Thread: Motor Bias
View Single Post
  #22   Spotlight this post!  
Unread 31-10-2005, 21:17
billbo911's Avatar
billbo911 billbo911 is offline
I prefer you give a perfect effort.
AKA: That's "Mr. Bill"
FRC #2073 (EagleForce)
Team Role: Mentor
 
Join Date: Mar 2005
Rookie Year: 2005
Location: Elk Grove, Ca.
Posts: 2,349
billbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond reputebillbo911 has a reputation beyond repute
Re: Motor Bias

Quote:
Originally Posted by gshosford
With the joystick in the full forward position, the right motor, for sake of explanation, was turning faster than the left motor. With the joystick in the full reverse position, the left motor was turning faster than the right motor.

This surprised both of us that were working on it because all the discussions state that the CIM has virtually no bias.

The observations were visual not audible. We could see that one motor was turning much faster than the other motor.

Mike Betts' response with the link to the free-speed data was helpful. Does anyone have the stall torque data?
I don't mean to state the obvious, but......
By any chance, were you configured for one joystick drive? If so, you could quite easily have this behavior even if you had two perfectly matched CIMs. All that would need to have happened for this was that the Y axis trim pot on the CH joystick be off center. This might not even show up with the stick in center position. With a dead band of ~+/- 10, you could have been adding 9 to one side and subtracting it from the other. Then in the opposite direction, the reverse would be true. Your description bears this out.