

Fluid Actuators from Disney Research Make Soft, Safe Robot Arms - spectruman
http://spectrum.ieee.org/automaton/robotics/robotics-hardware/beautiful-fluid-actuators-make-soft-safe-robot-arms#.VDaXD69x3zs.hackernews

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Fuzzwah
The section of the video where the robotic arm "plays ball" really impressed
me due to the kind of playfulness which it exhibited. Beyond being impressed
by the fluid actuator system I was just starting to be amazed at the
programming involved with making a robotic arm that can show such accuracy to
"catch" the ball and roll it back but also do it in such a playful manner.....
then the camera zooms out and shows that the arm was being controlled by a
human. Damn.

* I'm at working and watched the video with out sound, so maybe I missed as it was explaining what was going on.

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pwnna
The fact that you can have something responsive enough to _mirror_ human
movement is very impressive.

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tinco
You'll be amazed when you see the video of this device. It's accurate enough
to mirror human hand writing!

[http://en.wikipedia.org/wiki/Pantograph](http://en.wikipedia.org/wiki/Pantograph)

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Animats
That's a nice way to make a low-friction pneumatic or hydraulic cylinder. It's
not original with Disney. Rolling diaphragm seals for pneumatic and hydraulic
cylinders have been available commercially since the 1950s.
("[http://www.marshbellofram.com/belgas/files/2012/05/design_ma...](http://www.marshbellofram.com/belgas/files/2012/05/design_manual.pdf"))
It was used for humanoid robots as far back as 1985.
("[http://cyberneticzoo.com/robots/1985-mcandroid-jon-barron-
et...](http://cyberneticzoo.com/robots/1985-mcandroid-jon-barron-et-al-
british/"))

There's no power source in that demo. That's an un-powered Waldo, with the
manual operator providing all the power. If you put that mechanism in a robot,
you still need a motor, in addition to the four pneumatic cylinders and
plumbing for each joint. For Disney's anamatronic applications, where the
character is fixed in place and can have lots of plumbing to an external
control unit, it makes good sense. For working robots, not so much.

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lostdog
This pneumatic power design could improve working robots. Yes, you would still
need a motor to actuate each joint, but now you can put the motor anywhere.
Placing the motor in the torso removes weight from the arms, which means you
need less power to control the arms and the arms have less momentum, both of
which greatly increase safety.

~~~
Animats
True. You can also get rid of the motor entirely and just use proportional
valves and compressed air. Festo's robots work that way.

A common model of human and animal muscles is to treat them as two opposed
springs, where the spring constant and neutral point are both adjustable.
Mechanical systems for that have been built for research robots, but they're
mechanical nightmares of cables, pulleys, and springs. Two opposed air
cylinders, though, can directly implement a pair of adjustable springs. That's
been done a few times on research robots. This gives you muscles of adjustable
softness, just like humans. A running robot with spring-type energy recovery
could potentially be done that way. (Humans recover about 60-70% of energy
from one stride to another when running. Cheetahs, 90%.) Mechanical running
machines with springs for energy recovery have been built. With fixed springs
tuned for running, all they can do is run.

To make soft air springs work, you need position and pressure feedback on
everything, and small, fast servovalves. Fast servovalves tend to be very
expensive. They also have to be near the cylinders for good position control -
too much air line and there's no way you can make the system stiff when you
want to. Of course, you need compressed air.

Meanwhile, brushless DC motors have improved so much, and are so easy to
control now, that the trend is away from pneumatics and hydraulics. Boston
Dynamics' humanoid is all hydraulic (it's really a modified Big Dog), but
Schaft's is all electric. Google now owns both, of course.

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smtddr
If you liked this, check out another project from Disney labs called "Touché"
\--
[http://www.youtube.com/watch?v=E4tYpXVTjxA](http://www.youtube.com/watch?v=E4tYpXVTjxA)

For some reason, the girl's reactions to the 2 bzzzt-wrong sounds @ 2:55 are
hilarious.

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swartkrans
What is Disney's interest in this type of technology?

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sedachv
Disney has a whole R&D division to develop theme park attractions:
[http://en.wikipedia.org/wiki/Walt_Disney_Imagineering](http://en.wikipedia.org/wiki/Walt_Disney_Imagineering)

Alan Kay and Danny Hillis both used to work at Walt Disney Imagineering

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jobu
The big deal appears to be that the're using hydraulic cylinders with what's
called a rolling diaphragm: [http://machinedesign.com/hydraulics/rolling-
diaphragm-seals-...](http://machinedesign.com/hydraulics/rolling-diaphragm-
seals-stay-strong-under-pressure)

It doesn't look like a particularly new innovation, but perhaps something
that's not commonly used in robotics?

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tlb
I've used them in robot arm prototypes, but they're basically 3x as big as
regular cylinders (1.5x for the rolling diaphragm overhead, and another 2x
because you need two single-acting cylinders instead of a double-acting one).

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blhack
If you're interested in this, I highly recommend looking at the stuff that
Festo (a german industrial automation company) is doing:
[https://www.youtube.com/watch?v=u7KIp7A8iqs](https://www.youtube.com/watch?v=u7KIp7A8iqs)

(This is from 2008).

And not necessarily related, but really cool anyway:
[https://www.youtube.com/watch?v=nnR8fDW3Ilo](https://www.youtube.com/watch?v=nnR8fDW3Ilo)

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teddyh
It’s not a robot, it’s a Waldo¹ – a puppet, essentially. Which is fine for
Disney, which wants to make puppets for puppeteers, but this has basically
nothing to do with new developments in robotics.

①
[https://en.wikipedia.org/wiki/Remote_manipulator](https://en.wikipedia.org/wiki/Remote_manipulator)

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falcolas
What, aside from the reduced mass of the robot arms, makes it safe? How, aside
from operating pressure, is this different from traditional hydraulics?

I'm afraid I just don't see the novelty of a low pressure hydraulic system.

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nateguchi
I believe the new part is the "rolling diaphragm" actuators, which have a high
torque density.

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wffurr
And very low stiction compared to pistons.

FTA:

"With pneumatics and hydraulics, you can certainly get power and speed, but
you often need to deal with leaks and friction and elaborate arrangements of
pumps and valves and whatnot."

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Gracana
Is Disney Research really making cast parts for their prototypes, or are these
is this off-the-shelf technology from somewhere else?

[http://spectrum.ieee.org/img/fluidtrans2-1412583381292.jpg](http://spectrum.ieee.org/img/fluidtrans2-1412583381292.jpg)

[edit] Nevermind, in other photos it is clear that the parts are machined. I'm
still surprised they've gone to such lengths to remove weight in the
prototype, but that's more of a cool thing than something truly unexpected.

