Motor position control

[biallc]

Has anyone been able to successfully position a brushed DC motor using a motor controller and quadrature encoder with a microcontroller? By sucessfully position, I mean have the motor stop within 4 or less pulses of the desired encoder position and be able to repeat the process hundreds of time with approximately a 4-pulse (1 cycle) precision. Not interested in what a microcontroller can theoretically do. Practical experience doing this only, please. Thanks.

 

[kripacharya]

I think this would depend on the dynamics of the motor to a large extent. How fast was it going, what is its inertia, what braking mechanism you use, etc.
There obviously has to be some overshoot, and you could try to pre-compensate for the overshoot based on practical measurements/ experiment ?

And yes I have positioned dc motors quite accurately, but did not use quad encoders.

 

[biallc]

Indeed it does, kripacharya. We have the necessary means to compensate for overshoot, etc. At this point I am trying to ascertain whether anyone has successfully done this.

How did you position brushed DFC motors accurately without a quad encoder?

 

[kripacharya]

....How did you position brushed DFC motors accurately without a quad encoder?

i used hall sensors & small neodymium magnets. Speeds were slow ~5 - 50rpm range. Luckily the motors were attached to levers/arms so the movement range was much larger than available just at the shaft diameter.