Linear displacement
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Posts: 46,084
I am looking for suggestions for a hardware interface for my stamp. I want to
measure very small displacements (0 to 5mm) with 0.01mm accuracy. I don't
think I want to use an LVDT. Perhaps an optical sensor, Linear Hall effect,
??????????? I have some general ideas, but many heads are better than my one
bald one!
Any suggestions welcomed.
Ken
[noparse][[/noparse]Non-text portions of this message have been removed]
measure very small displacements (0 to 5mm) with 0.01mm accuracy. I don't
think I want to use an LVDT. Perhaps an optical sensor, Linear Hall effect,
??????????? I have some general ideas, but many heads are better than my one
bald one!
Any suggestions welcomed.
Ken
[noparse][[/noparse]Non-text portions of this message have been removed]
Comments
brainwork to get any repeatability with a hardware solution. You can buy
digital calipers or digital machine scales and interface them to a Stamp,
but these are usually only good to 0.001 inches, even though they claim
0.0005 inches.
When I worked for a company that manufactured leak detection equipment for
the service station industry, they used a calibrated piston / cylinder and
LVDT to detect very minute leaks in plumbing. The engineers claimed nothing
else worked as well.
Original Message
> I am looking for suggestions for a hardware interface for my stamp. I want
to
> measure very small displacements (0 to 5mm) with 0.01mm accuracy. I don't
> think I want to use an LVDT. Perhaps an optical sensor, Linear Hall
effect,
> ??????????? I have some general ideas, but many heads are better than my
one
> bald one!
resolution of an optical type system.
What kind of fluid are we talking? Is it always the same density/color?
What degree of accuracy is required? Is it under any pressure?
The calibrated piston sounds like the way to go if really fine accuracy is
needed.
Just a thought,
Jonathan
Original Message
From: "Rodent" <daweasel@s...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, March 20, 2003 10:43 AM
Subject: Re: [noparse][[/noparse]basicstamps] Linear displacement
> 0-5mm in 0.01mm increments is pretty fine and may require some serious
> brainwork to get any repeatability with a hardware solution. You can buy
> digital calipers or digital machine scales and interface them to a Stamp,
> but these are usually only good to 0.001 inches, even though they claim
> 0.0005 inches.
>
> When I worked for a company that manufactured leak detection equipment for
> the service station industry, they used a calibrated piston / cylinder and
> LVDT to detect very minute leaks in plumbing. The engineers claimed
nothing
> else worked as well.
>
>
Original Message
>
> > I am looking for suggestions for a hardware interface for my stamp. I
want
> to
> > measure very small displacements (0 to 5mm) with 0.01mm accuracy. I
don't
> > think I want to use an LVDT. Perhaps an optical sensor, Linear Hall
> effect,
> > ??????????? I have some general ideas, but many heads are better than my
> one
> > bald one!
>
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>
mentioned displacement. I only mentioned the fluid measurement because it
used LVDT as a way to measure minute increments.
What I was getting at was that with very fine measurements, using mechanical
means to "amplify" a measurement would be harder than other methods.
Original Message
> What about decreasing the diameter of the vessel? That would increase the
> resolution of an optical type system.
>
> What kind of fluid are we talking? Is it always the same density/color?
> What degree of accuracy is required? Is it under any pressure?
>
> The calibrated piston sounds like the way to go if really fine accuracy is
> needed.
>
Original Message
> > 0-5mm in 0.01mm increments is pretty fine and may require some serious
> > brainwork to get any repeatability with a hardware solution. You can buy
> > digital calipers or digital machine scales and interface them to a
Stamp,
> > but these are usually only good to 0.001 inches, even though they claim
> > 0.0005 inches.
> >
> > When I worked for a company that manufactured leak detection equipment
for
> > the service station industry, they used a calibrated piston / cylinder
and
> > LVDT to detect very minute leaks in plumbing. The engineers claimed
> nothing
> > else worked as well.
> >
> >
Original Message
> >
> > > I am looking for suggestions for a hardware interface for my stamp. I
> want
> > to
> > > measure very small displacements (0 to 5mm) with 0.01mm accuracy. I
> don't
> > > think I want to use an LVDT. Perhaps an optical sensor, Linear Hall
> > effect,
> > > ??????????? I have some general ideas, but many heads are better than
my
> > one
> > > bald one!
> >
> >
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the Subject
and
> Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
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>
>
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>
>
>
Original Message
> Mitutoyo offers a device with resolution of .0001 mm
> and an accuracy of .002 mm over 5,10,25,50 mm range.
> 4 um cycle square wave output, RS422 compatible.
> See "LGB/LGF linear gauges". My info is dated - Current
> devices may be better.
> > 0-5mm in 0.01mm increments is pretty fine and may require some serious
> > brainwork to get any repeatability with a hardware solution. You can buy
> > digital calipers or digital machine scales and interface them to a
Stamp,
> > but these are usually only good to 0.001 inches, even though they claim
> > 0.0005 inches.
> >
> > When I worked for a company that manufactured leak detection equipment
for
> > the service station industry, they used a calibrated piston / cylinder
and
> > LVDT to detect very minute leaks in plumbing. The engineers claimed
nothing
> > else worked as well.
> >
> >
Original Message
> >
> > > I am looking for suggestions for a hardware interface for my stamp. I
want
> > to
> > > measure very small displacements (0 to 5mm) with 0.01mm accuracy. I
don't
> > > think I want to use an LVDT. Perhaps an optical sensor, Linear Hall
> > effect,
> > > ??????????? I have some general ideas, but many heads are better than
my
> > one
> > > bald one!
daweasel@s... writes:
> Not sure he was wanting to measure a liquid when the original poster
> mentioned displacement. I only mentioned the fluid measurement because it
> used LVDT as a way to measure minute increments.
>
> What I was getting at was that with very fine measurements, using
> mechanical
> means to "amplify" a measurement would be harder than other methods.
I will not be measuring liquid. I will be measuring a deflection. I don't
have any experience with strain guages, but it would seem a strain guage
would not be real repeatable.????
[noparse][[/noparse]Non-text portions of this message have been removed]
daweasel@s... writes:
> How much $$ though? My suggestion is $100-150.
>
As little $$ as possible (of course). I think I may try to hack a caliper.
Can you tell me a little about the caliper RS232 output. What does it output,
a lineat voltage, ASCII stuff or????
[noparse][[/noparse]Non-text portions of this message have been removed]
calipers and linear scales requires you to clock each bit of data from the
unit. A level converter is required as the output voltage is very low due to
these units running off batteries.
I have some Stamp code I got from another user thats supposed to work with
the Mitutoyo calipers, and have messed around with a level converter some,
but don't have a fully functional unit yet. I have found several sources for
display heads for these devices -- one is www.wttool.com -- item #
1289-0465. They also sell the linear scales. I have another source, but I
need to track down their URL.
Original Message
> > How much $$ though? My suggestion is $100-150.
> >
>
> As little $$ as possible (of course). I think I may try to hack a
caliper.
> Can you tell me a little about the caliper RS232 output. What does it
output,
> a lineat voltage, ASCII stuff or????
proximity sensor".
--- goflo@p... wrote:
> Mitutoyo caliper protocol is 3-wire, CLK, DATA, REQ.
>
> CLK and DATA are open-collector outputs. 10K
> pull-ups
> work fine.
>
> Pulling REQ low produces 52 clocks, DATA valid on
> CLK low, each group of 4 bits represents a hex #,
> lsb to msb:
>
> d0-d3 0Fh
>
> d4 sign digit, 0 is positive, 1 negative
>
> d5-d10 measurement value, BCD, MSD to LSD,
>
> d11 decimal point position in the 6-digit
> measurement value, counting right to left
>
> d12 units, 0=mm, 1=inches
>
> IIRC CLK freq is 1562 Hz, or thereabouts.
>
> regards, Jack
>
> smartdim@a... wrote:
> >
> > In a message dated 3/20/2003 12:00:44 PM Pacific
> Standard Time,
> > daweasel@s... writes:
> >
> > > How much $$ though? My suggestion is $100-150.
> > >
> >
> > As little $$ as possible (of course). I think I
> may try to hack a caliper.
> > Can you tell me a little about the caliper RS232
> output. What does it output,
> > a lineat voltage, ASCII stuff or????
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
__________________________________________________
Do you Yahoo!?
Yahoo! Platinum - Watch CBS' NCAA March Madness, live on your desktop!
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protocol info. I had grafted a standard Molex KK connector on my calipers
and started working on an interface, but got sidetracked.
Original Message
> Mitutoyo caliper protocol is 3-wire, CLK, DATA, REQ.
>
> CLK and DATA are open-collector outputs. 10K pull-ups
> work fine.
>
> Pulling REQ low produces 52 clocks, DATA valid on
> CLK low, each group of 4 bits represents a hex #,
> lsb to msb:
>
> d0-d3 0Fh
>
> d4 sign digit, 0 is positive, 1 negative
>
> d5-d10 measurement value, BCD, MSD to LSD,
>
> d11 decimal point position in the 6-digit
> measurement value, counting right to left
>
> d12 units, 0=mm, 1=inches
>
> IIRC CLK freq is 1562 Hz, or thereabouts.
and an accuracy of .002 mm over 5,10,25,50 mm range.
4 um cycle square wave output, RS422 compatible.
See "LGB/LGF linear gauges". My info is dated - Current
devices may be better.
Jack
Rodent wrote:
>
> 0-5mm in 0.01mm increments is pretty fine and may require some serious
> brainwork to get any repeatability with a hardware solution. You can buy
> digital calipers or digital machine scales and interface them to a Stamp,
> but these are usually only good to 0.001 inches, even though they claim
> 0.0005 inches.
>
> When I worked for a company that manufactured leak detection equipment for
> the service station industry, they used a calibrated piston / cylinder and
> LVDT to detect very minute leaks in plumbing. The engineers claimed nothing
> else worked as well.
>
>
Original Message
>
> > I am looking for suggestions for a hardware interface for my stamp. I want
> to
> > measure very small displacements (0 to 5mm) with 0.01mm accuracy. I don't
> > think I want to use an LVDT. Perhaps an optical sensor, Linear Hall
> effect,
> > ??????????? I have some general ideas, but many heads are better than my
> one
> > bald one!
goflo@p... writes:
>
> Mitutoyo caliper protocol is 3-wire, CLK, DATA, REQ.
>
> CLK and DATA are open-collector outputs. 10K pull-ups
> work fine.
>
> Pulling REQ low produces 52 clocks, DATA valid on
> CLK low, each group of 4 bits represents a hex #,
> lsb to msb:
>
> d0-d3 0Fh
>
> d4 sign digit, 0 is positive, 1 negative
>
> d5-d10 measurement value, BCD, MSD to LSD,
>
> d11 decimal point position in the 6-digit
> measurement value, counting right to left
>
> d12 units, 0=mm, 1=inches
>
> IIRC CLK freq is 1562 Hz, or thereabouts.
>
> regards, Jack
>
Awesome......Thanks Jack!!!!!!!1
[noparse][[/noparse]Non-text portions of this message have been removed]
daweasel@s... writes:
> From what I have gathered so far, the output of the Mitutoyo and knock-off
> calipers and linear scales requires you to clock each bit of data from the
> unit. A level converter is required as the output voltage is very low due
> to
> these units running off batteries.
>
> I have some Stamp code I got from another user thats supposed to work with
> the Mitutoyo calipers, and have messed around with a level converter some,
> but don't have a fully functional unit yet. I have found several sources
> for
> display heads for these devices -- one is www.wttool.com -- item #
> 1289-0465. They also sell the linear scales. I have another source, but I
> need to track down their URL.
>
This is what's so great about this forum!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Lots
of help from the Stamp Brethren.
Thanks.....
Ken
[noparse][[/noparse]Non-text portions of this message have been removed]
CLK and DATA are open-collector outputs. 10K pull-ups
work fine.
Pulling REQ low produces 52 clocks, DATA valid on
CLK low, each group of 4 bits represents a hex #,
lsb to msb:
d0-d3 0Fh
d4 sign digit, 0 is positive, 1 negative
d5-d10 measurement value, BCD, MSD to LSD,
d11 decimal point position in the 6-digit
measurement value, counting right to left
d12 units, 0=mm, 1=inches
IIRC CLK freq is 1562 Hz, or thereabouts.
regards, Jack
smartdim@a... wrote:
>
> In a message dated 3/20/2003 12:00:44 PM Pacific Standard Time,
> daweasel@s... writes:
>
> > How much $$ though? My suggestion is $100-150.
> >
>
> As little $$ as possible (of course). I think I may try to hack a caliper.
> Can you tell me a little about the caliper RS232 output. What does it output,
> a lineat voltage, ASCII stuff or????
You could attach a mirror to the thing that will be displaced, shine a laser on
it, and measure the beam deflection on the side of a building several blocks
away [noparse]:)[/noparse]
I shouldn't type when it's so long after my bedtime..g'night.
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> I am looking for suggestions for a hardware interface for my stamp. I want to
> measure very small displacements (0 to 5mm) with 0.01mm accuracy. I don't
> think I want to use an LVDT. Perhaps an optical sensor, Linear Hall effect,
> ??????????? I have some general ideas, but many heads are better than my one
> bald one!
>
> Any suggestions welcomed.
>
> Ken
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
they are a bit expensive. check out their site at www.keyence.com.
Jim
Original Message
From: stan45039 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=0qAqRmBbGI6PGuHkm5scUwMAeR_Jg080NxEsL4AtXZhBLmD-_KL8xwdDnOYcQs7t032sAhBA]slogan@f...[/url
Sent: Friday, March 21, 2003 3:39 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Linear displacement
(Warning: semi tongue in cheek reply follows)
You could attach a mirror to the thing that will be displaced, shine a laser
on it, and measure the beam deflection on the side of a building several
blocks away [noparse]:)[/noparse]
I shouldn't type when it's so long after my bedtime..g'night.
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> I am looking for suggestions for a hardware interface for my stamp. I want
to
> measure very small displacements (0 to 5mm) with 0.01mm accuracy. I don't
> think I want to use an LVDT. Perhaps an optical sensor, Linear Hall
effect,
> ??????????? I have some general ideas, but many heads are better than my
one
> bald one!
>
> Any suggestions welcomed.
>
> Ken
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
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Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
many years ago.
Original Message
From: Jim Forkin [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=LJNIW39CqXlbaGG1hwdFuUTYa4MJpNmJNgz1dptCEFZaJh6a-IqGnJoelnlckouyFYn4TSPoTtk]jjf@p...[/url
Sent: Friday, March 21, 2003 9:35 AM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Re: Linear displacement
Ken, Keyence makes laser sensors which can accurately sense distances but
they are a bit expensive. check out their site at www.keyence.com.
Jim
Original Message
From: stan45039 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=Zkfy_gePNalJ5zBI7azwHcsi2kAGuRYB6dgCk4DHS3_AhroDZQ99SFQ8QCEJWS89FaMCzgn63eY]slogan@f...[/url
Sent: Friday, March 21, 2003 3:39 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Linear displacement
(Warning: semi tongue in cheek reply follows)
You could attach a mirror to the thing that will be displaced, shine a laser
on it, and measure the beam deflection on the side of a building several
blocks away [noparse]:)[/noparse]
I shouldn't type when it's so long after my bedtime..g'night.
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> I am looking for suggestions for a hardware interface for my stamp. I want
to
> measure very small displacements (0 to 5mm) with 0.01mm accuracy. I don't
> think I want to use an LVDT. Perhaps an optical sensor, Linear Hall
effect,
> ??????????? I have some general ideas, but many heads are better than my
one
> bald one!
>
> Any suggestions welcomed.
>
> Ken
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
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To UNSUBSCRIBE, just send mail to:
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[noparse][[/noparse]Non-text portions of this message have been removed]
to the moving arm of the balance shone through a V-shaped slit onto a photocell.
Amount on light proportional to the displacement. The instrument was capable of
measuring weights
down to tenths of milligrams.
Bob
nienhuis@w...
Original Message
From: Sadler Porter <porter.sadler@s...>
Reply-To: basicstamps@yahoogroups.com
Date: Fri, 21 Mar 2003 13:05:12 -0500
>There was also a company called cyberoptics that did something along this in
>many years ago.
>
>
Original Message
>From: Jim Forkin [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=GUfWiyQirPM0cpy5Iy5Mxn9KnU2RkyxFyKkAf7CQ65HteQOXQvxB02RmC7o6gKmumA8biPeK1Q]jjf@p...[/url
>Sent: Friday, March 21, 2003 9:35 AM
>To: basicstamps@yahoogroups.com
>Subject: RE: [noparse][[/noparse]basicstamps] Re: Linear displacement
>
>Ken, Keyence makes laser sensors which can accurately sense distances but
>they are a bit expensive. check out their site at www.keyence.com.
>Jim
>
>
Original Message
>From: stan45039 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=rWlAnESxqvXJ_oWcjmAlynM2hQMnKEHz5R8aVk9tgEiR_Hv73-gx7PPaaJ3YJ5xV8btvSbzW1Q]slogan@f...[/url
>Sent: Friday, March 21, 2003 3:39 AM
>To: basicstamps@yahoogroups.com
>Subject: [noparse][[/noparse]basicstamps] Re: Linear displacement
>
>
>
>(Warning: semi tongue in cheek reply follows)
>
>You could attach a mirror to the thing that will be displaced, shine a laser
>on it, and measure the beam deflection on the side of a building several
>blocks away [noparse]:)[/noparse]
>
>I shouldn't type when it's so long after my bedtime..g'night.
>
>
>
>--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
>> I am looking for suggestions for a hardware interface for my stamp. I want
>to
>> measure very small displacements (0 to 5mm) with 0.01mm accuracy. I don't
>> think I want to use an LVDT. Perhaps an optical sensor, Linear Hall
>effect,
>> ??????????? I have some general ideas, but many heads are better than my
>one
>> bald one!
>>
>> Any suggestions welcomed.
>>
>> Ken
>>
>>
>> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
>To UNSUBSCRIBE, just send mail to:
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>from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
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>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
>To UNSUBSCRIBE, just send mail to:
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>from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
>
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>
>
>[noparse][[/noparse]Non-text portions of this message have been removed]
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
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>
>
>
microscopes to measure parts of the inner ear responding to sound, with
(much) below micron resolutions.
Dennis
Original Message
From: stan45039 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=wActtO3e5p7IJM4akEqXqSisY3NYfDXHk4xQ2RkHprJ32fixhYwHFutxMzizU5BVrj2FGvjZQt3A]slogan@f...[/url
Sent: Friday, March 21, 2003 12:39 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: Linear displacement
(Warning: semi tongue in cheek reply follows)
You could attach a mirror to the thing that will be displaced, shine a
laser on it, and measure the beam deflection on the side of a building
several blocks away [noparse]:)[/noparse]
I shouldn't type when it's so long after my bedtime..g'night.
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> I am looking for suggestions for a hardware interface for my stamp. I
> want to
> measure very small displacements (0 to 5mm) with 0.01mm accuracy. I
don't
> think I want to use an LVDT. Perhaps an optical sensor, Linear Hall
effect,
> ??????????? I have some general ideas, but many heads are better than
my one
> bald one!
>
> Any suggestions welcomed.
>
> Ken
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject
and Body of the message will be ignored.
Your use of Yahoo! Groups is subject to
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with a string and retrun spring.
5 mm divided by 15 turns is 0.33 mm per revoltion.
that would offer the resolution you are looking for, but you would
need to interface it would an ADC.
http://www.spaceagecontrol.com/ptmain.htm
There are lots of digital calipers, some for $20.00 (like Harbor
Freight) and a few places that the interface is defined. one problem
is getting wires connected.
Dave
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> I am looking for suggestions for a hardware interface for my stamp.
I want to
> measure very small displacements (0 to 5mm) with 0.01mm accuracy. I
don't
> think I want to use an LVDT. Perhaps an optical sensor, Linear
Hall effect,
> ??????????? I have some general ideas, but many heads are better
than my one
> bald one!
>
> Any suggestions welcomed.
>
> Ken
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
a capacatance part in an RC loop.
Beau has posted on that in the past and offered a circuit some time
ago. I'm not sure of the accuracy, but again, an ADC would probably
be nessicary.
Dave
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> I am looking for suggestions for a hardware interface for my stamp.
I want to
> measure very small displacements (0 to 5mm) with 0.01mm accuracy. I
don't
> think I want to use an LVDT. Perhaps an optical sensor, Linear
Hall effect,
> ??????????? I have some general ideas, but many heads are better
than my one
> bald one!
>
> Any suggestions welcomed.
>
> Ken
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
Similar to tuning an old radio (some actually moved a slug in and out of a
coil for regular tuning) Personally though, I would use an LVDT. I'm not
exactly sure why the original poster seems to be against using an LVDT, they
can be extremely accurate. A laser seems to be a bit overkill. I would even
be as bold as to roll my own LVDT coils for this type of project if it were
up to me, but I'm odd that way. If you need a starter schematic let me know.
Well, that's my quarter!
-Beau Schwabe
>Also, if your device is not subject to vibration, a spring can act as
>a capacatance part in an RC loop.
>
>Beau has posted on that in the past and offered a circuit some time
>ago. I'm not sure of the accuracy, but again, an ADC would probably
>be nessicary.
>
>Dave
>
>
>
>--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> > I am looking for suggestions for a hardware interface for my stamp.
>I want to
> > measure very small displacements (0 to 5mm) with 0.01mm accuracy. I
>don't
> > think I want to use an LVDT. Perhaps an optical sensor, Linear
>Hall effect,
> > ??????????? I have some general ideas, but many heads are better
>than my one
> > bald one!
> >
> > Any suggestions welcomed.
> >
> > Ken
> >
> >
> > [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
bschwabe@a... writes:
> Actually the spring functions as a COIL in an a LC loop, C is a fixed value.
> Similar to tuning an old radio (some actually moved a slug in and out of a
> coil for regular tuning) Personally though, I would use an LVDT. I'm not
> exactly sure why the original poster seems to be against using an LVDT,
> they
> can be extremely accurate. A laser seems to be a bit overkill. I would
> even
> be as bold as to roll my own LVDT coils for this type of project if it were
> up to me, but I'm odd that way. If you need a starter schematic let me
> know.
>
> Well, that's my quarter!
> -Beau Schwabe
Beau,
I am not really "against" using an LVDT. I completely understand the
principle. It appears that is the way to go. So you actually "roll" your own?
I would like to try the same. If you can get me started in that area, I will
try it.
I guess my questions would be where to start. The deflections I am looking
for are 0 to 5mm. Not sure where to start for excitation voltage and
frequency. Thinking out loud, I will likely need to amplify the output,
rectify it, etc, etc.
I want the output to end up at TTL level so I can use the data with a uP for
a custom application.
Any thoughts are appreciated.
I also may go with the Veneer caliper approach, that is hack/modify the
caliper and use the serial output of the caliper....?????
Ken
[noparse][[/noparse]Non-text portions of this message have been removed]
>In a message dated 3/21/2003 3:03:04 PM Pacific Standard Time,
>bschwabe@a... writes:
>
> > Actually the spring functions as a COIL in an a LC loop, C is a fixed
> value.
> > Similar to tuning an old radio (some actually moved a slug in and out of a
> > coil for regular tuning) Personally though, I would use an LVDT. I'm not
> > exactly sure why the original poster seems to be against using an LVDT,
> > they
> > can be extremely accurate. A laser seems to be a bit overkill. I would
> > even
> > be as bold as to roll my own LVDT coils for this type of project if it were
> > up to me, but I'm odd that way. If you need a starter schematic let me
> > know.
> >
> > Well, that's my quarter!
> > -Beau Schwabe
>
>Beau,
>
>I am not really "against" using an LVDT. I completely understand the
>principle. It appears that is the way to go. So you actually "roll" your own?
> I would like to try the same. If you can get me started in that area, I
> will
>try it.
>
>I guess my questions would be where to start. The deflections I am looking
>for are 0 to 5mm. Not sure where to start for excitation voltage and
>frequency. Thinking out loud, I will likely need to amplify the output,
>rectify it, etc, etc.
>
>I want the output to end up at TTL level so I can use the data with a uP for
>a custom application.
>
>Any thoughts are appreciated.
>
>I also may go with the Veneer caliper approach, that is hack/modify the
>caliper and use the serial output of the caliper....?????
>
>Ken
Let me play with some values over the weekend, but yes I have "rolled" a wide
variety of coils. 5mm detection isn't a problem. The output is a varying
frequency that can easily be measured with a uP or Stamp. Off the top of my
head this would require 2 I/O pins. One for selecting Coil1 or Coil2, the
other
for reading the frequency produced by the coil. With the design in mind, you
could actually use a single coil, but you will experience drift due to
temperature variations, adding a second coil to the design operating
mechanically
180 deg out of phase will negate any drift due to temperature variations
and the
values returned will relate to one another as a percentage relative to location
of a metallic object between the coils.
-Beau Schwabe
A question and an idea in one. Would it be possible to cobble up an analog
of an LVDT using Hall Effect devices and permanent magnets? Mount the magnet
on the swing arm, suitably damped, and take the varying output of the Hall
Device as your signal. Set up as a comparator (it is at rest in range +-
allowable Hysteresis, or it isn't, with the Hall Device being one with a
comparator output) you get a binary one or zero, but no scalar values. Use a
linear output Hall Device and you get an analog scalar output. Feed it
through an ADC and you get digital word output representative of the
displacement. This eliminates coil winding and separate excitor sources.
Probably more expensive though. I just think it is a more flexible answer,
since it obviously lends itself to a lot of different apps.
Mic
Original Message
From: <smartdim@a...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, March 21, 2003 6:29 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Linear displacement
> In a message dated 3/21/2003 3:03:04 PM Pacific Standard Time,
> bschwabe@a... writes:
>
> > Actually the spring functions as a COIL in an a LC loop, C is a fixed
value.
> > Similar to tuning an old radio (some actually moved a slug in and out of
a
> > coil for regular tuning) Personally though, I would use an LVDT. I'm
not
> > exactly sure why the original poster seems to be against using an LVDT,
> > they
> > can be extremely accurate. A laser seems to be a bit overkill. I would
> > even
> > be as bold as to roll my own LVDT coils for this type of project if it
were
> > up to me, but I'm odd that way. If you need a starter schematic let me
> > know.
> >
> > Well, that's my quarter!
> > -Beau Schwabe
>
> Beau,
>
> I am not really "against" using an LVDT. I completely understand the
> principle. It appears that is the way to go. So you actually "roll" your
own?
> I would like to try the same. If you can get me started in that area, I
will
> try it.
>
> I guess my questions would be where to start. The deflections I am looking
> for are 0 to 5mm. Not sure where to start for excitation voltage and
> frequency. Thinking out loud, I will likely need to amplify the output,
> rectify it, etc, etc.
>
> I want the output to end up at TTL level so I can use the data with a uP
for
> a custom application.
>
> Any thoughts are appreciated.
>
> I also may go with the Veneer caliper approach, that is hack/modify the
> caliper and use the serial output of the caliper....?????
>
> Ken
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
less after! Sorry, folks.
Mic
Original Message
From: Beau Schwabe <bschwabe@a...>
To: <basicstamps@yahoogroups.com>
Sent: Friday, March 21, 2003 5:47 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Linear displacement
> Actually the spring functions as a COIL in an a LC loop, C is a fixed
value.
> Similar to tuning an old radio (some actually moved a slug in and out of a
> coil for regular tuning) Personally though, I would use an LVDT. I'm not
> exactly sure why the original poster seems to be against using an LVDT,
they
> can be extremely accurate. A laser seems to be a bit overkill. I would
even
> be as bold as to roll my own LVDT coils for this type of project if it
were
> up to me, but I'm odd that way. If you need a starter schematic let me
know.
>
> Well, that's my quarter!
> -Beau Schwabe
>
>
> >Also, if your device is not subject to vibration, a spring can act as
> >a capacatance part in an RC loop.
> >
> >Beau has posted on that in the past and offered a circuit some time
> >ago. I'm not sure of the accuracy, but again, an ADC would probably
> >be nessicary.
> >
> >Dave
> >
> >
> >
> >--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> > > I am looking for suggestions for a hardware interface for my stamp.
> >I want to
> > > measure very small displacements (0 to 5mm) with 0.01mm accuracy. I
> >don't
> > > think I want to use an LVDT. Perhaps an optical sensor, Linear
> >Hall effect,
> > > ??????????? I have some general ideas, but many heads are better
> >than my one
> > > bald one!
> > >
> > > Any suggestions welcomed.
> > >
> > > Ken
> > >
> > >
> > > [noparse][[/noparse]Non-text portions of this message have been removed]
> >
> >
> >To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> >from the same email address that you subscribed. Text in the Subject and
> >Body of the message will be ignored.
> >
> >
> >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
that would work.
www.bannerengineering.com (I think.)
> > value.
> > > Similar to tuning an old radio (some actually moved a slug in and out
> of a
> > > coil for regular tuning) Personally though, I would use an
> LVDT. I'm not
> > > exactly sure why the original poster seems to be against using an LVDT,
> > > they
> > > can be extremely accurate. A laser seems to be a bit overkill. I would
> > > even
> > > be as bold as to roll my own LVDT coils for this type of project if
> it were
> > > up to me, but I'm odd that way. If you need a starter schematic let me
> > > know.
> > >
> > > Well, that's my quarter!
> > > -Beau Schwabe
> >
> >Beau,
> >
> >I am not really "against" using an LVDT. I completely understand the
> >principle. It appears that is the way to go. So you actually "roll" your
> own?
> > I would like to try the same. If you can get me started in that area, I
> > will
> >try it.
> >
> >I guess my questions would be where to start. The deflections I am looking
> >for are 0 to 5mm. Not sure where to start for excitation voltage and
> >frequency. Thinking out loud, I will likely need to amplify the output,
> >rectify it, etc, etc.
> >
> >I want the output to end up at TTL level so I can use the data with a uP for
> >a custom application.
> >
> >Any thoughts are appreciated.
> >
> >I also may go with the Veneer caliper approach, that is hack/modify the
> >caliper and use the serial output of the caliper....?????
> >
> >Ken
>
>Let me play with some values over the weekend, but yes I have "rolled" a wide
>variety of coils. 5mm detection isn't a problem. The output is a varying
>frequency that can easily be measured with a uP or Stamp. Off the top of my
>head this would require 2 I/O pins. One for selecting Coil1 or Coil2, the
>other
>for reading the frequency produced by the coil. With the design in mind, you
>could actually use a single coil, but you will experience drift due to
>temperature variations, adding a second coil to the design operating
>mechanically
>180 deg out of phase will negate any drift due to temperature variations
>and the
>values returned will relate to one another as a percentage relative to
>location
>of a metallic object between the coils.
>
>
>-Beau Schwabe
In your original post you expressed a desire for 0.01mm accuracy. Over the
weekend
I was able to achieve an approximate .003mm over the range of 1cm. below
are my
results. Instead of having a secondary coil 180 out of phase, the only
difference
is that the secondary coil is used only as a reference for the sense
coil. However
with the same circuitry, you could still arrange the coils so that they are
both
operational.
http://www.angelfire.com/wizard/y2kbc/LVDT/
-Beau Schwabe
bschwabe@a... writes:
> In your original post you expressed a desire for 0.01mm accuracy. Over the
> weekend
> I was able to achieve an approximate .003mm over the range of 1cm. below
> are my
> results. Instead of having a secondary coil 180 out of phase, the only
> difference
> is that the secondary coil is used only as a reference for the sense
> coil. However
> with the same circuitry, you could still arrange the coils so that they are
>
> both
> operational.
>
> http://www.angelfire.com/wizard/y2kbc/LVDT/
>
> -Beau Schwabe
>
Beau,
AWESOME!!!!!!!!!!!!!!
Very nice. Thank you very much. You provided more than enough to get me
going.
Thank you very much!!
Ken
[noparse][[/noparse]Non-text portions of this message have been removed]
the bottom of the page - Any chance there's an extra zero
in there? 300 counts per cm is 30000 counts per meter, or
1 count per .0000333 meter, which is .0333 mm. What am I
missing?
best regards, Jack
Beau Schwabe wrote:
> ...
> http://www.angelfire.com/wizard/y2kbc/LVDT/
>Great stuff! I'm puzzled about the resolution figures at
>the bottom of the page - Any chance there's an extra zero
>in there? 300 counts per cm is 30000 counts per meter, or
>1 count per .0000333 meter, which is .0333 mm. What am I
>missing?
>
>best regards, Jack
>
>Beau Schwabe wrote:
> > ...
> > http://www.angelfire.com/wizard/y2kbc/LVDT/
Ohhh Rats! I hate it when I do that! Jack, your right it
should be cm instead of mm.
However, here is a case where it might be better to use the COUNT
command over the PULSIN command. Consider the original frequency
data with the addition of a new coil I wound with 30 turns.
Test# Option Pressed Released Coil
1 C 194.2Hz 192.9Hz 100T
2 HCT 529.1Hz 401.6Hz 100T
3 HC 507.6Hz 397.6Hz 100T
4 HCT 1724.0Hz 714.3Hz 30T (New Test)
Return Values for PULSIN:
Test# PULSIN PULSIN Delta Res/cm
1 2574 2592 18 .0555
2 945 1245 300 .0033
3 985 1257 272 .0037
4 290 699 409 .0024
Return Values for a COUNT duration of 125mS:
Test# COUNT COUNT Delta Res/cm
1 24 24 1 1
2 66 50 16 .0625
3 63 49 14 .0714
4 215 89 126 .0079
Return Values for a COUNT duration of 1000mS:
Test# COUNT COUNT Delta Res/cm
1 194 192 2 .5
2 529 401 128 .0078
3 507 397 110 .0091
4 1724 714 1010 .001
Return Values for a COUNT duration of 2000mS:
Test# COUNT COUNT Delta Res/cm
1 388 385 3 .3333
2 1058 803 255 .0039
3 1015 795 220 .0045
4 3448 1428 2020 .0005
-Beau Schwabe
[noparse][[/noparse]Non-text portions of this message have been removed]