Re: [Emc-users] Servo Drives

[Dave]

I believe that hunting is a natural process for a digital servo system.  
Most industrial servos use high resolution encoders - oftentimes 2500 
ppr which in quadrature is 10,000 counts per rev.   Finer seems to 
create less digital hunting - chatter or buzzing as the motor looks for 
the correct position.

The latency in those encoders might be an issue at high servo update 
rates > 1 khz.  In the FAQ they do talk about how the index signal can 
be corrupted by high magnetic fields and they mention stepper motors as 
a possible problem.

Still these are so inexpensive compared to everything else they would be 
worth a shot.

How do these compare to some of US Digital's low cost encoders?I've 
purchased a fair amount of other equipment from US Digital and I have 
been happy with their service but I have no experience with their 
miniature encoders.

Dave

On 1/13/2010 3:36 AM, K.J. Kirwan wrote:
> And here are links to those Digi-Key pages:
>
> The encoders:
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=AMT102-V%20KIT
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=AMT103-V
>
> And the "lump" line driver cables (which you will almost certainly want):
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=CUI-102E-10
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=CUI-103E-10
>
> And the "lump" line driver cable data sheets (such as they are):
> http://media.digikey.com/PDF/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/CUI-102E-10.pdf
> http://media.digikey.com/PDF/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/CUI-103E-10.pdf
>
> (BTW, those "lump" line drivers are pretty cheap,
> and might come in handy anywhere any single-ended
> TTL encoder needs a quick-and-dirty conversion to
> differential line drivers.  Just cut off the socket
> and wire the "lump" to whatever you like.  Viola!)
>
> As far as resolution, they are all the "same",
> in that they are DIP switch selectable in 16 steps
> from 48 PPR (3 RPM) to 2048 PPR (7500 RPM),
> in both binary and decimal resolutions,
> as per this table:
> http://media.digikey.com/pdf/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/DIP_switch_settings.pdf
>
> I would guess that the finer settings might exhibit hunting more?
> And that decimal settings might hunt more than binary settings?
>
> Dewey, what resolution are you using?
> Are you using only quadrature counting?
> Have you observed any hunting while quadrature counting?
> Have you ever tried using single-phase counting and
> did you ever see any extra counts?
> How many different resolution settings did you try if
> you ever went looking for hunting or extra counts?
>
> Again, the "extra" counts (if any) are not supposed to be a
> problem (numerically, at least) as long as they are counted
> using the quadrature method.  The jury might still be out on
> position-servo-loop closure, which is why I am trying to
> gather information from those who have actually used them.
>
> For those on the list who have more machining background and
> maybe a little less electronics background, what we are
> talking about here is that if you take any traditional
> optical encoder and a CUI AMT-102-V (or CUI AMT-103-V)
> capacitive encoder, both with the same resolution, and
> rotate them both (very, very slowly)...
>
> The optical encoder will count like this:
> Zero...
> One...
> Two...
> Three...
> Four...
> Five...
>
> But the AMT-102-V might(?) count like this (balanced?):
> Zero...
> One...
> TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree
> TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree
> Four...
> Five...
>
> Or it might(?) count like this (unbalanced low?):
> Zero...
> One...
> TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree
> Three...
> Four...
> Five...
>
> Or it might(?) count like this (unbalanced high?):
> Zero...
> One...
> Two...
> TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree
> Four...
> Five...
>
> (Digital logic experts please note that I am not saying
> anything special about the two-three transition, I just
> picked it at random for convenience in this example.)
>
> And if the counting business isn't bad enough already,
> it might be affected by how eccentric the shaft/disc is
> relative to the body.  (Remember, this is a kit-type
> encoder, it has no built-in ball bearings.)  So there
> might be an error variance that repeats every 360 degrees.
>
> Servo loop experts might be driven nuts by this, or they
> might just say widen the deadband and live with it.  But
> that might not make the problem go away completely when
> the following error is near the upper limit, because you
> can't be sure (or can you?) when you'll hit another
> hunting spot.  Or maybe the problem appears worse when
> following error is very small?
>
> Anyway, for those who are still following this thread,
> sorry if I've beaten the subject to death, but a low-cost
> en

Re: [Emc-users] Servo Drives

[Sven Wesley]

2010/1/13 Roland Jollivet 

> I just looked at the CUI page again. I must be dumb.
>
> Do you know or have seen a data-sheet with the stuff that matters?
> - Linearity
> - Cyclic error
> - Absolute error
> - Delay time
> - Rotational life
>
> Without these, any resolution above 200 starts to become meaningless.
>
> Roland
>
>
http://www.amtencoder.com/amtfaq.asp
http://www.amtencoder.com/AMTtech.asp
What do yo mean with rotational life? There's no mechanical wear as the
encoder disc is running free.
I run them at 800 CPR and the guy who recommended them to me uses 2048.
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Re: [Emc-users] Servo Drives

[Roland Jollivet]

I just looked at the CUI page again. I must be dumb.

Do you know or have seen a data-sheet with the stuff that matters?
- Linearity
- Cyclic error
- Absolute error
- Delay time
- Rotational life

Without these, any resolution above 200 starts to become meaningless.

Roland


2010/1/13 Sven Wesley 

> 2010/1/13 K.J. Kirwan 
>
> > And here are links to those Digi-Key pages:
> >
> > The encoders:
> >
> >
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=AMT102-V%20KIT
> >
> >
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=AMT103-V
> >
> > And the "lump" line driver cables (which you will almost certainly want):
> >
> >
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=CUI-102E-10
> >
> >
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=CUI-103E-10
> >
> > And the "lump" line driver cable data sheets (such as they are):
> >
> >
> http://media.digikey.com/PDF/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/CUI-102E-10.pdf
> >
> >
> http://media.digikey.com/PDF/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/CUI-103E-10.pdf
> >
> >
> I use these and I'm very satisfied. They were the solution when other
> encoders failed, there's a long mail thread about it if you're curious. I
> have a friend (he recommended them to me) who run these in very ruff
> conditions with monster servo's and a lot of disturbance around. Not a
> single step lost so far.
>
> I recommend!
>
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Re: [Emc-users] Servo Drives

[Sven Wesley]

2010/1/13 K.J. Kirwan 

> And here are links to those Digi-Key pages:
>
> The encoders:
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=AMT102-V%20KIT
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=AMT103-V
>
> And the "lump" line driver cables (which you will almost certainly want):
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=CUI-102E-10
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=CUI-103E-10
>
> And the "lump" line driver cable data sheets (such as they are):
>
> http://media.digikey.com/PDF/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/CUI-102E-10.pdf
>
> http://media.digikey.com/PDF/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/CUI-103E-10.pdf
>
>
I use these and I'm very satisfied. They were the solution when other
encoders failed, there's a long mail thread about it if you're curious. I
have a friend (he recommended them to me) who run these in very ruff
conditions with monster servo's and a lot of disturbance around. Not a
single step lost so far.

I recommend!
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Re: [Emc-users] Servo Drives

[K.J. Kirwan]

And here are links to those Digi-Key pages:

The encoders:
http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=AMT102-V%20KIT
http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=AMT103-V

And the "lump" line driver cables (which you will almost certainly want):
http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=CUI-102E-10
http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=CUI-103E-10

And the "lump" line driver cable data sheets (such as they are):
http://media.digikey.com/PDF/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/CUI-102E-10.pdf
http://media.digikey.com/PDF/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/CUI-103E-10.pdf

(BTW, those "lump" line drivers are pretty cheap,
and might come in handy anywhere any single-ended
TTL encoder needs a quick-and-dirty conversion to
differential line drivers.  Just cut off the socket
and wire the "lump" to whatever you like.  Viola!)

As far as resolution, they are all the "same",
in that they are DIP switch selectable in 16 steps
from 48 PPR (3 RPM) to 2048 PPR (7500 RPM),
in both binary and decimal resolutions,
as per this table:
http://media.digikey.com/pdf/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/DIP_switch_settings.pdf

I would guess that the finer settings might exhibit hunting more?
And that decimal settings might hunt more than binary settings?

Dewey, what resolution are you using?
Are you using only quadrature counting?
Have you observed any hunting while quadrature counting?
Have you ever tried using single-phase counting and
did you ever see any extra counts?
How many different resolution settings did you try if
you ever went looking for hunting or extra counts?

Again, the "extra" counts (if any) are not supposed to be a
problem (numerically, at least) as long as they are counted
using the quadrature method.  The jury might still be out on
position-servo-loop closure, which is why I am trying to
gather information from those who have actually used them.

For those on the list who have more machining background and
maybe a little less electronics background, what we are
talking about here is that if you take any traditional
optical encoder and a CUI AMT-102-V (or CUI AMT-103-V)
capacitive encoder, both with the same resolution, and
rotate them both (very, very slowly)...

The optical encoder will count like this:
Zero...
One...
Two...
Three...
Four...
Five...

But the AMT-102-V might(?) count like this (balanced?):
Zero...
One...
TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree
TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree
Four...
Five...

Or it might(?) count like this (unbalanced low?):
Zero...
One...
TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree
Three...
Four...
Five...

Or it might(?) count like this (unbalanced high?):
Zero...
One...
Two...
TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree
Four...
Five...

(Digital logic experts please note that I am not saying
anything special about the two-three transition, I just
picked it at random for convenience in this example.)

And if the counting business isn't bad enough already,
it might be affected by how eccentric the shaft/disc is
relative to the body.  (Remember, this is a kit-type
encoder, it has no built-in ball bearings.)  So there
might be an error variance that repeats every 360 degrees.

Servo loop experts might be driven nuts by this, or they
might just say widen the deadband and live with it.  But
that might not make the problem go away completely when
the following error is near the upper limit, because you
can't be sure (or can you?) when you'll hit another
hunting spot.  Or maybe the problem appears worse when
following error is very small?

Anyway, for those who are still following this thread,
sorry if I've beaten the subject to death, but a low-cost
encoder might be a good idea, provided it doesn't come
with a whole new set of gotcha's; which is why I'm so
interested in hearing from those who have actually used
them, especially in a position servo loop.

So I'll take any information I can get, and I can take
this off-list if everyone is tired of it.

Thanks,

Kim


Jeff Epler wrote:
> On Tue, Jan 12, 2010 at 08:47:28AM +0200, Roland Jollivet wrote:
> 
>>What's the resolution etc. of your encoder, and what did it cost?
>>
>>They seem reluctant to simply list pricing.
> 
> 
> I don't know about pricing direct from CUI, but digikey sells them
> starting at single quantity and will happily display the price ($29.95
> qty1, on down to $18,900 for 1000 of them).
> 
> Jeff
> 
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Re: [Emc-users] Servo Drives

[Jeff Epler]

On Tue, Jan 12, 2010 at 08:47:28AM +0200, Roland Jollivet wrote:
> What's the resolution etc. of your encoder, and what did it cost?
> 
> They seem reluctant to simply list pricing.

I don't know about pricing direct from CUI, but digikey sells them
starting at single quantity and will happily display the price ($29.95
qty1, on down to $18,900 for 1000 of them).

Jeff

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Re: [Emc-users] Servo Drives

[Roland Jollivet]

What's the resolution etc. of your encoder, and what did it cost?

They seem reluctant to simply list pricing.

Regards
Roland



2010/1/12 Dewey Garrett 

> I've got one of the cui encoders on one axis of a machine (dc brush motor).
> Photo of the index pulse and phaseA:
>
> http://www.panix.com/~dgarrett/stuff/cui_i_a.jpg
>
> They seem to be a good value.
>
> dewey
> --
> Dewey Garrett
>
>
>
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Re: [Emc-users] Servo Drives

[Dewey Garrett]

I've got one of the cui encoders on one axis of a machine (dc brush motor).
Photo of the index pulse and phaseA:

http://www.panix.com/~dgarrett/stuff/cui_i_a.jpg

They seem to be a good value.

dewey
-- 
Dewey Garrett


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Re: [Emc-users] Servo Drives

[Dave]

Wow, that is a big difference.  In fact that just doesn't sound right.   
That could make for a pretty noisy machine.

I was reading the specs of the encoders that these guys use 
recently  They are apparently smart encoders with an SPI  data 
interface.
http://www.dmm-tech.com/Dyn2-Driver.htmlThey sell the encoders 
separately also, but obviously the drive would have to be capable of 
handling the SPI interface.

I'm just now getting into an industrial machine project that has 8 axes  
with SEW servo drives.   The motors use absolute position encoders 
also.  Once they are referenced, they don't need to be re-referenced 
after a power down.   The previous machine builder was so confident in 
the encoders ability that there are no hard over travel limits on the 
machine, only soft limits are used which are set in the drives.

Siemens latest servo systems also use absolute encoders, reference them 
once and forget about them.

Dave

On 1/11/2010 10:33 AM, K.J. Kirwan wrote:
> The CUI capacitive encoders are relatively
> inexpensive, and there are line driver "lump"
> cables available if needed, but there are two minor
> cautions that may or may not affect you.  One is
> sensitivity to magnetic fields, and the other is
> quadrature count "hunting".
>
> You might want to be cautious about mounting the
> AMT102/103 capacitive encoders on the back of a
> motor (or anyplace else there is a strong
> magnetic field).  The encoder uses a "wavy"
> variable capacitor that repeats every 45 deg,
> and a hall effect device to determine which of
> the 8 repeats is the origin (for the index pulse).
> So strong magnetic fields may confuse operation
> of the index pulse.  This is mentioned (at least
> for stepper motors) in the fine print at the
> bottom of p.1 of the data sheets:
> http://www.cui.com/pdffiles/AMT102-V.pdf
> http://www.cui.com/pdffiles/AMT103-V.pdf
>
> Why do they specifically mention steppers?
> Maybe steppers leak more, or maybe the fields are
> closer to the back?  Maybe this hasn't been a problem
> with servos because they already have a feedback
> device?  I don't know but thought I'd mention it.
> At any rate it might be prudent to mount them away
> from electric motors, regardless of type.
>
> If you must mount them on the back of a motor, it
> should still work fine if you are willing to give up
> the index pulse (which usually means giving up proper
> homing).
>
> The quadrature count hunting means that you cannot
> use just the A output (or just the B output) to
> measure RPM.  At certain positions the encoder is
> allowed to hunt back and forth between two count
> values, even though no real motion is occurring.
> So there will appear to be extra counts there, if
> not observed using both A&  B in quadrature style.
> But the quadrature count is said to remain correct,
> even though it will sometimes seem "nervous".
>
> The "nervous" count may mean that at certain
> positions, the position display might be jumping
> back and forth between two values, maybe in a blur,
> even though that axis/joint is not moving.
>
> If it's a stepper system, and you're just using
> the encoder to confirm position and monitor the
> following error, then maybe the "hunting" (on the
> display) won't really bother you.
>
> But if it's a servo system, the hunting might add a
> little extra error or noise or vibration that you
> might find to be objectionable.  Here's an interesting
> video comparing the same servo loop (in position-hold
> mode) first using the AMT102 encoder (it seems to be
> a little more "growly") and then with a traditional
> optical encoder (it seems to be a little quieter).
>
> AMT102 vs R35i.avi (henrols)
> http://www.youtube.com/watch?v=jIrQLfcP_04
>
> I'm sure that in many applications the AMT102/3
> encoders will work just fine, I just wanted to point
> out a couple of minor problems in case they might
> affect your situation.
>
> John plans to try them on his Bridgeport II as stepper
> monitors when he gets the time to install them.  I'll
> look forward to seeing that and reporting on the results.
> And when I get some free time I'll post about these two
> "features" of the AMT102/3 on the wiki.
>
> Thanks,
>
> Kim
>
>
> Flying Electron wrote:
>
>> Thanks for the info on mounting the encoders.
>>
>> I decided to go with the mesa 5i23, those ebay amps, keling motors, and
>> the digikey encoders.
>>
>> I'll let everyone know how it works out when everything gets here.
>>
>> Thanks everyone for all the advice, it would have been impossible to
>> choose a combination without everyone's input.
>>
>> sam sokolik wrote:
>>
>>  
>>> http://www.electronicsam.com/images/KandT/pcbmill/bldcenc2.jpg
>>>
>>> The keling servos I got (also the KL23BLS-115) have 2 very shallow
>>> tapped  holes that line up to the mounting holes of the encoder.
>>> I found some laptop assembly screws that just happened to be the right
>>> length.  Mariss seems to love these encoders over the cheap us-digital
>>

Re: [Emc-users] Servo Drives

[K.J. Kirwan]

The CUI capacitive encoders are relatively
inexpensive, and there are line driver "lump"
cables available if needed, but there are two minor
cautions that may or may not affect you.  One is
sensitivity to magnetic fields, and the other is
quadrature count "hunting".

You might want to be cautious about mounting the
AMT102/103 capacitive encoders on the back of a
motor (or anyplace else there is a strong
magnetic field).  The encoder uses a "wavy"
variable capacitor that repeats every 45 deg,
and a hall effect device to determine which of
the 8 repeats is the origin (for the index pulse).
So strong magnetic fields may confuse operation
of the index pulse.  This is mentioned (at least
for stepper motors) in the fine print at the
bottom of p.1 of the data sheets:
http://www.cui.com/pdffiles/AMT102-V.pdf
http://www.cui.com/pdffiles/AMT103-V.pdf

Why do they specifically mention steppers?
Maybe steppers leak more, or maybe the fields are
closer to the back?  Maybe this hasn't been a problem
with servos because they already have a feedback
device?  I don't know but thought I'd mention it.
At any rate it might be prudent to mount them away
from electric motors, regardless of type.

If you must mount them on the back of a motor, it
should still work fine if you are willing to give up
the index pulse (which usually means giving up proper
homing).

The quadrature count hunting means that you cannot
use just the A output (or just the B output) to
measure RPM.  At certain positions the encoder is
allowed to hunt back and forth between two count
values, even though no real motion is occurring.
So there will appear to be extra counts there, if
not observed using both A & B in quadrature style.
But the quadrature count is said to remain correct,
even though it will sometimes seem "nervous".

The "nervous" count may mean that at certain
positions, the position display might be jumping
back and forth between two values, maybe in a blur,
even though that axis/joint is not moving.

If it's a stepper system, and you're just using
the encoder to confirm position and monitor the
following error, then maybe the "hunting" (on the
display) won't really bother you.

But if it's a servo system, the hunting might add a
little extra error or noise or vibration that you
might find to be objectionable.  Here's an interesting
video comparing the same servo loop (in position-hold
mode) first using the AMT102 encoder (it seems to be
a little more "growly") and then with a traditional
optical encoder (it seems to be a little quieter).

AMT102 vs R35i.avi (henrols)
http://www.youtube.com/watch?v=jIrQLfcP_04

I'm sure that in many applications the AMT102/3
encoders will work just fine, I just wanted to point
out a couple of minor problems in case they might
affect your situation.

John plans to try them on his Bridgeport II as stepper
monitors when he gets the time to install them.  I'll
look forward to seeing that and reporting on the results.
And when I get some free time I'll post about these two
"features" of the AMT102/3 on the wiki.

Thanks,

Kim


Flying Electron wrote:
> Thanks for the info on mounting the encoders.
> 
> I decided to go with the mesa 5i23, those ebay amps, keling motors, and 
> the digikey encoders.
> 
> I'll let everyone know how it works out when everything gets here.
> 
> Thanks everyone for all the advice, it would have been impossible to 
> choose a combination without everyone's input.
> 
> sam sokolik wrote:
> 
>>http://www.electronicsam.com/images/KandT/pcbmill/bldcenc2.jpg
>>
>>The keling servos I got (also the KL23BLS-115) have 2 very shallow 
>>tapped  holes that line up to the mounting holes of the encoder.
>>I found some laptop assembly screws that just happened to be the right 
>>length.  Mariss seems to love these encoders over the cheap us-digital 
>>ones for his step/dir servo drives
>>
>>YMMV
>>
>>sam
>>
>>
>>On 1/7/2010 03:36 PM, Flying Electron wrote:
>>  
>>
>>>Wow!  Thank you so much for the link.  The amps on ebay looks pretty
>>>much exactly what I am looking for.  I looked at the datasheet for the
>>>issue with the drive inputs being commoned at +5V like you pointed out,
>>>but I'm pretty sure I can hack up something to deal with that, like run
>>>the signals through a microcontroller to do whatever translation is
>>>necessary.  I especially like that they are all mounted in a nice box
>>>for me already :-)
>>>
>>>Getting closer.  Mesa card + Servo Amps are picked out.  Keling motors
>>>look good.
>>>
>>>Do you know if that amt102-v encoder need anything special to mount on
>>>the back of a NEMA 23 brushless motor like an adapter plate or anything
>>>like that?  Or do encoders and motors have standard mounting patterns so
>>>that all encoders fit all motors nicely?
>>>
>>>Yesterday I had no idea what I needed to buy or even what questions to
>>>ask, and today everything looks doable.
>>>
>>>
>>>
>>>sam sokolik wrote:
>>>   
>>>
>>>
there are always deals if you are patient.  Like..

Re: [Emc-users] Servo Drives

[Jon Elson]

sam sokolik wrote:
> http://www.electronicsam.com/images/KandT/pcbmill/bldcenc2.jpg
>
> The keling servos I got (also the KL23BLS-115) have 2 very shallow 
> tapped  holes that line up to the mounting holes of the encoder.
> I found some laptop assembly screws that just happened to be the right 
> length.  Mariss seems to love these encoders over the cheap us-digital 
> ones for his step/dir servo drives
>   
I got one of these a few months ago and the holes were NOT tapped at 
all, just dimples,
really in the casting.  So, I don't know if these holes are supposed to 
be tapped or not.

Jon

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Re: [Emc-users] Servo Drives

[Jon Elson]

Flying Electron wrote:
> Motors
> 
> [brushless] Pico Size 23 Brushless Servo (61ozin continous, 180ozin 
> peak, 1000 CPR) $120
> [brushless] Keling KL23BLS-115 Brushless Servo (61ozin continous, 180 
> ozin peak, 1000 CPR) $134
>   
The above two are the same motor.  Has Keling raised their prices?  
Also, note the
Keling motor does not have an encoder fitted to it.  I think your $134 
price is for their
size 34 motor.
> [brushed]  Keling KL23-130-60 Brushed Servo (50ozin continous, 350ozin 
> peak, 1000 CPR) $162
>   
Also note that many of the brushless motors on Keling's site are not in 
stock, but
essentially special order items.
> Most of the servo drives I have found have the PID loop built into 
> them.  Is this the normal case?
>   
Yes, certainly for industrial, high-end drives like Servo Dynamics and 
AMC, this is
true.  And, you pay for the necessary intelligence in the drive.
> Is it possible to run a brushed DC servo with just a simple H-Bridge 
> controlled directly by the PWM output and a direction signal?
Yes, but you have to be very careful about how you deal with overcurrent 
and current
limit situations.  Also, the motor inductance and the fast switching of 
the transistors
can produce a LOT of electrical noise.  That's why my drives (Pico 
Systems) have output filters, to
save you the hassles of noise getting into your encoders.

Jon


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Re: [Emc-users] Servo Drives

[Flying Electron]

Dave wrote:
> Yes, most low cost servo and stepper drives are interfaced via step and 
> direction.
>
> Up until the step and direction interface became popular the standard 
> was a +/- 10v analog input interface and the servo drive was operated in 
> a velocity mode or torque mode.
>
> I think that EMC2 might be the only low cost CNC software/hardware that 
> I know of that can output a PWM signal.
>
> The drives that you have listed as "not suitable" all have the PID 
> position loops on the drive itself.
>
> What kind of machine are you attempting to control?
>   
I'm upgrading a smt pick and place machine from steppers to servos so 
all the moves will be rapids from point to point, doesn't matter what 
path it takes to get to the end point as long as it gets there.  It's a 
frankenstein machine I built with axis travels of 750mm on the X and Y, 
works fine, but it badly needs a speed upgrade.  The machine originally 
had an AVR microcontroller generating steps for each axis and a windows 
box with a serial cable going directly to each axis sending commands to 
the AVR which would generate the steps to move the axis.

I've got EMC2 connected to the machine now, with the stepper drivers 
hooked up to the parallel port bypassing the AVR microcontrollers.  The 
windows box is still managing the show.  I've got a tclsh piped to a 
serial port on the linux box and the windows machine jogs, uploads gcode 
programs, and gets current position of the machine through the serial 
port connection by sending commands to emcsh.  I've also got the console 
output of emc piped out another serial port so that (PRINT messages in 
the gcode will be sent out the serial port back to the windows machine 
so the app running there can get notifications of where in the gcode 
program it's at so it can update it's own gui accordingly like showing 
what chip is currently on the nozzle and percentage of job completion.

It's a huge hack but it works. :-)


> One of the nice things about the newest Gecko servo drive is that it 
> will interface directly with a LPT port, even a low voltage 3.3 volt 
> port.  So depending on how you wire your machine no BOB may be required.
>
> (I have no interest in any drive or motor seller or manufacturer.)
>
> Dave
>
>   

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Re: [Emc-users] Servo Drives

[Flying Electron]

Thanks for the info on mounting the encoders.

I decided to go with the mesa 5i23, those ebay amps, keling motors, and 
the digikey encoders.

I'll let everyone know how it works out when everything gets here.

Thanks everyone for all the advice, it would have been impossible to 
choose a combination without everyone's input.

sam sokolik wrote:
> http://www.electronicsam.com/images/KandT/pcbmill/bldcenc2.jpg
>
> The keling servos I got (also the KL23BLS-115) have 2 very shallow 
> tapped  holes that line up to the mounting holes of the encoder.
> I found some laptop assembly screws that just happened to be the right 
> length.  Mariss seems to love these encoders over the cheap us-digital 
> ones for his step/dir servo drives
>
> YMMV
>
> sam
>
>
> On 1/7/2010 03:36 PM, Flying Electron wrote:
>   
>> Wow!  Thank you so much for the link.  The amps on ebay looks pretty
>> much exactly what I am looking for.  I looked at the datasheet for the
>> issue with the drive inputs being commoned at +5V like you pointed out,
>> but I'm pretty sure I can hack up something to deal with that, like run
>> the signals through a microcontroller to do whatever translation is
>> necessary.  I especially like that they are all mounted in a nice box
>> for me already :-)
>>
>> Getting closer.  Mesa card + Servo Amps are picked out.  Keling motors
>> look good.
>>
>> Do you know if that amt102-v encoder need anything special to mount on
>> the back of a NEMA 23 brushless motor like an adapter plate or anything
>> like that?  Or do encoders and motors have standard mounting patterns so
>> that all encoders fit all motors nicely?
>>
>> Yesterday I had no idea what I needed to buy or even what questions to
>> ask, and today everything looks doable.
>>
>>
>>
>> sam sokolik wrote:
>>
>> 
>>> there are always deals if you are patient.  Like...
>>> *KL23BLS-115**: $52/pcs brushless servos
>>> digikey amt102-v encoder 29.95.<-up to 2048 line - adjustable.
>>> ebay 3 amc amplifiers that take pwm+dir
>>> http://cgi.ebay.com/3-AXIS-A-M-C-PWM-Brushless-SERVO-AMPLIFIER-ASSEMBLY-NEW_W0QQitemZ260516353589QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ca7fc1635
>>> 179.95
>>>
>>> Not including shipping for 3 axis...  (not including mesa hardware)
>>> $425.80
>>> closed loop - priceless... ;)
>>>
>>> You would want to do your homework though - like the drive inputs seem
>>> to be common-ed to +5v.  (probably not an issue)
>>> (if I did the math right)
>>> sam
>>>
>>>
>>> *
>>> On 1/7/2010 01:29 PM, Flying Electron wrote:
>>>
>>>  
>>>   
 I'm deciding on what servo drive to use with the mesa FPGA card and it
 doesn't look too bad since there are not too many low cost options.  I'm
 constrained to a NEMA 23 size motor since a NEMA 23 stepper is on the
 machine right now and I want it to be a direct swap.  So far I've found
 from searching on google and from people's suggestions here on the
 mailing list:

 Drives
 ---
 [brushless] Pico Brushless PWM Servo Amp $150
 [brushed] Pico PWM Servo Amplifier $125

 Motors
 
 [brushless] Pico Size 23 Brushless Servo (61ozin continous, 180ozin
 peak, 1000 CPR) $120
 [brushless] Keling KL23BLS-115 Brushless Servo (61ozin continous, 180
 ozin peak, 1000 CPR) $134
 [brushed]  Keling KL23-130-60 Brushed Servo (50ozin continous, 350ozin
 peak, 1000 CPR) $162

 Not Suitable
 -
 dmm-tech.com -- RS232 based communication not PWM
 gecko   -- EMC2 cannot control PID loop (step/dir input, not
 pwm)
 viper -- EMC2 cannot control PID loop (step/dir input,
 not pwm)
 rutex -- EMC2 cannot control PID loop (step/dir input,
 not pwm)

 Most of the servo drives I have found have the PID loop built into
 them.  Is this the normal case?

 Is it possible to run a brushed DC servo with just a simple H-Bridge
 controlled directly by the PWM output and a direction signal?  I was
 looking at the Freescale MC33886 which I think could make a very simple
 and cheap H-Bridge.
 http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC33886VW-ND
 

 Anybody know of any companies or products I may have missed in my search?




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Re: [Emc-users] Servo Drives

[sam sokolik]

http://www.electronicsam.com/images/KandT/pcbmill/bldcenc2.jpg

The keling servos I got (also the KL23BLS-115) have 2 very shallow 
tapped  holes that line up to the mounting holes of the encoder.
I found some laptop assembly screws that just happened to be the right 
length.  Mariss seems to love these encoders over the cheap us-digital 
ones for his step/dir servo drives

YMMV

sam


On 1/7/2010 03:36 PM, Flying Electron wrote:
> Wow!  Thank you so much for the link.  The amps on ebay looks pretty
> much exactly what I am looking for.  I looked at the datasheet for the
> issue with the drive inputs being commoned at +5V like you pointed out,
> but I'm pretty sure I can hack up something to deal with that, like run
> the signals through a microcontroller to do whatever translation is
> necessary.  I especially like that they are all mounted in a nice box
> for me already :-)
>
> Getting closer.  Mesa card + Servo Amps are picked out.  Keling motors
> look good.
>
> Do you know if that amt102-v encoder need anything special to mount on
> the back of a NEMA 23 brushless motor like an adapter plate or anything
> like that?  Or do encoders and motors have standard mounting patterns so
> that all encoders fit all motors nicely?
>
> Yesterday I had no idea what I needed to buy or even what questions to
> ask, and today everything looks doable.
>
>
>
> sam sokolik wrote:
>
>> there are always deals if you are patient.  Like...
>> *KL23BLS-115**: $52/pcs brushless servos
>> digikey amt102-v encoder 29.95.<-up to 2048 line - adjustable.
>> ebay 3 amc amplifiers that take pwm+dir
>> http://cgi.ebay.com/3-AXIS-A-M-C-PWM-Brushless-SERVO-AMPLIFIER-ASSEMBLY-NEW_W0QQitemZ260516353589QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ca7fc1635
>> 179.95
>>
>> Not including shipping for 3 axis...  (not including mesa hardware)
>> $425.80
>> closed loop - priceless... ;)
>>
>> You would want to do your homework though - like the drive inputs seem
>> to be common-ed to +5v.  (probably not an issue)
>> (if I did the math right)
>> sam
>>
>>
>> *
>> On 1/7/2010 01:29 PM, Flying Electron wrote:
>>
>>  
>>> I'm deciding on what servo drive to use with the mesa FPGA card and it
>>> doesn't look too bad since there are not too many low cost options.  I'm
>>> constrained to a NEMA 23 size motor since a NEMA 23 stepper is on the
>>> machine right now and I want it to be a direct swap.  So far I've found
>>> from searching on google and from people's suggestions here on the
>>> mailing list:
>>>
>>> Drives
>>> ---
>>> [brushless] Pico Brushless PWM Servo Amp $150
>>> [brushed] Pico PWM Servo Amplifier $125
>>>
>>> Motors
>>> 
>>> [brushless] Pico Size 23 Brushless Servo (61ozin continous, 180ozin
>>> peak, 1000 CPR) $120
>>> [brushless] Keling KL23BLS-115 Brushless Servo (61ozin continous, 180
>>> ozin peak, 1000 CPR) $134
>>> [brushed]  Keling KL23-130-60 Brushed Servo (50ozin continous, 350ozin
>>> peak, 1000 CPR) $162
>>>
>>> Not Suitable
>>> -
>>> dmm-tech.com -- RS232 based communication not PWM
>>> gecko   -- EMC2 cannot control PID loop (step/dir input, not
>>> pwm)
>>> viper -- EMC2 cannot control PID loop (step/dir input,
>>> not pwm)
>>> rutex -- EMC2 cannot control PID loop (step/dir input,
>>> not pwm)
>>>
>>> Most of the servo drives I have found have the PID loop built into
>>> them.  Is this the normal case?
>>>
>>> Is it possible to run a brushed DC servo with just a simple H-Bridge
>>> controlled directly by the PWM output and a direction signal?  I was
>>> looking at the Freescale MC33886 which I think could make a very simple
>>> and cheap H-Bridge.
>>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC33886VW-ND
>>> 
>>>
>>> Anybody know of any companies or products I may have missed in my search?
>>>
>>>
>>>
>>>
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>>> Take advantage of Verizon's best-in-class app development support
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>>> Join now and get one step closer to millions of Verizon customers
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>>>
>>>
>>>
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Re: [Emc-users] Servo Drives

[Flying Electron]

Wow!  Thank you so much for the link.  The amps on ebay looks pretty 
much exactly what I am looking for.  I looked at the datasheet for the 
issue with the drive inputs being commoned at +5V like you pointed out, 
but I'm pretty sure I can hack up something to deal with that, like run 
the signals through a microcontroller to do whatever translation is 
necessary.  I especially like that they are all mounted in a nice box 
for me already :-)

Getting closer.  Mesa card + Servo Amps are picked out.  Keling motors 
look good.

Do you know if that amt102-v encoder need anything special to mount on 
the back of a NEMA 23 brushless motor like an adapter plate or anything 
like that?  Or do encoders and motors have standard mounting patterns so 
that all encoders fit all motors nicely?

Yesterday I had no idea what I needed to buy or even what questions to 
ask, and today everything looks doable.



sam sokolik wrote:
> there are always deals if you are patient.  Like...
> *KL23BLS-115* *: $52/pcs brushless servos
> digikey amt102-v encoder 29.95. <-up to 2048 line - adjustable.
> ebay 3 amc amplifiers that take pwm+dir
> http://cgi.ebay.com/3-AXIS-A-M-C-PWM-Brushless-SERVO-AMPLIFIER-ASSEMBLY-NEW_W0QQitemZ260516353589QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ca7fc1635
> 179.95
>
> Not including shipping for 3 axis...  (not including mesa hardware)
> $425.80
> closed loop - priceless... ;)
>
> You would want to do your homework though - like the drive inputs seem 
> to be common-ed to +5v.  (probably not an issue)
> (if I did the math right)
> sam
>
>
> *
> On 1/7/2010 01:29 PM, Flying Electron wrote:
>   
>> I'm deciding on what servo drive to use with the mesa FPGA card and it
>> doesn't look too bad since there are not too many low cost options.  I'm
>> constrained to a NEMA 23 size motor since a NEMA 23 stepper is on the
>> machine right now and I want it to be a direct swap.  So far I've found
>> from searching on google and from people's suggestions here on the
>> mailing list:
>>
>> Drives
>> ---
>> [brushless] Pico Brushless PWM Servo Amp $150
>> [brushed] Pico PWM Servo Amplifier $125
>>
>> Motors
>> 
>> [brushless] Pico Size 23 Brushless Servo (61ozin continous, 180ozin
>> peak, 1000 CPR) $120
>> [brushless] Keling KL23BLS-115 Brushless Servo (61ozin continous, 180
>> ozin peak, 1000 CPR) $134
>> [brushed]  Keling KL23-130-60 Brushed Servo (50ozin continous, 350ozin
>> peak, 1000 CPR) $162
>>
>> Not Suitable
>> -
>> dmm-tech.com -- RS232 based communication not PWM
>> gecko   -- EMC2 cannot control PID loop (step/dir input, not
>> pwm)
>> viper -- EMC2 cannot control PID loop (step/dir input,
>> not pwm)
>> rutex -- EMC2 cannot control PID loop (step/dir input,
>> not pwm)
>>
>> Most of the servo drives I have found have the PID loop built into
>> them.  Is this the normal case?
>>
>> Is it possible to run a brushed DC servo with just a simple H-Bridge
>> controlled directly by the PWM output and a direction signal?  I was
>> looking at the Freescale MC33886 which I think could make a very simple
>> and cheap H-Bridge.
>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC33886VW-ND
>> 
>>
>> Anybody know of any companies or products I may have missed in my search?
>>
>>
>>
>>
>> --
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>> Take advantage of Verizon's best-in-class app development support
>> A streamlined, 14 day to market process makes app distribution fast and easy
>> Join now and get one step closer to millions of Verizon customers
>> http://p.sf.net/sfu/verizon-dev2dev
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>> https://lists.sourceforge.net/lists/listinfo/emc-users
>>
>>
>> 
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Re: [Emc-users] Servo Drives

[sam sokolik]

there are always deals if you are patient.  Like...
*KL23BLS-115* *: $52/pcs brushless servos
digikey amt102-v encoder 29.95. <-up to 2048 line - adjustable.
ebay 3 amc amplifiers that take pwm+dir
http://cgi.ebay.com/3-AXIS-A-M-C-PWM-Brushless-SERVO-AMPLIFIER-ASSEMBLY-NEW_W0QQitemZ260516353589QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ca7fc1635
179.95

Not including shipping for 3 axis...  (not including mesa hardware)
$425.80
closed loop - priceless... ;)

You would want to do your homework though - like the drive inputs seem 
to be common-ed to +5v.  (probably not an issue)
(if I did the math right)
sam


*
On 1/7/2010 01:29 PM, Flying Electron wrote:
> I'm deciding on what servo drive to use with the mesa FPGA card and it
> doesn't look too bad since there are not too many low cost options.  I'm
> constrained to a NEMA 23 size motor since a NEMA 23 stepper is on the
> machine right now and I want it to be a direct swap.  So far I've found
> from searching on google and from people's suggestions here on the
> mailing list:
>
> Drives
> ---
> [brushless] Pico Brushless PWM Servo Amp $150
> [brushed] Pico PWM Servo Amplifier $125
>
> Motors
> 
> [brushless] Pico Size 23 Brushless Servo (61ozin continous, 180ozin
> peak, 1000 CPR) $120
> [brushless] Keling KL23BLS-115 Brushless Servo (61ozin continous, 180
> ozin peak, 1000 CPR) $134
> [brushed]  Keling KL23-130-60 Brushed Servo (50ozin continous, 350ozin
> peak, 1000 CPR) $162
>
> Not Suitable
> -
> dmm-tech.com -- RS232 based communication not PWM
> gecko   -- EMC2 cannot control PID loop (step/dir input, not
> pwm)
> viper -- EMC2 cannot control PID loop (step/dir input,
> not pwm)
> rutex -- EMC2 cannot control PID loop (step/dir input,
> not pwm)
>
> Most of the servo drives I have found have the PID loop built into
> them.  Is this the normal case?
>
> Is it possible to run a brushed DC servo with just a simple H-Bridge
> controlled directly by the PWM output and a direction signal?  I was
> looking at the Freescale MC33886 which I think could make a very simple
> and cheap H-Bridge.
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC33886VW-ND
> 
>
> Anybody know of any companies or products I may have missed in my search?
>
>
>
>
> --
> This SF.Net email is sponsored by the Verizon Developer Community
> Take advantage of Verizon's best-in-class app development support
> A streamlined, 14 day to market process makes app distribution fast and easy
> Join now and get one step closer to millions of Verizon customers
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> https://lists.sourceforge.net/lists/listinfo/emc-users
>
>
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Re: [Emc-users] Servo Drives

[Dave]

Yes, most low cost servo and stepper drives are interfaced via step and 
direction.

Up until the step and direction interface became popular the standard 
was a +/- 10v analog input interface and the servo drive was operated in 
a velocity mode or torque mode.

I think that EMC2 might be the only low cost CNC software/hardware that 
I know of that can output a PWM signal.

The drives that you have listed as "not suitable" all have the PID 
position loops on the drive itself.

What kind of machine are you attempting to control?

One of the nice things about the newest Gecko servo drive is that it 
will interface directly with a LPT port, even a low voltage 3.3 volt 
port.  So depending on how you wire your machine no BOB may be required.

(I have no interest in any drive or motor seller or manufacturer.)

Dave


Serial interface(UART,SPI),Pulse/Direction or CW/CCW,analog.

On 1/7/2010 2:29 PM, Flying Electron wrote:
> I'm deciding on what servo drive to use with the mesa FPGA card and it
> doesn't look too bad since there are not too many low cost options.  I'm
> constrained to a NEMA 23 size motor since a NEMA 23 stepper is on the
> machine right now and I want it to be a direct swap.  So far I've found
> from searching on google and from people's suggestions here on the
> mailing list:
>
> Drives
> ---
> [brushless] Pico Brushless PWM Servo Amp $150
> [brushed] Pico PWM Servo Amplifier $125
>
> Motors
> 
> [brushless] Pico Size 23 Brushless Servo (61ozin continous, 180ozin
> peak, 1000 CPR) $120
> [brushless] Keling KL23BLS-115 Brushless Servo (61ozin continous, 180
> ozin peak, 1000 CPR) $134
> [brushed]  Keling KL23-130-60 Brushed Servo (50ozin continous, 350ozin
> peak, 1000 CPR) $162
>
> Not Suitable
> -
> dmm-tech.com -- RS232 based communication not PWM
> gecko   -- EMC2 cannot control PID loop (step/dir input, not
> pwm)
> viper -- EMC2 cannot control PID loop (step/dir input,
> not pwm)
> rutex -- EMC2 cannot control PID loop (step/dir input,
> not pwm)
>
> Most of the servo drives I have found have the PID loop built into
> them.  Is this the normal case?
>
> Is it possible to run a brushed DC servo with just a simple H-Bridge
> controlled directly by the PWM output and a direction signal?  I was
> looking at the Freescale MC33886 which I think could make a very simple
> and cheap H-Bridge.
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC33886VW-ND
> 
>
> Anybody know of any companies or products I may have missed in my search?
>
>
>
>
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Re: [Emc-users] Servo Drives

[Peter C. Wallace]

On Thu, 7 Jan 2010, Flying Electron wrote:

> Date: Thu, 07 Jan 2010 11:29:10 -0800
> From: Flying Electron 
> Reply-To: "Enhanced Machine Controller (EMC)"
> 
> To: "Enhanced Machine Controller (EMC)" 
> Subject: [Emc-users] Servo Drives
> 
> I'm deciding on what servo drive to use with the mesa FPGA card and it
> doesn't look too bad since there are not too many low cost options.  I'm
> constrained to a NEMA 23 size motor since a NEMA 23 stepper is on the
> machine right now and I want it to be a direct swap.  So far I've found
> from searching on google and from people's suggestions here on the
> mailing list:
>
> Drives
> ---
> [brushless] Pico Brushless PWM Servo Amp $150
> [brushed] Pico PWM Servo Amplifier $125
>
> Motors
> 
> [brushless] Pico Size 23 Brushless Servo (61ozin continous, 180ozin
> peak, 1000 CPR) $120
> [brushless] Keling KL23BLS-115 Brushless Servo (61ozin continous, 180
> ozin peak, 1000 CPR) $134
> [brushed]  Keling KL23-130-60 Brushed Servo (50ozin continous, 350ozin
> peak, 1000 CPR) $162
>
> Not Suitable
> -
> dmm-tech.com -- RS232 based communication not PWM
> gecko   -- EMC2 cannot control PID loop (step/dir input, not
> pwm)
> viper -- EMC2 cannot control PID loop (step/dir input,
> not pwm)
> rutex -- EMC2 cannot control PID loop (step/dir input,
> not pwm)

Well, the step+dir drives will work but you wont have a full closed loop 
system.

>
> Most of the servo drives I have found have the PID loop built into
> them.  Is this the normal case?

For velocity mode drives, yes, the drive has a velocity control loop using 
tachometer or encoder feedback. EMC closes the position loop with this type of 
drive.

>
> Is it possible to run a brushed DC servo with just a simple H-Bridge
> controlled directly by the PWM output and a direction signal?  I was
> looking at the Freescale MC33886 which I think could make a very simple
> and cheap H-Bridge.
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MC33886VW-ND
> 

Yes, though tuning will be fussier than with a velocity mode servo drive

>
> Anybody know of any companies or products I may have missed in my search?
>
>

Yes, Mesa
We have some simple Hbridges that match the pinout of our FPGA cards

>
>
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Peter Wallace
Mesa Electronics

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