Goal. measure hot/cold liquid in Container where the container can be rotated 0-360 degrees and I should have the measure at continuously. If the volume of an upright container is 10 cm3, rotating it in any direction should result in 10 cm3 unless liquid has been poured.
I wanted to know when a container(assumes its a cuboid) is rotated at different points, with 2 capacitive sensors I will be able to calculate the volume based of the trapezium or triangle. But how will I apply such a concept to bottle that rotates 180 degrees. Please see attached diagram.
Also will this be the best type of non contact sensors that I can use or there are options for this scenario.
It sounds like one of these sensor types might be useful for your application:
Non-contact sensor; this sensor is stated to be based on capacitance:
Intelligent non-contact liquid level sensor is the use of water capacitance sensing to detect whether there is liquid present in the absence of a liquid proximity sensor, due to the distributed capacitance exists, so there is a certain static sensors capacitive sensors on the ground, when the liquid level rises slowly proximity sensor, the parasitic capacitance of the liquid will be coupled to the static capacitance, so that the final capacitance value of the sensor becomes large, the change in the capacitance signal input to a control IC for signal conversion, will vary capacitance is converted into a certain amount of change in the electrical signal, and then by a certain algorithm to detect and determine the extent of the amount of change, when the change amount exceeds a certain threshold level is considered to reach the sensing point.
I have been look at home-brew solutions using copper foil type, but might explore these as well.
But this appears to detect only if the liquid falls above or below a pre calibrated level. I don’t see it as providing a way for measurement. Basic idea would be to have a sensor that can be pre-calibrated with different liquid level and remain constant by being temperature/humidity/surface agnostic and hence used to gather measurement. This device seems like a high/low switch.
Both of these would only provide an indication of liquid at the level where they are placed. A number of them would need to be placed on a container to get any finer detail.
This publication by TI might be of interest.
And this one as well.
This work studies the TI FDC1004 for a senior thesis project.
For a round container place the sensor down the axis of the container?
Or else have three sensors spaced 120 degrees apart around the circumference and take
the average. This will work with any larger number of evenly spaced sensors too.
interesting paper @jpsabo. Thanks to all.
@MarkT I did not quite get what you were trying to say. Was that my initial theory of placing 2 sensors and finding the capacitive diff between the two sensors.
An alternative to using an Arduino to measure capacitance directly (eg Capacitive Sensing Library) might be the MPR121 touch sensor breakout.
An Arduino application of the MPR121 is described at this link with a video here.
I actually tried it with the MPR121 and it works great. I need play around with more to test out a few things and I will write back on any updates in terms of measuring accurately measuring a rotated container.