Calibration of position Sensors

[Caslo]

Hi

Does anybody knows of an instrument that I could use to calibrate a linear position sensor?

 

[byrdj]

how accurate, what range, and what type?

for my 2 to 20 inch lvdts, i use micrometer standards (when available). An adjustable guage block and a dial caliper most of the time.

 

[JJPellin]

For thrust position probes and radial vibration probes on rotating machinery we use a spindle micrometer to check accuracy and linearity over the full range. The probes we use are manufactured by Bently Nevada. I believe we buy the spindle micrometers from them as well. These probes have a linear range from about 0.010" to about 0.075" and are normally gapped at 0.050".

 

[Caslo]

Thanks for the reply guys.

I'm planning on using two different types of sensors.

An LVDT range 30mm
A Potentiometer 25mm
Both work with DC Voltage

The total length that I want to measure is 0.5 in.

I don't have any experience calibrating sensors.

When you buy them do they come calibrated for a specific input voltage or do I have to do this myself?

I was thinking of using a micrometer or caliper to determiner the actual linearity error and the calibration curve.

My goal is to be able to create an equation to use as input for a controller program.

An example of the equation would be like:
For a given excitation voltage V_in

Delta_X = a1+a0(Voltage)

Where: delta_x is displacement
a1 and a0 are linearity constants
Voltage is output voltage

Could you recommend some website or reference site where I could get more information

Any advice is welcome

Caslo,

 

[byrdj]

I have AC LVDTs from RDP

http://www.rdpe.com/us/index.htm

if you select tech manuals, then select E308 will be a dislay that gives detail.

you'll notice the generic cal procedure doesnot give full scale travel as a given, but is user defined. for my use i want my display to be in inches. but if it is in a control loop, the actual bump to bump travel is set for 0 to 100%

adding to my previous post, I have used a standard nut as calibration block, and my calipers to determine what actual displacement was.

to determine your actual lineartiy, you can use incremental shims and record output. I think you'll find the linearity of most off the shelf sensors better than you're ability to measure

 

[eromlignod]

Gauge blocks?

Don
Kansas City