Lineary actuator - direct drive

[Asbjørn]

The actuators like Copley Controls ServoTube, Parkers Powerrod and
Faulhabers Quickshaft are all based on a arrangement of magnets inside
a rod around a coil with phases U,V,W:

| U | V | W |
|S-N| |N-S| |S-N| |N-S| |S-N|--------> Force
| U | V | W |

(alse U, V and W can be staked on top of each other

Does anyone knows the relationship between coli length and magnetic
pitch (I can hardly imagine the coil being 3 times magnet lenght, som
it seems so).

Is it possible driving a constant force in any position - imagine:

| U | V | W |
N| |N-S| |S-N| |N-S| |S-N|----->(|HEAVYLOAD|)
| U | V | W |

Does anyone know the dimensions or how the principles work (is it
standard AC motor drive with 120 degrees lack)?!

Best Regards

Asbjørn

 

[Dave]

The actuators like Copley Controls ServoTube, Parkers Powerrod and
Faulhabers Quickshaft are all based on a arrangement of magnets inside
a rod around a coil with phases U,V,W:

| U | V | W |
|S-N| |N-S| |S-N| |N-S| |S-N|--------> Force
| U | V | W |

(alse U, V and W can be staked on top of each other

Does anyone knows the relationship between coli length and magnetic
pitch (I can hardly imagine the coil being 3 times magnet lenght, som
it seems so).

Is it possible driving a constant force in any position - imagine:

| U | V | W |
N| |N-S| |S-N| |N-S| |S-N|----->(|HEAVYLOAD|)
| U | V | W |

Does anyone know the dimensions or how the principles work (is it
standard AC motor drive with 120 degrees lack)?!




No one knows how it works, it's all magic!!

 

[Asbjørn]

The actuators like Copley Controls ServoTube, Parkers Powerrod and
Faulhabers Quickshaft are all based on a arrangement of magnets inside
a rod around a coil with phases U,V,W:

|  U  |  V  |  W  |
|S-N| |N-S| |S-N| |N-S| |S-N|--------> Force
|  U  |  V  |  W  |

(alse U, V and W can be staked on top of each other

Does anyone knows the relationship between coli length and magnetic
pitch (I can hardly imagine the coil being 3 times magnet lenght, som
it seems so).

Is it possible driving a constant force in any position - imagine:

|  U  |  V  |  W  |
N| |N-S| |S-N| |N-S| |S-N|----->(|HEAVYLOAD|)
|  U  |  V  |  W  |

Does anyone know the dimensions or how the principles work (is it
standard AC motor drive with 120 degrees lack)?!

No one knows how it works, it's all magic!!

And I vote for you leaving this group....

 

[[email protected]]

The actuators like Copley Controls ServoTube, Parkers Powerrod and
Faulhabers Quickshaft are all based on a arrangement of magnets inside
a rod around a coil with phases U,V,W:

|  U  |  V  |  W  |
|S-N| |N-S| |S-N| |N-S| |S-N|--------> Force
|  U  |  V  |  W  |

(alse U, V and W can be staked on top of each other

Does anyone knows the relationship between coil length and magnetic
pitch (I can hardly imagine the coil being 3 times magnet lenght, som
it seems so).

A linear stepping motor is just an unrolled stepping motor - the
Douglas W Jones Tutorial is a good place to start.

http://www.cs.uiowa.edu/~jones/step/index.html

Coil pitch and magnetic field pitch have to be the same.

Is it possible driving a constant force in any position - imagine:

Sort of. The force depends on the phase and magnitude of the current
through the coils and the exact phase position of the magnets vis-a-
vis the coils. You can use a couple of linear Hall sensors (mounted
outside the direct magnetic field of coils) to locate the position of
the moving magnets (or more precisely, the field they generate) vis-a-
vis the fixed coils, though you may well have to correct the Hall
outputs for the stray fields from the coils.

The force on the magnets is zero when the magnetic field is in phase
with the magnet and rises as the phase difference increases to 90
degrees. Sensible people tend to try to operate at a phase shift of
around 45 degrees, which only gives them 70.7% of the maximum force
available for a given coil current, but minimises the chance of
slipping a step.

You need to be able to program the currents through the two or three
sets of coils involved - for which you need a microstepping drive. It
is usual to rely on pulse width modulation to control the currents
through the coils.

It isn't a good idea to rely the inductance of the coils to filter out
the high frequency components in the coil current - the coil leads
then radiate a great deal of radio-frequency-interference, which can
upset the neighbours and the FCC. Use a pi filter mounted close to the
driver to minimise the size f the transmitting antenna.

<snip>

 

[Dave]

The actuators like Copley Controls ServoTube, Parkers Powerrod and
Faulhabers Quickshaft are all based on a arrangement of magnets inside
a rod around a coil with phases U,V,W:

| U | V | W |
|S-N| |N-S| |S-N| |N-S| |S-N|--------> Force
| U | V | W |

(alse U, V and W can be staked on top of each other

Does anyone knows the relationship between coli length and magnetic
pitch (I can hardly imagine the coil being 3 times magnet lenght, som
it seems so).

Is it possible driving a constant force in any position - imagine:

| U | V | W |
N| |N-S| |S-N| |N-S| |S-N|----->(|HEAVYLOAD|)
| U | V | W |

Does anyone know the dimensions or how the principles work (is it
standard AC motor drive with 120 degrees lack)?!

No one knows how it works, it's all magic!!

And I vote for you leaving this group....




I'm sorry Asbjorn but if you did some searches on google you can find loads
of useful information much more quickly than you will get it here. If then
after digesting all the information you have some more specific questions
then this is the place to ask and I'm sure many people will be ready to
respond.

BTW I did a search and found this interesting document:

http://www.aerotech.com/products/PDF/LMAppGuide.pdf

It's by no means everything but provides a good start with understanding and
was found at the bottom of the first search result from Wikipedia.

Dave.

 

[Jim Thompson]

And I vote for you leaving this group....

He who posts from googlegroups should watch his language or risk
permanent termination.

...Jim Thompson

 

[John Popelish]

The actuators like Copley Controls ServoTube, Parkers Powerrod and
Faulhabers Quickshaft are all based on a arrangement of magnets inside
a rod around a coil with phases U,V,W:

| U | V | W |
|S-N| |N-S| |S-N| |N-S| |S-N|--------> Force
| U | V | W |

(alse U, V and W can be staked on top of each other

Does anyone knows the relationship between coli length and magnetic
pitch (I can hardly imagine the coil being 3 times magnet lenght, som
it seems so).

Is it possible driving a constant force in any position - imagine:

| U | V | W |
N| |N-S| |S-N| |N-S| |S-N|----->(|HEAVYLOAD|)
| U | V | W |

Does anyone know the dimensions or how the principles work (is it
standard AC motor drive with 120 degrees lack)?!

I think you have gotten the relative spacing of coils and
magnets a little wrong. The cycle of magnetic poles (the
length between similar points in the repeating pattern of a
pair of magnets and the spaces between them ) must match the
cycle of coils (the length between the same point in the
repeating pattern of coils). So each 3 coils covers two
magnets. By varying the current direction and magnitude of
the current in each of the three coils, the set can
approximate the effect of a single coil that has an
arbitrary position in the coil pattern. That coil will
interact with the magnetic cycle of the permanent magnets in
a sinusoidal force pattern. There is a relative position
that produces maximum force in one direction, another
relative position (a half a pattern cycle away) that
produces a maximum force in the other direction, and a pair
of points half way between those positions that produce no
force.

The trick is to know where the magnets are, at all times,
with respect to the coil pattern, and continuously adjust
the 3 currents (in magnitude and direction) to keep the
total effect at one of the force peaks as the magnets move.
Which peak you choose depends on which way you want the
force to push. This is the linear analog of a permanent
magnet, rotary synchronous motor.

 

[sycochkn]

The actuators like Copley Controls ServoTube, Parkers Powerrod and
Faulhabers Quickshaft are all based on a arrangement of magnets inside
a rod around a coil with phases U,V,W:

| U | V | W |
|S-N| |N-S| |S-N| |N-S| |S-N|--------> Force
| U | V | W |

(alse U, V and W can be staked on top of each other

Does anyone knows the relationship between coli length and magnetic
pitch (I can hardly imagine the coil being 3 times magnet lenght, som
it seems so).

Is it possible driving a constant force in any position - imagine:

That would be a voice coil actuator with position sensing. force is related
to current. I guess you could use a load cell to sense force against an
object.

Bob

| U | V | W |
N| |N-S| |S-N| |N-S| |S-N|----->(|HEAVYLOAD|)
| U | V | W |

Does anyone know the dimensions or how the principles work (is it
standard AC motor drive with 120 degrees lack)?!

Best Regards

Asbjørn

 

[[email protected]]

He who posts from googlegroups should watch his language or risk
permanent termination.

Everybody gets permanently terminated eventually, so Jim's got it more
or less right for once.

As an intimidator, he doesn't really hack it, despite his imaginary
friends inside the FBI.

 

[Michael A. Terrell]

As an intimidator, he doesn't really hack it, despite his imaginary
friends inside the FBI.

The same ones you stated are keeping you out of the US?


--
aioe.org is home to cowards and terrorists

Add this line to your news proxy nfilter.dat file
* drop Path:*aioe.org!not-for-mail to drop all aioe.org traffic.

http://improve-usenet.org/index.html

 

[[email protected]]

   The same ones you stated are keeping you out of the US?

Do pay attention. I was merely suggesting that you tranquillised
yourself by taking over one of Jim Thompson's sillier delusions.

 

[Michael A. Terrell]

Do pay attention. I was merely suggesting that you tranquillised
yourself by taking over one of Jim Thompson's sillier delusions.

You pay attention, and put more effort in keeping your lies straight.


--
aioe.org is home to cowards and terrorists

Add this line to your news proxy nfilter.dat file
* drop Path:*aioe.org!not-for-mail to drop all aioe.org traffic.

http://improve-usenet.org/index.html

 

[Jim Thompson]

You pay attention, and put more effort in keeping your lies straight.

Slowman is so-o-o-o-o SLOW that he missed my offer to Bloggs to
introduce my "friends" if Bloggs would show his face. So far Bloggs
is a no show.

...Jim Thompson

 

[[email protected]]

Slowman is so-o-o-o-o SLOW that he missed my offer to Bloggs to
introduce my "friends" if Bloggs would show his face.  So far Bloggs
is a no show.

I didn't actually miss it, much as I would have liked to.

It was in the "heat pumps" thread, and I commented on it on January 1,
2008.

Jim is reliably out of touch with reality.

 

[Michael A. Terrell]

Jim is reliably out of touch with reality.

I find it only slighty interesting that you think that are the only
person here who is in touch with reality. How can everyone else in the
world be wrong? Humm????????????????????????


--
aioe.org is home to cowards and terrorists

Add this line to your news proxy nfilter.dat file
* drop Path:*aioe.org!not-for-mail to drop all aioe.org traffic.

http://improve-usenet.org/index.html

 

[[email protected]]

   I find it only slighty interesting that you think that are the only
person here who is in touch with reality. How can everyone else in the
world be wrong? Humm????????????????????????

Jim Thompson is definitely out of touch with reality. Everybody gets
things wrong to some extent, but he gets them wrong remarkably often
(whch is why I comment on it).

You don't have the same problem with reality - hardly anybody else
does - but you do have a remarkable knack for coming to conclusions
that can't be justified by the text that you are quoting, which would
suggest that you do need to find yourself a remedial English class.

It is posible that you might be conciously subverting the conventions
of logical argument for some hoped-for comic effect, but if you are
your dead-pan is pretty much perfect.

 

[[email protected]]

Jim Thompson is definitely out of touch with reality. Everybody gets
things wrong to some extent, but he gets them wrong remarkably often
(whch is why I comment on it).

You don't have the same problem with reality - hardly anybody else
does - but you do have a remarkable knack for coming to conclusions
that can't be justified by the text that you are quoting, which would
suggest that you do need to find yourself a remedial English class.

It is posible that you might be conciously subverting the conventions
of logical argument for some hoped-for comic effect, but if you are
your dead-pan is pretty much perfect.

Thanks for replying - I need to drive a finished motor like the
ServoTube XTA3810 with my own circuit, and the force, speed and
position controlability have to be individually independent. Thus a
magnetic pitch equal the lenght of each coil would creating 'dead
zones' where the actuator is unable to push against the object. The
actuator must be used as forcer for a grinding machine pressing with a
constant pressure and slowly "eating" through the material.

The Faulhaber QUICKSHAFT seems to have a 3,5/3 asymmetric relationship
between coil lenght and each magnet, thus making no deadzones where
force cannot be supplied to the rod.

I willl look into the material giving as links - once again thanks.

Best Regards

Asbjørn

 

[[email protected]]

On 16 Mar., 11:54, [email protected] wrote:

Thanks for replying - I need to drive a finished motor  like the
ServoTube XTA3810 with my own circuit, and the force, speed and
position controlability have to be individually independent. Thus a
magnetic pitch equal the length of each coil would creating 'dead
zones' where the actuator is unable to push against the object.

In a rotary stepper motor, the coil winding pattern repeats with the
same pitch as the magnetic field pattern.

The coil winding pattern always includes two or more coils per pitch
precisely to avoid this kind of dead zone.
With two coils, the arrangement is always designed so that the force
generated by each coil follows the sine and cosine of the phase angle
as the motor rotates/drives through a single pitch interval.

Dividing a single pitch interval in to 360 degrees, two coils are set
up to be 90 degrees apart, three coils 60 degrees and so on - the
advantage of increasing the number of phases is that you get a
smoother torque/force curve.

The actuator must be used as forcer for a grinding machine pressing
with a constant pressure and slowly "eating" through the material.

The Faulhaber QUICKSHAFT seems to have a 3,5/3 asymmetric relationship
between coil lenght and each magnet, thus making no deadzones where
force cannot be supplied to the rod.

It sounds as if you are going to have to do a bit more reading before
you fully understand what's going on - don't let it worry you, we've
all had to go through it. Eventually, you too will get to say "why
didn't I see that earlier" ...

 

[JosephKK]

The actuators like Copley Controls ServoTube, Parkers Powerrod and
Faulhabers Quickshaft are all based on a arrangement of magnets inside
a rod around a coil with phases U,V,W:

| U | V | W |
|S-N| |N-S| |S-N| |N-S| |S-N|--------> Force
| U | V | W |

(alse U, V and W can be staked on top of each other

Does anyone knows the relationship between coli length and magnetic
pitch (I can hardly imagine the coil being 3 times magnet lenght, som
it seems so).

Is it possible driving a constant force in any position - imagine:

| U | V | W |
N| |N-S| |S-N| |N-S| |S-N|----->(|HEAVYLOAD|)
| U | V | W |

Does anyone know the dimensions or how the principles work (is it
standard AC motor drive with 120 degrees lack)?!


No one knows how it works, it's all magic!!

Looks like straightforward electromagnetics to me. What is your
problem?