# Centrifugal force sensor

Hi there!

I would like to build a machine that has a rotating mechanism. I would be very interessting what kind of centrifugal force is going to build up when the machine spins the wheel.

Is there any sensor which would be able to detect the force (Newton/Kilogramms) that is applied to the outer edge of the wheel?

Hi Asuryan,

The idea is very much possible, depending on what you specs are. Please note that there is a difference between centrifugal force (the force that has to magically exist if you use a rotating frame of reference) and centripetal force (the force needed to keep something in a constant curved path around a point).

The easiest way that comes to mind is having a mass fixed on top of a force sensor (like a piezo) (if the wheel spins flat on the ground so gravity isn't a problem). Then by finding the force on that mass you can find the acceleration and then find the force for other objects.

Regards, Teunman

Do you have a formula for centrifugal force? lol.

Thanks guys.

Its a rotating frame on the ground, so not upright.

Okay I understand. So somehting like this (side view):

EDGE-|O----- (CENTEROFWHEEL)--------EDGE

Where | = piezo element and O = steelball with eg. 10gramms

And then measure the resistance of the piezo elemnent and calculate the force with the weight that presses against the piezo accoring to its weight. The radius and RPM (measured separately) are known.

One question though: how do I get the wires from the wheel to the Arduino that is not on the wheel?! O.o

F = kg * (ms^2/r) ?

F = Newton
kg = mass
ms = Meters per Second

Should that be enough? I think I can calculate the force but I would like actual readings because the load of the wheel can vary.

how do I get the wires from the wheel to the Arduino that is not on the wheel?

Slip rings is one way, but wireless (rf24 for instance) would be easier (at least mechanically). You would need a small Arduino on the wheel, though, to convert the data and send.

Robin2's Simple nRF24 tutorial

yeah, that seems good. Do keep in mind that you measure the centripetal force on the ball.

Also why exactly do you want to know the centripetal force?

Also look around for different types of force sensors (piezo was just an example).

Doing communication wireless indeed seems like the winners option

adwsystems: Do you have a formula for centrifugal force? lol.

It is a trick question.

Centripetal force = F = kg * (ms^2/r)

F = Newton kg = mass ms = Meters per Second r = radius

hence the question. Only one actually exists.

any sensor which would be able to detect the force

An accelerometer will measure the acceleration, then you multiply by the mass.

Or just calculate it from the RPM. The inwardly directed force that keeps a mass M moving in a circle of radius R is M V2/R with V = RPM2PI*R/60.