An "internal star" lock washer is different from a "split" lock washer. Instead of a cut circle bent to look like one turn of a helix, this looks like a solid ring, with spokes pointing toward the CENTER of the screw, each twisted slightly to bite on BOTH the upper and lower surfaces.)

This order guarantees that the POWER wire is HARD DOCKED to the contact on the case of the Victor, and there are NO loose wires from the fan to jam the screw. The lock washer also acts a a "tensioning spring" to insure it won't vibrate loose. The INTERNAL teeth make NUMEROUS bites around the perimeter of the lug, forcing GOOD contact (an EXTERNAL star may not bite the lugs AT ALL).

If you stacked in the REVERSE order, it forces the current THROUGH the fan lug, adding additional surface to surface contacts. If clean, it doesn't matter, but IF NOT, and there is corrosion on ANY of these surfaces, it WILL add resistance, and/or cause intermittent operation.

To reiterate: The most important things are: NO raw wires (only connect using the RIGHT sized lugs), ALL contact surfaces and connectors are CLEAN and FREE of oxides, and the POWER wire lug is against the Victor's frame contact (NOT the FAN wire).

This MAY sound like OVERKILL to some, but trust me, THIS WORKS. Once you get into this ritual HABIT, it only takes a few seconds per lug to do, and you've guaranteed they're all clean and have fantastic electrical contact.

I hope this helps!

- Keith

[Andrew Schuetze]

Originally Posted by kmcclary

5) Stacking order: Place the FAN wires on the screw FIRST, THEN an "internal star lock washer", THEN the power wiring. All Reds go on the "+" screw, All Blacks go on the "-" screw. Reattach the screws. From the BOTTOM UP, your stack should now be: Frame contact on Victor, POWER lead wiring, internal star lock washer, FAN lead wiring, screw head.

(

I would appretiate comments on what I understand to be a new idea for our team in regards to wiring of the cooling fans on the Victor's.

The above post is suggesting that the wire leads from the fan atop the SC be wired directly to the power terminals of that same Victor? If this is the case, have teams using this wiring scheme every had issues with inspection?

I really like the idea as it cleans up the nest of wires around the controllers. We have always ganged two or more cooling fan sets of leads to single female spade connectors and taken then to a circuit breaker panel and run them off of a single 20 amp breaker.


Thanks for your input in advance and the excellent idea if it jives with FIRST rules.

APS

[KenWittlief]

I think its fair to say that almost all teams connect the fans to the power side of the Victor, using crimp terminals, and Ive never heard of anyone having repeatable problems with that setup (you put them there, the bot acts funny, you power then from the breakers, the bot is ok, you put them back on the victor, the bot acts funny....)

the one thing I found is put the fan wires on first and put the terminal upside down and the power terminal rightsideup - they stack better that way - back to back.

[kmcclary]

Originally Posted by Andrew Schuetze

I would appretiate comments on what I understand to be a new idea for our team in regards to wiring of the cooling fans on the Victor's.

The above post is suggesting that the wire leads from the fan atop the SC be wired directly to the power terminals of that same Victor?

Correct.

Originally Posted by Andrew Schuetze

If this is the case, have teams using this wiring scheme every had issues with inspection? I really like the idea as it cleans up the nest of wires around the controllers.

This is a common, and legit configuration. We've NEVER had a problem with the inspectors.

For 99% of all apps, the tiny extra load won't matter. Payloads are normally intermittent, and it's only one fan. That's less than an amp, a few percent of the breaker's limit.

Drivetrains are normally the biggest current hogs, (and if you're THAT close to the limit, wiring the fan elsewhere probably won't help you... Look first for binding, friction, and/or review your design approach.) There are many ways to design drivetrains so they won't pop breakers. I could describe some, but that's not the point of THIS thread.

I can say though, on both of my teams we've always tied each fan to its Victor (AND designed for "robot wrestling stalls"), and have YET to pop a breaker. This year, we even held fast with TWO robots trying to push us away from the drop. So I know it CAN be done...

BTW, I also agree with the "flip the lug" comment. We do it, but I forgot to mention that. The final top-down order of a "fan up Victor" should be: Screw Head, Fan Lug (loop UP), internal star lockwasher, Power Lug (loop DOWN, and clearing the top surface of the Victor), bare Victor metal contact. All contact surfaces should be clean, and free of oxides.

The other thing I forgot to mention is to be sure the lugs are NARROW enough, so that they fit FLAT between the raised plastic bump "guides" on the Victor. They should NOT be at an angle, nor rock back and forth! If it is at an angle, it it WEDGED between the guides. One end is raised, and is not contacting correctly. To correct this, grind the lug width down with sandpaper, a file, or a Dremel tool so it fits nicely between the guides.

I hope this helps!

- Keith