Method for measuring position and angle

• US 5,551,158 A
• Filed: 09/06/1994
• Issued: 09/03/1996
• Est. Priority Date: 01/20/1992
• Status: Expired due to Fees

• Current Assignee: Demodulation Incorporated
• Original Assignee: RSO Corporation N.V.
• Inventors: Tyren, Carl, Persson, Leif A.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Bennett, G. Bradley
• Application Number:
  US08/256,490
• Time in Patent Office: 728 Days
• Field of Search: 33/1 N, 33/355 R, 33/361, 33/362, 33/201, 340/551, 340/572
• US Class Current: 33/1.00N
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01D 5/14 influencing the magnitude of a current or voltage
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10059 transponder driven
• CPC Class Codes: G08B 13/2408 using ferromagnetic tags
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 13/2431 Tag circuit details
• CPC Class Codes: G08B 13/2442 Tag materials and material properties thereof, e.g. magnetic material details
• CPC Class Codes: G08B 13/2474 Antenna or antenna activator geometry, arrangement or layout loop antennae H01Q1/22
• CPC Class Codes: G08B 13/2485 Simultaneous detection of multiple EAS tags

Abstract

Method for position measurement, whereby a magnetic field is generated in a measuring volume comprising one or several elongated elements of amorphous material, the magnetic properties of which being influenced by the magnetic field, is arranged in the measuring volume. The measuring volume is composed of several sub-volumes, and the extension of the sub-volumes in the desired measuring direction is chosen in such a way that the extension corresponds to the desired measuring resolution in the measuring directions. The change in magnetic or mechanical properties of the element caused by the magnetic flux intensity in the respective sub-volume along the longitudinal direction of the element is detected, the change being a measure of the position of the element.

Claims

1. Method for position measurement, whereby a magnetic field having a flux intensity is generated in a measuring volume comprising at least one elongated element of amorphous material, the magnetic/mechanical properties of which are influenced by the magnetic field, which is arranged in the measuring volume,

providing the magnetic field with a gradient in the measuring volume;

providing the measuring volume with a plurality of sub-volumes;

choosing extension of the sub-volumes in desired measuring directions in such a way that the extension corresponds to a desired measuring resolution in the measuring directions;

detecting a change in the magnetic/mechanical properties of the element caused by the magnetic flux intensity in a respective sub-volume along a longitudinal direction of the element, the change being a measure of a position of the element; and

the position measurement comprising the steps of;

measuring a gradient adapted to a total length of a total measuring area and magnetic working area of the element; and

measuring a gradient adapted to a sub-distance of a length of the total measuring area of the element.

2. Method as in claim 1, further comprising a step of providing the magnetic field with a known strength and direction in the longitudinal direction of the element in each sub-volume.

3. Method as in claim 1, further comprising a step of bringing a plurality of elements of said at least one element to self-oscillation mechanically;

and

detecting a resonance frequency of the plurality of elements as a position-determined measuring signal.

4. Method as in claim 1, further comprising a step of connecting the element magnetically to an inductive element in an electric resonance circuit.

5. Method as in claim 1, further comprising a step of bringing the gradient to adopt a known value in the measuring directions.

6. Method as in claim 5, further comprising a step of bringing the magnetic field to adopt a greater steepness concerning gradient in chosen regions of the measuring volume.

7. Method as in claim 1, further comprising the steps of:

generating the magnetic field in a uniform field direction in the measuring volume and with the field gradient perpendicular to field direction; and

providing the amorphous element with its longitudinal direction parallel to the field direction of the magnetic field, the measuring direction being parallel to the field gradient.

8. Method as in claim 1, further comprising the steps of:

generating the magnetic field with a uniform field direction and with a field gradient parallel to the field direction; and

arranging the amorphous element with its longitudinal direction parallel to the field direction of the magnetic field, the measuring direction being parallel to the field gradient.

9. Method as in claim 3, further comprising the steps of:

bringing the amorphous element to self-oscillation by an exciting signal of variable frequency, a certain phase shift arising between the exciting signal and a signal transmitted by the amorphous element;

locking the exciting signal at the resonance frequency; and

detecting a phase shift between the exciting signal and the signal transmitted by the amorphous element as a signal dependent on the position of the amorphous element.