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Barbara Schwartz March 3, 1994

RELEASE: 94-021


Demonstrating that science is catching up to science fiction, a robotic arm using its own vision-guided intelligent system grasped a freely moving ball aboard NASA's KC-135 reduced gravity aircraft Feb. 10, 1994. The Extravehicular Activity Helper/Retriever robotic system tests are the first to prove that autonomous robots can use computer vision to guide robotic manipulation and grasp of moving objects in microgravity.

"The significance of this successful achievement is that it is a major step towards intelligent robots that can perceive and respond to unstructured environments at the pace imposed by their environments while applying knowledge and skills to accomplish stated goals," said Jon Erickson, chief scientist of the Automation and Robotics Division.

Vision-guided grasping of moving objects is a basic skill both in space helper and retrieval tasks and in accomplishing the transition from flying to attach to a spacecraft. This latter is the case since the spacecraft is moving relative to the robot even if the robot is station keeping with the spacecraft.

A team of JSC engineers and support service contractors from Lockheed Engineering and Sciences Co., Mitre Corp., and GHG Corp., lead by project manager Keith Grimm of the Robotic Intelligence Section, has been working on the system for about a year and a half at a cost of less than $1 million. Grimm said it was worth the "roller coaster" ride on the KC-135 to obtain the better-than-anticipated results.

The robot arm and dextrous hand with its three active and two passive fingers caught the freely-moving four-inch ball seven times in a number of tries during the brief periods of microgravity induced on the aircraft.


The EVA Helper/Retriever's vision system is a commercial real-time stereo camera pair on a pan and tilt unit and a computer processor. The system continuously determines an object's position and velocity and feeds the measurements to the controls that direct the movements of the 7-degrees-of-freedom arm and its hand. The hand has a force-limited adaptive grasp that is able to catch the object without damaging or dropping it.

The commercial manipulator equipment was adapted to increase its speed. The hand was custom designed and built at JSC. Almost all of the computer software for autonomous operation of the system was designed, implemented, and tested at JSC. Grimm hopes that the proof-of-concept leads to continued development of more complex systems and testing on a future shuttle flight. An "intelligent" robot would be able to assist astronauts with many tasks on the space station.

"The robotics that we are working on are in the spirit of human and robot teams working together. We believe that automation and robotics enable human space missions and space exploration. This is not robots in place of humans. This is robots augmenting humans, making it easier for them to do the things they need to do," Erickson said.

Erickson added that this work is a good example of dual-use technology. The robotics systems being developed for use in space can easily be adapted by industry to benefit the public.



Video of selected tests may be seen through Internet with World Wide Web (WWW). To access, open the URL: or FTP to

Still photographs S94-27845, S94-27846, S94-27884 and S94-27894 are available through the Still Photograph Library at 713-483-4231.


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