Quote:
Originally Posted by Joe Johnson
0.9OHM? Not KOhm or MOhm? If so, something is wrong with your motor. Why did you switch to this motor? Do you have another you can use?
I like that it's on plastic and not on the chassis proper but how is it driving? I know that in the year of the Banebot shorting motor fiasco, there were a number of teams that reported the problem when driving through chain or gears, even with the motor can itself isolated. Chain and gears are not great conductors but they do get a lot better when there is pressure squishing out all the grease/oil at the interfaces.
Maybe this explains the "it happens when we stall the motor" behavior?
Back to the resistance value of 0.9Ohm, if you DID mount this motor to something connected to the chassis frame, you may not pass inspection:
R38 All wiring and electrical devices, including all Control System COMPONENTS, shall be electrically isolated from the ROBOT frame. The ROBOT frame must not be used to carry electrical current.
The blue box says >3Kohm is the check.
I smell a rat in that motor...
Dr. Joe J.
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Note: I was another mentor with djdaugherty as we were testing tonight.
Yes, We measured about 5 different 550's we had around. We did not check resistance to the can prior to mounting, we simply spun it up and it ran in both directions, and seemingly well. When we compare all the motors we dug out, all ran forward and backward, and measured motor leads to the can for all. Most varied anywhere from a few ohms (yes, ohms), up to 10's, and maybe a kohm here or there.
We had one motor that looks like it was never used before, and that was completely open between the motor leads and can (Mohm or greater). We ran that motor fine.
It seems like we should replace the one on teh robot with that one.
However - we havent changed it yet and haven't had any disables in the last while. I'm still leaning toward a comms issue although admit the motor is a problem also. I just can't understand what mode the is causing the disable. It seems like there has to be some trigger of a faulty somewhere...