Measuring quantity in a container

[Harini Krishna]

Hi,
We want to measure the quantity in the steel container placed on ABS plastic body. We are planning to go with flexible pressure sensor placed as shown in figure.
But i doubt if it would measure the correct quantity?
Can you suggest on how to place the pressure sensor so that the sensor measurements are accurate( we cannot place it above the plastic body due to application constrains).

Thankyou

 

[IRstuff]

The only way, short of burning, is to have the user enter the food items into the app that you probably will have for reading the weight. Or, weigh the individual food items during prep.

I'm having difficulty believing that this is for work, when you have no detailed requirements and no detailed concept and are asking strangers on the internet for help.



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[quark]

So, you want to manufacture lunch boxes with calorie content showing up once filled, for lazy, rich and health conscious guys. Good luck to you. I saw some super inventions by one of my previous companies, for commercial purposes, so I don't want to disappoint you.

As IRStuff already mentioned, the only way to check food strength is using a calorie meter and this is no more being practised as database usage is more handy now a days. Personalized and portable calorie meters are not a possibility, presently.

The option for pressure sensor is incorrect as solids don't exert uniform pressure as liquids do. If the solids are granular then cohesion forces between solid particles tend to reduce pressure at the bottom of container. Sometimes, at certain conditions, increased height of solids won't even impact the pressure at the bottom.

 

[IRstuff]

I think the OP is weighing the entire container, contents and all, and doing a simple tare weight, either store in memory, or measured prior to placing contents in the container.

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[btrueblood]

How will pressure be transmitted from the more rigid steel container to the abs shell and pressure sensor?

Why not a spring and a cheap capacitive, or IR reflective, or inductive displacement sensor? Better yet, why not graduations on the side of the cylinder to indicate filled volume (too low-tech?)

Measurement of calories is impossible without either burning in a bomb calorimeter (as suggested by IRstuff, but note that this method has issues with non-digestible materials) or by prior knowledge of the foodstuff calorie content per unit weight.

 

[IRstuff]

The OP stated they wanted to measure "weight" not volume.

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[Harini Krishna]

Hi,
Thank you for the suggestions
Burning food is not suitable for our application. So, there is no point in measuring the weight of the contents in the container when there is not scope of measuring calories without burning .
Can you suggest some methods to measure volume.

 

[IRstuff]

Why do you need volume and not weight? One without the other makes no sense, particularly since volume is even hard to measure, in a practical sense. The classic volumetric measurement is Archimedes' Principle, which can't be readily done with foodstuffs. Alternately, you could use a camera with structured light and with a laser distance measurement.

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[quark]

A simple way is to mark the internals as btrueblood suggested and then providing circumferential slide rule to check the calorie content by food item. This won't be appealing to premium segment, however. Why can't you go with a mobile phone type camera in the lid (the plastic one) and connect this to an existing database? Simpler version can be a mobile app.

 

[Strong]

If you want to measure weight, then use a load cell as use din digital scales. The tare function, as mentioned, would subtract the weight of the empty steel container so that weight of the contents in steel container is measured.

Walt