5 years ago.

magnetometer vs magnetic field sensor

Hi all, I am planning to build a project where it can be possible to detect the empty parking slots. There is one implementation present on the web using the waspmote platform which uses the magnetic field detection algo. That is if there is a park magnetic field will be changed and thus it will notify the end user about the presence of the car.

I need to know that can we do the same thing with the 3-axis magnetometer which comes with freescale microcontroller or we need to have separate magnetic field detection sensor. I observed 3-axis magnetometer is some thing else, it works more like a compass rather than to detect the presence of the object.

thanks in advance.

Comment on this question

1 Answer

5 years ago.

You could almost certainly work. How reliable is another matter.

The reliable way to make it work is to create a magnetic field yourself and then look for a car to disturb that.

What you can do with the sensor you have is use the earths magnetic field and look for that moving.

If you know that you are stationary then any movement in the direction the compass is pointing must be caused by large lumps of metal moving nearby.

The problem with this is that when you are generating the field you know exactly what to look for. When you are using the earths field then the signal with no car will depend on where you are and the change due to a car will also depend a lot on how things are set up, if just looked for any change you could pick up a car in the next bay by accident.

So as I started by saying, yes it will work unless you're in a building with a lot of structural steel that is blocking most of the earths field.. But you may end up having to be very careful how you install things or having to calibrate each bay individually, not something suitable for quick or large scale installation.