Back EMF DC Motor Feedback

[kodcyky]

Hi,
Is it normal for back emf signal to fluctuate with a constant speed?
For example, a fixed pwm value is used to drive the motor but the back emf signal of the motor fluctuate from 600mV to 800mV.
The same condition occurs after increasing or decreasing the pwm value with increased or decreased back emf respectively.
If it is normal, is there anyway to filter the signal to get a smoother graph?
Thanks in advance.

[ober]

Not familiar with Back EMF, can anyone share a bit here? What is back EMF?

[sataman]

Back EMF is like back current .. normally will accur in slop..example...the robot are moving down at the slop , the robot will run faster , in this case the motor become "generator" it will give back the current to the motor drive or controller , instate of motor drive is giving current to drive the motor..
It also can called " free fall" in vertical case the motor holding torque is not sufficient the hold the object , in will fall down , this case also will cause motor run faster,thus same story will happend..
in others word motor speed run faster then PWM signal user programm
This is what i understand about back EMF..dunno is it true or not