Yoctopuce Yocto-RangeFinder, Руководство пользователя

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them with software calibration which you can perform a posteriori on the measures of all Yoctopuce
sensors.
Calibration for temperature variations
To ensure proper operation of the sensor, you must run an automatic calibration process when the
temperature varies of more than 8°C. The Yocto-RangeFinder includes a temperature sensor located
right next to the distance sensor, allowing you to detect temperature variations and to run this
calibration if needed.
To know the current temperature, you must call the
get_currentTemperature()
method. To
know the latest calibration temperature, you must call the
get_hardwareCalibrationTemperature()
method. When the two are too far apart, you
must call the
triggerTemperatureCalibration()
method:
YRangeFinder rf = YRangeFinder. FirstRangeFinder () ;
Double currTemp = rf. get_currentTemperature () ;
Double calibTemp = rf. get_hardwareCalibrationTemperature () ;
if ( Math. abs ( currTemp - calibTemp ) > 8.0 ) {
rf. triggerTemperatureCalibration () ;
}
You do not need to put a target in front of the sensor to perform a temperature calibration.
Calibration to compensate reflections on a protection glass
Reflections caused by a protection glass introduce several types of biases in the measure. They can
be compensated only in applying the calibration procedures described below, in the given order.
These calibrations do not need to be repeated as long as the glass does not change position (this
calibration is relatively stable with regards to external conditions). But do not forget that even the best
calibration cannot compensate a too low signal/noise ratio. It is therefore critical to reduce as much
as possible the distance between the glass and the sensor, and to use the most transparent and
thinnest glass possible.
Before you start the calibration process, start by asserting that the sensor receives enough signal to
work. Even without calibration, at a relatively short distance, the sensor should be able to correctly
detect an object. If it is not the case, it means that the signal is too perturbed and you must either
move the glass closer to the sensor, or use a thinner glass, or most likely both. In good conditions,
the value measured by the sensor compared to the actual distance should conform to the following
graph:
The effect of an intervening glass on the distance measure, without calibration
Note the three areas of this graph: in the area close to the sensor, the measured value varies in
parallel to the distance of the object. In the median area, the measured value keeps on growing with
the distance, but the actual distance is more and more under-estimated. In the most distant area, the
measured value decreases, so that it is in no case possible to measure a distance, even after
calibration.
3. Working principle and limitations
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