Geometrical instruments – Gauge – Comparison with a standard
Reexamination Certificate
1999-05-11
2001-09-25
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Gauge
Comparison with a standard
C033S547000, C033S286000
Reexamination Certificate
active
06293027
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to distortion measurement systems and, more particularly, to distortion measurement of spacecraft structures in applications that require extremely precise dimensional relationships. Many spacecraft have a significant problem in that their on-orbit shape may be distorted from an ideal desired shape. The differences may be due to thermal distortion, manufacturing tolerances, alignment tolerances, deployment tolerances, or other sources. Distortions in shape can cause performance degradation in spacecraft applications that depend on precise dimensional relationships. For example, the spacing of antenna elements or other sensors may be critical to the results obtained in a particular application. In most cases, this degradation in performance could be corrected if the distortions could be accurately measured. If accurate measurements could be obtained, the effects of distortion could be removed either by calibration, i.e., by making adjustments to resultant data on the spacecraft or on the ground, or by shape adjustment using on-board actuators. Prior to the present invention, spacecraft structures for which distortion is a known problem have been designed to be as near to distortion-free as possible. In most cases, this approach imposes a penalty of increased weight and cost.
Although the problem and its solutions are described in this specification in relation to a spacecraft application, it will be readily understood that distortion measurement problems may also arise in other contexts. It will appreciated from the foregoing that there is a need for a system that can measure distortion, particularly of spacecraft structures, and make appropriate adjustments. The current invention proposes a unique way for measuring spacecraft distortions and making the appropriate adjustments to improve alignment and/or structural distortions. This unique method allows the measurements to be made rapidly enough to measure and correct dynamic distortions and also allows the more efficient use of limited illumination capability.
SUMMARY OF THE INVENTION
The present invention pertains to a system and a corresponding method for its use, for measuring distortion of a structure of interest, such as a spacecraft in orbit, and for making appropriate adjustments to compensate for the distortion. Briefly, and in general terms, the system of the invention comprises a plurality of targets affixed to the structure of interest; at least one target scanning module affixed to a reference point with respect to the structure of interest, wherein the target scanning module includes means for measuring a range and an angular position for each of the targets; and means for computing distortion measurements pertaining to the structure of interest from the measured ranges and angular positions of the targets.
More specifically, the system includes a first target scanning module for measuring the orientation of the structure of interest relative to a frame of reference, and a second target scanning module for measuring the shape of the structure of interest. Optionally, the system further comprises a plurality of actuators controllable to compensate for measured distortions in the structure of interest.
The invention may also be defined as 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. The system may further comprise a plurality of actuators controllable to compensate for shape distortion of the spacecraft structure of interest.
In the disclosed embodiment of the invention, 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 members of the first set of targets. 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. 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. Alternatively, the second scanning module includes a laser ranging module providing a laser beam; means for scanning the laser beam across members of the second set of targets; and means for determining the positions of the members of the second set from measured ranges and angular locations of the targets.
The invention may also be defined in terms of a method for measuring distortion of a structure of interest, the method comprising the steps of affixing a plurality of targets to the structure of interest; scanning the targets with at least one target scanning module affixed to a reference point with respect to the structure of interest; measuring a range and an angular position for each of the targets; and computing distortion measurements pertaining to the structure of interest from the measured ranges and angular positions of the targets. More specifically, the scanning step includes scanning with a first target scanning module for measuring the orientation of the structure of interest relative to a frame of reference, and scanning with a second target scanning module for measuring the shape of the structure of interest. The method may also include controlling a plurality of actuators to compensate for measured distortions in the structure of interest.
As applied to spacecraft structures, the method of the invention comprises the steps of affixing a first set of targets to a 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. The method may also include controlling a plurality of actuators to compensate for shape distortion of the spacecraft structure of interest.
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. The step of scan
Elliott Lee E.
Flannery John V.
MacKay Michael K.
DeJesus Lydia M.
Gutierrez Diego
Keller Robert W.
TRW Inc.
LandOfFree
Distortion measurement and adjustment system and related... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Distortion measurement and adjustment system and related..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Distortion measurement and adjustment system and related... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2507669