Actuator-Controlled Platform Sees Duty in Space and Factory
Kyle Maxey posted on October 26, 2015 |
Sometime in the near future, a packet of data will arrive and be rendered on the screen of a NASA technician manning a station at mission control.

As the packet resolves itself on the monitor, its dry arrangement of characters and digits will signal a planetary first. In the message, a satellite will confirm that it’s been successfully refueled by a robotic craft without human assistance.

Nearly five years in the works, NASA’s Robotic Refueling Mission (RRM) could be a seminal moment for the satellite industry. But without the help of a robot right here on Earth, NASA’s mission may have never left the launch pad.


Simulating Physics for NASA

Mike Fortier and his team at Mikrolar have been developing robotics solutions since the 1980s. During that time, Fortier has developed a number of technologies, but his strongest asset has been his ability to make high-resolution, high-precision hexapods that transform the way people develop technology.

A hexapod is a parallel robotic system that uses paired actuators to move a plate (and, more importantly, anything mounted to that plate) with six degrees of freedom.

Though hexapods (also known as Stewart platforms) have a variety of uses, they’ve most often been the key component in providing flight simulators with their motion.   

Given the nature of hexapods and Mikrolar’s expertise in engineering them, it was a no-brainer for NASA to reach out to Fortier and his team when they needed help developing testing equipment for the robot refueler.

“When satellites come to the end of their life, companies have to jettison them out of their orbit and launch another one,“ said Fortier. “That’s an expensive proposition.”

To try to extend satellite life, NASA engineers have been developing a robotic refueling system that can be launched from the International Space Station (ISS) with the specific mission to refuel a dying satellite without human intervention. Not a simple proposition.

Part of the trouble facing NASA when building the RRM was that they had no good way to test their prototypes in a zero-g environment.

That the RRM’s bot would have to strip a satellite of its heat sheathing, couple with it and then pump liquid fuel into its empty tank made for a lot of potential errors. In fact, even the slightest misstep by the RRM could nudge a satellite enough to push away from the refueling craft or potentially destabilize its orbit.

To give NASA its best chance of nailing the RRM’s design, Mikrolar’s engineers were put to work building a robot that “acted like the lack of gravity in space,” Fortier said.

To achieve this effect, Fortier’s team engineered a six-access robotic system that could rotate each of the six trucks located on a precise ring. On each of these trucks is located a rigid strut and two joints, all attached to the moving platform which holds the satellite.

In conjunction with a force feedback device, this combination of six struts and moving trucks allows Mikrolar to use a mathematical equation to manipulate the satellite as if it was floating in space.

Thanks to Siemens’s Solid Edge, Fortier admits that designing the RRM hexapod was just a matter of plugging in parametric models to configure the right machine. Programming the robot to behave like the vacuum of space was a different matter.

Putting his robot in context, Fortier stated, “NASA wanted us to provide a robot that could hold on to something that weighs 1,000 pounds and then, when something bumps into it, we feel that force and we float away from it like it would in a zero gravity environment.”

Fortier continued, “That’s a very interesting requirement for a robot. You have to do a lot of thinking to figure out how to simulate the lack of gravity.”

Working back and forth with NASA, Mikrolar’s team developed a sophisticated set of tools that blended real-time communications with 3D positioning and a sizable amount of math.

After painstaking programming, the team was successful in building and calibrating a robot that could move with the same precision and fluidity as it would in outer space.

Today, NASA is in the second phase of its RRM mission and several components have been delivered to the ISS in preparation for the world’s first robotic satellite refueling.

While the timing of that mission is still up in the air, it’s very likely that without Fortier’s team at Mikrolar, NASA’s ambitious project might still be grounded.


Another Robotic Revolution on the Shop Floor

Beyond its work with NASA, the engineers at Mikrolar are also pushing the boundaries of what can be done in factories here on Earth.

Not long ago, railroad products firm Strato contacted Mikrolar about improving their re-machining line by integrating a robotic setup. Strato’s vision was to completely rework the way they re-machine worn cast steel axles.

In the past, these one-ton items were being loaded and unloaded each time the worn piece moved from station to station along the re-machining line. Aside from the inherent danger in working with massive objects, the time being lost across each station transfer was stacking up dramatically.

After listening to Strato’s concerns, Mikrolar engineers suggested that Strato completely alter the way they run their re-machining operation.

Instead of having multiple stations, each for a separate task, Fortier and his team envisioned a new robotic system that would be handled only to insert a part and remove it. After the component was inserted into the re-machining fixture, Fortier’s robot would pick up a CMM tool and begin interrogating the part to find its center.

With a center established, further measurements were taken to determine how worn the axle was and how much welding would be required to bring it back to shape.

Once measurements were complete, the system turned over its information to a welding robot to correct the worn out part.

As soon as the welding process was complete, Fortier’s robot would snap back into action, taking another series of measurements to find imperfections in the welding robot’s job. With those errors in its memory, the Mikrolar robot would begin grabbing tools and perfecting weldments by milling errors out of each surface.

“I can’t give you the exact figures,” Fortier laughed, “but it’s safe to say that our robot has slashed the time it takes Strato to re-machine their parts.”

By reimagining the way that a re-machining line works, and finding a place for their robot to excel, Fortier’s team has introduced a new method of re-machining that previously didn’t exist.

“We’re still in the early phases with this,” Fortier concluded. “There aren’t a hundred companies running this type of line, but at this point it’s just about doing this same process a few more hundred times, then somebody will say, ‘hey, we need to get one of these systems too.’”


Siemens has sponsored ENGINEERING.com to write this article. It has provided no editorial input. All opinions are mine. —Kyle Maxey

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