Kaman SMU9200 - Manual (Page 13)

SMU-9000 User Manual 10
••••
Part III: Calibration
calibration process. The non-linearity of a system is calculated
using the least square method which represents error from a best
fit line through the data. When a specified range is less than 10%
of the sensor coil diameter, a linear output of less than
±
5% is
usually possible. For sensors with a larger “percentage-of-
diameter” calibrated range, 5
th
order coefficients of the natural
curvature can be provided upon request. By using this polynomial
correction with a computer or calculator program, linearity
performance of approximately 0.1% or better can be achieved (see
Figure 12).
Standard Calibration (Single Channel)
Calibration is a means to verify that system output relates to some
known physical displacement, a reference, or dimensional
standard with a known degree of accuracy. The accuracy of the
dimensional standard will directly affect the accuracy of
calibration, and thus the accuracy of any measurements taken.
Standard calibration produces an output voltage that varies from a
minimum desired output voltage when the target is closest to the
sensor (plus offset) to some maximum positive voltage when the
target is furthest from the sensor.
The SMU-9000 has two controls located inside the electronics
enclosure labeled “Zero” and “Gain” as shown in Figure 8. To
access these controls, remove the top cover.
Figure 8. Zero and Gain Controls
During calibration, the controls will interact with each other.
Because of this interaction, several iterations of a particular
procedure will have to be performed before a system is calibrated.