Magnetic position sensing using Hall Effect devices or Anisotropic Magneto Restrictive sensors is a well established method of positional location of rotational or linearly moving components by non contacting means. Multiple sensors offer very accurate resolution and are used extensively in many electronic and mechanical control systems.
A sensing application may range from a simple proximity switch (e.g. reed switch on a door or window security alarm) to encoder technology for motor control in automotive or aerospace applications.
Plastic bonded magnets are often used due to their magnetic isotropy and advantage of being able to produce multipole (fine pole) magnetisation patterns for accurate position sensing.