Patent ID: 6400138
Filing Date: 2002-06-04
Classification: G01B,G01D

Abstract:
An absolute inductive position sensor, comprising:a first member; a second member having a measuring axis, the first member and the second member relatively positionable along the measuring axis; at least two magnetic field generators, each magnetic field generator comprising at least one flux generator winding portion, each magnetic field generator activatable to generate a changing magnetic flux in a corresponding primary flux region in response to a drive signal; at least one plurality of flux coupling loops distributed along the measuring axis, at least one receptor portion of each flux coupling loop positionable within at least one of the primary flux regions and at least one secondary flux generator portion of each flux coupling loop positionable outside of the at least one primary flux regions within which the at least one receptor portion of that flux coupling loop is positionable, wherein, when at least one primary flux region is activated, an induced current is generated in the at least one receptor portion positionable in that at least one activated primary flux region in response to the changing magnetic flux in that at least one activated primary flux region, and the induced current in the corresponding at least one receptor portion activates at least one corresponding secondary flux generator portion to produce a secondary changing magnetic flux in the at least one activated secondary flux generator portion, a plurality of activated secondary flux generator portions producing a spatially modulated magnetic flux in at least one activated secondary flux region that is physically separated from the at least one activated primary flux region, each spatially modulated magnetic flux modulated along the measuring axis according to a predetermined function; and at least two sets of magnetic flux sensors, each set of magnetic flux sensors positioned to sense the changing magnetic flux in a corresponding activatable secondary flux region; wherein: each flux coupling loop has at least first and second portions spaced apart from each other across the measuring axis; the at least two magnetic field generators and the at least two sets of magnetic flux sensors are located on one of the first and second members, and the at least one plurality of flux coupling loops is located on the other of the first and second members; and each set of magnetic flux sensors generates at least one output signal based on the sensed magnetic flux, each output signal being a function of at least one of the relative position along the measuring axis between the first and second members and the pattern of the spatially modulated flux present in the activated secondary flux region associated with that set of magnetic flux sensors; and at any relative position between the first and second members, the absolute inductive position sensor can generate at least a first output signal from at least a first set of magnetic flux sensors by activating a first one of the at least two magnetic field generators, at least the first portions of at least a sub-plurality of the at least one plurality of flux coupling loops acting as the corresponding receptor portions, at least the second portions of the sub-plurality of the at least one plurality of flux coupling loops acting as the corresponding activated secondary flux generator portions, and the absolute inductive position sensor can generate at least a second output signal from at least a second set of magnetic flux sensors by activating a second one of the at least two magnetic field generators, at least the second portions of the sub-plurality of the at least one plurality of flux coupling loops acting as the corresponding receptor portions, at least the first portions of the sub-plurality of the at least one plurality of flux coupling loops acting as the corresponding activated secondary flux generator portions; and a relationship between at least the first and second output signals is unique for each relative position along the measuring axis between the first and second members.