I have a project where I need to be able to measure the volume of remaining liquid in a bottle based on weight. The idea is to use a Force Sensing Resistor:
(model FSR402-Short Tail: http://www.interlinkelectronics.com/FSR402short.php)
My issue is that I can't seem to get an accurate consistent reading on the pressure exerted on the device when any kind of shifting (such as replacing / refilling the bottle, moving the device location, etc) would create a huge variance in the data points. It can vary from 20-150 points easily... which is too large of a margin since 150 points could equate to about 500ml of liquid.
The idea was to loosely hang the bottle & connector to the pressure plate (see second image) using two centrally located screws. the pressure plate would have a set of two rubber feet perpendicular to the screw placements to allow the pressure to be focused on the rubber footing with the FSR.
This produced two main issues that I did not foresee with the CAD design:
- over-tightening/under-tightening of the screws
- inaccurate or inconsistent readings of the pressure from very minor shifts or bumps.
What can I do to improve my design, shown below?