communication errors at national

[Adams High Man]

whats up people? good job you champions!

so yea... our very first match, with about 15 sec to go, we got the evil blinking red no data/radio light. The robot came back 10 sec later, but we had been pushed off the ramp and lost :( . I went up to the controls guy, and he blamed our radio cables and gave us new ones. Yea, sure, it COULD have been our cables... but the kicker is that our ally died too! Anyone else on Curie have problems like that? we were on the blue side.

Then guess what. During semifinals, our robot drove for like 10 sec, then that red light started blinking again, and we were dead. It wasnt very good for us. without getting jostled or anything, the robot started working again with like 30 sec left in the match. We were on the blue side again. I myself wasnt down there during that match, but basicly the conversation between our drivers and the equipment guy was:
FIRST: it is your radio cables
us: you gave us these radio cables
FIRST: uh, it was a ground short

then supposedly one of the guys down there said something to the effect of: "we could find the problem in an hour, but we arnt going to"

so yea, i checked the robot out in the pits, and i couldnt find any shorts. It tethered up just fine.

It all seems pretty iffy, eh? eh? so did anyone else have communication errors like that?


have a good day all!

[Koci]

Match 90 on the Newton Field, right when autonomous ended, both us and our ally were disabled until 1:15 left in the match. None of the people working on the field understood it, so we replayed the match immediately. They thought there was something wrong with those big red emergency stop buttons, but we were never really given an explanation. I was glad they let us replay the match (we ended up tying), but they let the other team spend 10 minutes replacing their battery since they happened to bring a spare.

[Matt Leese]

If you lost radio communication for approximately 10 seconds, it sounds like your robot controller reset itself. When it does that, radio communication is lost and will re-establish itself. You either tripped the circuit breaker or your current draw was so great that it dropped the supplied voltage below 7.5 V and the robot controller reset. In this case, I highly doubt that there was a problem with FIRST's system.

Matt

[D.J. Fluck]

Also, i've seen that if the RC has a collision the RC can reset itself...

[Adams High Man]

Yea, it COULD have been our controller resetting... although both us and our ally lost communication . Also, i have noticed that when the RC resets, it takes less then a second to initialize. The OI takes like 5 sec to initialize, but that was plugged into the competition port... I highly doubt it was low voltage, as the battery was just charged, and during our first regional, we went all 3 practice matches on the same battery before we got low enough to reset. Our drive wheels arnt treaded, and they spin when the robot is pushing on the ramp, which was where we died, so i highly doubt they were stalled.

In the semifinals, the robot was dead for a heck of a lot longer then 10 sec... more like longer then a minute. Like i said, it started working again without getting hit by anything, and i couldnt find any loose wires afterwards.


ignore these links... i need them for a research paper in english and i am currently at school :yikes:

http://ccc.commnet.edu/libroot/hotpapertopics.HTM
http://www.soton.ac.uk/~engenvir/environment/noise_and_light/Noise.html
http://www.quiet.org/faq.htm
http://www.hsus.org/ace/12609
http://www.cenyc.org/HTMLPE/noise.htm
http://www.infoplease.com/ce6/sci/A0835810.html

[Al Skierkiewicz]

We have been trying to trace down some problems that we have encountered and other teams have related to us. I am sure that IFI is working on them too. It seems that on occasion a series of corrupt data packets get through. What effect this has is not clear yet because it does not always cripple communications. It seems that the modem, once it has lost handshake, will take a indefinite amount of time to relock. Of course, if you reset the robot controller it occurs quickly, but most of us can't run out onto the field during a match to reset the robot. I am suspecting an interaction between the radio modems and other radios. I would like to suggest to IFI to perform some hard testing with walkie talkies in close proximity to the control system. I am taking the side of RF interference causing distortion in the RF deck of the modem simply because I am more familiar with that type of interference. I have no hard evidence either way on this issue but will fill you in when we have something definite.

[dhendrix]

We too had problems in St. Louis and Houston.
We think it may be radio related, because we could
never find anything else. St. Louis was really bad, we
where dead one entire practice match for no apparent reason. In almost every match we had a short time
of no response from the robot. Then it would clear up.
We are going to do some relocating of electronics and do some shielding next year.

[Lloyd Burns]

We had a replay at GLR when the radio fell off the lexan wall, but during Curie practices our bot did its auton_mode thing; back and turn too much, then went forward to the far side of the ramp top. Then before reaching the ramp, it unexpectedly turned 20 degrees, and went straight up the ramp, pushed the boxes to the edge of the top, but not over, then backed down the ramp. Odd !

I was told Thunderchickens' radio modem data base could not have been responsible, being in another band (so why can't we use talkabouts ?) so I rewrote the code to read the program selection switches only once, at start-up, into a variable. I didn't download that program for a while, but it never happened again, even with the unchanged program.

Might this be the result of a large static build up on the ramp ?
Why does code that has seen two regionals suddenly misbehave..once only ?

[Dave Flowerday]

Originally posted by Lloyd Burns
I was told Thunderchickens' radio modem data base could not have been responsible
What is this 'radio modem data base'? I've never heard of it before.
being in another band (so why can't we use talkabouts ?)
First of all, the rule about not being allowed to use Talkabouts is really not enforced. Last year I used to kindly ask teams who were using them to stop; this year I just gave up. It seems a lost cause, and no one from FIRST seems to care. One of FIRST's reasons for not allowing them may be because some of the channels are in the 462MHz range which is almost exactly half of the frequency used by the radio modems, and harmonics could be a problem. The other reason I heard they weren't allowed is because FIRST themselves used to use FRS radios for communications. Personally, knowing how hard wireless interference issues are to diagnose, if you ask me the fewer RF devices in the area the better.
Might this be the result of a large static build up on the ramp ?
We didn't notice any static problems in Houston, and I think we were the team who had the most problems with it in the first place. However, your RC could have reset which could cause your program to start over.

[Ryan Albright]

we had that problem to but it was at the plant when we where building it luckly it never happened durning compettion but the quickiest thing to do is to reset the robot it takes 5 secs. The nice thing is there is are robot reset on the radiocontrolled part

[Lloyd Burns]

Dave:

Thunderchickens had a flyer (interesting terminology) advertising their scouting database: they were scouting all four fields at Houston, and claimed they were linked by some radio technology.

The idea of a radio quiet zone - no cells, no walkie talkies etc - is a good one, but it seems to be dissappearing in the face of disregard - as witness the above. It probably makes the diagnosis of control faults a lot harder, especially since it would be intermittent..

The Houston weather and the proximity to the gulf kept the humidity high. But the need to warm buildings in colder climes probably drove the RH to very low values - even with humidifying systems working to bring 'em up. If it goes too high, you get condensation in invisible areas of your plant. I'm glad that you guys got your static problems licked; it sounds like you did a lot of work on it.

[Matt Reiland]

We had a problem on Archimedes in the practice rounds where the robot never got communication the entire match, it had never happened to us in any regional or event. However after the match we noticed the next team in line had already hooked up their control system even though they weren't supposed to until after our match was over. Our theory was that this might have been on the same channel? Any one out there know if there are only two channels per side of the field or did we just have bad luck in this match?

[Dave Flowerday]

Originally posted by Matt Reiland
However after the match we noticed the next team in line had already hooked up their control system even though they weren't supposed to until after our match was over. Our theory was that this might have been on the same channel? Any one out there know if there are only two channels per side of the field or did we just have bad luck in this match?
Yup, I'll bet that's what happened. The radio modems we use are only capable of 40 channels. Divide by 4 (assuming they reused channels on Einstein since it was only used when the other fields were off) leaves you with 10 channels per field. The channels are close enough together that most likely Innovation First avoided assigning consecutive channels anywhere in the arena, so probably there were only 5 usable channels per field, which means that channels would have to be reused across the two sets of starting positions.

I don't know any of this for certain, but this seems logical.

[Jeff Waegelin]

I know in Archimedes QF 2.1, we put our robot out on the field, turned it on, and got a No Data/Radio light. We thought it was our radio not plugged in (happened to us on Thursday), but we checked it, and there were no problems. About that time, we realized 47 was checking their bot out, too, for the same reason. It turned out that the teams from QF 1 had left their controls plugged in. They unplugged their controls, and we were fine.

[Adams High Man]

more unrelated links for school... :ahh:

http://www.forestpests.org/southern/Diseases/wprd.htm

http://fhpr8.srs.fs.fed.us/idotis/diseases/wpnrootd.html

http://www.ag.uiuc.edu/cespubs/hyg/html/200104i.html

http://209.104.139.151/ipac20/ipac.jsp?session=105S515W016K1.21299&profile=main--1&uri=link=3100008@!235634@!3100001@!3100002&aspect=basic&menu=search&ri=1&source=209.104.139.151@!horizon&term=White+pine.&index=SUBJE#focus

[D.J. Fluck]

Heh, I send links to myself too, but Ive figured out that PM'ing them to myself works too ;)