Hi,
I’m using arduino for a microcontroller connected to a load cell, to measure mass. What are the different ways to measure mass, Mechatronically. I only know two: vibrations and directly (load cell)
Best wishes
Does load cell measure mass or weight?
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F=G*m1*m2/r^2 Newton's law of universal gravitation - Wikipedia and Cavendish's experiment?
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It measures mass.
I think a load cell is actually a force sensor.
If this is a homework question, just say so (and you'd get a better answer at physics.stackexchange.com), otherwise, just tell us what you're trying to do.
A load cell measures the force exerted by a mass in a (Earth's) gravitational field.
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I’m trying to explore different ways of measuring mass of something. I posted on mechanical engineering stack exchange and didn’t get any proper answers.
Words like "arduino measure mass" in a search engine might gain some results.
I thought you were interested in methods other than vibration and load-cell force.
Maybe float it and measure the displaced volume?
It would help to know what "something" is. Mosquito eye? Cat 797 dump truck? One of Saturn's moons?
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I'm pretty sure my digital postal scale doesn't use a load cell but I found How do scales & balances work?
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Classroom assignment?
Scales using a load cell are measuring mass indirectly via gravitational forces (weight), but are the most common technique on Earth for typical everyday masses.
For very small masses vibration frequency can be used - the most sensitive mass measurements use this technique as micro-machined vibrating springs can be made able to weigh things like virus particles or similar by the change in resonant frequency.
And of course for liquids of known density you can measure volume and infer mass.
Spring balances convert weight to displacement so can be used with linear encoders to weigh masses.
X-rays provide a crude measure of mass too as X-ray opacity depends roughly on the atomic number and is correlated with total mass.
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Thank you. I was thinking of using vibration. I was thinking of using an accelerometer. The mass would be small, 0-500g and I would want the device I make to be portable and small.
Personal project
One approach would be to buy a commercial pocket scale such as the one below, and connect the load cell within the device to an HX711, which would be connected to your Arduino.
You could leave the load cell within the pocket scale housing or extract it and put it into your own device.
I did something similar with a 200g pocket scale from American Weigh Scales: extracted the load cell (with its platform) and used it in a project with an HX711 + Arduino.
A load cell does not measure mass. Weight is not the same as mass.
You need to know about the redfinition of the kilogram - which is the SI unit of mass.
You could use a kibble balance, (look it up) or F=ma as described here
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I thought everyone understands that load cells are used to measure the force exerted by a mass in Earth's gravitational field, which is probably good enough for the OP's purposes (since they mentioned using a load cell in their original post).
Einstein, among many other lesser luminaries, considered the equivalence of inertial mass (the m used in Newton's Second Law, F = ma) to that of the gravitational mass (the "m" used in Newton's classic theory of gravitation, F = (G m1 m2)/r^2 ) to be one of Nature's deep mysteries.
As far as I know, that equivalence is still the case today, and is pretty useful for things like scales, etc.
@DaveEvans
my point was that if you need to make a measurement you need to know wwhat it is you are measuring.
weight and mass are not the same, but they are often confused simply because in our common experience
1: mass is "measured" by determining the downward force it exerts under gravity - eg a spring balance; and
2: the gravitational acceleration (remember F = ma) is pretty reliably constant in our normal environment.
Also remember in the above equation F and a are VECTOR quantities, while mass is scalar.
So a load cell provides a SCALAR output (voltage) indicating the component of the applied force in a direction orthogonal to its plane.
It only gives a true reading of weight (a force) it the plane of the load cell is accurately set orthogonal to the direction of the gravitational acceleration at that time; and only then if its stationary.
You first need to be clear about what it IS you want to measure, then use the right instruments to make the measurement.
For example you CAN use balance scales (even assymmetric scales) to measure mass by comparing their weights, because the effect of g cancels out.