November 19, 2014      

Ready for whatever the physical challenge

It’s only been a few short years since rigid exoskeletons first appeared. Very quickly after that it seemed as though they were making appearances on every news program everywhere,
demonstrating their ability to raise people up from a lifetime of being trapped in a wheelchair to one of walking upright once again.

With over 50 million Americans struggling with restricted mobility as a result of stroke, aging, injury and other conditions; and with a worldwide number that the World Bank claims approaches12 percent of the globe’s 7.2 billion people, it’s easy to see why rigid, wearable exoskeletons, and their ability to greatly enhance the lives of the handicapped, have been so well received.

Breakout year

2014 was a breakout year for exoskeletons. The field is now crowded and very active with competing brands from Ekso Bionics, ReWalk, Rex Bionics, Cyberdyne, and Parker-Hannifin.

Three of them: Ekso Bionics, ReWalk, and Cyberdyne have already gone public: Cyberdyne (7779:JP) got itself listed on the Tokyo Stock Exchange; Ekso Bionics’ public offering (EKSO:US) earned it over $30 million; and ReWalk (NASDAQ: RWLK) launched an initial public offering (IPO) for 3 million shares at $12 a share that saw prices shoot up nearly 83 percent to $21.90, and then hit a peak of $22.60, 88 percent higher than the IPO price. By the Friday of the IPO at noon, more than 7 million shares had traded.

WinterGreen Research puts this rehabilitation robot market size at $43.3 million with an expectation for dramatic growth to $1.8 billion by 2020. Not bad for youthful products fresh from development.

Heralded as miraculous by medicine and eyed closely by investors, rigid exoskeletons are beginning to impact rehabilitation medicine in a big way.

Then came soft

Now, however, a new breed of exoskeleton–the “soft” exoskeleton–is struggling into existence with a promise of therapeutic performance that tops that of its rigid brethren, while for investors it augers a bonanza of breathtaking profit.

Soft exoskeleton technology, as in the Soft ExoSuit technology developed by the Harvard Biodesign Laboratory, led by Professor Conor Walsh of the Wyss Institute for Biologically Inspired Engineering is a great leap forward in human augmentics.

Not intended for heavy-duty work as with paraplegia, the Soft ExoSuit can extend physical therapy to the home and improve outcomes for stroke patients capable of ambulation, but who struggle with slow, fatigue-inducing gait patterns as well as reduced movement during hip flexion and extension. With an annual 800,000 strokes per year, the Soft ExoSuit is a godsend for rehabilitation.

With upgrades in materials and design, the Soft ExoSuit’s capabilities might be extended to more demanding interventions. The concept is certainly there.

According to its developers, the Soft ExoSuit consists of a fabric base worn by the user under their pants. The fabric has features which enhance gait by assisting underlying biological muscles. Active components are added through cables attached to motors worn on the waist. The cables inject energy during specific times of the gait via controllers that use sensors to monitor the wearer’s movement and log it over time so that the clinicians can assess patient progress.

It’s an ingenious piece of engineering design that uses traditional materials, actuators and gears common to many robotics.

Similar is the equally ingenious piece of engineering from SRI International the SuperFlex undergarment, wearable robot, or soft robot. It was originally designed to lighten the load and avoid potential strain injury for soldiers carrying 100-lbs backpacks.

SRI clearly sees the progression from rigid to soft: “There’s been considerable buzz in recent years about exoskeletons, bulky and rigid robotic systems that can aid soldiers or allow paraplegics to stand upright. SRI’s work arguably represents the next generation of the concept, where the goal is more akin to constructing ‘exomuscles’ and ‘exotendons.'”

It’s with replacing these traditional materials where the new “ultra soft exoskeleton” design diverges from that of “soft exoskeleton”. And it’s with these ultra softs that all of human augmentics and exoskeleton technology may well be headed in the very near future.

It’s a future where compensating for any human biological limitation either natural or acquired–from a powered yoga suit to powering someone out of a wheelchair–can be achieved as easily as donning an ultra-thin body suit that’s barely discernible when wore beneath clothes. That would be an evolutionary milestone for humans and an enormous investment windfall for those who recognize the potential.

Key to it all is the addition of a new player: materials science.

Finally, materials science

Slowly, like two shy dance partners being pushed together, robotics and materials science have joined forces in an engineering laboratory at Purdue University to produce what might rightly be termed an “ultra soft” exoskeleton. The potential of “ultra soft” might well prove to be far in excess of its rigid and semi-soft predecessors.

And materials science seems to be making all the difference.

For some time now, Robotics Business Review has been searching materials science for a point of intersection where the two might meet on a common project.

Previously, we found and reported on a few laboratories that displayed fascinating materials that had great promise for robotics, but any actual intersection with robotics had yet to occur:

1. Robots Buff Up with Breakthrough Polymer Muscles
Elastic polymer dramatically increases strength, lift, extension and recovery

2. Super-strong Mechanical Muscle for Micro-scale Robots
Powerful, new micro-scale actuator flexes like a tiny beckoning finger

3. How Fishing Line Could Revolutionize Robotics
Strong, cheap muscles could revolutionize robotics

4. Materials Science Muscles into Robotics
Change in fundamentals of mechatronics to spur investment in vanadium

5. Liquid Metal Technologies
We also investigated a potential intersection with Liquidmetal alloys, a class of highly engineered materials called Bulk Metallic Glasses (BMG).”Liquidmetal is super strong, scratch and corrosion resistant, resilient and can be precision cast into complex shapes,” like the exterior skin of a robot or exoskeleton. We then queried the inventor of Liquidmetal, Atakan Peker, former VP of technology at Liquid Metal Technologies, now at Washington State University. Peker replied:

There are three unique aspects of amorphous alloys that may be useful for robotic applications:

  • Very high elasticity with very high strength (the best in metals)
  • Micro-forming of surface
  • Precision casting or near-to-net shape forming

The major problem with it all was no one seemed to be actively applying any materials science directly to robot development.

Let’s just call it “ultra soft”

Then up popped Rebecca Kramer, a scientist creating soft robots in a small lab at Purdue University in Indiana.

Bloomberg’s Sam Grobart reported in his “The Year Ahead: 2015” series: “A new kind of robot is being developed that will integrate directly into our clothing to monitor and assist our movement. Her research could someday lead to a revolution in what we wear, from rehabilitative clothing to military performance enhancers, to everyday athletic gear.”

In fact, her creation is so soft, and so unlike the “soft” suit from either Harvard or SRI, let’s just call it “ultra soft”.

Kramer is still a long way from enabling an “ultra soft” exoskeleton to capably support a paraplegic upright and to assist with walking, but her research and materials science are on the right path.

The goal is to make possible a class of soft robots where all the functional elements are embedded in a stretchable skin. This skin will include flexible electronics that are less sensitive to vibration than conventional hardware, making them rugged enough for space missions

Future generations of wearable robots will include systems constructed from conformable materials that do not constrain the natural motions of the wearer.

“Fabrics represent a class of highly conformable materials that have the potential for embedded function and are highly integrated into our daily lives. In this work, we present a robotic fabric with embedded actuation and sensing.

Human bodies are soft not rigid

“Attaching the same robotic fabric to a soft body in different ways leads to unique motions and sensor modalities with many different applications for robotics. In one mode, the robotic fabric acts around the circumference of the body, and compression of the body is achieved. Attaching the robotic fabric in another way, along one surface of a body for example, bending is achieved.

“Materials with variable stiffness have the potential to provide a range of new functionalities, including system reconfiguration by tuning the location of rigid links and joints. In particular, wearable applications would benefit from variable stiffness materials in the context of active braces that may stiffen when necessary and soften when mobility is required.

“In this work, we present fibers capable of being adjusted to provide variable stiffness in wearable fabrics. The variable stiffness fibers are made from shape memory materials, where shape memory alloy (SMA) is coated with a thin film of shape memory polymer (SMP). The fibers, which are fabricated via a continuous feed-through process, reduce in bending stiffness by an order of magnitude when the SMP goes through the glass transition.

“The transition between rubbery and glassy state is done by direct joule heating of the embedded SMA heater. Furthermore, we employ a COMSOL model to relate the current input to the time it takes the fibers to transition between stiffness states.”

The progression of the exoskeleton revolution is from rigid to soft to ultra soft. For now, however, rigid exoskeletons are performing near miraculous transformations in making the immobile mobile again, of turning disability into ability. Over time, innovation will push the technology closer toward the concept birthing itself in labs like Kramer’s.

There are literally millions of people whose lives can be completely changed and uplifted with these wearable robots. The record level of IPOs and the popularity of the investments will continue to rise as entire industries–and thousands of jobs–rise along with them.