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View Full Version : Trouble with photoswitches on the field.


PhilBot
03-14-2011, 07:52 AM
We had a LOT of trouble getting the line tracking to work at Pittsburgh this weekend.

We had line tracking working at home, and the first thing we did when we got to the comp was to re-calibrate the line sensors on the practice field.

Once we got on the real field, the bot just wanted to turn right (normal behavior if it can't see any sensors.) We suspected that they were also picking up the OTHER tape on the field (like around the tower carpet, or the join in down the center of the field, starting at the tracking Y) but shifting off that tape didn't seem to help. We only got one successful Uber tube scored.

Since we had powered our line sensors from the Solenoid 24V we had to enable the robot before we could calibrate them, so we couldn't do it on the field before a match. So we asked the FTA if there would be a chance to do calibrations during the lunch break (like past years with the vision camera) and we were told NO, there was no effect from lighting etc.

When I went back to the practice field there were no open spots, so we snuck onto an unused corner and attempted to find a spare piece of line tape. We got a piece from a roll used to mark the playing field, only to find that it was MUCH whiter then the tape used on the practice field. D'OH

With our prior settings, the tape was saturating the sensors (orange and red led) so we cranked them down, hoping for better results on the field. No luck.

Auto was basically a bust for us.

When we get the Cleveland we are going back to running the sensors on 12V so we can sneak in a calibration on the field prior to a practice run.

Phil.

PhilBot
03-17-2011, 08:19 AM
I just noticed this on the upcoming Championship schedule:

8:00 AM 8:45 AM FRC Fields Open to Teams for Robot Sensor Calibration

If it's planned for Championships, I wonder why they wouldn't let us do it at regionals ?

DonRotolo
03-17-2011, 08:46 PM
and we were told NO, there was no effect from lighting etc.In theory this should be true, but at NJ our autonomous stuttered EVERY TIME they turned up the lights at the beginning of a match.

The field lights are held at around 70% between matches, but shorthly after the bugle call starting the match, they brighten up to 100% over 1/2 second or so. That is the exact moment that our autonomous would stutter, hesitate, whatever you want to call it. Sometimes the lights were later, sometimes earlier - and the bot reacted to the lights every time. Or at least it seemed to, confirmed by watching match videos.

We're building a thin/lightweight glare shield for the line sensors to be installed in Virginia. We'll see what happens.