Position Sensors

Anne Ogborn says:

Create a gradiant in photoshop from black to white. Print it onto overhead transparency film. Arrange to run in the slot of a transmissive optoswitch. something like a Vactec 13D7-20 would work good

Shaft (rotary) Position Encoders

Global Positioning Systems (GPS)

Optical Ranging

Position related sensors:

• Motion: Change of position
• Fluid Flow: Change in position in a fluid
• Strain: Force of change of position
• Acceleration: Change in the rate of change of position.
• Proximity: Difference in position
• Altitude: Vertical position with respect to ground
• Direction: of change in position

See also:

• http://www.usdigital.com/products/disklinear/ +
• http://www.pcmx.net/gauge/ Interface cheap digital calipers to a PC
• http://www.micro-epsilon.com/ Annie Ogborn says: These folks are trying to be a one stop solution for position measurement.

Comments:

• A 'spiffy' position sensing system is air. It's sometimes used for precision gages, usually in the form of a gage to measure the difference between desired size and actual size.
  A simple application would be measuring the diameter of a hole, like a gas engine cylinder. A test plug is inserted in the hole. Around the periphery of the plug are several small holes that lead to a central air supply. A T from the supply also leads to a fine needle valve. A sensitive pressure sensor between the arms of the T is nulled out by adjusting the needle valve, with the plug inserted in a standard cylinder. When the plug is inserted in a larger cylinder, the air pressure in this leg will be reduced. The pressure sensor can be calibrated for size.
  
  This technique has been superseded for many applications by the linear differential variable transformer. It might make more sense to move this comment to 'proximity'.
  
  Anne Ogborn+

Location Data, Physical Address +

Code:

• Annie Ogborn says: I also just made a cool discovery.
  You know the rubbery ferrite fleximble magnet material?
  It's available in sheets to make 'fridge magnet' type things, with an adhesive backing. Any crafts store.
  
  I just noticed that the polarization is in narrow strips, horizontally like this
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  The spatial wavelength is about 1/8", so you could make a handy position sensor or linear stepper out of it.
  

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