Microgravity, Mesh-Crawling Legged Robots

These relatively inexpensive robots may be used in search and rescue operations.

The design, fabrication, and microgravity flight-testing are part of a continuing development of palm-sized mobile robots that resemble spiders (except that they have six legs apiece, whereas a spider has eight legs). Denoted SpiderBots (see figure), they are prototypes of proposed product line of relatively inexpensive walking robots that could be deployed in large numbers to function cooperatively in construction, repair, exploration, search, and rescue activities in connection with exploration of outer space and remote planets.

Relative to other legged robots, including ones reported in previous NASA Tech Briefs articles, SpiderBots are smaller, less power-hungry, and more specialized. A SpiderBot at the present stage of development is designed primarily to demonstrate that it can crawl on a flexible rectangular mesh (in micro-gravity) and secondarily that it can walk on flat surfaces and assemble simple structures. Each leg includes two spring-compliant joints and a gripping actuator. The SpiderBot moves in a hard- coded set of tripod gaits involving alternating motions of legs variously anchored or not anchored to a mesh.

The robots were recently tested on a reduced gravity aircraft and were able to demonstrate crawling along the mesh during the microgravity portion of the parabolic flight. In one contemplated improvement, feedback from sensors on the feet would provide indications of success or the lack thereof in gripping a mesh, thereby contributing to robust, fault-tolerant operation.

This work was done by Alberto Behar, Neville Marzwell, Jaret Matthews, and Krandalyn Richardson of Caltech; Jonathan Wall and Michael Poole of Blue Sky Robotics; David Foor of Texas A&M University; and Damian Rogers of ISU (International Space University) for NASA’s Jet Propulsion Laboratory.
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