Distortion measurement and adjustment system and related method for its use

• US 6,293,027 B1
• Filed: 05/11/1999
• Issued: 09/25/2001
• Est. Priority Date: 05/11/1999
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Inc. (Northrop Grumman Corporation)
• Inventors: MacKay, Michael K., Flannery, John V., Elliott, Lee E.
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): DEJESUS, LYDIA M
• Application Number:
  US09/309,554
• Time in Patent Office: 868 Days
• Field of Search: 335/46, 332/86, 332/03, 332/031.8, 335/45, 335/47, 335/49, 335/51, 382/152, 382/153, 382/286, 382/287
• US Class Current: 33/546
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/16 for measuring the deformation in a solid, e.g. optical strain gauge
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves

Abstract

A technique for measuring distortion in a structure of interest, such as a spacecraft antenna reflector (18), and optionally compensating for the distortion. A first set of targets (22) on the structure (18) is scanned by an attitude transfer system (24) to measure the angular location and range of each target relative to a reference point on another structure (12) having a frame of reference. The orientation of the structure of interest is them determined from the measured locations of the targets. A second set of targets (60 or 82) on the structure of interest is scanned by a figure sensing module (26) located at a reference point on the structure itself. From measured angular locations and ranges of the second set of targets, any shape distortion in the structure of interest can be determined, and distortion may be corrected with the use of actuators (98).

Claims

1. A system for measuring distortion of a spacecraft structure of interest, the system comprising:

a first set of targets affixed to the spacecraft structure of interest;

a first target scanning module affixed to a reference point on a frame of reference independent of the spacecraft structure of interest, wherein the first target scanning module includes means for measuring a range and an angular position for each of the first set of targets;

means for computing the orientation of the spacecraft structure of interest relative to the frame of reference, from the measured ranges and angular positions of the first set of targets;

a second set of targets affixed to the spacecraft structure of interest;

a second scanning module affixed to a reference point on the spacecraft structure of interest, wherein the target scanning module includes means for measuring a range and an angular position for each of the second set of targets with respect to the reference point; and

means for computing shape distortion measurements pertaining to the spacecraft structure of interest from the measured ranges and angular positions of the second set of targets;

wherein the first scanning module includes a laser radar module, and a pair of scan mirrors controllable to direct a laser beam from the laser radar module toward successive targets in the first set of targets to obtain range and angular position data for each target in the first set of targets;

and wherein the second scanning module includes a light source, and a plurality of light-sensing cameras for detecting the angular positions of the second set of targets, from a direction of arrival of light emanating from the light source and reflected from the targets;

and wherein the position of each of the second set of targets is determined by triangulation based on receipt of light from each target by at least two of the light-sensing cameras.

2. A system as defined in claim 1, and further comprising:

a plurality of actuators controllable to compensate for shape distortion of the spacecraft structure of interest.

4. A method as defined in claim 1, and further comprising:

controlling a plurality of actuators to compensate for shape distortion of the spacecraft structure of interest.

3. A method for measuring distortion of a spacecraft structure of interest, the system comprising the steps of:

affixing a first set of targets to the spacecraft structure of interest;

scanning the first set of targets with a first target scanning module affixed to a reference point on a frame of reference independent of the spacecraft structure of interest, wherein the scanning step includes measuring a range and an angular position for each of the first set of targets;

computing the orientation of the spacecraft structure of interest relative to the frame of reference, from the measured ranges and angular positions of the first set of targets;

affixing a second set of targets to the spacecraft structure of interest;

scanning the second set of targets with a second scanning module affixed to a reference point on the spacecraft structure of interest, wherein the scanning step includes measuring a range and an angular position for each of the second set of targets with respect to the reference point; and

computing shape distortion measurements pertaining to the spacecraft structure of interest from the measured ranges and angular positions of the second set of targets;

wherein the step of scanning with the first scanning module includes actuating a laser radar module, and controlling a pair of scan mirrors to direct a laser beam from the laser radar module toward successive targets in the first set of targets;

and wherein the step of scanning with the second scanning module includes actuating a light source, and detecting in a plurality of light-sensing cameras the angular positions of the second set of targets, from a direction of arrival of light emanating from the light source and reflected from the targets;

and wherein the position of each of the second set of targets is determined by triangulation based on receipt of light from each target by at least two of the light-sensing cameras.