When NASA Langley Research Center hired Honeybee Robotics
Spacecraft Mechanisms Corp. to develop a totally mechanical tool changer, the
requirements were anything but simple. For starters, the tool changer was to be
designed for the end of what Langley's Lunar Surface Manipulation System (LSMS)
team describes as a robot that could unload landers. After the landers are
unloaded, the tool changer must also be able to mate with tools to perform
various science experiments.
In essence, this robot could be likened to a crane but with more
dexterity. And on top of all the other requirements, this dexterous crane had
to be able to work remotely so that it could be used on an unmanned mission
without human interaction.
Design Scope
To start, NASA gave Honeybee a project envelope - a
footprint to stay within - that included all the requirements for load ratings
and misalignment allowances.
Lee Carlson, a systems engineer who was part of the Honeybee
team, describes the project from a design perspective: "The crane might be
sitting on the lander deck or on the lunar surface and then be driven quite a
distance away from the tool to be mated to. This required designing for large
misalignment allowances - and that was our first design challenge. We had to
design the device so that the end of the crane and target tool could be
misaligned by as much as a couple inches in any direction with up to 20 degrees
angular misalignment when attempting a mate."
Other requirements included having the tool changer be capable of carrying about 1,000 lb. And since this
was a lunar project, it has to be tolerant to moon dust. These two design
criteria required special seals to protect large roller bearings.
The original assignment called
for "dumb" tools requiring no power. The crane would do all the work. Tools
would range from a forklift attachment, a shovel or scoop for acquiring surface
samples or digging, or even a bucket for lifting human passengers.
The Scope Expands
Then NASA decided it wanted the capability of attaching
an electronic or electromechanical tool to the end of the crane. Now the tool
changer would also have to provide an electrical connection. Solving this
problem fell to Carlson.
"The contract was expanded to add an electrical connector to the
existing mechanical connector, which meant that we had to have a power source
on the crane itself. However, space to accommodate an electrical connector had
not been accounted for because it was not a part of the original contract and
the budget did not allow for starting from scratch.
Carlson had to work within the
constraints of the current design because NASA did not want a redesign of the
whole tool changer. They just wanted to add an electrical connector to it
without increasing the current envelope. With only about 2½ x 4 inch of free
space to incorporate the male side of the new autonomous connector (the
connector has to mate itself to a female connector mounted on the tool), the
task before Carlson was not an easy one.
To compensate for the new
requirement, Honeybee designed both the male and female sides of the connector.
The female side had to be inexpensive and easy to create because each tool
would have to have its own female connector versus a single male connector
attached to the crane.
The male connector has all the
moving parts. It is cylindrical and populated with 11 1/16-inch diameter
aluminum pins plated with gold over nickel configured in a standard MIL/Spec
pattern. The connector rides on compact slides - miniature guides made by NB
Corp. The top faces of the two glides face each other and Honeybee's components
reside in between the two glides supporting the connector. This configuration
reduces the moment loads on the slides.
"We use a total of six slides
within the space - three on each side," says Carlson. "The slides ride on each
other in the manner of drawer slides stacked to extend the distance they can
open a drawer. Our configuration achieves an extension of the movement equal,
approximately, to the length of three slides. So instead of a half-inch stroke,
we could get an inch-and-a-half stroke within a very, very small footprint. Low
mass, low load and very low profile were all required for this application."
Larry Hansen is general sales manager
- director at NB Corp. of America
Rob, even if the moon program is cancelled, I can think of all kinds of cool industrial applications for an end-of-arm tool changer of this type. So I don't think I would quite say that this technology has "nowhere to go."
I have designed a number of robot arms, some featured in Design News. It is relatively easy to design an arm, but much more challenging to include a path for the routing and preservation of cables. Good luck adding them after the fact. The moon also has some temperature extremes depending on wich side of the moon the crane is on.
Gravity is 1/6 that of earth so there will be some advantage there...
I agree completely Dave. I'm just disappointed we won't get to see this type of equipment deployed on the moon. I know it's not practical, and I know we're broke, but I still have a soft spot for the idea of heading to the moon and beyond. My kids didn't get the see the excitement of the space program of the 60s and 70s. The shuttle program didn't quite carry the same level of human ambition.
I was born after the end of the Apollo program, but when I was a kid, I read every book I could about manned spaceflight (especially Apollo). It was a big inspiration to me, and probably a major influence on my decision to become an engineer. The U.S. retreat from manned spaceflight after the Challenger explosion, while it may have made sense from a safety perspective, was very disappointing to kids like me, who wanted to see the space program continue to push forward.
The most exciting missions in recent years were the Mars landers Spirit and Opportunity. Hopefully, these missions helped to get some kids excited not only about space exploration, but also robotics, sensors, etc.
My company, BRP, is working on developing prototype Moon and Mars rovers for the Canadian Space Agency. Since Canada does not have its own launch vehicles or facilities, I'm not quite sure what's being planned in terms of potential missions, but it's encouraging to see this kind of work. (If Design News is interested in doing a stort on this, I would be glad to get you in touch with the appropriate people).
The space program of the 60s and 70s was a magical time where it seems we were unlimited in our potential for space travel. It is a shame that we have not been able to duplicate that enthusiasm in these recent decades. On another note - I could really relate to the additional requirement that was added after the original design was contracted, with no additional budget to implement it. How many times has that happened to any engineer that has been in industry awhile?! Looks like they did a great job coming up with a solution.
Yes, the 60s and 70s were a magic time for space achievement, Nancy. I think that will come around again, perhaps prompted by China's entry into space exploration. Those magic days of the 60s and 70s were prompted by Soviet exploration. We just need new prompting.
I find it ironic that the initial impetus for the space program was in response to Sputnik and the Cold War, and now the revival of the space program may be a reality due to Chinese efforts now becoming a campaign issue...our scientific endeavors are politically motivated, but I guess that is what it takes to get government funding.
Yes, it is ironic, Nancy. I guess the cliche is true, necessity is the mother of invention. Right now it's not necessary for the U.S. to explore space. We may see it as necessary if another country gets intrested. Although some still believe Frank Zappa is the mother of invention.
He certainly was in the 60s Rob LOL I almost fell over in Barnes and Nobles yesterday. I was looking through books on marketing and stuck in between Guerilla Marketing in 30 Days and the Ultimate Guide to Facebook advertising was Marketing Lessons from the Grateful Dead...No kidding! Maybe we should try some of their techniques to create a market for a viable space program!
That's funny about the Dead, Nancy. But it makes sense. Before Jerry died, the Dead ran a very prosperous organization. For years, they were the highest grossing tour act. They knew how to build a community and sustain it for years.
Hmmmm...maybe I bought the wrong book. Think I'll hop on Amazon and take another look...it's all about community building nowadays regardless of your field! Maybe we can apply it here and convince a race horse trainer to name a promising colt, "Back to the Moon." Just think - "Back to the Moon" triple crown winner named official mascot for U.S. space program! As my son would say, I must be butter 'cause I'm on a roll LOL
That's a great line from your son, Nancy. And I like the idea of a horse named Back to the Moon.
As for the Dead, they had a huge following that moved with the band from city to city. And the band ran its finances like a business. There were roughly 250 employees. The Dead was also way ahead on the breakdown of the recording industry. They encouraged their fans to tape concerts and share the recordings. They figured it would deepen the fans relationship to the band and encourage live ticket sales.
That's really interesting, Rob - they really were visionary in their marketing approach. They could see long term and were willing to do so. It's all about relationship. No matter how much technology serves to dehumanize communication - we still crave relationship and always will. I bet their Likes would have been off the charts if Facebook was around back then. I am buying the book! Now all we need to do is transfer their ideas to the space program.
I was born after the moon missions also. I was so excited to hear that president Bush announce that we are going back then very disappointed when it was cancelled. I'm just hoping that Space X and other companies will be able to reduce the cost of the man missions so we can go back to the moon and beyond. I know it's a long shot but there is still hope.
In spite of its immediate deployment issue, I was very much intrigued by the design ingenuity of the Honeybee Robotics team in the use of composite materials to improve the mass to strength ratio and introduction of variable degrees of rotation in allowing this versatile machine to move. Hope we find another opportunity to use such concepts in future.
Lunar dust is pretty wicked stuff. It's abrasive, much like ground glass and very, very fine, so it easily finds its way through seals. Static electricity can also cause lunar dust to be attracted onto and into equipment. It's believed that some lunar equipment has been damaged in the past by lunar dust clinging to the equipment's reflective surfaces. Once covered in dust, the surface is no longer reflective and the equipment begins to overheat.
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