- Tue Apr 05, 2016 12:46 pm
I have kind of the same problem at the moment. These are the options I have evaluated so far:
Use a pressure sensor like the Bosch BME280. They are really precise and a contact to Bosch Sensortec suggested to use this sensor. However, he left me with the open question of how to make the sensor water resistant.
Ultra-sonic sensors are quite obvious. I started with the hc-sr04 and did quite a lot of optimizing. I managed to get it to 0.4cm on a scale of up to 2m. However, I would like to have it much more precise as well. The bigger problem is air moisture and I decided to use a different approach. At the moment I'm hacking on a K-14WP10. We'll see what precision can be squeezed out of this beast.
Might sound funny, but I seriously thought about using a rubber dug, attached to a rubber ring, which is attached to two deflection pulleys. Now you can use a grey code encoder on one of the pulleys. However, the accuracy is way above 0.1mm and having a mechanical solution can break easily.
I think I will go with #1, even if it's still quite hard. If you would do the same, one recommendation: You have to use another sensor for air pressure outside and only work with the difference of the two sensors. Otherwise you'll have different measures, depending on the weather.