Dp sensor o2 compensation #396
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algo.py
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| try: | ||
| self._flow_sensor.set_o2_compensation(o2_saturation_percentage) | ||
| except Exception as e: | ||
| self.log.exception(e) | ||
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This is not good.
A flow sensor should behave as a flow sensor.
NullDriver should behave like magic mock in this case and simply do nothing.
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Done
Now I check if the relevant method exists in the driver class..
(There are other flow sensors which do not need this compensation)
drivers/hsc_pressure_sensor.py
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| @@ -38,8 +43,26 @@ def set_calibration_offset(self, offset): | |||
| def get_calibration_offset(self): | |||
| return self._calibration_offset | |||
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| def set_o2_compensation(self, o2_percentage): | |||
| # update compensation only when o2 changes more than 5% | |||
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Don't explain what, explain why
drivers/hsc_pressure_sensor.py
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| (1 - o2_percentage) * self.DENSITY_REST_OF_GASSES) | ||
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| self._o2_compensation_ratio = sqrt(self.DENSITY_AIR / corrected_density) | ||
| log.debug(f"HSC pressure sensor updated comensation ratio " |
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Don't use f-string in log messages, use % format specifiers and pass the format arguments to the logging function in order to take advantage of the deferred formatting by the logging module.
This is PyLint warning logging-not-lazy (W1201).
See This section
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Done
Good point. thanks
The differential pressure sensor driver uses Bernoulli's equation, to cast the dp measurement into flow.
This calculation depends on the flowing gas density, and is currently calibrated for the density of air.
But, as oxygen percentage rises, the density rises too, which should result in lower flow values.
In this issue, the measured oxygen saturation is passed to the differential pressure driver, which calculates the new density, and the compensation for corrected flow.