OBJECT TRACKING AND ORIENTATION DETERMINATION MEANS, SYSTEM AND PROCESS

• US 3,868,565 A
• Filed: 07/30/1973
• Issued: 02/25/1975
• Est. Priority Date: 07/30/1973
• Status: Expired due to Term

• Current Assignee: Kaiser Aerospace & Electronics Corporation
• Original Assignee: Jack Kuipers
• Inventors: Kuipers, Jack
• Primary Examiner(s): Corcoran, Robert J.
• Application Number:
  US05/383,688
• Time in Patent Office: 575 Days
• Field of Search: 324/41,43R,34R 318/16,647,653 343/1CS 340/258C
• US Class Current: 324/207.26
• CPC Class Codes: F41G 7/00 Direction control systems for self-propelled missiles flight control B64C, G05D1/00 ; counter-measures against guided missiles F41H11/02; spin-stabilised missiles F42B10/26; self-propelled or guided missiles having direction control systems only installed aboard F42B15/01; rocket torpedoes F42B17/00; marine torpedoes or sea-mines having self-propulsion means F42B19/00; locating by use of radio or other waves G01S; computing aspects G06
• CPC Class Codes: G01S 1/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 1/08 Systems for determining direction or position line
• CPC Class Codes: G01S 1/42 Conical-scan beacons transmitting signals which indicate at a mobile receiver any displacement of the receiver from the conical-scan axis, e.g. for "beam-riding" missile control

Abstract

A field (e.g., a magnetic field) which nutates about a pointing vector is used to both track or locate an object in addition to determining the relative orientation of this object. Apparatus for generating such a field includes mutually orthogonal coils and circuitry for supplying an unmodulated carrier, hereafter called DC signal, to one coil and an AC modulated carrier signal, hereafter called AC signal, to at least one (usually two) other coil, such that the maximum intensity vector of a magnetic field produced by the currents in the coils nutates about a mean axis called the pointing vector direction of the field. The generated field is sensed in at least two orthogonal directions at the object to be tracked and whose orientation is to be determined. The sensed signals provide an indication of the direction and orientation of the object relative to the coordinates of the generating means.

Claims

1. An object locating system which comprises:

a. means for radiating a directable nutating field about a pointing vector direction;

b. means located at the object to be tracked, for sensing the nutating field; and

c. means for determining the direction to the object relatiave to the coordinate frame of the radiating means.

2. The object locating system of claim 1 in which the object is free to translate and to orient in two-dimensions, and in which the said field radiating means commprises orthogonal radiators and said field sensing means comprises orthogonal sensors, said radiators and sensors being in the plane of the two dimensions and sources of a DC reference signal and an AC reference signal to be passed through the two radiators and means for measuring and processing the signals induced thereby in the sensors to determine the translation and orientation of said object.

3. The object locating system of claim 1 in which the object is free to translate and orient in three dimensions and in which said field radiating Means comprises three orthogonal radiators and said sensing means comprise three orthogonal sensors and sources of a DC reference signal, a first AC reference signal and a second AC reference signal phase quadrature related to the first AC signal to be passed through each of the three radiators and means for measuring and processing the signals induced in the sensor coils to determine the translation and orientation of said object.

4. A process for tracking an object, which comprises:

(a) radiating a nutating field about a pointing vector;

(b) sensing the generated field in at least two axes of the object to be tracked; and

(c) moving the nutating field until the field signals sensed on the two axes indicate that the object lies along the pointing vector.

5. The process of claim 4 in which the object is free to translate and orient in two dimensions and in which the field is sensed in two dimensions.

6. The process of claim 4 in which the object is free to translate and orient in three dimensions and in which the field is sensed in three dimensions.

7. A process for tracking an object relative to the coordinate frame of a radiator, which comprises:

a. radiating a nutating field about a pointing vector;

b. sensing the radiated field in at least two orthogonal axes at the object, to produce an output signal for each axis; and

c. determining after appropriate coordinate transformation processing, the directional position of the object and also its angular orientation, both relative to the coordinate frame of the radiating means.

8. The process of claim 7 in which the object is free to translate and to orient in two dimensions, the field nutates by nodding in the plane of the two dimensions, and in which the field is also sensed in the two dimensions.

9. The process of claim 7 in which the object is free to translate and to orient in three dimensions, the field nutates by describing a conical motion about the pointing vector, and in which the field is sensed in the three dimensions.

10. The process as set forth in claim 7 wherein said determining step includes the steps of deriving a signal, based on the sensing of the nutating field, which is related to the misdirection, if any, of the pointing vector and applying the signal to the radiator.

11. An object tracking system comprising means for radiating a directable nutating field about a pointing vector which is the axis of nutation;

means located at the object for sensing the nutating field; and

, means for deriving a signal, based on the sensing of the nutating field, which is related to the misdirection, if any, of said pointing vector, means for redirecting said pointing vector toward said object in accordance with said error signal.

12. The system as set forth in claim 11 wherein:

said radiating means includes means for generating a pointing vector having at least two independent components which are a function of at least two primary reference signals and means for transforming said primary reference signals in accordance with presumed pointing angle inputs to direct said pointing vector in a direction corresponding to said presumed pointing angle inputs;

wherein said sensing means comprises means for sensing components of the field generated by the nutating field about said pointing vector and means for transforming the sensed components in accordance with said presumed pointing angle inputs to yield a set of reconstructed reference signals; and

, wherein said deriving means comprises means for comparing at least some of said reconstructed reference signals with at least some of said primary reference signals, deriving pointing angle error signals and altering the pointing angle input signals of said transforming means in accordance therewith to tend to null the pointing error.

13. The system as set forth in claim 12 wherein said directable field is an electromagnetic field, said radiating means including orthogonal radiators, said primary reference Signals being a DC signal and a first AC signal.

14. The system as set forth in claim 13 wherein said sensing means includes orthogonal sensors.

15. The system as set forth in claim 14 wherein the object is free to translate in two dimensions and to orient in the same two dimensions, and in which there are at least two orthogonal radiators and sensors in each of said radiating and sensing means, respectively, the radiators and sensors being in the plane of the two dimensions.

16. The system as set forth in claim 14 wherein the object is free to translate in three dimensions and to orient in three dimensions, in which there are three orthogonal sensors and radiators in each of the sensing and radiating means, respectively, and in which a second AC signal in phase quadrature with said first AC signal is one of said primary reference signals.

17. The system as set forth in claim 12 which further comprises means for determining the orientation of said object.

18. The system as set forth in claim 17 wherein said directable field is an electromagnetic field, said radiating means including three orthogonal radiators;

said sensing means including three orthogonal sensors, said primary reference signals being a DC signal, a first AC signal and a second AC signal in phase quadrature with said first AC signal.

19. The system as set forth in claim 18 wherein said means for determining the orientation of said object comprises means for analyzing two of said reconstructed reference signals to determine two degrees-of-freedom of orientation and means for determining the phase relationship between at least one primary reference AC signal and the corresponding reconstructed AC reference signal to determine the third degree-of-freedom of orientation.

20. The system as set forth in claim 19 wherein said pointing error signals are determined by the presence or absence of a reference signal variant in one of said reconstructed reference signals and wherein said two degrees-of-freedom of orientation are determined by detecting the presence of a DC signal in the other two of said reconstructed reference signals.

21. The object tracking system as set forth in claim 11 which includes means for tracking the angular orientation of the object, said system comprising:

means for generating a series of three parimary reference signals;

first means for transforming said primary reference signals in accordance with a first transformation representing a presumed pointing angle;

means including three orthogonal radiators for radiating said transformed primary reference signals;

means including three orthogonal sensors for sensing the transformed primary reference signals, said sensing means being rigidly affixed to the object;

second means for transforming said sensed signals in accordance with a second transformation which is the inverse of a presumed set of orientation angles;

third means for transforming said sensed signals in accordance with a third transformation which is the inverse of said first transformation;

means for comparing the sensed signals so transformed with said primary reference signals and altering, if necessary, the presumed pointing and orientation angles.

22. An object tracking system for tracking the position and angular orientation of an object, said system comprising:

means for generating a series of three primary reference signals;

first means for transforming said primary reference signals in accordance with a first transformation representing a presumed pointing angle;

means including three orthogonal radiators for radiating said transformed primary reference signals;

means including three orthogonal sensors for sensing the transformed primary reference signals, said sensing means being rigidly affixed to the object;

second means for transforming said sensed signals in accordance with a second transformation which is the inverse of a presumed set of orientation angles;

third means for transforming said sensed signals in accordance With a third transformation which is the inverse of said first transformation;

means for comparing the sensed signals so transformed with said primary reference signals and altering, if necessary, the presumed pointing and orientation angles.