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Posted by Gordon McComb on February 22, 2007, 11:29 am
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Mike wrote:
> Anything else I should know or be worried about? Is all of this normal
> behavior, and what I should expect from other hobby servos?
Servo makes and even models vary, so your findings here are not
necessarily reflective of all analog servos. However it serves as a
starting point. There may be differences even among the same model if
they are made some time apart. More servos are being redesigned to use
microcontrollers rather than the older all-analog or analog IC
controller, so it's important to test a relatively new servo.
In any case, it's always useful to try increasing the frame rate of
servos to improve their torque, and it's a shame more servo controller
boards don't have this feature. I've been whining about it for several
years. You should also experiment with dynamically changing the refresh
rate to see if that helps performance. Most applications do not require
high holding torques, you can fall back to lower frame rates. Use the
faster rate when the motor is moving a load.
You do have to be careful about the increased current load, and the
possible affects the added heat has on the motor itself. Assuming a
servo with a standard PM motor, these motor don't use "brushes" per se,
but just a copper wire that will probably not last as long at the higher
currents. The trade off is higher performance but a shorter motor life.
For some applications and budgets this is acceptable.
-- Gordon
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> behavior, and what I should expect from other hobby servos?