Magnetic position sensors

Abstract

Magnetic position sensors are popular in industrial and automotive applications since they are robust, resistant to dust and oil, and can be cheap. This was traditionally accompanied by low accuracy. However, new precise magnetic position sensors have been developed which can achieve 0.015% error and 10 nm resolution. The maximum achievable range is about 20 m. DC magnetic position sensors use a permanent magnet as a field source; a magnetic field sensor measures the field from that source, which is a function of distance. As a field sensor, magnetoresistors are often used instead of traditional Hall sensors. Eddy current position sensors also work with non-magnetic conduction targets. Magnetostrictive position sensors are based on the time of flight of the elastic waves excited in the magnetostrictive material. These sensors can be several meters long and their applications range from level meters to hydraulics. Magnetic trackers and long-range position sensors utilize AC field sources, which are detectable from distances up to 20 m. Compared to optical instruments, magnetic trackers do not need a direct view. Their applications include surgery, mixed reality, and underground and underwater navigation.