CIM motors vibrate/jitter

[Chris_Ely]

Originally Posted by Wzup4021

We don't have any wheels hooked up to it, as it is just on a C-channel frame. When we enable it, the lights on the Talons flicker between red and orange. When it is disabled, they don't jitter.

Are these Talon SRs? If so, then red/orange flashing is the fault code for under voltage (<3.3V), over temperature (>170C), or shorted output transistor.

[Wzup4021]

Yes, I believe they are the Talon SR motor controllers. This doesn't seem like an error code, as it is flashing extremely fast, as in 15+ times per second, and the motors are actually moving. They are hooked up identical to our robot, so they shouldn't be under volted. They have fans on top of them, and the flashing is all they do, so it can't be over heating. I also doubt that it is a shorted out transistor, seeing as we have tried different talons. It must be something to do with the DSC or CRio, however we have no clue what. We've reconnected everything, but nothing seems to work.

[RufflesRidge]

Have you tried calibrating them as suggested by dellagd above? It sounds like they are getting a signal right on the edge of neutral and based on timing jitter it is alternating between neutral and a very low speed reverse.

[magnets]

It's probably a race condition in your software. Can you post your code?

[Al Skierkiewicz]

The LED indication you describe is the Talon responding to a command that takes it in and out of the 4% of deadband condition. Something is commanding the Talons to do that. The Flashing orange is the indication that your are close to the deadband condition and the flashing red is an indication that a throttle command has been sent to the Talon. The LED flashes Red or
Green in proportion to the throttle command sent to the controller.

[jboivin]

Good day,

I am wondering if any success has been seen on this issue. Our robot is seeing a similar issue with running the CIMs. With a configuration of the driver station without the Xbox controller that runs our drive train, the motors will behave in our Auto-tests. But, after being left on for a duration of time, one, and sometimes two, of our CIMs begins to jitter, and the robot becomes non-static.

If the Xbox controller is plugged in, the error still occurs, and any usage of the controller does not clear the twitch condition.

After a power reset, it seems to work okay, but then it comes back.

I'm suspecting digital cables too close to power lines and is getting a induction that the software can't clear out.

thanks for any input,
WPI in three days !!!

Jim Boivin
Mentor, FRC Team 811, FLL Referee/Judge/Coach

[DjScribbles]

Your first step should be to calibrate the motor controllers, as was suggested above, this issue (if you've ruled out code and joystick calibration as sources) is likely due to a PWM signal that is slipping out of the deadband.

Other possible sources are bad ribbon cables from the DSC (with this I believe you would see jitter even while driving) and battery voltage/reset conditions.