i am needing to measure the angle of an arm. I would like the readout
to be very accurate to .001 degrees. Has this been done. I thought
of measuring the optical pulses through a digital encoder like used in
a digital mouse. thanks in advance for the help.
Rick Wells
Greetings Rick,
You can do this mechanically but the system will need to be very rigid
and virtually lash free. Any slop will need to be less than the
resolution and accuracy desired. You will also need to account for
hysteresis in the moving parts. Assuming you can do this then listed
below are some links that may help.
https://sdp-si.com/eStore/Direct.asp?GroupID=205
Anti-backlash gears from SDP/SI, about $100.00 US for 72 tooth gear
that might work.
https://sdp-si.com/eStore/Direct.asp?GroupID=590
Metal spur gears from SDP/SI, about $12.00 US for a 20 tooth gear that
might work with the above gear.
http://www.usdigital.com/products/ed3/
A digital readout from US Digital that will read rotary encoders in
quadrature. About $104.00 US.
http://www.usdigital.com/products/s6/
A 2500 count digital encoder from US Digital that will return 10,000
pulses when read in quadrature with the above readout.
360/10,000=.036 degrees. With the above gears and a 10 tooth gear you
can reduce further the system to attain .001 degree resolution. It's
up to you now to build something accurate enough. Maybe your best bet
is to instead figure out what the range is going to be, how many
degrees total you will be moving, and use a laser micrometer to
measure the position of the end of the arm. A 1 inch long arm rotated
1 degree will raise one end about .017". This means that you can use
the arm length as a reducer, similar to a gear reduction.
ERS