Multiple receivers allow tracking of several body parts. Certain metals in the environment can reduce accuracy. Only useful up to about 6 feet. Mechanical Very accurate and precise. Mechanical linkage places an unnatural inertia on the user.
Machanical linkage can prevent the user from moving to some locations.
Force feedback can be integrated into the system. Multiple sources can provide a 3D fix. Single source often used in second-person VR systems. Single source can be effectively used in a fishtank-VR system. Line of sight required.