A Positioning System for On-orbit Assembly Robot Using Multiple Images
- Paper number
IAC-06-C2.P.1.02
- Author
Mr. Heihachiro Kamimura, Japan Aerospace Exploration Agency (JAXA), Japan
- Coauthor
Dr. Shin-ichiro Nishida, Japan Aerospace Exploration Agency (ISTA/JAXA), Japan
- Year
2006
- Abstract
On-orbit assembly is a technology for robotic construction of large structures on orbit. The robot is furnished with a bore sight camera at its end-effector and performs automatic positioning of the end-effector or a grasped object using positional information obtained by image measurement. A demonstration of automatic positioning using the image measurement was performed on ETS-VII(Engineering Test Satellite 7) which was launched by NASDA in 1997. However, the demonstration suffered from misdetection of the markers employed since the lighting conditions on orbit changed and the image measurement relied only on brightness of the marker which consisted of black and white colors. From the ETS-VII on-orbit demonstration it was established that color information is indispensable for the robot positioning system used on orbit, requiring the development of a method to measure a position and attitude of a target using a color marker. Initial work verified that the color image measurement system showed excellent performance under various lighting conditions. However, relative position and attitude were not determined when the color marker was partly in shadow. An enhanced system based on previous work capable of functioning under any lighting conditions on orbit has been developed using a novel method for image measurement. The method employs a color marker and LED(Light Emitting Diode) as artificial light source. A scene including the color marker is captured with LED turned on and off at several exposure levels. By performing pixel-by-pixel arithmetic operations among the captured images, an image with wide dynamic range was obtained, which yielded high extraction rate of the marker. The relative position and attitude were determined from the positional relationships between color discs of the marker. Employing the image measurement system described above, a laboratory model of the positioning system for on-orbit assembly robot has been constructed. The system has been tested under simulated on-orbit lighting environment and it has been shown that the positioning system can be operated under any lighting conditions.
- Abstract document
- Manuscript document
IAC-06-C2.P.1.02.pdf (🔒 authorized access only).
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