Digital image system for determining relative position and motion of in-flight vehicles

• US 5,493,392 A
• Filed: 05/23/1994
• Issued: 02/20/1996
• Est. Priority Date: 12/15/1992
• Status: Expired due to Term

• Current Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Original Assignee: Mcdonnell Douglas Corporation (The Boeing Co.)
• Inventors: Blackmon, James B., Stone, Kenneth W.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US08/247,922
• Time in Patent Office: 638 Days
• Field of Search: 250/206.1, 250/206.2, 356/139.03, 356/141.5, 348/135, 244/171
• US Class Current: 356/139.03
• CPC Class Codes: B64G 1/22 Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
• CPC Class Codes: B64G 1/36 using sensors, e.g. sun-sensors, horizon sensors

Abstract

The system includes a reflector assembly mounted on a first one of a pair of spacecraft. The reflector assembly includes a mirror around which are positioned a mirror and retroreflectors. A light source mounted on the second spacecraft illuminates the assembly the reflections from which are directed into a radiometer which is also mounted on the second spacecraft. The mirror has a known curvature, and the known curvature in conjunction with the retroreflectors allow calculation of the position and motion parameters of the first spacecraft relative to the second.

Claims

1. A system for determining relative position and relative motion of a plurality of in flight vehicles, comprising:

a light assembly mounted on a first vehicle of the plurality of vehicles, said light assembly including a plurality of light sources, said light assembly including a reflector, said plurality of light sources including a first set of light sources mounted at the periphery of said reflector and a second set of light sources mounted at the periphery of said reflector;

a light source mounted on a second vehicle of said plurality of vehicles for illuminating said reflector;

a light source control means electrically connected to said light source for activation and deactivation thereof;

a video-radiometer mounted on said second vehicle, said video-radiometer receiving light from said assembly, said video-radiometer discerning light emitted from each of said plurality of light sources, said video-radiometer having an electrical output which includes data relating to light received from said assembly;

a computer for receiving the electrical output including the data, said computer operatively connected to said light source control for allowing said video-radiometer to selectively receive light originating from extraneous sources and light originating from both said light assembly and from extraneous sources, said computer having a software program which utilizes the electrical output data to calculate position and motion parameters of the vehicles;

a display means electrically connected to said computer for receiving electrical output therefrom for displaying the position and motion parameters in order to facilitate link up or docking of the vehicles.

2. The system of claim 1 wherein said first set of light sources generally lie in a plane generally facing said video-radiometer in order to direct light thereto, said reflector lying at least partly outside the plane in order to allow calculation of pitch, yaw, bearing and motion parameters or the first vehicle relative to the second vehicle.

3. The system of claim 1 wherein said plurality of light sources emit light in radial directions to enable said video-radiometer to receive light from said plurality of light sources within a desired range of orientations of said light assembly relative to said video-radiometer.

4. The system of claim 1 wherein said computer includes software which converts the data from said video-radiometer into digital form and stores the digitized data in computer memory.

5. The system of claim 4 wherein said software utilizes the digitized data to calculate pitch, yaw, bearing and motion parameters of the first vehicle relative to the second vehicle based on trigonometric relationships between locations of said light sources, reflection points of said reflector and said video-radiometer where light from said light sources and said reflector are received.

6. The system of claim 1 wherein said computer includes an array processor controller for receiving image data relating to the light originating from said light assembly and from extraneous sources from said video-radiometer and for receiving image data relating to the light originating from extraneous sources from said video-radiometer and for subtracting the image data relating to the light originating from said light assembly and from extraneous sources from the image data relating to the light originating from extraneous sources in order to isolate the light from the light sources from extraneous light and thereby generally eliminate undesired light signals from the image data used to determine the relative position and motion of the vehicles.

7. The system of claim 1 wherein said video-radiometer includes video camera means constructed such that the received light falls within the dynamic range of the video camera means without use of any automatic gain control means for video camera means.

8. The system of claim 6 wherein the software program in response to operator input commands the computer to take an image without said light source illuminating said reflector and to take an image with said light source illuminating said reflector, the program acquires background light signal and source light signal from the data relating to light received from said assembly, the program subtracts the background signal from the source signal and utilizes the result to determine relative location of three reflector assembly signals, the program utilizes the relative location of the three reflector assembly signals to determine reflector assembly centroids and position window, the program utilizes the reflector assembly centroids and position window to calculate attitude, range and bearing parameters and rate of change of attitude, range and bearing parameters and the rate of change of attitude, range and bearing parameters to said display means.

9. A system for determining relative position and relative motion of a plurality of in-flight vehicles, comprising:

a reflector assembly mounted on a first vehicle of said plurality of vehicles, said reflector assembly including a reflector and a plurality of retroreflectors, said plurality of retroreflectors including a first set of retroreflectors mounted at the periphery of said reflector, each of said first set of retroreflectors being spaced from each other, and a second set of retroreflectors mounted at the periphery of said reflector, said second set of retroreflectors being in general alignment with one of said first set of retroreflectors, and one of said second set of retroreflectors being generally proximal to said one of said first set of retroreflectors relative to spacing between said each of said first set of retroreflectors, so that said plurality of retroreflectors are adapted for accurately determining relative roll position parameters and roll motion parameters of the vehicles;

a source of electromagnetic radiation mounted on a second vehicle of said plurality of vehicles, said source directing radiation at said assembly for the illumination thereof;

a video camera mounted on said second vehicle, said video camera receiving radiation reflected from said assembly and having an electrical output which includes data relating to radiation reflected from said assembly;

a computer for receiving the electrical output including the data, said computer having a software program which utilizes the electrical output data to calculate position and motion parameters of the vehicles; and

further including an array processor controller for receiving image data relating to the electromagnetic radiation originating from said reflector assembly and from extraneous sources from said video camera and image data relating to electromagnetic radiation originating from extraneous sources from said video camera and for subtracting the image data relating to the electromagnetic radiation originating from said reflector assembly and from the extraneous sources from the image data relating to the electromagnetic radiation originating from the extraneous sources in order to isolate the electromagnetic radiation from the electromagnetic radiation sources from electromagnetic radiation from extraneous sources and thereby generally eliminate undesired electromagnetic radiation signals from the image data used to determine the relative position and motion of the vehicles; and

a computer monitor electrically connected to said computer for displaying the position and motion parameters in order to facilitate link up or docking of the vehicles.

10. A system for determining relative position and relative motion of a plurality of in-flight vehicles, comprising:

a reflector assembly mounted on a first vehicle of said plurality of vehicles, said reflector assembly including a reflector and a plurality of retroreflectors, said plurality of retroreflectors including a first set of retroreflectors mounted at the periphery of said reflector, each of said first set of retroreflectors being spaced from each other, and a second set of retroreflectors mounted at the periphery of said reflector, said second set of retroreflectors being in general alignment with one of said first set of retroreflectors, and one of said second set of retroreflectors is radially adjacent to said one of said first set of retroreflectors so that said plurality of retroreflectors are adapted for accurately determining relative roll position parameters and roll motion parameters of the vehicles;

a source of electromagnetic radiation mounted on a second vehicle of said plurality of vehicles, said source directing radiation at said assembly for the illumination thereof;

a source control means electrically connected to said source of electromagnetic radiation for activation and deactivation thereof and electrically connected to said computer for computer operation of said source control means for controlling radiation emission from said source in order to allow said video camera to selectively receive source radiation reflected from said assembly and to selectively receive extraneous radiation reflected from said assembly in order to isolate the reflected source radiation from reflected extraneous radiation;

a video camera mounted on said second vehicle, said video camera receiving radiation reflected from said assembly and having an electrical output which includes data relating to radiation reflected from said assembly;

a computer for receiving the electrical output including the data, said computer having a software program which utilizes the electrical output data to calculate position and motion parameters of the vehicles; and

a computer monitor electrically connected to said computer for displaying the position and motion parameters in order to facilitate link up or docking of the vehicles.