Dead reckoning optoelectronic intelligent docking system

• US 4,834,531 A
• Filed: 10/31/1985
• Issued: 05/30/1989
• Est. Priority Date: 10/31/1985
• Status: Expired due to Fees

• Current Assignee: Energy Optics, Inc. (American Millennium Corporation Incorporated)
• Original Assignee: Energy Optics, Inc. (American Millennium Corporation Incorporated)
• Inventors: Ward, Steven M.
• Primary Examiner(s): Buczinski, Stephen C.
• Assistant Examiner(s): Wallace, Linda J.
• Application Number:
  US06/793,292
• Time in Patent Office: 1,307 Days
• Field of Search: 356/1, 356/4, 356/5, 356/152, 244/161, 244/164, 244/171, 358/100, 358/103, 358/107, 358/108, 358/125
• US Class Current: 356/5.08
• CPC Class Codes: B64G 1/646 Docking or rendezvous systems refueling in space B64G1/4024
• CPC Class Codes: G01S 17/875 for determining attitude

Abstract

An intelligent, optoelectronic docking system for use in manned or unmanned spacecraft for automatically docking with a target spacecraft. The system is a multifaceted, active sensor using a controlling microprocessor to integrate the operation of independently triggerable laser sources for target illumination and optical receiver arrays for target detection. Returning signal waveforms are processed to sense the direction, range, and attitude of a target docking surface which may be equipped with passive optical aids to enhance the reflective signature. The docking system reconfigures its active sensor elements as the target range closes by sequentially employing three laser transceiver arrangements. As a result, the system effectively tracks a target from a range of several hundred meters down to a range of only a few centimeters. The system microprocessor operates on data received from each sensor arrangement to generate the information necessary to guide a host spacecraft safely through hard docking maneuvers. Wide field coverage is achieved without moving parts by electronic selection of independently directed laser beams.

Claims

1. An Optoelectronic system for docking a host object to a target object having a docking port comprising:

(a) first optical means secured on said host object and effective for both establishing a source of light radiation waveforms and receiving reflected light radiation;

(b) data processing means comprising a master central processing unit associated with said first optical means effective to analyze target information to produce guidance commands for maneuvering said host object to dock with said target object;

(c) second optical means secured on said target object and effective for returning incident light radiation in the direction of said source of light radiation, said second optical means comprising a pattern of three retroreflectors separated and arranged in an isosceles triangle about said docking port and a retroreflective image plate juxtaposed to said docking port, said image plate being defined by a flat surface having a centroid thereon and having a preselected perimetric shape subtending a contrasting crosshair pattern of nonretroreflective material effective to identify said centroid;

said first optical means comprising first, second and third optoelectronic sensors including first, second and third microcomputers, respectively, and first, second and third range processing circuits, respectively, connected therewith, said first and said second optoelectronic sensors being configured for illuminating at preselected target distances said retroreflectors and said image plate and detecting and processing light illumination waveforms returned from said retroreflectors, and said third optoelectronic sensor being configured for further illuminating within preselected target distances said image plate and detecting and processing light illumination waveforms returned therefrom, each of said optoelectronic sensors, associated microcomputers and range processing circuits being configured for determining within preselected target distances and independently of the other said optoelectronic sensors the position and range of said target object from said host object and transmitting information on said position and range to said master central processing unit;

said first optoelectronic sensor comprising a pulsed array laser radar subsystem;

said second optoelectronic sensor comprising a continuous array laser radar subsystem; and

said third optoelectronic sensor comprising a charge coupled device television laser radar subsystem.

2. A system according to claim 1, wherein said first optoelectronic sensor is adapted to operably scan the target over ranges from approximately one thousand meters to approximately thirty meters and is effective to illuminate said second optical means in order to detect the returned light and sense the angular direction and range of the target spacecraft and to transfer the information to said data processing means.

3. A system according to claim 2, wherein said first sensor is composed of a first and a second set of elements arranged in an array, each element of the first set comprising a pulsed laser transmitter and each element of the second set comprising a light radiation receiver being sensitive solely to a predetermined narrow band of light radiation.

4. A system according to claim 3, wherein said first set of elements are effective to propagate independent beams of laser light through a system of lenses to effect a cooperative beam pattern, wherein substantially one degree horizontal by twenty degrees vertical beam cross-sections of each element are effective to illuminate mutually exclusive but juxtaposed fields in space, and wherein the combination of all said beam cross-sections is arranged to cover the entire optically effective field of view of the first optical means.

5. A system according to claim 3, wherein said second set of elements are arranged to view space through a system of lenses to effect a cooperative pattern of viewing fields, wherein substantially twenty degree horizontal by one degree vertical field cross-sections of each element are effective to view mutually exclusive but juxtaposed fields in space, and wherein the combination of all fields is arranged to cover the entire optically effective field of the first optical means.

6. A system according to claim 3, wherein said first sensor further includes a single element light radiation receiver effective to view the entire optically effective field of view of the first optical means and to initially detect light radiation waveforms returned from said target object to thereby effect through said first microcomputer activation of said second set of elements;

a first range processing circuit effective to measure the round trip propagation time of the light emanating from said first optical means and returned from said second optical means; and

a first microcomputer effective to activate said transmitter elements, to monitor said receiver elements and to process data from the sensor elements to determine target direction and range.

7. A system according to claim 6, wherein each said transmitter comprises a combination of a laser pulse forming network and a pulsed laser diode, and wherein each transmitter is responsive to be selectively triggered by said first microcomputer to establish laser beam emanation for the duration of said pulse.

8. A system according to claim 6 wherein each said receiver is composed of a combination of light detector, signal amplifier and digital latching circuit with the binary state of each said latch effective to represent the presence or absence of a target return, and wherein the state of each said latch is selectively readable and clearable by the first microcomputer.

9. A system according to claim 6, wherein said single element receiver comprises a light detector and lense system arranged to sense the entire optically effective field of the first optical means, a signal amplifier and a digital latching circuit with the binary state of said latch effective to represent the presence or absence of a target return, and wherein the latch output state is coupled both to the first microcomputer and the first range processing circuit.

10. A system according to claim 6, wherein said first range processing circuit comprises a high frequency clock and a digital counter circuit effective to count clock cycles occurring between laser pulse transmission and laser pulse reception and to transfer said count data to said first microcomputer.

11. A system according to claim 10, wherein said first microcomputer is effective to selectively and sequentially trigger each transmitter element, execute a delay, selectively read and clear the binary state of each said receiver element and store said count data and data identifying the transmitter and receiver elements associated with each target return.

12. A system according to claim 1, wherein said second optoelectronic sensor is adapted to operably scan the target over ranges of approximately fifty meters to approximately three meters, to illuminate said retroreflectors of said second optical means, to detect the returned light radiation, to sense the direction and range of each of said retroreflectors and to transfer target information to said data processing means.

13. A system according to claim 12, wherein said second sensor is composed of a first and second set of elements arranged in an array, each element of the first set comprising a continuous laser transmitter having the amplitude of its output light modulated in the waveform of a sine function;

and each element of the second set comprising a light radiation receiver being sensitive solely to a narrow band of radiation of the wavelength of the transmitted light.

14. A system according to claim 13 wherein said first set of elements are effective to propogate independent beams of laser light through a system of lenses to effect a cooperative beam pattern, wherein substantially one degree horizontal by twenty degrees vertical beam cross-sections of each element are effective to illuminate mutually exclusive but juxtaposed fields in space, and wherein the combination of all said beam cross-sections is arranged to cover the entire optically effective field of view of the first optical means.

15. A system according to claim 13, wherein said second set of elements are arranged to view space through a system of lenses to effect a cooperative pattern of viewing fields, wherein substantially twenty degree horizontal by one degree vertical field cross-sections of each element are effective to view mutually exclusive but juxtaposed fields in space, and wherein the combination of all fields is arranged to cover the entire optically effective field of view of the first optical means.

16. A system according to claim 13, wherein said second range processing circuit comprises a heterodyne phase comparator effective to measure the propagation phase delay between the transmitted modulation wave and the received modulation wave and to transfer the phase delay data to said second microcomputer.

17. A system according to claim 1, wherein said third optoelectronic sensor is adapted to operably scan the target over ranges of approximately five meters to essentially zero, to illuminate said retroreflective image plate of the second optical means, to image the returned light radiation, to sense the direction, attitude and range of said retroreflective image plate and to transfer target information to said data processing means.

18. A system according to claim 17, wherein said third sensor comprises a continuously emitting diode laser array effective to illuminate said image plate;

an arrangement of multiple narrow beam diode lasers having the same wavelength of said illumination lasers effective to designate predetermined spots on the image plate of the target spacecraft;

a solid state imaging device having a field of view essentially equivalent to the optically effective field of view of said first optical means and a central optical axis and being sensitive solely to a narrow band of radiation of the wavelength of said illuminating lasers effective to generate two dimensional, time sequential image frames of said image plate scene;

video processing means effective to generate pre-selected data for identifying the position, size and shape of said image plate perimeter and crosshair pattern; and

a third microcomputer effective to process said data from said video processor to determine target spacecraft direction, range and attitude.

19. A system according to claim 18, wherein all elements of said diode laser array are effective to emit continously through an optical lens system to generate an illumination field equivalent to the optically effective field of view of the first optical means.

20. A system according to claim 19, wherein said narrow beam lasers are composed of three or more continuously emitting lasers arranged offset from and symmetrically about said imaging device with each said beam being directed through the field of view of the imaging device toward a common point on said central axis effective to designate spots on the image plate, wherein the position of each said spot in said image has a known relation to the range from said imaging device to the spot designated on the target.

21. A system according to claim 18, wherein said solid state imaging device comprises a charge coupled television camera having a two dimensional array of light sensitive pixel elements and a pinhole optical system effective to create time sequential frames of focussed and properly exposed images of said image plate and to output a digital representation of each image pixel of each said frame to said video processing means.

22. A system according to claim 18, wherein said video processing means comprises a pre-programmed digital system effective to identify the perimetric image of said image plate and said crosshair pattern, to output data relating the shape and orientation of said images, to output the relative image location of the image plate centroid and to output the relative image location of each of said bright spots with all of said outputs transferred to said third microcomputer.

23. A system according to claim 1, wherein said data processing means is effective to test the operational state of each of said sensors, to activate said first sensor to acquire said target spacecraft and to sequentially activate said second and third sensors, depending on target range, to track said target during the docking operation.