Patent ID: 6574498
Filing Date: 2003-06-03
Classification: A61B

Abstract:
A method for determining a position and an orientation of a workpiece relative to a primary coordinate system, comprising the steps of:(a) providing a primary reference transducer that interacts with a primary field; (b) providing a plurality of secondary reference transducers that interact with a secondary field different from said primary field, said secondary transducers being in a fixed mutual spatial relationship so as to define a secondary coordinate system, said primary reference transducer being in a fixed spatial relationship to said secondary transducers; (c) measuring at least one value of said primary field, using said primary reference transducer; (d) inferring, from said at least one value of said primary field, a position and an orientation of said reference transducers relative to the primary coordinate system, thereby determining a position and an orientation of said secondary coordinate system relative to the primary coordinate system; (e) providing the workpiece with at least one workpiece transducer that interacts with said secondary field; (f) measuring a plurality of values of said secondary field, using said secondary reference transducers and said workpiece transducer; (g) inferring, from said values of said secondary field, a first measure of a position of the workpiece relative to said secondary coordinate system; and (h) combining said first measure of said position of the workpiece relative to said secondary coordinate system with said position and said orientation of said secondary coordinate system relative to the primary coordinate system to provide the position and the orientation of the workpiece relative to the primary coordinate system.