5 ms·

Tensegrity

60 points by ics 12y ago

gkop 12y ago
Probably the very coolest way to set up a hammock: https://www.youtube.com/playlist?list=PL4IGA3iO2R62SAhLcIbKE2fCAcXbY-1K9 https://www.youtube.com/playlist?list=PL4IGA3iO2R62SAhLcIbKE...
kristopolous 12y ago
There's a lot more to this... I've been a fan of these studies for a long time in the way of holistic dynamic analysis of systems - problems that usually get a statistical analysis approach. I think there's another school of thought that can lead to higher fidelity predictions - and these tensegrity systems are examples of that nonformalized and unstudied school. Although these systems can be treated through classical analysis, there's something a bit more compelling about how they are truly faceted in ways that facilitate further nuanced analysis - and not the other way around, where the systems are a product of an analysis. It's a short-circuiting of the classical methods of scientific analysis and somewhat defies the limitation of models that we are so accustomed to. Instead, they embody an underlying system with dynamic networked coherent responses. I've thought that there's something fundamentally different about them and a way to punch through some of the computational, analytical, and measurement barriers presented by classical analysis on traditional systems. I've met one person, http://ti.arc.nasa.gov/profile/Vytas_SunSpiral/ http://ti.arc.nasa.gov/profile/Vytas_SunSpiral/ who thought the same way I have with a requisite technical background to see the implications of this school of thought, and so far, that is all other than perhaps, Buckminster Fuller in his 1982 book, Synergetics - which deals with the same concept. I worked on this a few years and then I put it down, about 12 years ago. I hit the end of my cognitive ability in the research and haven't returned. It's a redefinition of analytical engagement. The classical Aristotelian discreteness is a limiting factor in its development. Stepping outside this while maintaining a descriptive formality of what constitutes this form of analysis is exceedingly difficult. I apologize that this is so vague but it is, for the most part, completely unexplored. I think there's a very real possibility of coming up with a divergent philosophy of science with a completely different disciplinary system - but with higher accuracy and fidelity of analysis and results of some of the problems which are for intents and purposes, currently intractable due to the compounding effects of being multi-faceted systemic problems. Here we are, we can construct highly-coupled, dynamic, reactive, but ultimately stable systems - the same class of systems we see in our "unformed" natural world. That's the key insight - that this is a real thing and that there is a distinct and different way of dealing with it - and that it can be exploited generally. This I believe, is inherently revolutionary. If you've read all this and don't think I'm nutso, then congratulations, we can work together maybe. Just respond below. I think this could honestly be the most productive and meaningful project that people could ever engage themselves in.
- FiatLuxDave 12y ago
  I saw Vytas' presentation at the NIAC symposium a few weeks ago, and as someone whose only previous exposure to tensegrity systems was the typical outsider's view of its use in architecture and toys, I have to say that his robots are damn cool. I'll post a link to the video after I get out of the meeting I have in a few minutes, if no one beats me to it. If you haven't seen this stuff it's worth seeing just for the cool factor alone. I agree with you that one of the most difficult things about tensegrity structures is predicting their behaviour under stress and failure - and since behaviour under exactly those circumstances is also one of the main strengths of the concept, that kinda sucks. It's like trying to sell a car which gets better gas mileage, but you can't really predict how much. Better but unpredictably better can be a hard sell and especially bad when trying to optimize a plan for. I see a lot of parallels between the concept of tensegrity and certain concepts of resilient design of complex software. In both cases, testing (and having good test cases) is a vital component of testing. In both cases, even with testing it is hard to have a good predictive model of failure, because at a certain level the complexity of test cases can start to compete with the design itself. What I see as the really cool thing about what Vytas is doing, is the addition of controls (e.g. motors etc) to tensegrity structures. This only adds to the complexity when it comes to testing, because now there are many more variables. However, if this is a huge issue, it is theoretically possible to set the controls in such a way that it actually reduces the space of possible behaviours, and thus makes analysis more tractable. Of course, I think it's much cooler to go the other way and make the darn things do crazy stuff, but it all depends upon what you need out of a design. It's somewhat the same issue with a robotic arm: it can move in so many ways, sometimes the easy or safest way to do a job is to restrict the possibilities (like not letting it move into a danger zone). But making it dance is more fun!
  - akagogino 12y ago
    I'm working with Vytas at NASA on the control issues for these tensegrity robots. One of our main ways to address the complexity issue is to use machine learning to determine control parameters. We have been using traditional evolutionary techniques as well as some techniques related to importance sampling. A counterintuitive result of using evolutionary controls is that the control problem does not necessarily become more difficult as the complexity of the structure increases. This is because the number of good solutions may increase faster than the solution space. Currently in hardware, we are building relatively simple structures, but we hope to expand to more complex ones in the future.
whiddershins 12y ago
there's a cool book called Anatomy Trains that analyzes the elements of the human body as forming a tensegretic structure, rather than a compression structure. So don't think of all the bones stacking on top of each other like stone, but instead being held in constant tension by muscles and ligaments. Also in the introduction it shows you how to make a tensegretic tetrahedron out of chopsticks and rubber bands. Pretty good stuff. http://www.anatomytrains.com/fascia/tensegrity/ http://www.anatomytrains.com/fascia/tensegrity/
lotsofmangos 12y ago
Cellular cytoskeletons are another interesting area to look for these kind of structures.
gdubs 12y ago
I went through a period of being obsessed with Buckminster Fuller's work. I took a trip to Montreal to visit the Canadian Centre for Architecture a while back, and at the library got to view this old construction kit called Tensegritoy. [1] 1: http://tensegrity.wikispaces.com/Tensegritoy http://tensegrity.wikispaces.com/Tensegritoy
nvader 12y ago
Reminds me of the Stick Bomb. http://en.wikipedia.org/wiki/Stick_bomb http://en.wikipedia.org/wiki/Stick_bomb
- Duhveed 12y ago
  especially when a cable snaps
- throw_away 12y ago
  from the references: http://lunatim.com/kinart/stickhistory.htm http://lunatim.com/kinart/stickhistory.htm this is amazing. now I'm strongly resisting the urge to order a couple hundred tongue depressors.
  - ars 12y ago
    > now I'm strongly resisting the urge to order a couple hundred tongue depressors. Give in: http://smile.amazon.com/gp/product/B0033F7YQW/ http://smile.amazon.com/gp/product/B0033F7YQW/
agumonkey 12y ago
Ha, I was thinking about similar system but non static, absorbing multi-state ones. Fuels my curiosity back, so thanks.
Duhveed 12y ago
love tensegrity! I'm working on a springy tensegrity bar stool.
ribs 12y ago
Every year I've gone to Burning Man I've lived in a tensegrity-supported structure. See http://shelter-systems.com http://shelter-systems.com
- kd5bjo 12y ago
  Tensegrity structures don't have any internal bending forces, just tension and compression. Those tents appear to be based on bent or curved struts exerting forces in several directions, so I doubt they're actually tensegrity structures.
Animats 12y ago
Designing structures such that all elements are either in tension or compression, with no bend moments, used to be very important in the era of iron bridges. Truss type railroad bridges were built that way. Often the joints were actual pins, so that no bend moment could be applied at a joint. Iron didn't handle bend moments well, but cast iron could handle pure compression and wrought iron could handle pure tension. Steel is equally strong in tension and compression, and once good steel became cheap, structural design was much less constrained. (Mass production of steel came later than is generally realized. Until about 1890, good steel was about as rare as titanium is now. Steel swords go back a long way, but I-beams don't.)
nazca 12y ago
I just bought a "Tensegrity" tent... it isn't pure tensegrity (there is one small bent pole) but it gets close. https://www.sierradesigns.com/product/tensegrity-2-elite https://www.sierradesigns.com/product/tensegrity-2-elite
andrewliebchen 12y ago
Diller + Scofidio's Blur building (http://www.dsrny.com/#/projects/blur-building http://www.dsrny.com/#/projects/blur-building), in addition to being an awesome environmental experience, was a tensegrity structure.
ealloc 12y ago
What happens if a single cable snaps? It seems like all the strucutral members in the network will then experience a "bending moment", yet the structure depended on the lack of bending moment for rigidity.

60 points by ics 12y ago

gkop 12y ago

Probably the very coolest way to set up a hammock: https://www.youtube.com/playlist?list=PL4IGA3iO2R62SAhLcIbKE2fCAcXbY-1K9 https://www.youtube.com/playlist?list=PL4IGA3iO2R62SAhLcIbKE...

kristopolous 12y ago

There's a lot more to this... I've been a fan of these studies for a long time in the way of holistic dynamic analysis of systems - problems that usually get a statistical analysis approach. I think there's another school of thought that can lead to higher fidelity predictions - and these tensegrity systems are examples of that nonformalized and unstudied school. Although these systems can be treated through classical analysis, there's something a bit more compelling about how they are truly faceted in ways that facilitate further nuanced analysis - and not the other way around, where the systems are a product of an analysis. It's a short-circuiting of the classical methods of scientific analysis and somewhat defies the limitation of models that we are so accustomed to. Instead, they embody an underlying system with dynamic networked coherent responses. I've thought that there's something fundamentally different about them and a way to punch through some of the computational, analytical, and measurement barriers presented by classical analysis on traditional systems. I've met one person, http://ti.arc.nasa.gov/profile/Vytas_SunSpiral/ http://ti.arc.nasa.gov/profile/Vytas_SunSpiral/ who thought the same way I have with a requisite technical background to see the implications of this school of thought, and so far, that is all other than perhaps, Buckminster Fuller in his 1982 book, Synergetics - which deals with the same concept. I worked on this a few years and then I put it down, about 12 years ago. I hit the end of my cognitive ability in the research and haven't returned. It's a redefinition of analytical engagement. The classical Aristotelian discreteness is a limiting factor in its development. Stepping outside this while maintaining a descriptive formality of what constitutes this form of analysis is exceedingly difficult. I apologize that this is so vague but it is, for the most part, completely unexplored. I think there's a very real possibility of coming up with a divergent philosophy of science with a completely different disciplinary system - but with higher accuracy and fidelity of analysis and results of some of the problems which are for intents and purposes, currently intractable due to the compounding effects of being multi-faceted systemic problems. Here we are, we can construct highly-coupled, dynamic, reactive, but ultimately stable systems - the same class of systems we see in our "unformed" natural world. That's the key insight - that this is a real thing and that there is a distinct and different way of dealing with it - and that it can be exploited generally. This I believe, is inherently revolutionary. If you've read all this and don't think I'm nutso, then congratulations, we can work together maybe. Just respond below. I think this could honestly be the most productive and meaningful project that people could ever engage themselves in.

FiatLuxDave 12y ago
I saw Vytas' presentation at the NIAC symposium a few weeks ago, and as someone whose only previous exposure to tensegrity systems was the typical outsider's view of its use in architecture and toys, I have to say that his robots are damn cool. I'll post a link to the video after I get out of the meeting I have in a few minutes, if no one beats me to it. If you haven't seen this stuff it's worth seeing just for the cool factor alone. I agree with you that one of the most difficult things about tensegrity structures is predicting their behaviour under stress and failure - and since behaviour under exactly those circumstances is also one of the main strengths of the concept, that kinda sucks. It's like trying to sell a car which gets better gas mileage, but you can't really predict how much. Better but unpredictably better can be a hard sell and especially bad when trying to optimize a plan for. I see a lot of parallels between the concept of tensegrity and certain concepts of resilient design of complex software. In both cases, testing (and having good test cases) is a vital component of testing. In both cases, even with testing it is hard to have a good predictive model of failure, because at a certain level the complexity of test cases can start to compete with the design itself. What I see as the really cool thing about what Vytas is doing, is the addition of controls (e.g. motors etc) to tensegrity structures. This only adds to the complexity when it comes to testing, because now there are many more variables. However, if this is a huge issue, it is theoretically possible to set the controls in such a way that it actually reduces the space of possible behaviours, and thus makes analysis more tractable. Of course, I think it's much cooler to go the other way and make the darn things do crazy stuff, but it all depends upon what you need out of a design. It's somewhat the same issue with a robotic arm: it can move in so many ways, sometimes the easy or safest way to do a job is to restrict the possibilities (like not letting it move into a danger zone). But making it dance is more fun!
- akagogino 12y ago
  I'm working with Vytas at NASA on the control issues for these tensegrity robots. One of our main ways to address the complexity issue is to use machine learning to determine control parameters. We have been using traditional evolutionary techniques as well as some techniques related to importance sampling. A counterintuitive result of using evolutionary controls is that the control problem does not necessarily become more difficult as the complexity of the structure increases. This is because the number of good solutions may increase faster than the solution space. Currently in hardware, we are building relatively simple structures, but we hope to expand to more complex ones in the future.

whiddershins 12y ago

there's a cool book called Anatomy Trains that analyzes the elements of the human body as forming a tensegretic structure, rather than a compression structure. So don't think of all the bones stacking on top of each other like stone, but instead being held in constant tension by muscles and ligaments. Also in the introduction it shows you how to make a tensegretic tetrahedron out of chopsticks and rubber bands. Pretty good stuff. http://www.anatomytrains.com/fascia/tensegrity/ http://www.anatomytrains.com/fascia/tensegrity/

lotsofmangos 12y ago

Cellular cytoskeletons are another interesting area to look for these kind of structures.

gdubs 12y ago

I went through a period of being obsessed with Buckminster Fuller's work. I took a trip to Montreal to visit the Canadian Centre for Architecture a while back, and at the library got to view this old construction kit called Tensegritoy. [1] 1: http://tensegrity.wikispaces.com/Tensegritoy http://tensegrity.wikispaces.com/Tensegritoy

nvader 12y ago

Reminds me of the Stick Bomb. http://en.wikipedia.org/wiki/Stick_bomb http://en.wikipedia.org/wiki/Stick_bomb

Duhveed 12y ago
especially when a cable snaps
throw_away 12y ago
from the references: http://lunatim.com/kinart/stickhistory.htm http://lunatim.com/kinart/stickhistory.htm this is amazing. now I'm strongly resisting the urge to order a couple hundred tongue depressors.
- ars 12y ago
  > now I'm strongly resisting the urge to order a couple hundred tongue depressors. Give in: http://smile.amazon.com/gp/product/B0033F7YQW/ http://smile.amazon.com/gp/product/B0033F7YQW/

agumonkey 12y ago

Ha, I was thinking about similar system but non static, absorbing multi-state ones. Fuels my curiosity back, so thanks.

Duhveed 12y ago

love tensegrity! I'm working on a springy tensegrity bar stool.

ribs 12y ago

Every year I've gone to Burning Man I've lived in a tensegrity-supported structure. See http://shelter-systems.com http://shelter-systems.com

kd5bjo 12y ago
Tensegrity structures don't have any internal bending forces, just tension and compression. Those tents appear to be based on bent or curved struts exerting forces in several directions, so I doubt they're actually tensegrity structures.

Animats 12y ago

Designing structures such that all elements are either in tension or compression, with no bend moments, used to be very important in the era of iron bridges. Truss type railroad bridges were built that way. Often the joints were actual pins, so that no bend moment could be applied at a joint. Iron didn't handle bend moments well, but cast iron could handle pure compression and wrought iron could handle pure tension. Steel is equally strong in tension and compression, and once good steel became cheap, structural design was much less constrained. (Mass production of steel came later than is generally realized. Until about 1890, good steel was about as rare as titanium is now. Steel swords go back a long way, but I-beams don't.)

nazca 12y ago

I just bought a "Tensegrity" tent... it isn't pure tensegrity (there is one small bent pole) but it gets close. https://www.sierradesigns.com/product/tensegrity-2-elite https://www.sierradesigns.com/product/tensegrity-2-elite

andrewliebchen 12y ago

Diller + Scofidio's Blur building (http://www.dsrny.com/#/projects/blur-building http://www.dsrny.com/#/projects/blur-building), in addition to being an awesome environmental experience, was a tensegrity structure.

ealloc 12y ago

What happens if a single cable snaps? It seems like all the strucutral members in the network will then experience a "bending moment", yet the structure depended on the lack of bending moment for rigidity.