FlexiForce user manual

02/05/09 FlexiForce Sensor User Manual (Rev G)
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CALIBRATION
Calibration is the method by which the sensor’s electrical output is related to an actual
engineering unit, such as pounds or Newtons. To calibrate, apply a known force to the sensor,
and equate the sensor resistance output to this force. Repeat this step with a number of known
forces that approximate the load range to be used in testing. Plot Force versus Conductance
(1/R). A linear interpolation can then be done between zero load and the known calibration
loads, to determine the actual force range that matches the sensor output range.
Resistance Curve: Conductance Curve:
CALIBRATION GUIDELINES
The following guidelines should be considered when calibrating a sensor:
• Apply a calibration load that approximates the load to be applied during system use,
using dead weights or a testing device (such as an MTS or Instron). If you intend to use a
"puck" during testing, also use it when calibrating the sensor. See Sensor Loading
Considerations for more information on using a puck.
• Avoid loading the sensor to near saturation when calibrating. If the sensor saturates at a
lower load than desired, adjust the "Sensitivity."
• Distribute the applied load evenly across the sensing area to ensure accurate force
readings. Readings may vary slightly if the load distribution changes over the sensing
area.
• Sensors should be calibrated at the same temperature for which testing will occur. This is
especially important for High-Temp Sensors, as these sensors have a wide operating
temperature range. If multiple temperatures are used during testing, calibrate the sensors
at those same multiple temperatures.
Note: Read the Sensor Performance Characteristics section before performing a Calibration.