Patent ID: 8278913

Claim:
A tracker assembly for positioning a medical tool, comprising: a first linkage; a second linkage adapted to support a medical tool proximate a free end of said second linkage, said second linkage further including a shaft; a joint assembly connecting said first and second linkages and providing two degrees of freedom between said linkages, said joint assembly comprising: a bracket interconnectable to the first linkage and having at least a first aperture for slidably and rotatively receiving the shaft of the second linkage; a drive gear having a central aperture for slidably receiving said shaft, wherein said drive gear is rotatively fixed relative to said shaft; a rotary encoder mounted to said bracket and be operatively interconnected to a driven gear, wherein teeth of the driven gear are meshed with teeth of the drive gear; a linear magnetic encoder mounted to said bracket, wherein said linear magnetic encoder reads a liner position of a magnetic strip that moves axially with said shaft.