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Custom Curve Linearization
Easy Programming for Custom Nonlinear Curve Fits

   Applicable to Micron Process, Strain Gauge, Load Cell Meters,
Frequency / Rate Meters, Totalizers

DC Voltmeters & DC Ammeter
CE Mark
  
UL Mark
RoHS Mark
Made in California

Features
  • Achieves exceptional accuracy with low-cost transducers.
  • Extends transducer operating range on high and low ends.
  • Solves application problems involving non-linear relationships.
  • Available with Extended versions of Micron digital panel meters, counters and timers.
  • Easy setup by entering data points into a computer spreadsheet, or typing in desired readings for actual signal inputs. 
  • Exceptional accuracy from 0.1% to 0.01% of full scale with few data points, made possible by curvilinear spline fits.

Description
Custom curve linearization is a feature available with the Extended option version of all Micron digital panel meters, counters and timers, excluding only the temperature meter, which already has built-in linearization curves.

Benefits. Custom curve linearization can provide exceptional accuracy from low cost transducers of these are repeatable. It can extend the working range of transducers on their high and low ends. It can also solve special application problems where there is a non-linear relationship between the input and the desired readout.

Implementation. Linearizing is implemented in the form of 20 nonlinear spline-fit segments, which provide much better accuracy than a larger number of straight line segments. The typical error will be from 0.1% to 0.01% of full scale, depending on the number of data points used for setup, the error in the data points, and the severity of non-linearities or discontinuities.
Easy Setup
Setup of a Micron Linearizing Process Meter requires an external PC, which is connected to the meter via RS232 or USB cable, and utilizes linearizing software furnished by Micron Electronics.  A serial communications board is required, but can be removed from the meter following setup. Three meter programming methods are offered:
  1. Spreadsheet Method:  Data points consisting of the input signal in Volts or Amps and the desired reading are entered into an Excel spreadsheet or into a text file using a space, comma or tab as the delimiter. There can be up to 180 data points. Micron's software then calculates 20 spline-fit segments and downloads their coefficients into the meter.

  2. Actual Input Method:  The meter is hooked up to the actual signal source, and the user enters the desired readings for different signal levels. There can be up to 180 input / reading combinations. Micron's software then calculates 20 spline-fit segments and downloads their coefficients into the meter. This method automatically compensates for any errors in the transducer.

  3. Polynomial Method: The mathematical formula relating the input to the output is entered into the computer, which then uses this data to calculate the spline-fit segments. This method is ideal if the mathematical relationship is knows, for example to calculate the contents of a tank based on the known geometry of the tank.
Application Examples
  • Altimeters, since the relationship between pressure and altitude is very non-linear.
  • Rate of ascent based on successive altimeter readings.
  • Volume of irregularly-shaped tanks, such as horizontal cylinders, based on measured liquid level or liquid pressure at the base of the tank.
  • Non-linear transducers, such as thermistors or CdS cells.
  • Fine-calibration of linear transducers, since even nominally linear transducers will have nonlinear components.
  • Extending the working range of transducers, since many transducers become nonlinear at their low and high ends.
  • Compensating for inaccuracy of low-cost transducers.
 

Measuring tank volume

The Extended Micron process meter can display the volume of irregularly shaped tanks based on measured tank level or static pressure at the base of the tank. An example is a cylindrical tank lying on its side. The tank can further be tilted to facilitate drainage, as illustrated.

 Displaying tank volume using a linearizing digital panel meter
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