2010 PEACHTREE REGIONAL

[goldenglove002]

In regards to the final match of the day, I can't say I'm happy with what happened. But it is what it is. Both alliances had great robots, and I wish we had gotten to see a real match occur in the end.

I was one of the team members in the question box, and this is what we were told by the refs and other staff. What happened to our robot was something of a "freak accident". The main breaker somehow slipped out of place by fractions of fractions of an inch. Never in my 3 years in FRC had I seen something like that occur. For team 34, they had 12 volts showing on their battery for the very beginning of the match. Then it died. It was a battery borrowed from the field, so we were all thinking there was something defective with the battery. The field staff said that because it had shown power at the begining it had to have been an issue on the robot. Would have been nice to let us check the voltage on the battery after the match to solve the mystery, but it'll just remain that way I guess. We could have gone on forever out there and never gotten anywhere, so thats that.

Anyways, congratulation to all the winners out there. It was a fun 3 days.

[rspurlin]

The Field management system keeps a log of data coming from the Drivers Station (classmate) and the robot. Those logs were reviewed for both teams that had issues in the final match. There was nothing in those logs that pointed to any kind of field error. Both robots had steady battery voltage throughout the match (all 135 seconds). The battery from 34 was later removed and tested. It still showed a full charge. What was relayed to me later was that it was apparently a failure of the main breaker. My own team has had some experience this year with the main breakers not actuating properly.

We do not have the luxury of rerunning matches until we get a result that has nothing whatsoever to do with robot parts failing. Would you also want to rerun a match when a robot breaks a chain 2 seconds into autonomous? Perhaps the biggest difference there is that no one would claim field failure when a mechanical part breaks.

For those that think that gracious professionalism should extend to the beneficiary of these failures calling for an extra match, where's the professionalism in not accepting the very best efforts of the volunteers who do their very best to run the event as fairly as possible? We'd all like to see every match decided with all robots performing at their best, but sometimes that doesn't happen and we have to accept it. Graciously.

[Ed Sparks]

Concerning the final match between alliance 1 and 3 ...........

The field did not fail. Unfortunately the main breaker on our robot did ......

I've seen this several times before concerning other teams, but this time it bit us. Our robot turned on just fine and connected properly to the FMS but one second into autonomus, communications was lost. The 120 Amp breaker opened up (not tripped) when the significant current started flowing (because we turn on our drive motors during autonomus).

I'm proud of our team, our robot, and especially our drive team. I would only change one thing if I could ............... that dang breaker.

This is a somewhat common problem so be warned. It could happen to you next time .......

Congrats to alliance #1. We'll meet again next year.

[Al Skierkiewicz]

Ed,
Too late to check now, but the breaker does have a failure mode that that prevents high current flow but appears normal otherwise. As a test, if the red button is tapped lightly and the breaker opens or becomes intermittent, the internal contacts are out of alignment.
There are also issues if the mounting/frame should flex, small cracks in the case develop. I have seen cracks pull the internals out of alignment.

Do you still have the breaker?

[Vikesrock]

Originally Posted by Al Skierkiewicz

Ed,
Too late to check now, but the breaker does have a failure mode that that prevents high current flow but appears normal otherwise. As a test, if the red button is tapped lightly and the breaker opens or becomes intermittent, the internal contacts are out of alignment.
There are also issues if the mounting/frame should flex, small cracks in the case develop. I have seen cracks pull the internals out of alignment.

Do you still have the breaker?

Al, is this misalignment more likely to occur this year with the violent impacts caused by bump traversal?

I might be adding something to our pre-match checklist...

[MikeReilly]

What a regional!

I would first like to express the amazing professionalism that the mentors have expressed in this thread. Martin Wilson (1771) and Ed Sparks (34) are showing just what this is about. Ironically, Martin won the Woodie Flowers Award last year, and our team "broke", and now Ed has incurred the same fate. Might there be a Woodie's curse?....(insert spooky sound here).

It was very different having the first weekend of matches this year. Thank you and congrats so much to the volunteers, refs and judges for your patience with our teams while we knew you were learning too.

Congrats to all involved, but especially to our new partner/mentee GSMST, Team 3318 for their Rookie All-Star Award!!
Also from our school district, Gwinnett County: 1379 winning the Industrial Design for the sexiest bot, 1261 with an inaugural Dean's List winner. 3 awards and a regional win for our school system is pretty cool!

See you at the Dome!

[Ed Sparks]

Originally Posted by Al Skierkiewicz

Do you still have the breaker?

Yep, It's still on our robot (but not for long). It's mounted on a piece of 1/4" polycarbonate that spans two frame struts. I doubt that the breaker had a chance to flex but I'll check things out when it gets home.

Thanks!

[ebarker]

Originally Posted by goldenglove002

Never in my 3 years in FRC had I seen something like that occur.

Breaker failures are not unknown. There were several reported in last year. We even had one that was caught before ship date.

Originally Posted by rspurlin

where's the professionalism in not accepting the very best efforts of the volunteers who do their very best to run the event as fairly as possible?

Absolutely - kudos to the volunteers !! They made the best call they could. Especially it being a week one event !!!!!

1771 / 1466 / 1683 flat out had the best game in town next to our b-list robot. We build robots like Georgia Tech does football. Pretty good but not good enough. 1771 rolls into the Peachtree like Alabama or Texas football. Definitely on their game.

Super congrats to the winning alliance. I wish we could have made it a little more tense and closer finish. Enjoy the win.

Originally Posted by Al Skierkiewicz

Ed, Do you still have the breaker?

Our breaker is on the bot and shipping to North Carolina. We are going to replace it. We can bag it for someone to look at or we can take a look at it ourselves. Are you interested in looking at it ? Do you want to see it in Atlanta?

Originally Posted by MikeReilly

Congrats to all involved, but especially to our new partner/mentee GSMST, Team 3318 for their Rookie All-Star Award!!
Also from our school district, Gwinnett County: 1379 winning the Industrial Design for the sexiest bot, 1261 with an inaugural Dean's List winner. 3 awards and a regional win for our school system is pretty cool!

The Dean's List thing is something that concerned me (because of the short notice) but my fears evaporated when the winners were announced. The Dean's List winners are outstanding !! I got to spend some time with one of them at a previous engagement. Outstanding indeed !! Gwinnett county did great and also congrats to CircuitRunners for producing an EI and a Dean's List'er. In their 3rd year of existance and a TON of work Westminster 2415 bagged a Chairman's - Congratulations -well deserved !!

And super Congratulations to Ed Sparks for the WFFA. I was surprised to learn that he was not a prior recipient. Congrats indeed !

[Al Skierkiewicz]

On the breaker, we should start a different thread in Electrical I think. The breaker problem I have seen in the past is due to a manufacturing error. As the parts are resistance welded, one of the contacts is welded out of alignment. Since the breaker is a bi-metal disk formed in a particular way to stay in contact until heated, this misalignment has changed it's shape. Although it passes testing, slight vibration causes the breaker contacts to separate. As a defect, the problem exists from the very beginning so a breaker that has made it through several matches and practice does not fall into this category. These breakers all fall subject to the tapping of the release button.
The base structure of the breaker is bakelite or similar material. If a crack develops in the base, the parts pull out of alignment inside the breaker and it becomes subject to electrical failure with movement. Hard hits to the robot frame coming off the bump could damage the breaker. Ed Sparks, I doubt a breaker mounted on polycarbonate could be damaged in this way but hardware may have been over tightened or something could have hit the breaker. In reading over the thread again, it was posted that the robot never stopped monitoring +12 volts throughout the match, so I am confused as to the report of a bad breaker.
Ed Barker and others, you can easily open a suspect breaker by drilling through the rivets that hold it together. This will reveal the internal contacts and spring action. If you find something interesting, I would like to see it in Atlanta.

[rspurlin]

I've seen students tighten the mounting bolts so much that the housing of the breaker cracks. This makes me think we could be causing the problem ourselves. I'd like to see some more info ont he best tests for these to weed out potential problem breakers. Perhaps this is something that inspectors could also look for.

[Ed Sparks]

So it looks like 34 and 1311 both had a main breaker failure on the last match of the finals. What are the odds? There's gonna be a lot of nervous teams in future finals.

I'll put future comments on this into the "new thread" when I have some credible data and I will definately disect the culprit when it arrives back in Alabama.

[Al Skierkiewicz]

Ed,
I reread the post from Alex on page 2. He said you had power at the beginning of the match but then failed. He also mentioned you had a field provided battery? Is it possible we are looking at the wrong part? Bad battery, cable or connector?

[Ed Sparks]

Originally Posted by Al Skierkiewicz

Ed,
I reread the post from Alex on page 2. He said you had power at the beginning of the match but then failed. He also mentioned you had a field provided battery? Is it possible we are looking at the wrong part? Bad battery, cable or connector?

Al,

It's true that we used a field battery so I suppose I cannot completely rule battery or connector failure out. We apparently had full voltage at linkup and then nothing 3 minutes later. I'm still leaning to the breaker. I actually saw this breaker failure happen to another team on Friday (I was on the field as an inspector/troubleshooter).

[ebarker]

Originally Posted by Al Skierkiewicz

Ed,
I reread the post from Alex on page 2. He said you had power at the beginning of the match but then failed. He also mentioned you had a field provided battery? Is it possible we are looking at the wrong part? Bad battery, cable or connector?

I just reread the post also. His comment about a 'field' battery has to be in reference to team 34 and if I were a good lawyer I'd classify it as hearsay. I'd prefer to defer to Ed Sparks et. al on their battery supply.

Regarding the ref statement about 12 volts - I'm with you there. I don't know how you get a good telemetry stream stating you have 12 volts and then can state there is no power to the robot. I'm NOT throwing the volunteers under the bus. They made their call and I'm good with that. But it don't make sense.

We can't do our assessment until April 1st in Raleigh. I'll quarantine the part and meet you in Atlanta. I don't want to open it until you have had a chance to see the part.

I absolutely don't believe we had a battery problem. We spent a fortune on a new 10 bay Deltran charger and had a total of 6 brand new batteries in our fleet plus 4 from last year. And a couple of students working on power management. We played ONE match per battery the entire weekend. The battery would come out and straight back to the charger. I know it isn't optimal for the battery but we can deep cycle them after the event. Even with all that effort we don't have the S/N on the battery for the failed match. We need to improve that.

One issue we need to inspect is a loose connector to the PD or power switch. That is an open question in addition to the potential defect on the switch.

Don't you love it - great great training ground for the students !!

"Just because it looks like a robot doesn't mean it is a robot." - Ed Barker

Al, BTW - I got drafted as a rookie barely useful robot inspector under the fine tutelage of Ed Sparks. I didn't get to put as much into it as I would have liked but hopefully it helped out. I think I'd like to volunteer to help out in Raleigh. Who do I talk to?

[Al Skierkiewicz]

Ed,
You were trained by one of the best. If you would like to help out, go to VIMS and sign in for Raleigh. If they have open positions they will contact you. If you work there and like it as much as Ed and I like it, we might need some inspectors in Atlanta.
Do you know what the charge current on the multibay charger is? These batteries get really upset if you charge at over 6 amps. I suspected early on in the build that battery damage from falling off the bumps and other rough handling would be a problem. As you know I want to find a smoking gun on problems like this.