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Author Topic: Following Error  (Read 3188 times)

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Re: Following Error
« Reply #30 on: June 30, 2018, 12:47:49 AM »
Hi,
sure do, feedback control and all the maths that go with it are pretty close to the high water mark as far as my expertise and
education go. It is very much a challenge to get involved in it all over again, a welcome challenge. I thank you for the
opportunity to do so.

Craig
My wife left with my best friend...
     and I miss him!
Re: Following Error
« Reply #31 on: June 30, 2018, 02:16:41 AM »
Craig, your welcome, and thank you.
We’ll pick this up at a later date. “Her inside” has a list about yeh long. Prioritize, that’s word of the day. It’s worth it, 45years and counting.

Lou
Re: Following Error
« Reply #32 on: June 30, 2018, 08:31:35 AM »
if price is a factor then just use a stepper for get the closed loop I have a scratch built plasma with large stepper gear reduction vampire drives and a hilcon controller running mach 4 plasma it never misses a step my gantry is over 100 pounds  just use the right size motor 
Re: Following Error
« Reply #33 on: June 30, 2018, 04:15:57 PM »
Hi,
as OP explained in an earlier post the feedback steppers and drives were cheaper than two shaft steppers and encoders, so in a sense price was a factor and
closed loop steppers and drives resulted.

Like you jcoldon my open loop steppers haven't missed a step in four years. Correctly sized/driven/specified steppers used within their limits DON"T lose steps, they are
remarkably simple, reliable, powerful and very economically priced. They certainly are a boon to hobby CNCers.

I do recall though when I was fist building and operating my mill very concerned about losing steps. At that time I had some cheap drivers and missing steps was a distinct
possibility. As I have 5 phase Vexta steppers good drives are not cheap. I did in the end get proper Vexta 5 phase drivers, they are powered offline 230VAC and have a DC link voltage
of about 150VDC. My steppers now sing along and never even look like missing a step.

None the less the manufacturers trolling their 'closed loop steppers...never miss a step' wares were very seductive. Many a hobbyist have stumped up the dollars to buy. The
manufacturers must be congratulated for their marketing effort, they have made millions by playing on a hobbyists fear of losing steps.

In very similar fashion Tecknics have done a great job marketing their 'stepper killer' servos. Their servos are good but there are better for less. Congratulations to Tecknics.

Craig
My wife left with my best friend...
     and I miss him!
Re: Following Error
« Reply #34 on: July 19, 2019, 08:05:41 AM »
I had following errors and, after watching the real-time numbers change in the HiCON test page, I changed the gain on the command and encoder so that they would match. The encoder was changed to have a gain of -1 as the encoder responded opposite of the command signal. I also changed the gain of the command to 2. Finally, I had to lower the acceleration and velocity to allow the motors to run without any 'slippage'.