Sep 19 2017

Soft Robots

vaderhandPart of the reason I like science fiction is because it can be a thought-experiment about future technology and society. For this reason, like any self-respecting nerd, I often pay close attention to the details of how future technology is portrayed. Stepping out of the movie-as-entertainment and storytelling for minute, and focusing on the ideas that went into crafting a vision of technology advanced beyond our current tech – how did they do? What assumptions did the creators make, and did they break any laws of physics.

I tend to be most fascinated by what hidden assumptions and biases go into visions of the future. I wrote about this previously with respect to spaceship design. The same idea applies to how robots are portrayed in science fiction.

For example, perhaps my biggest peeve is Star Wars (probably because it is a beloved franchise). I don’t necessarily mind the design of droids, because you can argue that they are intended to look unmistakably mechanical. However, we get a few glimpses of artificial robotic limbs – Luke’s hand and Vader’s arm, for example. These appear to be entirely constructed of wires and pulleys. Vader’s arm is the worst – the stump is nothing but a mass of wires.

This image of artificial robotic parts is almost ubiquitous in science fiction, although recently there are some great examples of moving past this cliche. Just compare the original West World, where robot faces look convincingly human, until they are removed and revealed to be rigid metal with wires underneath. The recent series West World, however, portrays soft 3D printed robotic technology. That’s what I’m talking about. Soft Robots

There are many reasons why we would want to develop soft robotic technology. In industry there are applications that require flexibility, including manipulating small or soft parts. We also might want soft robots anytime they need to interact with humans or other living things, especially medical applications.

Soft life-like prosthetics are the holy grail. We can make soft skin, flexible joints, and a rigid frame. Perhaps the biggest obstacle at this point is making soft artificial muscle. We are making some progress, which I will get to shortly, but it remains difficult to imitate living muscle.

Like many technologies I discuss here, in order for artificial muscles to be useful they need to have a suite of simultaneous properties, the lack of any one can be a deal-killer. The ideal battery, for example, needs to have high capacity, low weight, many recharge cycles, relatively quick recharging, able to discharge fast enough to power demanding devices, should be stable (not burst into flames), and be made of materials that are cheap, abundant, and non-toxic.

For artificial muscles they need to be soft, have high tensile strength, and be able to contract and expand repeatedly without limit, with both rapid and fine control, able to produce significant power, under conditions compatible with a living user. A technology can have most of these properties but be very slow, and therefore useless as a prosthetic, and only potentially useful for narrow niche applications. Another technology might be too weak to be of practical use, even if everything else is perfect.

As with battery and other technologies, I often read about “breakthroughs” where one feature is significantly advanced, and the press release glosses over the glaring deficits or casually states, “Researchers are now working on fixing this deal-breaking deficit, which they are confident they can do in the next funding cycle.”

This brings us to the latest news on soft robotics which prompted this post – researchers at Columbia University have designed a soft artificial muscle that is able to contract and expand with electrical or thermal control, and:

 The new material has a strain density (expansion per gram) that is 15 times larger than natural muscle, and can lift 1000 times its own weight.

Impressive – but where is the deal breaker? Here’s one:

After being 3D-printed into the desired shape, the artificial muscle was electrically actuated using a thin resistive wire and low-power (8V). It was tested in a variety of robotic applications where it showed significant expansion-contraction ability, being capable of expansion up to 900% when electrically heated to 80°C. Via computer controls, the autonomous unit is capable of performing motion tasks in almost any design.

Requiring heat of 80°C (176°F) is not practical for human applications. This could be useful in industrial applications, however. Also, it seems like it can be actuated just with electrical stimulation of 8 volts, which could work. But here is the real limitation:

The researchers will continue to build on this development, incorporating conductive materials to replace the embedded wire, accelerating the muscle’s response time and increasing its shelf life.

The “response time” is the critical bit. Watch the video’s on the link – the contraction and relaxation of the artificial muscle is slow. It literally moves at about the speed of a sloth, so this would be great for robotic sloths, but not so much for human prosthetics.

As always, I hope the researchers are successful in solving these issues. The response time is a non-trivial problem, however, and may be intrinsic to the technology. Popular discussions (flowing from the press release) of such technology always assumes that the advance is on a trajectory to the final goal, but that is often not the case. We may not get to an artificial muscle with human-level or greater properties via this technology. This could easily be a dead end if the response time problem is unfixable.

Still, even a dead end can be useful if it teaches us something, and may help point to the way to whatever technology will ultimately work. Or maybe not – we still don’t have room temperature superconductors or a viable storage option for hydrogen fuel cells, despite all the advances made.

What this means is that it is difficult to predict when we will cross the finish line to a viable technology. Success is not simply a matter of tweaking or iterating current technology. It may require an entirely new material or approach, and such advances are impossible to predict. I do think we’ll get there eventually, but who knows how long it will take.

Human-level soft robotic muscles, however, would be a tremendous technology to have, and will rapidly revolutionize the prosthetic industry.



8 responses so far

8 thoughts on “Soft Robots”

  1. edwardBe says:

    In my opinion, the cyberpunk novelists, especially William Gibson, got at least one aspect of artificial body parts right with the concept of biochips that allow an untrained person to directly interface with an airplane and fly it, for instance, and the concept of “jacking-in to cyberspace” to steal or modify data in storage. Gibson also had one character who had replacement eyes (made by optic manufacturers) but they were visibly artificial and she also had retractable razor blades implanted in her fingertips.

    Some of his characters had permanent cranial implants, which in the case of one young girl, allowed her to contact voodun “gods” that were depicted as having been created within cyberspace itself and were not actually spirits, she just saw them as such, although other people were depicted as sometimes being possessed by them outside cyberspace. So his approach varied from the visibly artificial to something completely invisible to other people. He also wrote one novel built around a rock star who falls in love with an ostensibly female entity who exists only online. The ultimate VR experience, I guess, but no glasses needed. She was an interactive hologram.

    I suspect we may be less than ten years away from some form of biochip socket. I think I read recently on the Genetic Literacy Project about a possible integrated circuit implant in mice. This might be the direction of an artificial pancreas, kidney, thyroid or other glands and/or organs.

  2. Dan Dionne says:

    I really appreciate the discussion of soft robots versus how popular media portrays them. It bugs me to no end when some high-tech war robot hundreds of years in the future has all its joints and half its internals exposed. At LEAST have a cloth cover to keep out water, mud, and dust. A few video games have recognized this (Metal Gear Solid 4, a couple of the newer Calls of Duty) while many do not. I love Titanfall’s mechs, but they’re still big goofy clanking bots.

    One sci-fi franchise that was way ahead of its time was Alien. Ash and Bishop were full of soft plastic, strange little translucent bulbs, and tubes of milky white fluid. Really striking, and not the usual wires and pistons.

  3. SteveA says:

    The conversation reminds me of one of my favourite Simpsons quotes:

    A Scratchy automaton takes off the top of its skull to reveal all the wiring inside. Marge turns to Homer and says: “See all that stuff in there, Homer. That’s why your robot never worked.”

    Dan Dionne
    I was about to say the same about the Alien androids. The idea of ‘wet’ workings was really effective.

  4. Lobsterbash says:

    Did Star Trek do a reasonable job with Data? I seem to recall a scene or two of implausibly stiff material being exposed just beneath the surface.

    What about Battlestar Galactica’s “skin jobs?”

    Then there are silly nano machine-directed organisms that are more difficult to classify, like John Connor’s body being repurposed in Genisys, or reconstructed protomolecule bodies from The Expanse.

  5. Lobsterbash says:

    Forgot to mention that I’m surprised there was no mention of the humanoid robot from Ex Machina, which Steve and company did a review of. That iteration seemed reasonable for soft robotic implementation.

  6. Sarah says:

    It has to be at 80 degrees C to operate at all? Yeah that’s not remotely human-viable.

  7. Lobsterbash says:

    “Up to 900% at 80C”… that might mean a lower efficiency at lower temperatures. Meaning, 80C isn’t required to work at all.

  8. praktik says:

    Expanse is a wicked book series for grounding its ships and infrastructure in real life constraints.

    They follow Novella’s advice, acceleration is used as gravity. High Gs need special gel couches and even drug cocktails, to keep people conscious on “high burn”

    Space battles in the books are just wicked for the way these rules act on the interplay in a battle

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