[Emc-users] New kind of stepper motor on eBay

[Chris Albertson]

Hi,

Has anyone here experience with this?

I think these are new. I've seen them on some web sites and also eBay. I
can't find any good engineering information yet, like user manuals or
speed/torque plots but the idea is great.

They are an integrated closed loop driver/controller and motor. The
feedback loop is done inside the motor. They are MUCH better at holding
torque at high speed than are normal steppers. More like a servo but at
much lower cost. The motor accepts DC power (about 36 volts) and step
and direction. Here is one example from eBay

Building the driver into the motor is good. For closed loop control the
driver must be matched to the motor so you would always buy them in pairs
anyway. Placing them in one unit saves the need to run a lot of wire and
all the noise problems and lowers the over all cost. The driver cane made
simpler and cheaper because it does not need to be general purpose, it just
drive the motor with known inductance and resistance.

http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver.....
<http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver-2-in-1-L112mm-3Nm-24-48VDC-CNC/192011640913?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D40130%26meid%3Dbc8047bd176346b9a8fbf5703256f1ef%26pid%3D100005%26rk%3D4%26rkt%3D6%26sd%3D262565354603>

I saw a youtube video demo of one of these that showed it holding
position. It was using almost no current and the motor was cool. But then
if you apply force to the shaft the current zooms up to counter the applied
force, like a servo Basically it IS a servo. There is an optical
encoder. The above web page has a block diagram.

All the good info is in Chinese. Perhaps someone here is good at technical
Chinese. My wife can read only the very basic stuff and Google translation
is not so good. I think these are designed and sold into the Chinese
domestic market hence no US sales office or English technical documents.

This eBay unit is cheaper than a conventional setup. I think this is the
way things are moving

[Marcus Bowman]

I read about these a little while ago. They are not Chinese; they are made in the USA.
I seem to remember they were a Kickstarter campaign, and I read a bit about them on Hackaday.
Seemed like a good idea, but they are expensive.
Maybe the Chinese copies are cheaper, of course.
The maths they are based on is interesting, and somewhat complex, but clever.

Marcus

Post by Chris Albertson
Hi,
Has anyone here experience with this?
I think these are new. I've seen them on some web sites and also eBay. I
can't find any good engineering information yet, like user manuals or
speed/torque plots but the idea is great.
They are an integrated closed loop driver/controller and motor. The
feedback loop is done inside the motor. They are MUCH better at holding
torque at high speed than are normal steppers. More like a servo but at
much lower cost. The motor accepts DC power (about 36 volts) and step
and direction. Here is one example from eBay
Building the driver into the motor is good. For closed loop control the
driver must be matched to the motor so you would always buy them in pairs
anyway. Placing them in one unit saves the need to run a lot of wire and
all the noise problems and lowers the over all cost. The driver cane made
simpler and cheaper because it does not need to be general purpose, it just
drive the motor with known inductance and resistance.
http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver.....
<http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver-2-in-1-L112mm-3Nm-24-48VDC-CNC/192011640913?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D40130%26meid%3Dbc8047bd176346b9a8fbf5703256f1ef%26pid%3D100005%26rk%3D4%26rkt%3D6%26sd%3D262565354603>
I saw a youtube video demo of one of these that showed it holding
position. It was using almost no current and the motor was cool. But then
if you apply force to the shaft the current zooms up to counter the applied
force, like a servo Basically it IS a servo. There is an optical
encoder. The above web page has a block diagram.
All the good info is in Chinese. Perhaps someone here is good at technical
Chinese. My wife can read only the very basic stuff and Google translation
is not so good. I think these are designed and sold into the Chinese
domestic market hence no US sales office or English technical documents.
This eBay unit is cheaper than a conventional setup. I think this is the
way things are moving
--
Chris Albertson
Redondo Beach, California
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[Gene Heskett]

Post by Chris Albertson
Hi,
Has anyone here experience with this?
I think these are new. I've seen them on some web sites and also
eBay. I can't find any good engineering information yet, like user
manuals or speed/torque plots but the idea is great.

I think so too. But I am so used to thinking in in/lbs, and have never
seen a formula or a chart that converts Nm to in/lbs, so I've no clue if
they might be usable for me. So what is 3Nm equ to?

I haven't a clue if it would fit for the X drive on the Sheldon, and not
hit the bed at 112mm long. It would awfull close, little or no room for
paint.

Post by Chris Albertson
They are an integrated closed loop driver/controller and motor. The
feedback loop is done inside the motor. They are MUCH better at
holding torque at high speed than are normal steppers. More like a
servo but at much lower cost. The motor accepts DC power (about 36
volts) and step and direction. Here is one example from eBay
Building the driver into the motor is good. For closed loop control
the driver must be matched to the motor so you would always buy them
in pairs anyway. Placing them in one unit saves the need to run a lot
of wire and all the noise problems and lowers the over all cost. The
driver cane made simpler and cheaper because it does not need to be
general purpose, it just drive the motor with known inductance and
resistance.
http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver..
...
<http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver-
2-in-1-L112mm-3Nm-24-48VDC-CNC/192011640913?_trksid=p2047675.c100005.m1
851&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D40130%26me
id%3Dbc8047bd176346b9a8fbf5703256f1ef%26pid%3D100005%26rk%3D4%26rkt%3D6
%26sd%3D262565354603>
I saw a youtube video demo of one of these that showed it holding
position. It was using almost no current and the motor was cool. But
then if you apply force to the shaft the current zooms up to counter
the applied force, like a servo Basically it IS a servo. There is an
optical encoder. The above web page has a block diagram.
All the good info is in Chinese. Perhaps someone here is good at
technical Chinese. My wife can read only the very basic stuff and
Google translation is not so good. I think these are designed and
sold into the Chinese domestic market hence no US sales office or
English technical documents.
This eBay unit is cheaper than a conventional setup. I think this
is the way things are moving

I'm sure of it. That posted price is about $65 less than when I checked
last. So the switchover will be considerably speeded up unless the
freight eats the difference. And it does eat much of it at $38 freight
from HongKong. That brings the per axis cost up to $126 for the 3Nm
unit.

Cheers, Gene Heskett

[andy pugh]

Post by Gene Heskett
I think so too. But I am so used to thinking in in/lbs, and have never
seen a formula or a chart that converts Nm to in/lbs, so I've no clue if
they might be usable for me. So what is 3Nm equ to?

Is that lbs mass or lbs force?

1Nm is 8.85 lb-in. Or about 3/4 of a lb-ft.

[Ken Strauss]

-----Original Message-----
Sent: Saturday, May 27, 2017 6:06 PM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] New kind of stepper motor on eBay

Post by Gene Heskett
I think so too. But I am so used to thinking in in/lbs, and have
never seen a formula or a chart that converts Nm to in/lbs, so I've no
clue if they might be usable for me. So what is 3Nm equ to?

Is that lbs mass or lbs force?
1Nm is 8.85 lb-in. Or about 3/4 of a lb-ft.
--

They sound similar to the stuff from Clearpath:
https://www.teknic.com/products/clearpath-brushless-dc-servo-motors/

[Chris Albertson]

Gene,

3Nm is about 425 inch pounds. Roughly 140 in oz to 1Nm

I went to school in the late 70's to early 80's and even then all the
science and engineering classes used metric. I could not even tell you
what 1g is in Imperial units but it is just under 10 m/sec squared.

In theory freight is the same for any motor of about the same size and
power.

I'm looking for a motor to lift the Z-axis of a Harbor Freight minimill.
Almost every conversion I have seen with the mini mill the Z axis has the
worst performance. In the design I'm using the z-motor is geared down 2:1
which means it spins faster so lower torque. This may be the place use
the closed loop 3Nm motor. I'll use a 5-pitch ball screw and 2:1
reduction timing belt drive. This means the motor sees 10 pitch or .0005
per full step. and then likely have to use 1/4 steps. The X and Y axis
are pretty light weight, anything would work.

Post by Gene Heskett

Post by Chris Albertson
Hi,
Has anyone here experience with this?
I think these are new. I've seen them on some web sites and also
eBay. I can't find any good engineering information yet, like user
manuals or speed/torque plots but the idea is great.

I think so too. But I am so used to thinking in in/lbs, and have never
seen a formula or a chart that converts Nm to in/lbs, so I've no clue if
they might be usable for me. So what is 3Nm equ to?
I haven't a clue if it would fit for the X drive on the Sheldon, and not
hit the bed at 112mm long. It would awfull close, little or no room for
paint.

Post by Chris Albertson
They are an integrated closed loop driver/controller and motor. The
feedback loop is done inside the motor. They are MUCH better at
holding torque at high speed than are normal steppers. More like a
servo but at much lower cost. The motor accepts DC power (about 36
volts) and step and direction. Here is one example from eBay
Building the driver into the motor is good. For closed loop control
the driver must be matched to the motor so you would always buy them
in pairs anyway. Placing them in one unit saves the need to run a lot
of wire and all the noise problems and lowers the over all cost. The
driver cane made simpler and cheaper because it does not need to be
general purpose, it just drive the motor with known inductance and
resistance.
http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver..
...
<http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver-
2-in-1-L112mm-3Nm-24-48VDC-CNC/192011640913?_trksid=p2047675.c100005.m1
851&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D40130%26me
id%3Dbc8047bd176346b9a8fbf5703256f1ef%26pid%3D100005%26rk%3D4%26rkt%3D6
%26sd%3D262565354603>
I saw a youtube video demo of one of these that showed it holding
position. It was using almost no current and the motor was cool. But
then if you apply force to the shaft the current zooms up to counter
the applied force, like a servo Basically it IS a servo. There is an
optical encoder. The above web page has a block diagram.
All the good info is in Chinese. Perhaps someone here is good at
technical Chinese. My wife can read only the very basic stuff and
Google translation is not so good. I think these are designed and
sold into the Chinese domestic market hence no US sales office or
English technical documents.
This eBay unit is cheaper than a conventional setup. I think this
is the way things are moving

I'm sure of it. That posted price is about $65 less than when I checked
last. So the switchover will be considerably speeded up unless the
freight eats the difference. And it does eat much of it at $38 freight
from HongKong. That brings the per axis cost up to $126 for the 3Nm
unit.
Cheers, Gene Heskett
--
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
------------------------------------------------------------
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[Chris Albertson]

Post by Gene Heskett
I'm sure of it. That posted price is about $65 less than when I checked
last. So the switchover will be considerably speeded up unless the
freight eats the difference. And it does eat much of it at $38 freight
from HongKong. That brings the per axis cost up to $126 for the 3Nm
unit.

It might cost less. With normal open loop steppers and analog drives like
the Gekko or Leadshine we need to over specify the motors or run them
considerable under their maximum rating so we are SURE not to skip steps
even in the worst case. But with closed loop servos we can push the
limit and buy a smaller motor for the same job. So you can't compare
motors of the same power, less power is needed for closed loop. That
said. With no experience with these, I'd buy the larger size first

Yes, until an importer buys these in bulk we will have to pay to ship them
one at a time at much higher price.

[Erik Christiansen]

Post by Gene Heskett
I think so too. But I am so used to thinking in in/lbs, and have never
seen a formula or a chart that converts Nm to in/lbs,

But on just about any full linux distro under your roof, you have:

$ units
You have: 3 N m
You want: lbf in
* 26.552237
/ 0.03766161

The first is the forward conversion, the second is the reciprocal.
(Use "units -1" if that's annoying.)

Post by Gene Heskett
so I've no clue if they might be usable for me. So what is 3Nm equ to?

Most of the advertisements seem to be in oz-in, so to "imperialise", I'd:

You have: 3 N m
You want: ozf in
Unknown unit 'ozf'
You want: oz force in
* 424.8358
/ 0.0023538506

Ah, now, that's substantial, in the size range I tend to look at.

Erik

P.S. As a side issue, I couldn't remember the imperial g, but:
You have: gravity
You want: ft/s^2
* 32.174049
/ 0.03108095

Yes, now I remember using 32, back as a schoolkid, before we went
metric.

[Fox Mulder]

Looks to me just like a stepper motor with integrated motor driver without feedback. Maybe the Mechaduino is more like a closed-loop stepper-servo. I have ordered some PCBs from DirtyPcb and will assemble them when they arrive. Hope they are as good as announced.

https://www.kickstarter.com/projects/tropicallabs/mechaduino-powerful-open-source-industrial-servo-m

https://hackaday.io/project/11224-mechaduino

Ciao,
Rainer

Post by Erik Christiansen

Post by Gene Heskett
I think so too. But I am so used to thinking in in/lbs, and have never
seen a formula or a chart that converts Nm to in/lbs,

$ units
You have: 3 N m
You want: lbf in
* 26.552237
/ 0.03766161
The first is the forward conversion, the second is the reciprocal.
(Use "units -1" if that's annoying.)

Post by Gene Heskett
so I've no clue if they might be usable for me. So what is 3Nm equ to?

You have: 3 N m
You want: ozf in
Unknown unit 'ozf'
You want: oz force in
* 424.8358
/ 0.0023538506
Ah, now, that's substantial, in the size range I tend to look at.
Erik
You have: gravity
You want: ft/s^2
* 32.174049
/ 0.03108095
Yes, now I remember using 32, back as a schoolkid, before we went
metric.
------------------------------------------------------------------------------
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[Chris Albertson]

On Sat, May 27, 2017 at 9:51 PM, Fox Mulder <***@gmx.net> wrote:

These little machaduino boards look good for small size motors they replace
the driver board

The Leadshine and other Chinese versions are not copies because
(1) They use 10000 line quadrature encoders not the magnetic sensor and
(2) They can handle much more powerful motors. The Kickstarter project is
for smaller motors, the max DC volts in looks to be 25V but I could but
quickly find the max current.

But if these go into mass production and the price gets to be less then the
current $45 each I'd buy a few or being open source maybe make something
based on in.

Post by Fox Mulder
https://www.kickstarter.com/projects/tropicallabs/
mechaduino-powerful-open-source-industrial-servo-m
https://hackaday.io/project/11224-mechaduino
--

Chris Albertson
Redondo Beach, California

[Gene Heskett]

Post by Chris Albertson
These little machaduino boards look good for small size motors they
replace the driver board
The Leadshine and other Chinese versions are not copies because
(1) They use 10000 line quadrature encoders not the magnetic sensor
and (2) They can handle much more powerful motors. The Kickstarter
project is for smaller motors, the max DC volts in looks to be 25V but
I could but quickly find the max current.

What I've looked at is the A4954? specs, 2 amps. And I believe the v max
is 35 volts but that would have to be a resistive load. The previous
Allegro chip that xylotek uses, the A3977 IIRC, is a similar but 3 amp
chip, and I have destroyed 3 of those on 28 volts on the micro-mill from
HF. I have not managed to damage a 2M542 driver yet, even with shorts or
cross connected motor coils, it detects the error and disables itself,
indicating that with a red led, running it at close to max current and
around 43 volts. Motor is an 8 wire NEMA 24 wired parallel. I have 4 of
them on the micromill, and 2 of them on TLM, but they are only running
on around 38 volts. Heating on those rises as the voltage is lowered
because of the higher % of on times I'm guessing, and they are not
recommended below 24 volts. And one on the sheldon running the x motor.

Post by Chris Albertson
But if these go into mass production and the price gets to be less
then the current $45 each I'd buy a few or being open source maybe
make something based on in.

Post by Fox Mulder
https://www.kickstarter.com/projects/tropicallabs/
mechaduino-powerful-open-source-industrial-servo-m
https://hackaday.io/project/11224-mechaduino
--

Chris Albertson
Redondo Beach, California

Cheers, Gene Heskett

[Chris Albertson]

Post by Fox Mulder
Looks to me just like a stepper motor with integrated motor driver without
feedback.

You ar right. The feedback being referred to is "current feedback". A
conventional stepper driver just sends out a pre-programmed voltage.

My mistake to point out the wrong unit. THIS is a better example of a
Chinese closed loop stepper motor: (1145 inch oz)
http://www.ebay.com/itm/NEMA34-8Nm-1145ozin-2phase-closed-loop.....
<http://www.ebay.com/itm/NEMA34-8Nm-1145ozin-2phase-closed-loop-easy-servo-motor-with-hybrid-drive-kit-/172437306014?hash=item2826107a9e:g:KVMAAOSwJ7RYSQyo>


There are also cheaper version but this is a large one from a respected
brand name..

These guys sell them also and have decent technical explanations on their
web site.
http://catalog.orientalmotor.com/category/s-short-range-servo-motor-drivers

[Gene Heskett]

Post by Chris Albertson

Post by Fox Mulder
Looks to me just like a stepper motor with integrated motor driver
without feedback.

You ar right. The feedback being referred to is "current feedback".
A conventional stepper driver just sends out a pre-programmed voltage.
My mistake to point out the wrong unit. THIS is a better example of a
Chinese closed loop stepper motor: (1145 inch oz)
http://www.ebay.com/itm/NEMA34-8Nm-1145ozin-2phase-closed-loop.....
<http://www.ebay.com/itm/NEMA34-8Nm-1145ozin-2phase-closed-loop-easy-s
ervo-motor-with-hybrid-drive-kit-/172437306014?hash=item2826107a9e:g:KV
MAAOSwJ7RYSQyo>

Here is an even better deal, free shipping at $87.88:

<http://www.ebay.com/itm/2ph-NEMA34-86mm-8-5N-5A-1000line-Encoder-closed-loop-Stepper-Motor-Drive-Kit-JMC/112370267424?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D2220072%26algo%3DSIM.MBE%26ao%3D2%26asc%3D40130%26meid%3Db9a1e8107cd14f288e85e24e68e99981%26pid%3D100005%26rk%3D2%26rkt%3D6%26sd%3D112333425559>

Post by Chris Albertson
There are also cheaper version but this is a large one from a
respected brand name..
These guys sell them also and have decent technical explanations on
their web site.
http://catalog.orientalmotor.com/category/s-short-range-servo-motor-dr
ivers

Cheers, Gene Heskett

[Lester Caine]

Post by Fox Mulder
Looks to me just like a stepper motor with integrated motor driver without feedback. Maybe the Mechaduino is more like a closed-loop stepper-servo. I have ordered some PCBs from DirtyPcb and will assemble them when they arrive. Hope they are as good as announced.
https://www.kickstarter.com/projects/tropicallabs/mechaduino-powerful-open-source-industrial-servo-m

Has the latest batch of boards already sold out ?

[Fox Mulder]

Post by Lester Caine

Post by Fox Mulder
Looks to me just like a stepper motor with integrated motor driver without feedback. Maybe the Mechaduino is more like a closed-loop stepper-servo. I have ordered some PCBs from DirtyPcb and will assemble them when they arrive. Hope they are as good as announced.
https://www.kickstarter.com/projects/tropicallabs/mechaduino-powerful-open-source-industrial-servo-m

Has the latest batch of boards already sold out ?

Seems so. I ordered bare PCBs which i have to equip myself with the
corresponding parts.

[Gene Heskett]

Post by Erik Christiansen

Post by Gene Heskett
I think so too. But I am so used to thinking in in/lbs, and have
never seen a formula or a chart that converts Nm to in/lbs,

$ units
You have: 3 N m
You want: lbf in
* 26.552237
/ 0.03766161
The first is the forward conversion, the second is the reciprocal.
(Use "units -1" if that's annoying.)

Post by Gene Heskett
so I've no clue if they might be usable for me. So what is 3Nm equ to?

You have: 3 N m
You want: ozf in
Unknown unit 'ozf'
You want: oz force in
* 424.8358
/ 0.0023538506
Ah, now, that's substantial, in the size range I tend to look at.
Erik
You have: gravity
You want: ft/s^2
* 32.174049
/ 0.03108095
Yes, now I remember using 32, back as a schoolkid, before we went
metric.

Thats all we had when I was in school, in the '40's. The only metrics I
was exposed to then was in my electronics stuff as I learned it,
beginning also in the '40's while WW-II was in full swing. :) Theres
been a whole lot of water under the bridge since then.

Cheers, Gene Heskett

[Erik Christiansen]

Post by Gene Heskett

Post by Erik Christiansen
You have: gravity
You want: ft/s^2
* 32.174049
/ 0.03108095
Yes, now I remember using 32, back as a schoolkid, before we went
metric.

Thats all we had when I was in school, in the '40's. The only metrics I
was exposed to then was in my electronics stuff as I learned it,
beginning also in the '40's while WW-II was in full swing. :) Theres
been a whole lot of water under the bridge since then.

Yup, if you said today "Don't hide your light under a bushel.", the
literal part of the analogue would probably no longer be recognised
as a candle put under an upturned 35 litre wooden measuring bucket.

Erik

[Gene Heskett]

Post by Erik Christiansen

Post by Gene Heskett

Post by Erik Christiansen
You have: gravity
You want: ft/s^2
* 32.174049
/ 0.03108095
Yes, now I remember using 32, back as a schoolkid, before we went
metric.

Thats all we had when I was in school, in the '40's. The only
metrics I was exposed to then was in my electronics stuff as I
learned it, beginning also in the '40's while WW-II was in full
swing. :) Theres been a whole lot of water under the bridge since
then.

Yup, if you said today "Don't hide your light under a bushel.", the
literal part of the analogue would probably no longer be recognised
as a candle put under an upturned 35 litre wooden measuring bucket.
Erik

It would at least require an explanation for any one under 30 unless they
are a regular church attendee. It been that long since I heard
reference to it, and that came from the back side of a pulpit.

Cheers, Gene Heskett

[Andrew]

Hello Chris,

I might be missing something, but I don't think it's a closed loop motor.
They never mention position loop, and I can't see an encoder.

Post by Chris Albertson
Hi,
Has anyone here experience with this?
I think these are new. I've seen them on some web sites and also eBay. I
can't find any good engineering information yet, like user manuals or
speed/torque plots but the idea is great.
They are an integrated closed loop driver/controller and motor. The
feedback loop is done inside the motor. They are MUCH better at holding
torque at high speed than are normal steppers. More like a servo but at
much lower cost. The motor accepts DC power (about 36 volts) and step
and direction. Here is one example from eBay
Building the driver into the motor is good. For closed loop control the
driver must be matched to the motor so you would always buy them in pairs
anyway. Placing them in one unit saves the need to run a lot of wire and
all the noise problems and lowers the over all cost. The driver cane made
simpler and cheaper because it does not need to be general purpose, it just
drive the motor with known inductance and resistance.
http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-Integrated-Driver.....
<http://www.ebay.com/itm/Nema23-57BYG-Stepper-Motor-
Integrated-Driver-2-in-1-L112mm-3Nm-24-48VDC-CNC/
192011640913?_trksid=p2047675.c100005.m1851&_trkparms=aid%
3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D40130%26meid%
3Dbc8047bd176346b9a8fbf5703256f1ef%26pid%3D100005%26rk%3D4%
26rkt%3D6%26sd%3D262565354603>
I saw a youtube video demo of one of these that showed it holding
position. It was using almost no current and the motor was cool. But then
if you apply force to the shaft the current zooms up to counter the applied
force, like a servo Basically it IS a servo. There is an optical
encoder. The above web page has a block diagram.
All the good info is in Chinese. Perhaps someone here is good at technical
Chinese. My wife can read only the very basic stuff and Google translation
is not so good. I think these are designed and sold into the Chinese
domestic market hence no US sales office or English technical documents.
This eBay unit is cheaper than a conventional setup. I think this is the
way things are moving
--
Chris Albertson
Redondo Beach, California
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[Nicklas Karlsson]

Post by Chris Albertson
...
They are an integrated closed loop driver/controller and motor. The
feedback loop is done inside the motor. They are MUCH better at holding
torque at high speed than are normal steppers. More like a servo but at
much lower cost. The motor accepts DC power (about 36 volts) and step
and direction. Here is one example from eBay

I made my own driver cards with closed loop controller. With my driver control loop could be run once for each switch which is equal to twice the switching period. I think it make a lot of sense to build like this.

Post by Chris Albertson
Building the driver into the motor is good. For closed loop control the
driver must be matched to the motor so you would always buy them in pairs
anyway. Placing them in one unit saves the need to run a lot of wire and
all the noise problems and lowers the over all cost. The driver cane made
simpler and cheaper because it does not need to be general purpose, it just
drive the motor with known inductance and resistance.

To build driver into motor may be a problem for heat dissipation. To match motor is usually done with a set of parameters. Placing them in one unit may increase price for internal power supply and other common parts but decrease cost for angular sensor. It is good for seller because they could sell more, both card and motor.

[Chris Albertson]

On Sun, May 28, 2017 at 1:48 PM, Nicklas Karlsson <

Post by Nicklas Karlsson

...

I made my own driver cards with closed loop controller. With my driver
control loop could be run once for each switch which is equal to twice the
switching period. I think it make a lot of sense to build like this.

I would really like to hear more about this. What encoders and processor
and I don't understand which "switching period" you mean what is the
length of the period. What size motors?

I'm using position feedback to control both my 4 and 6 wheel drive mobile
platforms. The wheels are driven with either 75 or 100 to 1 gearboxes, one
motor per wheel. I did not have to make a controller card the little
single board computer boards work just fine with only an external h-bridge.