Automate turning of manual rotary switch?
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From: JosephKK on 3 Apr 2010 05:10 On Fri, 02 Apr 2010 16:03:07 -0500, John Fields <jfields(a)austininstruments.com> wrote: >On Fri, 02 Apr 2010 13:39:24 -0700, "JosephKK"<quiettechblue(a)yahoo.com> >wrote: > >>On Wed, 31 Mar 2010 22:38:15 +0100, "markp" <map.nospam(a)f2s.com> wrote: > >>>Another interesting possibility is having some kind of torque sensor on the >>>shaft itself. By measuring the torque as the switch clicks into place it >>>might be possible to reliably detect it. Can you get torque sensors like >>>that? >>> >>>Mark. >>> >>Sure, but what you measure is torque reaction on the motor housing. >>8-) > >--- >Nope. > >Wrap a strain gage around the shaft and measure its resistance change as >the shaft twists, differentially, under it. > >Also, I'm pretty sure there are torque sensors which are mounted in >shaft couplings ($$$) which'll do the trick. > >JF You can do it that if you want, many do.
From: Robert Baer on 4 Apr 2010 11:47 JosephKK wrote: > On Fri, 02 Apr 2010 16:03:07 -0500, John Fields <jfields(a)austininstruments.com> wrote: > >> On Fri, 02 Apr 2010 13:39:24 -0700, "JosephKK"<quiettechblue(a)yahoo.com> >> wrote: >> >>> On Wed, 31 Mar 2010 22:38:15 +0100, "markp" <map.nospam(a)f2s.com> wrote: >>>> Another interesting possibility is having some kind of torque sensor on the >>>> shaft itself. By measuring the torque as the switch clicks into place it >>>> might be possible to reliably detect it. Can you get torque sensors like >>>> that? >>>> >>>> Mark. >>>> >>> Sure, but what you measure is torque reaction on the motor housing. >>> 8-) >> --- >> Nope. >> >> Wrap a strain gage around the shaft and measure its resistance change as >> the shaft twists, differentially, under it. >> >> Also, I'm pretty sure there are torque sensors which are mounted in >> shaft couplings ($$$) which'll do the trick. >> >> JF > > You can do it that if you want, many do. Maybe a dirty trick of laser interference on the shaft?
From: John Fields on 4 Apr 2010 10:59 On Fri, 2 Apr 2010 22:54:46 +0100, "markp" <map.nospam(a)f2s.com> wrote: > >"John Fields" <jfields(a)austininstruments.com> wrote in message >news:2tmcr59sifnbisqh8v26qh47nlfepo4s67(a)4ax.com... >> On Fri, 2 Apr 2010 21:18:52 +0100, "markp" <map.nospam(a)f2s.com> wrote: >> >> >>>Thanks John. I actually haven't seem the real switch yet, but I know >>>sometimes these things can require quite a bit of torque to overcome the >>>click position. I think I'll need to measure it first so I can choose an >>>appropriate R/C servo. >> >> --- >> This is starting to get interesting. :-) >> >> How ugly can the rig be? >> >> JF > >Just about as ugly as it needs to be, this thing is out of site in a control >room and there's plent of room as it's an open rack. What they don't want is >to modify any of the control logic or wiring as they have a maitenance >contract with a third party. I want to come up with a solution that's >completely non-intrusive that simply automates the otherwise manually >controlled on/off switch. --- Are you allowed to modify the existing panel in order to mount the necessary motors, sensors, etc.? JF
From: markp on 4 Apr 2010 14:47 "John Fields" <jfields(a)austininstruments.com> wrote in message news:q4ahr5htbr88vpbcuppj80cbqlls5eqlt0(a)4ax.com... > On Fri, 2 Apr 2010 22:54:46 +0100, "markp" <map.nospam(a)f2s.com> wrote: > >> >>"John Fields" <jfields(a)austininstruments.com> wrote in message >>news:2tmcr59sifnbisqh8v26qh47nlfepo4s67(a)4ax.com... >>> On Fri, 2 Apr 2010 21:18:52 +0100, "markp" <map.nospam(a)f2s.com> wrote: >>> >>> >>>>Thanks John. I actually haven't seem the real switch yet, but I know >>>>sometimes these things can require quite a bit of torque to overcome the >>>>click position. I think I'll need to measure it first so I can choose an >>>>appropriate R/C servo. >>> >>> --- >>> This is starting to get interesting. :-) >>> >>> How ugly can the rig be? >>> >>> JF >> >>Just about as ugly as it needs to be, this thing is out of site in a >>control >>room and there's plent of room as it's an open rack. What they don't want >>is >>to modify any of the control logic or wiring as they have a maitenance >>contract with a third party. I want to come up with a solution that's >>completely non-intrusive that simply automates the otherwise manually >>controlled on/off switch. > > --- > Are you allowed to modify the existing panel in order to mount the > necessary motors, sensors, etc.? > > > JF I think so, at least to put some holes in it. There are a few pre-existing holes that I could use if necessary but not quite in the right place. Mark.
From: JosephKK on 5 Apr 2010 22:03
On Sun, 04 Apr 2010 08:47:02 -0700, Robert Baer <robertbaer(a)localnet.com> wrote: >JosephKK wrote: >> On Fri, 02 Apr 2010 16:03:07 -0500, John Fields <jfields(a)austininstruments.com> wrote: >> >>> On Fri, 02 Apr 2010 13:39:24 -0700, "JosephKK"<quiettechblue(a)yahoo.com> >>> wrote: >>> >>>> On Wed, 31 Mar 2010 22:38:15 +0100, "markp" <map.nospam(a)f2s.com> wrote: >>>>> Another interesting possibility is having some kind of torque sensor on the >>>>> shaft itself. By measuring the torque as the switch clicks into place it >>>>> might be possible to reliably detect it. Can you get torque sensors like >>>>> that? >>>>> >>>>> Mark. >>>>> >>>> Sure, but what you measure is torque reaction on the motor housing. >>>> 8-) >>> --- >>> Nope. >>> >>> Wrap a strain gage around the shaft and measure its resistance change as >>> the shaft twists, differentially, under it. >>> >>> Also, I'm pretty sure there are torque sensors which are mounted in >>> shaft couplings ($$$) which'll do the trick. >>> >>> JF >> >> You can do it that if you want, many do. > Maybe a dirty trick of laser interference on the shaft? Maybe it does not have to be laser interference, you could just measure the angular displacement of a couple of pair of optical encoder rings mounted to the shaft. You can even get sealed versions for dirty environments. |