Team Update 17

No rule changes or clarifications. Lots of information and lessons learned about software and electrical.

http://www.usfirst.org/uploadedFiles/Robotics_Programs/FRC/Game_and_Season__Info/2011_Assets/Team_Updates/Team%20Update%2017.pdf

Perhaps the lack of game rule changes means that they’ve found a solution to the minibot tower scoring issue, or that they’re close enough to one that they don’t feel a need to change the mechanic.

As always, clarification regarding inspection, electrical systems, and whatnot is welcomed, since we’ll see more teams on the field earlier.

I’m surprised that there are no actual rule changes. Well actually I’m surprised the game plays so well. So I guess I’m not surprised about the lack of changes.

I wonder if the CAN errors happened enough that they had to be mentioned in the update. We had one CAN error, and it just HAPPENED to occur in round 1 of the finals :confused:

I think my team had two during qualifications. Then for eliminations we blew a jaguar so CAN didn’t exactly work anymore.

After having multiple CAN issues at Alamo we finally swapped out the CAN network for PWM and never had an issue after. I would recommend everyone having issues seriously consider swapping. We will also probably be swapping the jaguars for victors as the reliability of the jaguars has been far too suspect to trust.

We also swapped our CAN system out for PWM near the 5th week of build, we are happy with the decision but really wanted to get CAN properly working.

Come on, we learned that way back in 2009. Get with the times, man. :rolleyes:

With 1771 we had occasional issues but never enough to make me say “screw this” and swap them. However, at Alamo with 2415 this year, CAN cost us 2 matches and potentially being in a picking position. Might not have changed the outcome at all but still not moving for 2 matches for an error out of our control is a huge problem in my opinion.

We used CAN successfully last year, and are planning on using it this year. We will try the simulation procedure outlined in team update 17 and see how it goes. If it fails, we will switch to PWM. If it works, we will try it in a practice match before competition.

I have heard that there may be a CAN issue with using the CrIO imaging tool this year.

:smiley: Hey cool they used 11 as the example for BOM naming!

I think Team 11 is still using CAN, do those of you who had issues suggest switching out to PWM?

/15minutesoffame

We have 8 Jaguars using CANbus this year, and much prefer the CANbus wiring to PWM cables. I know there were teams at GSR over the weekend having significant issues with CANbus, and one team even switched over to using PWM control of their Jags during Friday afternoon, but we did not see any problems. The field crew were keeping a very close eye on the diagnostics tab of our driver station (thank you!), especially during the later stages of eliminations. We’ve used CANbus every year since it became available and have been very happy with the results.

We have also not seen the same reliability issues with Jaguars - the worst thing that happened to us this year was a Jag on our practice bot randomly changing from id=3 to id=59 overnight. It took a few minutes to work out what the problem was but once we reset the id everything was fine. We number all of our Jags so we’ll know if it ever happens again to the same one.

If anything, I’d say that we have more experience of Victors failing than of Jaguars failing, but I’d be more inclined to put that down to our team getting better at not sprinkling robot electronics with metal shavings since we last used Victors than any intrinsic reliability difference.

Noel

Using 2Can or the Serial to CAN bridge on the black jags? We tried using a 2CAN and had nothing but problems once we had some longer wire runs and more devices on the bus. In the end we scraped it and went with PWM.

We are using the serial to CAN bridge. We’ve never tried the 2Can.

Noel

“If a team is using a CAN network on the robot, they should check the messages in the “Diagnostic” tab of the Driver Station before a match starts to ensure that there aren’t any scrolling CAN timeouts.”

Can someone please explain how messages get on the diagnostics tab? We’re using Java and currently outputting text to the User Messages portion of the Operation tab using the DriverStationLCD object when we catch a CANTimeoutException. How are other people handling these exceptions?

Wow, Chris your future perception is impeccable considering the CAN functionality was introduced in 2010 :wink: . Can we get some picks in the upcoming Regionals and Championship? :smiley:

Looks like I will be teaching my Comp Team how to read CAN Errors. I hope it works at competition because it was working fine in the lab. The only time I had issue last year was when the serial cable would shake loose (cRIO was near the kicker). I ended up replacing those modular adapters
(6P6C to DB-9 Female) recommended for use in the Getting Started Guide. It works, and the instructions are easier for teams to follow using COTS adapters, but vibration is a major issue. You will get a more vibration resistant connector if you use old serial cables or solder directly to DB9 connectors. I think there are old serial cable instructions in this white paper. Also, we started soldering the 100 ohm resistor to a small PCB so the the leads don’t break. So a good cable is not simple to make, but can save you headaches later. Maybe AndyMark will start selling prefabbed serial cables for those who don’t buy those nice little 2CAN devices…

EstopRobotics carries them.

CAN Starter pack (DB9 - RJ12, 2 terminators, and 3 cords)