torque sensor
Archiver
Posts: 46,084
I am a mechanical engineering student working on my senior thesis. The
project calls for sensing the amount of torque being applied through a drive
shaft.
I have been looking for sensors online, and have had little luck. Can
anyone recommend a sensor or technique for transducing torque to my BS2? Torque
is
between 100 and 200 ft-lb, and I would like to keep the cost of the sensor
under 500 bucks. any and all help would be GREATLY appreciated.
Regards,
Joe C.
[noparse][[/noparse]Non-text portions of this message have been removed]
project calls for sensing the amount of torque being applied through a drive
shaft.
I have been looking for sensors online, and have had little luck. Can
anyone recommend a sensor or technique for transducing torque to my BS2? Torque
is
between 100 and 200 ft-lb, and I would like to keep the cost of the sensor
under 500 bucks. any and all help would be GREATLY appreciated.
Regards,
Joe C.
[noparse][[/noparse]Non-text portions of this message have been removed]
Comments
>I am a mechanical engineering student working on my senior thesis. The
>project calls for sensing the amount of torque being applied through a
>drive shaft.
> I have been looking for sensors online, and have had little luck. Can
>anyone recommend a sensor or technique for transducing torque to my BS2?
>Torque is
>between 100 and 200 ft-lb, and I would like to keep the cost of the sensor
>under 500 bucks. any and all help would be GREATLY appreciated.
>
>Regards,
>Joe C.
Some years ago, I helped build a "low bucks" engine dyno
to use with engines in the 150 - 250 HP range.
We used a large irrigation water pump for "the load" and a
4-speed transmission to match the engine RPM to the load.
The pump was mounted in a cradle so it could rotate slightly
along it's centerline, and an arm off the cradle was attached
to a small hydraulic cylinder, the other end of which was
attached to a stationary point on the frame of the dyno.
A pressure sensor screwed into the hydraulic cylinder was
used to measure pressure that is proportional to torque.
You just need to do a bit of math with the piston area of the
hydraulic cylinder, and the length of the torque arm from the
centerline of the rotating shaft to convert hydraulic pressure
to torque.
Perhaps something like that would meet your needs?
Steve
I'm guessing you want to measure torque as applied to a driven load. If your
drive source is reasonably small, I would consider building a cage around it
with the one side on hinges, and the anti-torque side resting on a hydraulic
cylinder/sensor. Make sure you have a mechanical stop in both directions for
both the anti-torque component (slowing down) as well as catastrophic sensor
failure (a leak). Then use the math described in the other post to calculate
force, etc... This could be a very short-stroke piston as it shouldn't
really move at all if all is well. Possibly a brake caliper or drum slave
cylinder from an auto salvage-yard would do the job, and be quite
affordable.
Another, perhaps more elegant way to do this would be to put a strain gauge
on one support arm of the drive source. If you zero it at no load, and then
calibrate it at full load and below (lock-up the motor temporarily and
supply various torques via a pipe wrench and a fish scale) that should give
you a series of known torque points and know resistance values, which you
can interpolate via the B-Stamp. That way you're not trying to predict how
much actual flex you have in your torque arm, only the actual resistance
value at know/applied torques. I would guess that with some careful
calibration you should get down to a few percent accuracy. A strain gauge
has really low resistance, so consider using a Kelvin or Wheatstone Bridge
to measure it. Here's a link to measurement bridge theory -
http://chem.ch.huji.ac.il/~eugeniik/instruments/test/bridges_theory.html.
The nice thing about a K or W bridge is that the resistance of the
measurement leads is nulled out, so your sensor wires can be hundreds of
feet long if you like, and still measure a resistance down to a fraction of
an ohm. Also, here's a link to a windmill site using strain gauges in a
Wheatstone Bridge array. http://www.windmill.co.uk/strain.html.
We also used to measure all sorts of flexing with laser interference
patterns on deformed (strained) components and the like, but I'm guessing
that goes way beyond what you have in mind (or budget). Still, it's the
coolest thing around since it can show stress risers in a part which can
help predict where it will fail under stress.
Hope this helps...
Mike Sokol
www.modernrecording.com
mikes@m...
301-739-6842 (Office)
301-964-5682 (Mobile)
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Original Message
From: <joecasa@a...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, January 04, 2004 6:19 PM
Subject: [noparse][[/noparse]basicstamps] torque sensor
> I am a mechanical engineering student working on my senior thesis. The
> project calls for sensing the amount of torque being applied through a
drive shaft.
> I have been looking for sensors online, and have had little luck. Can
> anyone recommend a sensor or technique for transducing torque to my BS2?
Torque is
> between 100 and 200 ft-lb, and I would like to keep the cost of the sensor
> under 500 bucks. any and all help would be GREATLY appreciated.
>
> Regards,
> Joe C.
>
>
> [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.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
I'm guessing you want to measure torque as applied to a driven load. If your
drive source is reasonably small, I would consider building a cage around it
with the one side on hinges, and the anti-torque side resting on a hydraulic
cylinder/sensor. Make sure you have a mechanical stop in both directions for
both the anti-torque component (slowing down) as well as catastrophic sensor
failure (a leak). Then use the math described in the other post to calculate
force, etc... This could be a very short-stroke piston as it shouldn't
really move at all if all is well. Possibly a brake caliper or drum slave
cylinder from an auto salvage-yard would do the job, and be quite
affordable.
Another, perhaps more elegant way to do this would be to put a strain gauge
on one support arm of the drive source. If you zero it at no load, and then
calibrate it at full load and below (lock-up the motor temporarily and
supply various torques via a pipe wrench and a fish scale) that should give
you a series of known torque points and know resistance values, which you
can interpolate via the B-Stamp. That way you're not trying to predict how
much actual flex you have in your torque arm, only the actual resistance
value at know/applied torques. I would guess that with some careful
calibration you should get down to a few percent accuracy. A strain gauge
has really low resistance, so consider using a Kelvin or Wheatstone Bridge
to measure it. Here's a link to measurement bridge theory -
http://chem.ch.huji.ac.il/~eugeniik/instruments/test/bridges_theory.html.
The nice thing about a K or W bridge is that the resistance of the
measurement leads is nulled out, so your sensor wires can be hundreds of
feet long if you like, and still measure a resistance down to a fraction of
an ohm. Also, here's a link to a windmill site using strain gauges in a
Wheatstone Bridge array. http://www.windmill.co.uk/strain.html.
We also used to measure all sorts of flexing with laser interference
patterns on deformed (strained) components and the like, but I'm guessing
that goes way beyond what you have in mind (or budget). Still, it's the
coolest thing around since it can show stress risers in a part which can
help predict where it will fail under stress.
Hope this helps...
Mike Sokol
www.modernrecording.com
mikes@m...
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Original Message
From: <joecasa@a...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, January 04, 2004 6:19 PM
Subject: [noparse][[/noparse]basicstamps] torque sensor
> I am a mechanical engineering student working on my senior thesis. The
> project calls for sensing the amount of torque being applied through a
drive shaft.
> I have been looking for sensors online, and have had little luck. Can
> anyone recommend a sensor or technique for transducing torque to my BS2?
Torque is
> between 100 and 200 ft-lb, and I would like to keep the cost of the sensor
> under 500 bucks. any and all help would be GREATLY appreciated.
>
> Regards,
> Joe C.
>
>
> [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.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
Go to www.omega.com...they have several torque sensors that may meet
your needs.
John
--- In basicstamps@yahoogroups.com, joecasa@a... wrote:
> I am a mechanical engineering student working on my senior thesis.
The
> project calls for sensing the amount of torque being applied
through a drive shaft.
> I have been looking for sensors online, and have had little luck.
Can
> anyone recommend a sensor or technique for transducing torque to my
BS2? Torque is
> between 100 and 200 ft-lb, and I would like to keep the cost of the
sensor
> under 500 bucks. any and all help would be GREATLY appreciated.
>
> Regards,
> Joe C.
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
If you're using a dc electric motor to drive the load, you could
probably measure current through the field and armature, then use
those values to calculate the amount of flux which is directly
related to the amount of torque produced. The general idea is
basically something like this anyway. Could also do it with an AC
motor but I don't recall much of my AC motor theory at the moment.
Just something to think about if the torque measurement is only a
small portion of your project, and you're using an electric motor to
drive the load.
Ron
--- In basicstamps@yahoogroups.com, joecasa@a... wrote:
> I am a mechanical engineering student working on my senior thesis.
The
> project calls for sensing the amount of torque being applied
through a drive shaft.
> I have been looking for sensors online, and have had little luck.
Can
> anyone recommend a sensor or technique for transducing torque to my
BS2? Torque is
> between 100 and 200 ft-lb, and I would like to keep the cost of the
sensor
> under 500 bucks. any and all help would be GREATLY appreciated.
>
> Regards,
> Joe C.
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
Extrapolating on my original strain-gauge post, if you mounted the drive
motor vertically on a lazy-Susan type bearing, and had a 1-ft radius arm
pushing against a side-ways mounted weight scale with an RS-232 output, you
could read off the torque in ft-lbs directly from the scale itself. Use a 90
degree gearbox if you need to get horizontal. Make the arm shorter or longer
as necessary and scale the output level. Bada-bing, bada-boom.
Mike Sokol
www.modernrecording.com
mikes@m...
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Original Message
From: "Ron Jeremy" <ronjeremy912@y...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, January 06, 2004 1:53 PM
Subject: [noparse][[/noparse]basicstamps] Re: torque sensor
> Joe,
>
> If you're using a dc electric motor to drive the load, you could
> probably measure current through the field and armature, then use
> those values to calculate the amount of flux which is directly
> related to the amount of torque produced. The general idea is
> basically something like this anyway. Could also do it with an AC
> motor but I don't recall much of my AC motor theory at the moment.
> Just something to think about if the torque measurement is only a
> small portion of your project, and you're using an electric motor to
> drive the load.
>
> Ron
>
> --- In basicstamps@yahoogroups.com, joecasa@a... wrote:
> > I am a mechanical engineering student working on my senior thesis.
> The
> > project calls for sensing the amount of torque being applied
> through a drive shaft.
> > I have been looking for sensors online, and have had little luck.
> Can
> > anyone recommend a sensor or technique for transducing torque to my
> BS2? Torque is
> > between 100 and 200 ft-lb, and I would like to keep the cost of the
> sensor
> > under 500 bucks. any and all help would be GREATLY appreciated.
> >
> > Regards,
> > Joe C.
> >
> >
> > [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.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
>
>
or are you trying to read the torque as function of shaft twist?
I recall Land and Sea making a unit that sensed torque on a shaft
through a non-contact RF transmitter reciever. Was around $3500 for
the kit.
I bet you could copy it cheaper though.
Craig
> > --- In basicstamps@yahoogroups.com, joecasa@a... wrote:
> > > I am a mechanical engineering student working on my senior
thesis.
> > The
> > > project calls for sensing the amount of torque being applied
> > through a drive shaft.
> > > I have been looking for sensors online, and have had little
luck.
> > Can
> > > anyone recommend a sensor or technique for transducing torque
to my
> > BS2? Torque is
> > > between 100 and 200 ft-lb, and I would like to keep the cost
of the
> > sensor
> > > under 500 bucks. any and all help would be GREATLY appreciated.
> > >
> > > Regards,
> > > Joe C.
> > >
> > >
> > > [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.
> >
> >
> > Yahoo! Groups Links
> >
> > To visit your group on the web, go to:
> > http://groups.yahoo.com/group/basicstamps/
> >
> > To unsubscribe from this group, send an email to:
> > basicstamps-unsubscribe@yahoogroups.com
> >
> > Your use of Yahoo! Groups is subject to:
> > http://docs.yahoo.com/info/terms/
> >
> >
> >
> >
along with the voltage.
Some AC inverter drives (motor speed contorllers) offer torque as a
calculated value for output.
Torque on the shaft can be done a bunch of ways. one that comes to
mind is to use a hydraulic coupling that will compress the hydraulic
fluid. a hydraulic slip coupling to transfer that to a stationay
gauge or sensor and as Mike Says, Badda-Bing !
A rotating sensor and rotary coupling for the eleclectonics to send
the signals, Badda-boom.
Most of these are get-out-your-checkbook solutions.
Dave
--- In basicstamps@yahoogroups.com, joecasa@a... wrote:
> I am a mechanical engineering student working on my senior thesis.
The
> project calls for sensing the amount of torque being applied
through a drive shaft.
> I have been looking for sensors online, and have had little luck.
Can
> anyone recommend a sensor or technique for transducing torque to my
BS2? Torque is
> between 100 and 200 ft-lb, and I would like to keep the cost of the
sensor
> under 500 bucks. any and all help would be GREATLY appreciated.
>
> Regards,
> Joe C.
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
If the torque shaft wasn't spinning too fast, say a few hundred RPM or so, I
might consider mounting the whole BS board directly on the driveshaft hooked
up to a strain gauge of sorts. Then you could either have the Stamp log the
torque data for recovery later, or if you need real-time data readout,
perhaps a bluetooth connection could capture it. Would that work spinning
round and round???
Of course, watch out for balance issues and such. I can't remember my
centripetal acceleration math, but if you know the radius of spin and the
RPM, you can predict the g-forces involved.
Also, is there a pick-off from the bluetooth receiver that could count the
breaks in transmission as the shaft spins??? Could be a free way to get
accurate RPM as well.
Mike Sokol
www.modernrecording.com
mikes@m...
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Original Message
From: "Dave Mucha" <davemucha@j...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, January 07, 2004 10:50 AM
Subject: [noparse][[/noparse]basicstamps] Re: torque sensor
> If your motors are AC, you can monitor the sine wave and amp load
> along with the voltage.
>
> Some AC inverter drives (motor speed contorllers) offer torque as a
> calculated value for output.
>
> Torque on the shaft can be done a bunch of ways. one that comes to
> mind is to use a hydraulic coupling that will compress the hydraulic
> fluid. a hydraulic slip coupling to transfer that to a stationay
> gauge or sensor and as Mike Says, Badda-Bing !
>
> A rotating sensor and rotary coupling for the eleclectonics to send
> the signals, Badda-boom.
>
> Most of these are get-out-your-checkbook solutions.
>
> Dave
>
>
>
>
> --- In basicstamps@yahoogroups.com, joecasa@a... wrote:
> > I am a mechanical engineering student working on my senior thesis.
> The
> > project calls for sensing the amount of torque being applied
> through a drive shaft.
> > I have been looking for sensors online, and have had little luck.
> Can
> > anyone recommend a sensor or technique for transducing torque to my
> BS2? Torque is
> > between 100 and 200 ft-lb, and I would like to keep the cost of the
> sensor
> > under 500 bucks. any and all help would be GREATLY appreciated.
> >
> > Regards,
> > Joe C.
> >
> >
> > [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.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
>
>
Couple some weight (mass) to the power source. Using a rotary encoder
you could determine the speed at which the mass is rotating/accelerating.
Knowing these two things, you can calculate the Torque as it is the
product of the Angular Acceleration and Inertia.
Disclaimer: It's been a long time since college Physics, so maybe I'm
overlooking something quite basic. If I am, hopefully somebody will
correct me! Not only that, but I forget the original poster's
requirements!
amg
On Wed, 7 Jan 2004 13:00:49 -0500 "Mike Sokol - Fits & Starts"
<mike@f...> writes:
> Hmmmmm, more ruminations.......
>
> If the torque shaft wasn't spinning too fast, say a few hundred RPM
> or so, I
> might consider mounting the whole BS board directly on the
> driveshaft hooked
> up to a strain gauge of sorts. Then you could either have the Stamp
> log the
> torque data for recovery later, or if you need real-time data
> readout,
> perhaps a bluetooth connection could capture it. Would that work
> spinning
> round and round???
>
> Of course, watch out for balance issues and such. I can't remember
> my
> centripetal acceleration math, but if you know the radius of spin
> and the
> RPM, you can predict the g-forces involved.
>
> Also, is there a pick-off from the bluetooth receiver that could
> count the
> breaks in transmission as the shaft spins??? Could be a free way to
> get
> accurate RPM as well.
>
> Mike Sokol
> www.modernrecording.com
> mikes@m...
>
>
> " One should not increase, beyond what is necessary,
> the number of entities required to explain anything"...
> -William of Occam-
>
>
>
Original Message
> From: "Dave Mucha" <davemucha@j...>
> To: <basicstamps@yahoogroups.com>
> Sent: Wednesday, January 07, 2004 10:50 AM
> Subject: [noparse][[/noparse]basicstamps] Re: torque sensor
>
>
> > If your motors are AC, you can monitor the sine wave and amp load
> > along with the voltage.
> >
> > Some AC inverter drives (motor speed contorllers) offer torque as
> a
> > calculated value for output.
> >
> > Torque on the shaft can be done a bunch of ways. one that comes
> to
> > mind is to use a hydraulic coupling that will compress the
> hydraulic
> > fluid. a hydraulic slip coupling to transfer that to a stationay
> > gauge or sensor and as Mike Says, Badda-Bing !
> >
> > A rotating sensor and rotary coupling for the eleclectonics to
> send
> > the signals, Badda-boom.
> >
> > Most of these are get-out-your-checkbook solutions.
> >
> > Dave
> >
> >
> >
> >
> > --- In basicstamps@yahoogroups.com, joecasa@a... wrote:
> > > I am a mechanical engineering student working on my senior
> thesis.
> > The
> > > project calls for sensing the amount of torque being applied
> > through a drive shaft.
> > > I have been looking for sensors online, and have had little
> luck.
> > Can
> > > anyone recommend a sensor or technique for transducing torque to
> my
> > BS2? Torque is
> > > between 100 and 200 ft-lb, and I would like to keep the cost of
> the
> > sensor
> > > under 500 bucks. any and all help would be GREATLY appreciated.
> > >
> > > Regards,
> > > Joe C.
> > >
> > >
> > > [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.
> >
> >
> > Yahoo! Groups Links
> >
> > To visit your group on the web, go to:
> > http://groups.yahoo.com/group/basicstamps/
> >
> > To unsubscribe from this group, send an email to:
> > basicstamps-unsubscribe@yahoogroups.com
> >
> > 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.
>
>
> Yahoo! Groups Links
>
> To visit your group on the web, go to:
> http://groups.yahoo.com/group/basicstamps/
>
> To unsubscribe from this group, send an email to:
> basicstamps-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject to:
> http://docs.yahoo.com/info/terms/
>
>
>
>
________________________________________________________________
The best thing to hit the internet in years - Juno SpeedBand!
Surf the web up to FIVE TIMES FASTER!
Only $14.95/ month - visit www.juno.com to sign up today!