Angular position sensor

• US 4,584,577 A
• Filed: 10/17/1983
• Issued: 04/22/1986
• Est. Priority Date: 10/20/1982
• Status: Expired due to Fees

• Current Assignee: Brookes & Gatehouse Ltd. (Government of Norway)
• Original Assignee: Brookes & Gatehouse Ltd. (Government of Norway)
• Inventors: Temple, Andrew W.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Heim, Michael F.
• Application Number:
  US06/542,659
• Time in Patent Office: 918 Days
• Field of Search: 336/45, 340/870.32, 340/870.33, 340/870.35, 200/6 A, 74/471 XY, 33/1 N, 33/1 PT, 324/208, 324/207
• US Class Current: 340/870.32
• CPC Class Codes: G01D 5/2073 by movement of a single coil with respect to two or more coils
• CPC Class Codes: G01S 3/043 Receivers
• CPC Class Codes: Y10T 74/20201 Control moves in two planes

Abstract

An angular position sensor comprising a generator coil driven by an oscillator to provide an alternating magnetic field which is symmetrical about an axis, an annular rotor of electrically-conductive or magnetic material such that it distorts the magnetic field around it and arranged so that it is asymmetrical about its axis of rotation and lies outside the equatorial plane of the magnetic field and two sensing coils disposed within the magnetic field. As the rotor 16 rotates about its axis the emfs induced in the sensing coils vary in dependence upon the angular position of the rotor relative to the axis of the undistorted magnetic field.

Claims

1. An angular position sensor comprising:

a generator coil drivable to provide an alternating magnetic field symmetrical about a central axis of said generator coil;

a pair of sensing coils arranged so that the plane containing each sensing coil is orthogonal to the plane contianing the other said sensing coil and to that containing said generator coil; and

a body of electrically-conductive material, at least a part of which is disposed outside the planes containing said generator and sensing coils and which is rotatable about said central axis of said generator coil;

the emfs induced in said sensing coils by said magnetic field being dependent on the angular position of said body relative to the axis of symmetry of the undistorted magnetic field.

2. A sensor for sensing angular position about an axis of rotation;

the sensor comprising;

means for generating an alternating magnetic field symmetrical about said axis of rotation;

a body asymmetrical about said axis at least a part of which lies outside an equatorial plane of said alternating field and extending perpendicular to said axis, the body being of material such as to distort said alternating field so as to provide a resultant field asymmetrical about said axis of rotation;

said body being rotatable about said axis of rotation whereby said resultant field is rotatable about said axis; and

at least one sensing coil disposed within said resultant field;

the emf induced in said sensing coil being dependent on the angular position of the resultant field, and, hence, of said body relative to said axis of rotation.

3. The invention set forth in claim 2 wherein said sensing coil is disposed so that the plane containing said sensing coil is parallel to said axis of the alternating magnetic field.

4. The invention set forth in claim 3 including a further sensing coil so disposed that the plane containing said further sensing coil is perpendicular to the plane containing said sensing coil.

5. The invention set forth in claim 2 wherein said rotatable body is of electrically-conductive material.

6. The invention set forth in claim 2 wherein said rotatable body is of magnetic material.

7. The invention set forth in claim 6 wherein said rotatable body is of ferrite.

8. The invention set forth in claim 2 wherein said means for generating said magnetic field is fixed and further including:

gimbal mounting means for mounting said rotatable body; and

joystick means coupled to said rotatable body, whereby said body is movable about a fixed centre from a neutral position in which said rotatable body is disposed in the plane of said generator coil;

the emf induced in said sensing coil being related to the position of said joystick means relative to said neutral position.

9. An angular position sensor comprising:

receiver means for receiving an electromagnetic signal;

signal means coupled to said receiver means for generating two output signals each of which represents the vector component of said electromagnetic signal in one of two intersecting inclined directions;

means for generating an alternating magnetic field;

said means for generating including two coils whose central axes are inclined to one another at the same angle as said inclined directions;

a body rotatable about an axis perpendicular to the plane defined by said intersecting inclined directions;

said body being asymmetrical about its axis of rotation;

at least a portion of

said body lying outside said plane and being of material such that it distorts said magnetic field; and

a sensing coil disposed within said magnetic field;

whereby the emf induced in said sensing coil is dependent on the position of said body relative to said magnetic field and, hence, on the direction from which said electromagnetic signal approaches said receiving means.

10. An angular position sensor comprising:

a generator coil drivable to provide an alternating magnetic field symmetrical about a central axis of said generator coil and defining a first generally planar region;

a sensing coil disposed such that its central axis is orthogonal to that of the generator coil and defining a second generally planar region; and

a body, at least a part of which is disposed outside said first and second planar regions containing said generator and sensing coils respectively, and rotatable about the central axis of one of said generator or sensing coils;

the body being of material capable of distorting said alternating field to provide a resultant field asymmetrical about said axis of rotation;

the electromagnetic coupling between said generator coil and said sensing coil being dependent on the angular position of said resultant field and, hence, of said body about its axis of rotation.

11. An angular position sensor in accordance with claim 10 for sensing the angular position of a rotatable member wherein said body is coupled for rotation with said rotatable member;

whereby the electromagnetic coupling between said generator coil and said sensing coil is dependent on the angular position of said rotatable member about the axis of rotation.

12. The invention set forth in claim 11 wherein said member is a shaft and further includes a vane mounted on said shaft whereby said shaft is rotated, in use, by wind incident on said vane;

the electromagnetic coupling between said generator and sensing coils being dependent on the incident wind direction relative to said axis of rotation.