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-   -   HELP NEEDED! Camera twitches while disabled (http://www.chiefdelphi.com/forums/showthread.php?t=54500)

lkdjm 18-02-2007 22:37

HELP NEEDED! Camera twitches while disabled
 
Our camera's pan servo motor twitches to the right (looking at the front view of camera) while the robot is disabled or "killed". Everything else works fine (so far) but the twitching is killing the servo. The tilt servo motor is fine. Like I said, the camera has no problem in normal or autonomous mode. It tracks and finds the light perfectly. We are concerned that this will happen before and after every match while the bots are disabled. This will soon kill our pan servo motor. Any and all help is GREATLY APPRECIATED!

David Doerr 18-02-2007 23:09

Re: HELP NEEDED! Camera twitches while disabled
 
Our camera was doing exactly that. I found the camera would quiet down and behave normally (steady at neutral pan and tilt) by bypassing our installed camera servo pwm wiring. I suspect electrical noise induced in the idle pwm circuits while in disable mode - possibly from the camera's TTL serial wiring.

Alan Anderson 18-02-2007 23:49

Re: HELP NEEDED! Camera twitches while disabled
 
David's right. It's crosstalk from the camera serial data being interpreted as pwm signals by the servo. I saw several cameras including ours at competition last year "nodding" while they were disabled, often seemingly in time with the music being played. :)

With the servo and camera data wiring separated, the problem goes away.

pheadxdll 19-02-2007 07:34

Re: HELP NEEDED! Camera twitches while disabled
 
I have this problem also. Would insulated wires being together be enough to cause this interference? It seems unlikely to be but we definately have the same problem. I'd hate to mess up my pretty wiring to stretch the TTL wire away from the rest of the wires.

gnirts 19-02-2007 11:04

Re: HELP NEEDED! Camera twitches while disabled
 
Quote:

Originally Posted by lkdjm (Post 581245)
This will soon kill our pan servo motor.

Do oscillations wear down the servos that quickly?

Dave Flowerday 19-02-2007 11:34

Re: HELP NEEDED! Camera twitches while disabled
 
Our camera did this as well last year, causing it to knock into a CIM motor when disabled. It was kind of loud and sounded like a woodpecker. While you can fix it by moving the wires further apart or possibly by using shielded wire for the camera serial connection, I wouldn't worry about it. Our robot did that the whole season last year and it never became an issue. The servo didn't wear out or anything.


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