The Creepiest Looking Artificial Muscle Motor Ever
Nick Gilbert
at 12:04 PM 14 Mar 2020
Comments 0
Auckland's self-commutating motor
Auckland's self-commutating motor
IMAGE BY University of Auckland, YouTube

It takes a lot to creep us out. Most of us here at PopSci, and a lot of you as well, and seen all sorts of weird, uncanny robots and bizarre biological specimens, but the simple sight of this New Zealand-made artificial muscle - and now high-torque motor - seemed to touch a nerve. Thankfully, it will also turn out to be incredibly useful in a variety of applications.

The slightly wrong looking, but actually incredibly useful tech you see above is a self-commutating motor - that is, a motor that doesn't require any extra electronics to monitor and moderate the operation of the motor itself. Like our muscle reflex, the muscle motor can 'sense' when a particular area needs to do work as current is passed along it, and react accordingly.

"Your muscles can detect their own position, and your brain incorporates that information to work out how to not drive your finger drunkenly into your eyeball."Ben O'Brien, a post-doctural student at the University of Auckland and one of the lead researchers on this electostatic motor project at the university's Bioengineering Institute, says this sensing works in a similar way to how our body works.

"The muscles are self sensing. So hopefully if you haven't been drinking too much - it's still early for Friday drinks over there [in Australia] - but if you close your eyes you can touch your nose," he said. 

"The reason you can do this is that your muscles are self sensing, they can detect their own position, their own sort of 'state', and your brain incorporates that information to work out how to not drive your finger drunkenly into your eyeball.

"Now, artificial muscles can do the same thing. We can give artificial muscles the ability to self sense, to metaphorically touch their own nose, and using that we can distribute sensitivity throughout the system."

Unlike electromagnetic motors, that require separate complicated electronics and copper wiring in order to moderate and regulate the electrical current driving the movement, this self-commutating engine handles all that itself, thanks to an 'electrode' network made of carbon grease, that you can simply paint onto the muscle.

"In the motor, we use a different technology called the dielectric elastomer switch. Now, what that is is basically a piece of carbon, grease, and when you stretch it, it stops conducting. It's just a switch. If you compress it, it conducts, if you stretch it, it stops. By combining these switching elements with the muscles, we can actually distribute intelligence throughout the artificial muscle device, by creating networks."

"Now, what that is is basically a piece of carbon and grease, and when you stretch it, it stops conducting. It's just a switch." Dr O'Brien says that, in this way, the muscles can actually act as transistors, in which you can embed intelligence in a similar fashion to embedding intelligence in a computer. We're a long way from artificial muscle computers but according to Dr O'Brien, in robotics you don't need a lot of intelligence to do some cool stuff.

Welcome to the Real World

At this point in time, says Dr O'Brien, they're not quite efficient enough, if you were to build them in a real world scenario, to entice everyone to trade in their electromagnetic motors for this kind of electrostatic one. Even though recent advances by institutes such as Stanford Research International have radically increased the energy capacity of electrostatic motors (by 100 times, in fact), it will probably be at least ten years before we get to a point where they may be a worthwhile alternative. 

One of the co-authors on the study, Dr Iain Anderson, says that this kind of motor would be good right now in any application where you want a motor generating a high amount of torque, but without working at high speed. However, the lack of an electromagnetic field, plus the actual materials used in the motor's construction could actually make it useful for heck of a lot more.

"One other possibility, which we haven’t really explored that well, is in places where you have very high strength magnetic fields," he says. 

"MRI devices, wind jet turbines, essentially any place where an electromagnetic motor wouldn’t be too happy. So with this technology, it could be possible for an electrostatic motor like this, we can get rid of all the metal parts, and could operate something instead of an electromagnetic motor.”

The prototype in the video has a metal bearing, but according to the Auckland team, you can easily substitute that for a non metallic substance.

"The switches are literally painted on, a painted on electrode. You could potentially do this in your own kitchen."The other plus to this, of course, is that if you do away with rigid components and instead use artificial muscles, you end up with a motor that you can stack, but also with a motor that you can place in non-standard locations, or even pack away into a tight space before use.

"So perhaps it could be curved during its operation, it can be inside a stucture that’s deformed. It could even be stored in a deformed shape, and then later flattened out for use,” says Dr O'Brien.

Motors Made of Water

For DIY-ers, though, perhaps the most compelling aspect of this research is that it actually requires very few components to make. You  can ditch the copper, ditch the rare earth metals, and instead make something that you could put together in your own home.

“Bear in mind, the motor you see in that video is entirely hand made," says Dr Anderson, "and the switches are literally painted on, a painted on electrode. 

"So it becomes possible to make a motor like this with rubber and a flexible electrode on it, all made entirely in polymer, which in fact you could do in your own kitchen, if you wanted. Not that you’d want to do that [Dr Anderson later explains it would probably leave quite the mess], but you don’t need to worry about getting lots of copper wire, and machines to do this and that. It’s relatively easy to make.

"Also, to make good electromagnetic motors," says Dr O'Brien, "you need good magnetic materials. Things like rare earth metals, they’re, well, rare."

“We’ve used salt water for an electrode, with carbon grease on the bottom side, and salt water on the other.”

"I think that's why they're called rare earth metals," says Dr Anderson. Cue earth-science-joke laughter from the three of us (feel free to chuckle along at home).

"I think so, too," says Dr O'Brien. "But there is potentially an environmentally sustainable advantage to using this."

At this point, though, it occurred to us that carbon-based grease, derived as it is from petroleum, probably isn't amazingly environmentally friendly either.

>Dr O'Brien agrees that would pose some problems, but you can use a host of different substances as an electrode. The lack of a need for a strong electrical current means that you don't need highly conductive materials to make it work.

“We’ve used salt water for an electrode," says Dr Anderson. "We built a dielectric elastomer device with carbon grease on the bottom side, and salt water on the other.”

They add that you could even have salt water as the electrode on both sides if you really wanted, but it makes it difficult because, for one, it's quite difficult to see a transparent membrane such as the one in this motor when it's moving inside water. But secondly it's even more messy than using carbon grease. Getting the salt water into containers to use in the motor also poses problems.

Even still, we asked whether such a motor might also double as an aquarium. "Let's not go there," laughs Dr Anderson.

Either way, though, the research the University of Auckland have done into self-driving artificial muscle motors might mean that one day, you could have one of these things pumping away at a power plant or a hospital near you. A little gross at first, perhaps, but also very, very cool.

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