ATTITUDE SENSOR, AND SYSTEM FOR CONTROLLING ATTITUDE OF AN OBJECT

• US 3,658,427 A
• Filed: 11/28/1969
• Issued: 04/25/1972
• Est. Priority Date: 11/28/1969
• Status: Expired due to Term

• Current Assignee: Anthony B. Decou
• Original Assignee: Anthony B. Decou
• Inventors: DeCou, Anthony B.
• Primary Examiner(s): Bennett, Jr., Rodney D.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US04/880,617
• Time in Patent Office: 879 Days
• Field of Search: 356/1,141,152,110,106 250/203,199 343/9 244/3.16
• US Class Current: 356/139.03
• CPC Class Codes: B64G 1/244 Spacecraft control systems
• CPC Class Codes: B64G 1/36 using sensors, e.g. sun-sensors, horizon sensors
• CPC Class Codes: B64G 1/363 using sun sensors
• CPC Class Codes: B64G 3/00 Observing or tracking cosmonautic vehicles
• CPC Class Codes: G01C 21/025 with the use of startrackers
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49

Abstract

Apparatus for sensing attitude of an object with respect to the direction of incident coherent light, by sensing the relative phase of such light at two spaced-apart points which are located adjacent the object and which move with the object. The relative phase of the light is sensed by producing interference fringes with the light picked-up at the two spaced-apart points. The position of the fringes on a surface is an indication of the relative phase at the two spaced-apart points and thus of the attitude of the object. For automatic control, the motion of the fringes is automatically sensed by photoelectric means to produce an electrical signal for controlling the attitude of the object in a manner to oppose departures from the desired attitude.

Claims

1. Apparatus for sensing the angular orientation of an object with respect to a source of light, comprising:

means secured to said object for receiving coherent light from a common source at two spaced-apart positions;

means for comparing the phases of said light at said positions to produce indications of changes in the relative phase thereof;

said means for comparing phases comprising means for superimposing said light from said two spaced-apart positions to produce optical fringes indicative of said relative phase; and

photosensitive means impinged by said superimposed light for sensing changes in the positions of said fringes and for producing electrical signals representative thereof.

2. Apparatus in accordance with claim 1, wherein said photosensitive means comprises a plurality of adjacent electrically separate photosensitive elements and corresponding separate electrical connections to said elements.

3. Apparatus in accordance with claim 2, comprising computer means supplied with said electrical signals for performing computation functions to produce an output signal representative of said relative phase.

4. Apparatus in accordance with claim 1, in which said phase-comparing means comprises means for directing light from said two positions at different angles onto a common surface.

5. Apparatus in accordance with claim 1 comprising a laser light source, said coherent light comprising light from said source.

6. Apparatus for sensing the angular orientation of an object with respect to a source of light, comprising:

means secured to said object for receiving coherent light at two spaced-apart positions;

means for comparing the phases of said light at said positions to produce indications of changes in the relative phase thereof;

in which said receiving means are controllably orientable toward a distant luminous astronomical body to receive light therefrom, said apparatus comprising optical filter means for limiting light applied to said phase-comparing means to a narrow band of wavelengths such that light from said astronomical body is temporally coherent at said receiving means.

7. The method of sensing the angular orientation of an object with respect to a luminous body comprising filtering light received from said body, at two adjacent locations fixed with respect to said body, to a degree sufficient to produce substantial temporal coherence of said light at said two locations, and comparing the phases of said filtered light.

8. The method of determining the angular orientation of an object, comprising orienting said object to receive light at two locations thereon from a common source of coherent light and measuring the relative phase of said light at said two locations, and orienting said object so that light is received at said two locations from a luminous astronomical body.

9. Apparatus for controlling the angular orientation of an object, comprising:

means secured to said object for receiving coherent light from a reference source at two spaced locations fixed with respect to sAid object;

means for comparing the phases of said light at said two locations to produce signals representative of the relative phase of said light at said two locations; and

control means responsive to said signals to rotate said object in a direction to oppose changes in said relative phase;

in which said phase-comparing means comprises means for directing coherent light from said two locations onto a common surface region from different angles to produce optical fringes having positions representative of said relative phase, and photosensitive means responsive to said fringes to produce electrical signals representative of said relative phase, said control means comprising computer means supplied with said signals for producing a control signal indicative of the magnitude and polarity of departure of said relative phase from a reference value, and torquing means supplied with said control signal to rotate said object.