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Artificial Retinas Can Balance a Pencil On Its End
mikejuk writes "A team of researchers has built a neural information system that is good enough and fast enough to balance a pencil in real time. If you think it's an easy task, try it! The Institute of Neuroinformatics, ETH / University Zurich have used what look like video cameras to do the job but in fact they are analog silicon retinas. They work so fast that even with fairly basic hardware they can balance a pencil."
This is impressive bit of tech. Robotic vision has historically been a tough field.
Anyone knowledgeable enough on the subject to speculate on the implications or interesting uses of this technology?
September 26, 2008
My friends and I used to do that back in middle school to pass the time. Not build artificial retinas; balance pencils on our fingers (on eraser or tip).
Just to get one thing straight: A robot balancing a pencil is not a breakthrough. Similar tasks are standard textbook material, often implemented using fuzzy logic.
But the way they have done it may or may not be cool. Hard to tell.
Unless I'm mistaken, from looking at the picture the camera's "eyes" are placed orthogonally, instead of side by side like a human's. That's an advantage, since we know the machine then has real 3D position info, as opposed to a human's stereoscopic 3D vision. Try it yourself: when you balance a pencil, do you fail more often sideways or towards and away from yourself?
This is an impressive bit of controls engineering, but let's not compare apples to oranges: the machine is designed for this task, and the human is not. It's in a way impressive that humans are as good as we are at this task despite not having been constructed to do it.
Similar: http://www.hizook.com/blog/2009/08/03/high-speed-robot-hand-demonstrates-dexterity-and-skillful-manipulation
It uses high speed visual servoing to dribble a ping-pong ball and to toss and catch a cell phone.
Ironcially, I am listening to President Obama's speech as I write this, and his advisors (and speech) seem clueless about the changing nature of economics given robotics and other automation, AI, better design, and voluntary social networks (even as I think he means well and it is good for the US that he his helping create some jobs by increasing some exports):
http://www.earthtechling.com/2011/01/obama-visits-ge-wind-turbine-plant/
Pres. Obama can talk all he wants about "winning a global competition", but the average human worker anywhere is not going to win a competition with advanced robots... Humans need to learn to "cooperate", not "compete".
Economic solutions (my comments):
http://knol.google.com/k/paul-d-fernhout/beyond-a-jobless-recovery/38e2u3s23jer/2
From a comment I posted yesterday in relation to an (purported) demo of a cold fusion device:
http://www.journal-of-nuclear-physics.com/?p=360&cpage=6#comment-20270
In brief, a combination of robotics (and other automation, all made possible by cheaper computing), better design (whether from cold fusion devices or thin-film solar panels), and voluntary social networks (especially with volunteers cooperating through the internet on free and open source digital public works), are decreasing the value of most paid human labor by the law of supply and demand. Cheaper energy will only accelerate this trend, since often you can substitute energy for labor and thought.
At the same time, demand for goods and services is limited for a variety of reasons. These reasons include some classical ones, like a cyclical credit crunch or a concentration of wealth (with that concentration aided by automation, intellectual monopolies, and the rich getting richer and buying up more and more resources like land for rent seeking). The reasons also including some heterodox alternative economics ones, like people moving up Maslow's Hierarchy of Needs as they get a lot of "stuff" and move on to other pursuits than materialism (including spiritual aspirations, self-actualization, and social connections in communities), and as people embrace a growing environmental consciousness of "Reduce, Reuse, Recycle" to protect the biosphere.
In general, mainstream economists ignore these issues or have very unexamined beliefs about them. Imaginative innovation, like economist Julian Simon talks about in "The Ultimate Resource", makes possible many wonderful potentialities if we think them through. Please don't let your inventiveness or cold fusion get blamed for any issues caused by unimaginative scarcity-based economic models held onto with almost a religious fervor by so many (see "The Market as God" by theologian Harvey Cox in the Atlantic). Mainstream economist have long used such scarcity-based models to apologize for an overly hierarchical social order that we probably did not even need in the past -- search on "The Mythology of Wealth". Still, some degree of centralization can be a good thing; see Manuel De Landa on "meshworks and hierarchies", and how they keep turning into each other and how all real systems are mixtures of both. So, we need to think and experiment regarding ways to allow our 21st century society to function in a healthy way given all the 21st century technology people like yourself are busy creating in all sorts of areas.
A New York Times article called: "They Did Their Homework (800 Years of
A 21st century issue: the irony of technologies of abundance in the hands of those still thinking in terms of scarcity.
Considering that it's a completely different problem, it should be easy to impress you. How about a robot that you instruct to open the pantry, but it opens the bathroom door instead?
Can those fancy algorithms make a pencil disappear?
#DeleteChrome
It never seems to be able to damp down the movement. It should be able to reduce amplitude to less then a centimetre or so.
http://michaelsmith.id.au
Wrong. Read TFA, and if necessary read their paper, and try again. They used a relatively simple feedback mechanism and simple algebra, not Lagrange equations.
If you have fast enough feedback, then the displacements (and hence, angles) involved in the equations of motion for the inverted pendulum are really small, and hence the transcendentals involved can probably be approximated by the small angle approximation -- and then the "algorithms" (solutions to the equations of motion) are pretty simple I think.
Also, I'm not sure that standing a pencil on end is the same thing as an inverted pendulum, because the bottom end isn't secured for the pencil (correct?). For an inverted pendulum, if you oscillate the base fast enough the pendulum will remain upright (see the wikipedia article you linked) -- so it's pretty trivial to stand a pencil on end in this fashion, I think (just attach it to something that oscillates -- a speaker will probably do).
I have seen this demo in person and chatted at length with its creator. It uses a custom sensor chip that does some analog temporal filtering and thresholding of light intensity at each pixel, sending events when the threshold is crossed. The intent of the authors seems to be to mimic the human visual system in silicon, even if it makes no engineering sense whatsoever. The demo was extremely sensitive to fluorescent lighting; the author had to run out and buy an incandescent desk lamp to get it to work at all. The event-based image representation makes it incompatible with everything that has been learned in computer vision over the last decade.
I'm thinking the same thing - this is my attempt at frist post using only my retinas, and frankly it's not exactly looking like a success.
Do not balance pencil on remaining retina :(
Well, it's all control theory. If all you want to do is something stupid and trivial like balancing an inverted pendulum, then the math isn't too hard and the algorithm is comparatively simple. If you want to do anything more complex, then you have to start using more complex math.
It's not so hard to turn the 'inverted pendulum' into a more complex case where simple trigonometry and algebra doesn't work: mount your pendulum on a turntable.
Stop playing with that pencil. It's all fun and games until someone loses a silicon retina.
You are not a brain: http://books.google.com/books?id=2oV61CeDx-YC
As TFA mentions, the larger the object, the slower the reaction time is needed.
So balancing a pencil is more impressive than a broomstick because it requires quicker reactions.
At the end of the video, when the tech removes the pencil, it looks like he's pulling it up out of some sort of indent. If that "indent" was a rubber aperture, this might not be as impressive as it first looked. Was the pencil being "balanced" on end or with the first 1/4 inch inserted into something?
I would love for this to be as cool as it looks, so someone please explain where I'm making a mistake.
You are welcome on my lawn.
... that balancing such an object requires the use of several fancy algorithms:
This is proof that, just exactly as I asserted, all you need is relatively simple feedback as long as it's fast enough.
Yep, that was me. I guess I should go back to my MIT professors and let them all know that they're full of hooey. I've sure been shown up by Jane Q. Public!
Or, on the other hand, I could look at the video these fellows provided. Doing that, I might notice that the system is barely stable, very noisy, does not deal with perturbation very well, and accumulates error. I could then read the paper and see, under the section called "VI Control System" it explicitly states that they are using a PD system (proportional and derivative), as described in the system of two differential equations. Then I could read the sentence, "Our system normally balances an object for several minutes before losing it..." which would probably be because they don't have an I term to worry about accumulating error. Lack of an I term makes the system drift, and you can see in the video that it nearly hits the edge of the actuator workspace a few times. Striking the limit of motion would be a catastrophic change in actuator impedance and cause the pencil to be dropped. The fact that they had to include a D term means that there is more than just straight (linear) feedback. But, hey, I guess those MIT professors didn't actually know what they were talking about when they taught us 18.03 Differential Equations. Either that or Ms. Public can't read papers very well, and doesn't recognize a differential equation when she sees one.
Again, I'll state, Ms. Public, please stay away from designing any systems that are critical to support or protection of human life. You have now repeatedly demonstrated your incompetence to do so in a public forum.
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
But that's separate from the point I was making, which is that the inverted pendulum problem, without further complications, does not require advanced math to solve if your feedback/control loop is fast enough.
Unless you qualify a PID control system as a relatively simple feedback system, particularly when applied to a linearized system (which is what appears to be the case -- extremely fast observation and actuation make it easier to make a small angle assumption). PID controllers are something you can learn in an undergrad control class. While a complete understanding of their behavior and the art of designing one for a given system can be very challenging, the concepts are straightforward. I'd consider a non-linear Lyapunov controller or something with a measure of optimality in it to be a 'complex' feedback algorithm.
And I learned all this at a lowly state school (Texas A&M to be precise). I'm happy that Ms. Public can understand the fundamentals of it.
I was thinking the same thing myself. The video starts with a hand on the pencil, so you don't get to see the pencil actually placed. At the end, it's like the platform is pulled to the corner while the pencil is removed. It should be fairly easy to snag the pencil while the device is operating, but instead it's a drawn out drag to the corner. And what's the left hand doing off camera at the very end of the video?
Real, fake? I can't say. The way the video is shown makes me suspect it's fake.
"Lame" - Galaxar
:-)
I'm glad someone is paying attention. :-)
I was just watching some Star Trek: Enterprise episodes and when I saw all these big starships (Andorian vs. Vulcan in that case) shooting at each other, it just seemed, well, here they have warp drive, anti-matter energy, anti-gravity, and all they can think to do with it all is fight over some planets, when the whole universe is full of matter they can use to reorganize into space habitats and starships?
Anyway, I'm not saying you don't make a good point. But this is a deep issue that seems to me is being widely ignored. It relates to so many of these issue coming up as we approach one or more singularities. How do you suggest I approach that?
A 21st century issue: the irony of technologies of abundance in the hands of those still thinking in terms of scarcity.
A decade or so ago, I was really into nanotechnology, and proselytized to all who would listen and many who wouldn't. I got somewhere with it, but mostly I just wasted time and money (and annoyed the pig). I'm not sure how best to approach it; the singularities are, by definition, "opaque" as in it's very difficult to know what's going to happen on the other side, due to the rapid technological change that we will experience.
I mean, just understanding the digital abundance is difficult for some. I signed my folks up for Netflix yesterday, and that got my dad to understand it partially, "Wow we can watch just about any movie" (except, of course, the first 3 he looked up...). But trying to explain to him that in the future, he'd be able to choose "Corvette" from the Netflix menu and one would appear in his yard, he said "yeah in science fiction"; he's clearly not ready.
I'm very much looking forward to the day when I can make reliable personal backups, so traveling will no longer have risk.
But in a very real sense, we will never be "post-scarcity". One of my goals is to Dyson-sphere off every available star, rationing the energy so that we can make the universe live longer (we know it will die a heat death rather than collapse, as of about 15 years ago). So even once we've achieved nanotechnology, we'll still be in conflict with other life forms that like their stars the way they are, thanks.
Anyway, last night's post was somewhat similar to the reaction I had about 30 pages into "The Gripping Hand", which was "please dear god let them stop using that phrase!" :)
I feel fantastic, and I'm still alive.
the PID algorithm is four lines of code. the RST also. But to prove the properties of either, you must understand Z-transforms (which really are Laplace transforms for sampled functions).
You can tune your PID using Ziegler-Nicholls, and that requires absolutely no knowledge of maths. To tune it optimally, you need a very good physical model, and pretty involved maths.
So I don't know what the other guy's argument were, but you might have been both perfectly right.
People have been doing this since the 90s. Here is a paper where they say they use a 30 fps camera. I am sure you can find an older one. I saw one in 1996. http://www.manuelstuflesser.net/stuflesser_paper.pdf Also, if you ask CV people they don't think they are part of AI. Some of them use AI, but there are many tools used.
Do not balance pencil on remaining retina .(
Fixed that for you. :D