Magnet position sensing system

• US 4,422,041 A
• Filed: 07/30/1981
• Issued: 12/20/1983
• Est. Priority Date: 07/30/1981
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Lienau, Jeffrey A.
• Primary Examiner(s): Strecker, Gerard R.
• Assistant Examiner(s): Edmonds, Warren S.
• Application Number:
  US06/288,595
• Time in Patent Office: 873 Days
• Field of Search: 324/207, 324/208, 324/179, 324/174, 324/228, 324/232, 340/686, 89/1.8, 89/1.816, 89/8, 244/3.16
• US Class Current: 324/207.23
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01D 5/2033 controlling the saturation of a magnetic circuit by means of a movable element, e.g. a magnet
• CPC Class Codes: G01P 3/665 for projectile velocity measurements

Abstract

Magnetic position sensing for an object is disclosed wherein the analogue the distance between an object and a sensor is detected for indicating changes in object position in one, two, or three dimensions. An accurate, and continous output signal indicative of object position and incremental changes in that position are obtained. Additionally, magnetic sensing provides motion sensing of a support structure or velocity and acceleration sensing of an object.

Claims

1. A magnetic position sensing circuit comprising:

an object having a longitudinal axis and adapted for displacement substantially along said axis;

magnetic means disposed selectively on said object for producing a plurality of magnetic fields, said magnetic means being a plurality of spaced apart magnetic field producing members disposed around the circumference of the object for radiating individual magnetic fields circumferentially outward from the object;

sensing means disposed adjacent to said object for sensing magnetic field strength indicative of lateral and longitudinal position changes of said magnetic means relative to said sensing means, said sensing means being a plurality of sensor elements disposed in a plurality of parallel planes passing through the object and each element being disposed for sensing positional changes in the object;

signal processing means for indicating the changes in lateral and longitudinal position between said sensing means and said magnetic means; and

a centerline axis normal to said planes, said sensor elements being equidistant from said centerline.

2. A magnetic sensing circuit as set forth in claim 1 wherein said plurality of magnetic field producing members are electromagnets.

3. A magnetic sensing circuit as set forth in claim 2 wherein said object is cylindrical, and wherein said sensor elements disposed in plural planes comprise four sensor elements in each plane disposed along respective coordinate axes, each plane being substantially normal to the longitudinal axis of said object when said object is at rest.

4. A magnetic sensing circuit as set forth in claim 3 wherein respective first and second pairs of sensors being in said planes are disposed coaxially on opposite sides of said cylindrical object for sensing deviation of position of said object therebetween in response to object motion, and said signal processing means comprises a difference signal measuring system and recording circuit for indicating changes in position and attitude in response to movement of said cylindrical object through said planes.