Electro-optical imaging array and camera system with pitch rate image motion compensation which can be used in an airplane in a dive bomb maneuver

• US 5,844,602 A
• Filed: 12/03/1996
• Issued: 12/01/1998
• Est. Priority Date: 05/07/1996
• Status: Expired due to Term

• Current Assignee: Goodrich Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Recon/Optical, Inc. (Bourns Incorporated)
• Inventors: Hines, George, Bennett, Russell A., Lareau, Andre G., Beran, Steven R., Bown, Michael
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): VINCENT, DAVID ROBERT
• Application Number:
  US08/762,385
• Time in Patent Office: 728 Days
• Field of Search: 348/295, 348/208, 348/145, 348/146, 348/144, 348/147, 348/148
• US Class Current: 348/144
• CPC Class Codes: G01C 11/02 Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/684 performed by controlling the image sensor readout, e.g. by controlling the integration time
• CPC Class Codes: H04N 23/6842 by controlling the scanning position, e.g. windowing
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 25/53 Control of the integration time
• CPC Class Codes: H04N 3/155 Control of the image-sensor operation, e.g. image processing within the image-sensor

Abstract

A camera system is described which is based on an electro-optical imaging array performs electronic image motion compensation without moving parts during a reconnaissance maneuver in which the aircraft is experiencing a non-zero rate of change in the pitch axis, such as in a dive bomb maneuver when the pilot is pulling out of the dive. The camera system has a camera control computer that calculates a pixel information transfer rate for the array based on parameters supplied by the aircraft'"'"'s navigation system and pre-mission known parameters, including the aircraft'"'"'s velocity, height above ground, attach angle, pitch angle, and rate of change in pitch during the period in which the array is taking successive exposures of the scene. The camera control computer supplies information to the drive and control electronics that control the transfer of pixel information in the array. In a preferred embodiment, the array is exposed to the scene of interest in a series of rapid exposure intervals and generates a frame of imagery during each exposure. By virtue of the electronic image motion compensation, each frame of imagery is a high resolution image of the scene of interest, far surpassing images created by an electro-optical array if the present image motion compensation technique were not performed.

Claims

1. An electro-optical camera system with electronic image motion compensation, said camera system suitable for installation in a reconnaissance aircraft having a navigation system determining the velocity, height, and pitch attitude of said aircraft during a reconnaissance maneuver, comprising, in combination,

an array of photosensitive cells arranged in rows and columns, said cells storing pixel information representing a scene of interest, said array of cells having means for transferring pixel information stored in said cells from one row to an adjacent row;

a camera control computer responsive to said navigation system for computing a pixel information transfer rate for said array of cells based on said velocity, height, and pitch attitude;

said camera control computer further determining a pixel information transfer rate for said array of cells during a condition in which said aircraft is experiencing a non-zero rate of change of the pitch of said aircraft and said array is oriented in a forward oblique orientation relative to said aircraft;

said camera control computer and control circuitry adjusting the charge transfer rate of said array to substantially match the rate of image motion of said terrain of interest during successive exposures of said array to said terrain of interest during the period in which said aircraft is experiencing a non-zero rate of change in the pitch of said aircraft;

said array can generate a series of images of said terrain of interest and wherein the resolution of said images is preserved

and wherein said camera control computer calculates said pixel information transfer rate according to the following relationship;

##EQU4## where F is the focal length of a lens placed in the optical path between said array and the scene of interest;

V is the velocity of said aircraft;

H is the altitude of said aircraft above the earth;

Px is a measure of the size of an individual cell in said array;

α

is a measure of aircraft pitch angle in degrees;

φ

is a measure of a depression angle of said lens relative to said aircraft;

θ

i is a field angle associated with a point in said array chosen for synchronization of image motion compensation; and

ω

is a measure of the rate of change of the pitch orientation of said aircraft relative to an inertial frame of reference.

2. A method of imaging a scene of interest by an aerial reconnaissance camera system installed in an aircraft, said aerial reconnaissance camera system comprising an array of photosensitive cells arranged in rows and columns and a camera control computer for controlling the operation of said array, said aircraft having a navigation system for providing information as to the velocity, height, and pitch attitude of said aircraft relative to the earth, comprising the steps of:

supplying from said navigation system the current velocity, height and pitch attitude of said aircraft;

determining the current rate of change of the pitch of said aircraft;

calculating a pixel information transfer rate for said array of cells from said current velocity, height and pitch attitude and said current rate of change of the pitch of said aircraft that is substantially equal to the rate of motion of an image of said scene of interest in the focal plane of said array; and

exposing said array of cells to radiation from said scene of interest and simultaneously transferring pixel information in said array of cells row by row in accordance with said calculated pixel information transfer rate;

resolution of an image generated by said array of cells is preserved

and wherein said pixel information transfer rate is calculated according to the following relation;

##EQU5## where F is the focal length of a lens placed in an optical path between said array and said scene of interest;

V is the velocity of the aircraft;

H is the altitude of the aircraft above the earth;

Px is a measure of the size of a cell in said array;

α

is a measure of a pitch angle of said aircraft in degrees;

φ

is a measure of a depression angle of said lens relative to said aircraft;

θ

is a field angle associated with a point in said array chosen for synchronization of image motion compensation; and

ω

is a measure of the rate of change of pitch of said aircraft relative to an inertial frame of reference.