January 25, 2014

Information for this posting is derived from the following sources:  Design News Daily: Ms. Ann Thryft and NASA-Ames Research Center.

It is no secret that missions sponsored by the United States using manned space craft have been eliminated from the federal budget.  After Apollo the “wise men” in our federal government decided there was no need to continue the effort. “We can always hitch a ride with the Russians”.   Hitching a ride has turned out to be extremely expensive, not to mention giving up our hard-won position of technological dominance in that field of endeavor.   One day we will wake up to discover the Chinese have landed a man on the Moon and have declared that body to be their real estate.   Abdication of our position in manned space does not mean NASA is not working and shifting their focus to other areas of research.  One absolutely fascinating area is described as TENSEGRITY.  Tensegrity uses Super Ball Bots, which look like spheres, but constructed quite differently. They’re being designed to go to Jupiter’s moon Titan.

Like the robotic droplets, Super Balls Bots’ main mission is gathering scientific data. The larger version, with a mass of 75 kg, will carry all three scientific instrumentation packages: Atmospheric and Meteorology, Analytical Chemistry, and Imaging. The smaller version, with a mass of 40 kg, will carry only the Atmospheric and Meteorology and Imaging packages. These are described in some detail in a presentation given last spring by the main researchers at NASA Ames Research Center.  What’s different about them is they’re constructed according to the principles of “tensegrity,” a term coined by Buckminster Fuller, known for popularizing the geodesic dome. The term combines “tension” and “structural integrity.” It works on principles of how force is distributed through a structure that are different from those of rigid structures.  Tensegrity’s global distribution of force gives maximum strength to a structure without adding a lot of weight, and minimizes the number of points of local weakness. Many natural forms are constructed this way, such as microtubes and microfilaments within cells. The human skeleton is an example of biotensegrity.

A description of the missions is given by NASA as follows:

Small, light-weight and low-cost missions will become increasingly important to NASA’s exploration goals. Ideally teams of small, collapsible robots, weighing only a few kilograms apiece, will be conveniently packed during launch and would reliably separate and unpack at their destination. Such robots will allow rapid, reliable in-situ exploration of hazardous destination such as Titan, where imprecise terrain knowledge and unstable precipitation cycles make single-robot exploration problematic. Unfortunately landing lightweight conventional robots is difficult with current technology. Current robot designs are delicate, requiring a complex combination of devices such as parachutes, retrorockets and impact balloons to minimize impact forces and to place a robot in a proper orientation. Instead, we are developing a radically different robot based on a “tensegrity” built purely upon tensile and compression elements. Such robots can be both a landing and a mobility platform allowing for a dramatically simpler mission profile and reduced costs. These multi-purpose robots can be light-weight, absorb strong impacts, are redundant against single-point failures, can recover from different landing orientations and are easy to collapse and uncollapse. These properties allow for unique mission profiles that can be carried out with low cost and high reliability. We believe tensegrity robot technology can play a critical role in future planetary exploration.

The phases for this effort are as follows:

Achieving Objective 1:
Our Phase II study will build a prototype tensegrity landing and mobility platform in hardware. The primary focus will be on demonstrating mobility, and formal evaluation of payload protection in hardware.

Achieving Objective 2:
n Phase II we will attempt to show that control is robust and practical. In Phase II we propose to evaluate closed-loop control methods that allow the tensegrity to sense and navigate to a desired location. In addition we will evaluate control for larger tensegrity designs, robustness in difficult environments, and extend control to low-gravity environments.

Achieving Objective 3:
Tensegrity robots have the potential to revolutionize many different mission destinations. We will extend our Phase I trade-study for a Titan mission to include the critically important thermal and energy analysis, large-scale tensegrities that are capable of offering more payload protection and improved mobility, as well as low-gravity landing and mobility analysis unique to small asteroids.

Significance to NIAC:
Completing Objective 1 will give insights into costs, performance, risks, development time and technologies that will be needed to make a viable platform. In addition it will dramatically improve confidence that tensegrity structures are a good platform for landing and mobility. Completing Objective 2 will validate that a tensegrity robot is a viable mobility platform that could dramatically reduce cost and increase reliability of missions that need mobility. Completing Objective 3 will allow us to evaluate the costs, risks and benefits for using tensegrities for a wide range of missions.

Significance to NASA in General:
Success in in this study could dramatically reduce costs and increase reliability for all NASA missions that use robotics, or need a landing platform.

The NASA program undertaken by Ames is fascinating.  Let’s take a look.  The mission itself is given with the following two slides:



The following slide indicates how the ball-bots are deployed.





You can see from the JPG above the structure is composed of interlinking rods and tubes capable of supporting scientific instrumentations while surviving a “hard” landing on a rigid surface.   The basic concepts are given below.



Three structural types were considered.



To me, the most remarkable feature is how the bots are collapsed for storage and travel.


An actual device is as follows:



There were multiple schools involved with the research and development of these devices.  In the NIAC project report, there are twenty-six (26 ) students involved; five (5) schools “state-side” and three (3) schools from various parts of the world.  Marvelous collaboration on this one project WITH published papers spreading the information.  In my opinion, this is the way we “kick the can down the road”.  I definitely applaud the work of NASA and the institutions involved with this project.

I definitely welcome your comments.


2 Responses to “TENSEGRITY”

  1. Its like you read my mind! You appear to know a lot about this, like you
    wrote the book in it or something. I think that you can do with a few pics to
    drive the message home a little bit, but other than that, this
    is fantastic blog. An excellent read. I will definitely be back.


    • cielotech Says:

      Thank you so much ionic. Many thanks for the very kind comments. Tensegrity is a bit “off the wall” but fun to write about. There are “tons” of garbage on the “net” so I’m just truing to raise the bar. Take care.


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