On Thu, 28 Oct 2021, Chris Albertson wrote:
Date: Thu, 28 Oct 2021 12:23:34 -0700
From: Chris Albertson <[email protected]>
Reply-To: "Enhanced Machine Controller (EMC)"
<[email protected]>
To: "Enhanced Machine Controller (EMC)" <[email protected]>
Subject: Re: [Emc-users] Fwd: Requesting a short history review,
if you'd be so kind.
Gene is getting good results with his 3-phase steppers and no PID control
in LCNC because the 3-phase steppers have internal PID position control
loops in the motor driver electronics. These motors have an encoder wheel
for feedback. So these steppers are basically the same as a servo with
feedback implemented on the servo driver.
From my experience with motion control (robots), the BEST place to run the
control loop is in hardware attached to the motor. Typically, this is a
microcontroller There, the loop can run as fast as it needs to and the
timing jitter is a non-issue.
This is unrelated to the drive technology but rather LinuxCNCs step generation
performance relative to servo thread jitter. A similar issue affects all
connected drive types (jitter in the command or feedback or both)
Peter Wallace
Mesa Electronics
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