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Re: Are motor speeds proportional to PWM value?
All good answers. For accurate speed control you have to close the feedback loop. The typical way is to add an encoder which measures the speed of the wheels. Without a way to measure speed you have an open loop with no feedback, you set the control value and hope.
A closed feedback loop sets the control value (servo pwm) to the motor controller, the controller pulses the 12V to the motor, also called PWM but different, the motor under load does it's thing, the drive train takes some power through friction, the wheels turn, you measure the speed and increase or decrease the motor control value based on the difference between what you are reading and what you desired.
This is a simple explaination of proportional feedback, look up PID on CD for many articles.
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Andrew Nicholson
2011 FRC Robot Inspector (Seattle, Portland)
Mentor FRC 1778 "Chill Out", FTC 3018, 3940 "Hawks", 4434 "Heat Misers"
"Everything should be made as simple as possible, but no simpler."
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