Position sensor
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I have a rotating arm which is position controlled by a geared stepper motor
shaft. It rotates approx 360 degrees at < 1 RPM. We need to indicate a
"home" position to better than 0.09 degrees accuracy. This translates to
better than 0.005" at the end of the 3.5" arm. Does anyone have suggestions
for an angle sensor, (or a position sensor at the end of the arm)?
Hopefully cheap & simple.
Thanks in advance,
Ray McArthur
shaft. It rotates approx 360 degrees at < 1 RPM. We need to indicate a
"home" position to better than 0.09 degrees accuracy. This translates to
better than 0.005" at the end of the 3.5" arm. Does anyone have suggestions
for an angle sensor, (or a position sensor at the end of the arm)?
Hopefully cheap & simple.
Thanks in advance,
Ray McArthur
Comments
a) potentiometer
b) hall effect sensor and a small magnet
c) mechanical contact
d) photo interrupter
Expensive:
d) absolute encoder
ACJacques
rjmca wrote:
>
> I have a rotating arm which is position controlled by a geared stepper motor
> shaft. It rotates approx 360 degrees at < 1 RPM. We need to indicate a
> "home" position to better than 0.09 degrees accuracy. This translates to
> better than 0.005" at the end of the 3.5" arm. Does anyone have suggestions
> for an angle sensor, (or a position sensor at the end of the arm)?
> Hopefully cheap & simple.
>
> Thanks in advance,
> Ray McArthur
I don't know about the 0.005 inch accuracy
good chance of achieving it
can you make arm longer for purpose of sensor only? ( add extension on only
for sensor)
richard
Original Message
From: A.C.Jacques <acjacques@i...>
To: <basicstamps@egroups.com>
Sent: Tuesday, June 27, 2000 2:29 PM
Subject: Re: [noparse][[/noparse]basicstamps] Position sensor
> Cheap suggestions
> a) potentiometer
> b) hall effect sensor and a small magnet
> c) mechanical contact
> d) photo interrupter
> Expensive:
> d) absolute encoder
>
> ACJacques
>
> rjmca wrote:
> >
> > I have a rotating arm which is position controlled by a geared stepper
motor
> > shaft. It rotates approx 360 degrees at < 1 RPM. We need to indicate a
> > "home" position to better than 0.09 degrees accuracy. This translates
to
> > better than 0.005" at the end of the 3.5" arm. Does anyone have
suggestions
> > for an angle sensor, (or a position sensor at the end of the arm)?
> > Hopefully cheap & simple.
> >
> > Thanks in advance,
> > Ray McArthur
>
>
>
>
>I have a rotating arm which is position controlled by a geared stepper motor
>shaft. It rotates approx 360 degrees at < 1 RPM. We need to indicate a
>"home" position to better than 0.09 degrees accuracy. This translates to
>better than 0.005" at the end of the 3.5" arm. Does anyone have suggestions
>for an angle sensor, (or a position sensor at the end of the arm)?
>Hopefully cheap & simple.
Hi Ray,
Dynamics Research has optical encoders that exceed these specs. Check:
http://www.drc.com/main/bus_area/encoder/intro.htm
I've used the Model M21 - ~4000 counts/revolution. A great product but like
all high resolution optical encoders has an etched glass disk that breaks
easily. These things are very sensitive to side load on the shaft,
excessive RPM and torque, etc.
US digital has optical encoders with mylar disks that are much more robust,
although I don't *think* they have anything with enough resolution for your
app. Check to be sure:
http://www.usdigital.com
Best, Duncan