Since we wanted to do further experiments but couldn’t use our construction for it, because we could not solve the mechanical problem in time, we used another construction from fischertechnik from the 1980’s that has been laying around in our school ever since (unopened!) – a plotter.
We exchanged the steel tubes for carbon ones and changed the design a little bit as well. Instead of a pencil it now carries the sensor.
We used a motor shield from Adafruid, added an SD-Card-Shield we built ourselves from an Micro-SD-Card Adapter our self, an LCD-Display and Bluetooth to make the device controllable via a Smartphone-App. We programmed this app with "app inventor 2".
You can choose the sensor range and the scanning area from your smartphone – we developed some kind of protocol to transfer these informations back to the Arduino to do the measurement and record the data.
If you press the start button the sensor drives to a reference point.
From there it begins to measure bidirectional to save some time.
The data is saved to the SD-Card in a special format – it can be copied to the command window of mathworks and executed directly. You instantly have all the matrices you need to visualize or calculate the magnetic field. We did some short tests with a “normal” magnetic sensor and datalogger, that just records the overall magnetic field (no orientation) – and it seemed ok ;-)
We can now analyze the magnetic field by measurement of its flux density and visualize it in 3D. For the moment we only scan regions (a plane) and measure the three-dimensional vector (BX | BY | BZ) | of every single measuring point with assigned coordinates (Y X) automatically - and the result is a vector field.
So far we measured metallic different objects to watch whether you can recognize for example a current-carrying wire formed as a heart, a saw blade and a bullet casing (we found in Berlin after new years eve; it is an empty blanket, don’t worry).
Coming back to magnetic fields, we can determine the spatial orientation and intensity of the magnetic flux at any given point on a 2d plane (scanner area). As a result, we have a 5D-vector field of the examined magnets, which can be visualized with the aid of mathematics programs such as MATLAB and investigated further.