Device for determining the spatial position of a sensor element which is displacement relative to a reference element

• US 5,747,996 A
• Filed: 06/20/1996
• Issued: 05/05/1998
• Est. Priority Date: 03/09/1994
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Fuchs, Manfred H.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US08/667,287
• Time in Patent Office: 684 Days
• Field of Search: 324/207.17, 324/207.18, 324/207.19, 324/207.26, 324/247, 178/18-20, 128/653.1, 345/158, 345/163, 342/463
• US Class Current: 324/207.17
• CPC Class Codes: G01B 7/004 for measuring coordinates of points
• CPC Class Codes: G01R 33/02 Measuring direction or magnitude of magnetic fields or magnetic flux G01R33/20 takes precedence

Abstract

A device for determining the spatial position of a sensor element (3) which is spatially displaceable relative to a reference element (1), includes three coils (4, 5, 6) which are arranged in the sensor element (3), consist of at least one wire turn, and are wound about a common center (7), at least three coils (2) which are arranged in the reference element (1) in spatially remote positions and consist of at least one wire turn, a current generator (11) for exciting the sensor element coils (4, 5 6) or the reference element coils (2) by means of a presettable excitation alternating current, and a processing circuit (15) for the voltages induced in the reference element coils (2) or in the sensor element coils (4, 5, 6). The processing circuit includes an arithmetic circuit which calculates, on the basis of the induced voltages, the distance coordinates x_m, y_m and z_m of the center (7) of the sensor element coils (4, 5, 6) in a coordinate system associated with the reference element (1), as well as a feedback circuit (13) which controls the excitation currents in dependence on the amplitude of the induced voltages.

Claims

1. A device for determining the spatial position of a sensor element which is spatially displaceable relative to a reference element, comprising:

three sensor element coils which are arranged in the sensor element, consist of at least one wire turn and are wound about a common center;

at least three reference element coils which are arranged in the reference element spaced apart from each other and consist of at least one wire turn, said reference element coils all facing in substantially the same direction;

a current generator for exciting the sensor element coils or the reference element coils by means of a presettable excitation alternating current;

a processing circuit for voltages induced in the reference element coils in response to the current generator exciting the sensor element coils or in the sensor element coils in response to the current generator exciting the reference element coils, which processing circuit comprises an arithmetic circuit that calculates, on the basis of the induced voltages, distance coordinates x_m, y_m, and z_m of the center of the sensor element coils in a coordinate system associated with the reference element; and

a feedback circuit which controls the excitation currents in dependence on the amplitude of the induced voltages.

2. A device as claimed in claim 1, wherein winding axes of the sensor element coils extend in mutually perpendicular directions.

3. A device as claimed in claim 1, wherein the induced voltages are applied to the processing circuit via a frequency-sensitive and/or phase-sensitive amplifier which is coupled to the current generator so as to receive a signal generated by the current generator that determines the range of phase and/or frequency selectivity of the amplifier.

4. A device as claimed in claim 1, wherein the current generator is connected, via a multiplexer, to the sensor element coils or to the reference element coils, and that the coils so-connected can be excited successively in time by currents of the same frequency.

5. A device as claimed in claim 1, wherein the sensor element coils or the reference element coils can be simultaneously driven by excitation alternating currents of different frequency.

6. A device as claimed in claim 1, wherein at least five reference element coils are arranged in the reference element, and the processing circuit is programmed so that the angular position of the sensor element can also be calculated.

7. A device as claimed in claim 6, wherein the processing circuit is programmed so that first the coordinates x_m, y_m and z_m are calculated, and subsequently two angular coordinates are calculated in mutually perpendicular planes which extend through the center of the sensor element coils.

8. A device as claimed in claim 2, wherein the induced voltages are applied to the processing circuit via a frequency-sensitive and/or phase-sensitive amplifier which is coupled to the current generator so as to receive a signal generated by the current generator that determines the range of phase and/or frequency selectivity of the amplifier.

9. A device as claimed in claim 2, wherein the current generator is connected, via a multiplexer, to the sensor element coils, acting as excitation coils, or to the reference element coils, and that the excitation coils can be excited successively in time by currents of the same frequency.

10. A device as claimed in claim 3, wherein the current generator is connected, via a multiplexer, to the sensor element coils, acting as excitation coils, or to the reference element coils, and that the excitation coils can be excited successively in time by currents of the same frequency.

13. A device as claimed in claim 4, wherein at least five reference element coils are arranged in the reference element, and the processing circuit is programmed so that the angular position of the sensor element can also be calculated.

14. A device as claimed in claim 5, wherein at least five reference element coils are arranged in the reference element, and the processing circuit is programmed so that the angular position of the sensor element can also be calculated.

15. A device as claimed in claim 1, wherein the reference element forms a boundary plane and the reference element coils are placed about said boundary plane at a maximumly large distance relative to each other.

16. A device as claimed in claim 15, wherein the reference element coils are placed in said boundary plane so as to be co-planar.

17. A device as claimed in claim 1, wherein the reference element forms a boundary plane and the reference element coils are placed in said boundary plane so as to be co-planar.

11. A device as claimed in claim characterized in wherein the current generator is connected, via a multiplexer, to the sensor element coils, acting as excitation coils, or to the reference element coils, and that the excitation coils can be excited successively in time by currents of the same frequency.

12. A device as claimed in claim 11, wherein at least five reference element coils are arranged in the reference element, and the processing circuit is programmed so that the angular position of the sensor element can also be calculated.

18. A device for determining the spatial position of a sensor element which is spatially displaceable relative to a reference element, the reference element forming a boundary plane, comprising:

three sensor element coils which are arranged in the sensor element, consist of at least one wire turn and are wound about a common center;

at least three reference element coils placed about the boundary plane at a maximumly large distance relative to each other and consist of at least one wire turn, said reference element coils all facing in substantially the same direction;

a current generator for exciting the sensor element coils or the reference element coils by means of a presettable excitation alternating current;

a processing circuit for voltages induced in the reference element coils in response to the current generator exciting the sensor element coils or in the sensor element coils in response to the current generator exciting the reference element coils, which processing circuit comprises an arithmetic circuit that calculates, on the basis of the induced voltages, distance coordinates x_m, y_m, and z_m of the center of the sensor element coils in a coordinate system associated with the reference element; and

a feedback circuit which controls the excitation currents in dependence on the amplitude of the induced voltages.

19. A device as claimed in claim 18, wherein the reference element coils are placed in said boundary plane so as to be co-planar.