The Robot That Goes With The Flow

The Robot That Goes With The Flow

The new robot at NASA’a Langley Research Center does not walk or talk or wish to become human. It’s not even a complete humanoid shape, it’s just an arm.

But it does make carbon-fiber composite objects that us humanoids are not capable of producing.

ISAAC (Integrated Structural Assembly of Advanced Composites) is a 21-foot tall robotic arm that can move along a track, and lay down pre-impregnated reinforcing fiber, such as carbon fiber.  NASA acquired it, at a cost of $1.7 million, after a 2-year campaign led by Chauncey Wu, a Senior Aerospace Engineer at the research center. ISAAC was delivered on Sept. 30, 2014, moved into its rails on October 14, and began laying up composites on Dec. 3, just 6 days ago.

ISAAC can build composite parts by depositing sticky, pre-impregnated carbon fiber at very precise positions and angles. This precision will allow objects – parts of a space vehicle, for example – to be reinforced in ways that conform more closely to the actual flow of loads in the part when it is in use.  This maximizes the efficiency of the reinforcement and potentially reduces weight and materials cost.

ISAAC was built by Electroimpact, Inc., a supplier of industrial robotic systems. Andy Purvis, of Electroimpact, describes ISAAC as a basic Titan robotic arm that has been souped up for greater precision and versatility. It has an enhanced CNC controller, and secondary feedback added to its joints, so it can position itself with greater accuracy. A typical robot of this type – widely used in the automotive and aerospace industries – would manage accuracy to about 40/1000-inch. ISAAC can get within about 10/1000-inch. The controller is also faster, allowing it synchronize better. It can have more inputs and outputs, controlling up to 27 axes, so it can be paired with other robots to work in conjunction.

Wu explains that conventionally in the aerospace industry, carbon fiber parts been laid up by orienting  unidirectional fiber reinforcement at 0º, 90º, +45º or -45º.  This can be done manually, using a template for precision, and it has been standard practice for carbon fiber composite fabrication.

The ISAAC system can make reinforcement to follow complex curves, one strand at a time. With the proper engineering analysis to determine the actual load path through the part, the reinforcement can be laid down to follow that path without approximating to a 0º, 90º or 45º angle, eliminating unnecessary reinforcement, making every gram of carbon fiber count. It can reduce weight, and improve strength.

Andy Purvis explains the importance of it this way. “Think about a branch on a tree. If you look at the grain of the wood where the branch joins the trunk, you see the fibers grow in a shape that maximizes their efficiency. That was determined by evolution. It took a long time.  What Chauncey is trying to do is short-circuit the evolutionary process and get it into our structures.”

ISAAC can build parts up to about 21 feet in diameter. The more practical size constraint is probably the availability of an autoclave or oven (depending on the resin) large enough to cure the part.

The first project for ISAAC will be a research job for the Aeronautics Research Mission Directorate’s Advanced Composites Project (ACP). The second is the Composites for Exploration Upper Stage (C-EUS) Project, a partnership between the Space Technology Mission Directorate and Human Exploration Mission Directorate that is led by the Marshall Space Flight Center. The C-EUS Project is a three-year effort to design, build, test and address flight certification of a large composite shell suitable for the second stage of the Space Launch System.

Wu emphasizes that the purpose of NASA’s robotic arm is research, to see how far this technology can be taken. “My vision for ISAAC does not end with fiber placement. There are a lot of improvements we can make in the process. Because of the configuration of machine, we can stow the fiber placement head and pick up another end effector to do other processes. Stitching, curing on fly, nondestructive evaluation, friction-stir welding, machining, ultrasonic foil lamination… I call it a Swiss army knife. You’re using the same robotic mobility platform but doing different jobs.  What we do with this should only be limited by the imagination.”

Is this technology applicable to Architecture? Andy Purvis suggests, ‘Yes, but…” The great value of such a machine, according to Purvis, is in being able to reduce waste of expensive material such as carbon fiber, and reduce weight of parts in a weight-critical application such as space flight. These properties are not as significant advantages in an architectural application where a lower-cost material such as fiberglass is being used, and weight is not as critical a factor.

However, the engineering lessons learned may well have applicability, even if the machinery needs to be modified to make it a practical solution for construction applications.  Even some of the secondary know-how may prove valuable in translating this technology into other industries.  For example, when the machine is laying up composites, it’s building three dimensional structures without a mold to support them, and the resin is still tacky and uncured.  How can the object keep its shape while it’s being built and awaiting curing?  Wu’s team has been experimenting with putting silicone blocks on either side to keep wet structures from collapsing.  (An active human-robot partnership…)

NASA has been a prodigious engine of basic research for over half a century.  The research for space exploration has spun off a wide array of earth-bound innovations as well.  Chauncey Wu’s research combines the rights materials and the right scale that could lead to additive fabrication (3-D printing) for composite architectural and structural elements.  Presently, this is mostly done by subtractive digital fabrication processes: using a CNC miller to cut away a block of foam into a mold, and then laying up fiberglass composite by hand on the mold.  The CNC milling is a slow process.  ISAAC can lay up fiber at 2000 inches per minute, and there is no need for a mold.

“As it becomes more mature and friendlier and computational power goes up,” suggests Purvis, “I think it will become something architects can access and utilize.”

Oh, and BTW, there’s a 3-D printer onboard the International Space Station, where they’re exploring digital fabrication in zero-G.

Thanks to Chauncey Wu and Kathy Barnstroff of NASA, and Andy Purvis of Electroimpact, Inc.

Images courtesy of NASA Langley Research Center.