elim field issue?

[R.C.]

We had this issue but not at Atlanta. In 2 matches at Davis, we started our auto and then we didn't move in teleop. It seemed as the field missed our tele op. We called a timeout but couldn't see anything wrong. Next match we moved just fine.

-RC

[steelerborn]

I am not to savvy when it comes to electrical problems.
But we had a similar problem last year with current running through the bot.
What may be the problem is an exposed wire that was touching a metal part sending current through the frame. We had a hard time connecting to the field for all of our second regional last year.

If you guys were running then losing coms this may be the culprit.
Then when the bot goes back to the pit, to try and solve the problem the exposed wire may have been moved slightly, and not touching a metal component. This could have been completely by accident and the problem may never occur again. But you may be out multiple matches before the wire is moved.

I know that experience last year motivated us to mount all of our electronics on thick plastic to eliminate this problem (overkill because it added a ton of weight that wasn't necessary).

[MagiChau]

Originally Posted by steelerborn

I am not to savvy when it comes to electrical problems.
But we had a similar problem last year with current running through the bot.
What may be the problem is an exposed wire that was touching a metal part sending current through the frame. We had a hard time connecting to the field for all of our second regional last year.

If you guys were running then losing coms this may be the culprit.
Then when the bot goes back to the pit, to try and solve the problem the exposed wire may have been moved slightly, and not touching a metal component. This could have been completely by accident and the problem may never occur again. But you may be out multiple matches before the wire is moved.

I know that experience last year motivated us to mount all of our electronics on thick plastic to eliminate this problem (overkill because it added a ton of weight that wasn't necessary).

Use zip ties :O

[Ryan Gordon]

Originally Posted by steelerborn

I am not to savvy when it comes to electrical problems.
But we had a similar problem last year with current running through the bot.
What may be the problem is an exposed wire that was touching a metal part sending current through the frame. We had a hard time connecting to the field for all of our second regional last year.

If you guys were running then losing coms this may be the culprit.
Then when the bot goes back to the pit, to try and solve the problem the exposed wire may have been moved slightly, and not touching a metal component. This could have been completely by accident and the problem may never occur again. But you may be out multiple matches before the wire is moved.

I know that experience last year motivated us to mount all of our electronics on thick plastic to eliminate this problem (overkill because it added a ton of weight that wasn't necessary).

For us, we had several of the experts check it, including Big Al, all with the prognosis that everything is fine.

We're still not sure what was going on. We replaced a Jaguar that we thought might've been shorting but it still happened. Our last guess was the wireless bridge but there were no more wireless bridges to test it out.

We were literally standing next to 254 on the Archimedes field when their robot lost comm. during the elim. rounds and it exhibited exactly the same symptoms we had.

[Alan Anderson]

A working autonomous but no control during teleop is a pretty specific symptom. It points to the Classmate losing its connection with the USB devices. Letting it go to sleep before connecting to the field has been known to cause this problem. It can supposedly be recovered from by rescanning the input devices.

[Tom Line]

Originally Posted by Alan Anderson

A working autonomous but no control during teleop is a pretty specific symptom. It points to the Classmate losing its connection with the USB devices. Letting it go to sleep before connecting to the field has been known to cause this problem. It can supposedly be recovered from by rescanning the input devices.

We had this issue once, at the West Michigan District. The quick-thinking driver and driver coach rescanned the devices and then was able to start driving.

[Bill_B]

Originally Posted by steelerborn

I am not to savvy when it comes to electrical problems.
But we had a similar problem last year with current running through the bot.
What may be the problem is an exposed wire that was touching a metal part sending current through the frame. We had a hard time connecting to the field for all of our second regional last year.

.....

A single exposed wire touching the frame would not cause current to run in the frame other than charging its capacitance, that is, minuscule. The possibility of serious short circuits is the principal reason FRC robots are forbidden from using the chassis grounding method that is nearly universal among automobiles. In that case, a wire that contacted frame metal via frayed insulation would almost certainly be a short circuit.

Part of your electrical self-inspection should be a voltage check between all of your fuse-block outputs and the frame. It should be zero in all cases, of course. Resistance checks are a bit trickier, but so is infinity. Just ask Buzz Lightyear. I haven't watched event inspectors, but I'd guess they do some elementary measurements, don't they?

[johnr]

Erich, where you watching the match when 888 went dead? If you are going by the posted results i think there is something wrong with them or i may be totally mistaken on the location of driver station. I do know that they worked on that bot a long time and maybe i just saw people working on it and figured that was the team behind glass. After about sixty matches, to go down without a fight is just a bitter pill to swallow. I just feel really bad for our seniors.

[Liz Smith]

Originally Posted by johnr

Erich, where you watching the match when 888 went dead? If you are going by the posted results i think there is something wrong with them or i may be totally mistaken on the location of driver station. I do know that they worked on that bot a long time and maybe i just saw people working on it and figured that was the team behind glass. After about sixty matches, to go down without a fight is just a bitter pill to swallow. I just feel really bad for our seniors.

Apparently, 888 narrowed down their issue to a bad digital sidecar. One indication was that their RSL never turned on at all. Tough break that it happened in the crucial elimination rounds.

[EricH]

Originally Posted by johnr

Erich, where you watching the match when 888 went dead? If you are going by the posted results i think there is something wrong with them or i may be totally mistaken on the location of driver station.

I was going by the posted results, as I was really only watching Archimedes. I'm guessing that you got the wrong drivers station, or the wrong match, or maybe they hadn't changed the number yet.

But, if it's a bad digital sidecar, then it is not a field issue, at least on that field.

So far, we've had:
888, Curie--bad sidecar.
910, Newton, QF4-3--unknown (Red 1). Suspected that the Classmate lost USB.
254, Archimedes, SF1-1--unknown (Red 1). Suspected that the Classmate lost USB.
2854, Archimedes, quals/QFs--unknown, different symptoms.

Sounds like a coincidence to me.

[steelerborn]

Okay thanks I love learning about new things.
That is what first is all about.

Actually we also didn't isolate the crio from the frame.

The ispectors did a great job and did check.
But we went through with a bad crio.
When we told them we would have to switch it out they just said okay and let us go through.
When we were mounting it we had someone make a mistake.
So that was our problem.
I just had to ask a mentor to get the exact reason.

But I think it sounds like just a coincidence too. With different symptoms as well.

[FoleyEngineer]

Just got back from Championships. Had a GREAT time! Was a huge bummer to lose the rubber match and not have 3 on 3. That's the only way I want to win or to lose - with everyone at full strength!

Here's what happened...

1) Never lost comm the whole event.
2) First playoff match our alliance captain was in the Red 1 station and had intermittent comm during their match. Cost us the match 12 to 9.
2) Second playoff match everyone ran and we won it 12 to 8 I think.
3) Third playoff match we're in Red 1.
- Robot works fine in systems check right before putting it on the field (with a tether of course).
- We power up on the field, go to the driver station, everyone gets comm but our station (R1).
- I run out onto the field and the FTA joins me. We look at the radio and it has Power and Ethernet but no Data/Activity.
- He says to recycle the radio or robot. I ask which he wants and he says do the whole robot. I do so and walk back to the Driver Station.
- Everything comes up fine. We run auton, never "hit" anything or any bumps or anything but notice it ends it's auton run by just "coasting" to a stop (not normal). We look down and see no comm!
- FTA runs over to our station and resets something but it doesn't come back.
- After the match we all look and again, Power, Ethernet, no Data Activity to the field radio.
- FTA says he's seen a lot of radios just crapping out and maybe that happened to ours even though it comes back the next time. No recourse, we're done for the championships. Blech.

I'm going to run that same radio (we have two) back at the school for a few weeks and see if it ever loses comm again. We'll run it literally for dozens of hours and if it never loses comm again, I have to believe it's a flakey field issue. If it fails, then I'll swap in the backup radio and see how that goes.

BTW, our entire electrical system is on thick lexan, nothing is grounded to the frame, everything is shielded, zip tied and super clean. I really, really doubt it's a wiring fault. We did check multiple times as part of our pre-inspection checklist for all 4 events we've been to including Championship and nothing is connected to ground. Also, our power cable to our radio is very securely taped to the radio. You can not possibly remove it without taking a 2" wide piece of tape wrapped around it from the top to the bottom of the radio. It cannot shake or jiggle loose. Same for the ethernet.

If you all have any suggestions for other diags to do, we'll give them a run when we get it back in a couple weeks. Would be great to track this down as it cost us huge.

Thanks!
John

[AlexD744]

Originally Posted by EricH

I was going by the posted results, as I was really only watching Archimedes. I'm guessing that you got the wrong drivers station, or the wrong match, or maybe they hadn't changed the number yet.

But, if it's a bad digital sidecar, then it is not a field issue, at least on that field.

So far, we've had:
888, Curie--bad sidecar.
910, Newton, QF4-3--unknown (Red 1). Suspected that the Classmate lost USB.
254, Archimedes, SF1-1--unknown (Red 1). Suspected that the Classmate lost USB.
2854, Archimedes, quals/QFs--unknown, different symptoms.

Sounds like a coincidence to me.

Actually, I beleive Andy from 233, 254's alliance member, told me that they had replaced their radio, still had the problems and then were in the process of replacing their cRio. And I bleive that they didn't have any problems after that. I also beleive 51, our opponent on Galileo, also replaced their cRio and at least for the match we played them in they were fine. Our team was also losing and regaining comms, and after we got out, we were told that it was most likely our cRio. I beleive it could be the ethernet jack in the cRio gets worn, between tethering and coding and eveything.

[NickE]

Originally Posted by AlexD744

Actually, I beleive Andy from 233, 254's alliance member, told me that they had replaced their radio, still had the problems and then were in the process of replacing their cRio. And I bleive that they didn't have any problems after that.

Correct. According to the FTA, it appeared that the cRio had "stopped running the program" mid-match, so we borrowed 971's cRio and had no further problems.

[Ryan Gordon]

Originally Posted by NickE

Correct. According to the FTA, it appeared that the cRio had "stopped running the program" mid-match, so we borrowed 971's cRio and had no further problems.

Ah, nice. I'm starting to think 2854 was having the same issue with a bad cRIO. Especially since we took it off of our robot last year as well.