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Embedded Systems

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Testing Liquid Level Sensors Trial 2

Sensor Test #3 : Liquid Level Sensor Test 2

with an actual container this time

Methodology

First, we laser cut the sides of a single column from 1/4in acrylic and made a waterproof column (turns out waterproofing is VERY difficult). Then, we wrapped the liquid level sensor in cling wrap to simulate the bag at the back of the collection container and to ensure that the liquid sensor is reusable by not allowing it to touch the "urine." Below are pictures of the container and the sensor. Notice that there is a black box in the bottom of the container--this is to account for the 1" actuation depth of the sensor. It is just a solid black box that we 3D printed to fill most of the volume of the first 1" of the container. 


Results

So this section might be more accurately titled: 'What went wrong'. When we measured the different depths of liquid, the resistance changed in the ten-thousands decimal place, which would be perfect if it was consistent--but it wasn't. There was just simply too much variance and resistance value jumping for us to get a solid characteristic. That's not to mention the fact that the reading consistently decreased (the longer we waited on the resistance to stabilize, the more it dropped and dropped and dropped). It was hopeless. The solution: Just let the sensor touch the liquid and test again! But the again, if we're allowing the sensor to touch the urine, then it has to be trashed, which means each container starts at $200... for holding pee. Back to the drawing board once again! AAARRRRAAAGGGGGHHH.

Phillip TrentComment