Abstract: Methods, apparatuses, and systems for computer-aided tracking, navigation, and motion tracking. In one embodiment, a system for determining a spatial position, including a tracking device and a processor. The tracking devices has a working end, a reference end, a plurality of links connecting the working end to the reference end, wherein each link has at least one degree of freedom relative to an adjacent link, and a plurality of sensors measuring the orientation of the links in a plurality of degrees of freedom, wherein X is a minimum number of degrees of freedom about which information is required to define the spatial position. The processor receives information from the sensors and determine the spatial position of the working end of the tracking device relative to the reference end of the tracking device based on information from the sensors measuring Y degrees of freedom, wherein Y is greater than X.