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Evolved antenna

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Re: Evolved antenna

#41

Post by dnautics »

scrooched_moose wrote: post #39
sevensor wrote: post #27

Earlier quoted context omitted.

There's a reason that conventional design uses models that abstract away the particulars -- in this case the evolved solution isn't robust to process variation in the FPGA. It's really easy for optimization to exploit irrelevant details to give you designs that aren't very useful. I'm no skeptic when it comes to EAs -- I did my dissertation using them, and I've subsequently written one of my own -- but you have to ha…

Are you aware of anyone who has recreated the process, except with a large pool of different FPGAs from different manufacturers and running designs on a random one each time? I'd imagine with even a moderate pool (~10?) the variation falls away and you're left with a robust design, although the process will take significantly longer.

apparently it is not possible because contemporary FPGAs do not give you low-level access to modify the floorplan.

Re: Evolved antenna

#42

Post by dnautics »

not in the article (or the linked): Over the lifetime of the spacecraft, Did it perform as well or better than the conventional? Does anyone know?

Re: Evolved antenna

#43

Post by chiph »

mrguyorama wrote: post #14
dbcurtis wrote: post #6

Interesting to see this antenna here. I heard the creator speak at a local IEEE event a few years ago. Quite remarkable. Nobody would intuit an antenna design like that. Great demonstration of the power of GA. Antenna optimization software has changed antenna design completely. Before wide-spread computer simulation, there was an awful lot of antenna range cut-and-try. Antennas are much better now. Learning to drive…

Another good example of this is fractal antenna design that allowed significant efficiency/space improvements in mobile phones and allowed one physical antenna to work for multiple frequencies quite well. https://en.wikipedia.org/wiki/Fractal_antenna

One of my high-school science-fair projects was a fractal high voltage insulator. The idea was that since high voltage follows the surface of an object, why not give it a lot of surface to run out of energy on? I failed of course - the ceramic was too hard to work (I dulled so many saw blades). And I didn't have an oven to bake it at the required temperature profile, nor a high-voltage lab to test my designs. But a cool idea anyway.

Re: Evolved antenna

#44

Post by caf »

dbcurtis wrote: post #6

Interesting to see this antenna here. I heard the creator speak at a local IEEE event a few years ago. Quite remarkable. Nobody would intuit an antenna design like that. Great demonstration of the power of GA. Antenna optimization software has changed antenna design completely. Before wide-spread computer simulation, there was an awful lot of antenna range cut-and-try. Antennas are much better now. Learning to drive…

...there was an awful lot of antenna range cut-and-try.

My mother's beach house still has a shed full of various aluminium pieces, many of them part of a range of semi- or fully-built customised Yagi designs, the legacy of years of my father's cut-and-try attempts to optimise very marginal UHF television reception.

Re: Evolved antenna

#45

Post by therein »

scrooched_moose wrote: post #17
aequitas wrote: post #7

Reminds me of an old article about evolutionary circuit design. The computer was tasked with creating a osscilator using physical hardware. It created a really complex and unconventional design that no-one understood, but it worked, only not work outside of the lab. As it turned out the algorithm had designed it in a way that it used the radio noise from the computer it was running on as a source. It had effectively…

Was it Creatures From Primordial Silicon? http://www.netscrap.com/netscrap_detail.cfm?scrap_id=73 They used a FPGA for voice detection. It was fascinating they didn't understand how it worked, and it wasn't a universal design because it depended on manufacturing variation.

Thanks for sharing that. This was an absolutely fascinating read. I am assuming there are many contemporary projects that replicated this workflow with modern FPGA, right? Anything on GitHub? I have a TinyFPGA sitting here, I could try stuff on that.

Re: Evolved antenna

#46

Post by namibj »

dnautics wrote: post #41
scrooched_moose wrote: post #39

Earlier quoted context omitted.

Are you aware of anyone who has recreated the process, except with a large pool of different FPGAs from different manufacturers and running designs on a random one each time? I'd imagine with even a moderate pool (~10?) the variation falls away and you're left with a robust design, although the process will take significantly longer.

apparently it is not possible because contemporary FPGAs do not give you low-level access to modify the floorplan.

They don't force -sign the bitstream. iCE40 is also afaik reversed.

Re: Evolved antenna

#47

Post by dbcurtis »

guelo wrote: post #37
dbcurtis wrote: post #29

Earlier quoted context omitted.

Well..... for some definition of accurate. For large antennas with thin structures, the typical solver is "Method of Moments". NEC2 was developed by the government and is public domain. It is quite popular, and does some things well but it is also easy to stumble into modeling bugs/deficiencies, and isn't much use above high UHF. But is very useful if you know how not to step in the bugs, and is free. NEC4 falls unde…

Sounds like there's some manual steps to create the simulation. I'm wondering how these genetic algorithms can automatically feed into the simulation and get back a single number to drive the GA fitness function.

Well, I used a Yagi optimizer at one point. With that system, the antenna was parameterized. I specified certain fixed values, like overall boom length and nominal element diameter, and total number of elements. The element lengths and spacings were free for optimization. Fitness function was a scoring of front-to-back ratio, front-to-side ratio, and max allowable SWR over a frequency range of interest, with a goal of maximum forward gain. The optimizer tuned the free variables.

For different applications the various scoring measurements would be adjusted differently. (Sometimes you care greatly about minimizing back and side lobes, other times not so much, for instance.)

Re: Evolved antenna

#48

Post by PavlovsCat »

aequitas wrote: post #7

Reminds me of an old article about evolutionary circuit design. The computer was tasked with creating a osscilator using physical hardware. It created a really complex and unconventional design that no-one understood, but it worked, only not work outside of the lab. As it turned out the algorithm had designed it in a way that it used the radio noise from the computer it was running on as a source. It had effectively…

It was also in this list:

https://news.ycombinator.com/item?id=18415031

> Genetic algorithm is supposed to configure a circuit into an oscillator, but instead makes a radio to pick up signals from neighboring computers

Re: Evolved antenna

#49

Post by namibj »

chiph wrote: post #43
mrguyorama wrote: post #14

Earlier quoted context omitted.

Another good example of this is fractal antenna design that allowed significant efficiency/space improvements in mobile phones and allowed one physical antenna to work for multiple frequencies quite well. https://en.wikipedia.org/wiki/Fractal_antenna

One of my high-school science-fair projects was a fractal high voltage insulator. The idea was that since high voltage follows the surface of an object, why not give it a lot of surface to run out of energy on? I failed of course - the ceramic was too hard to work (I dulled so many saw blades). And I didn't have an oven to bake it at the required temperature profile, nor a high-voltage lab to test my designs. But a c…

You want a shere/distance/minimize maximum curvature.

Re: Evolved antenna

#50

Post by Izkata »

scrooched_moose wrote: post #17
aequitas wrote: post #7

Reminds me of an old article about evolutionary circuit design. The computer was tasked with creating a osscilator using physical hardware. It created a really complex and unconventional design that no-one understood, but it worked, only not work outside of the lab. As it turned out the algorithm had designed it in a way that it used the radio noise from the computer it was running on as a source. It had effectively…

Was it Creatures From Primordial Silicon? http://www.netscrap.com/netscrap_detail.cfm?scrap_id=73 They used a FPGA for voice detection. It was fascinating they didn't understand how it worked, and it wasn't a universal design because it depended on manufacturing variation.

I remember reading this years ago, and always found this part by far the most interesting:

> A further five cells appeared to serve no logical purpose at all--there was no route of connections by which they could influence the output. And yet if he disconnected them, the circuit stopped working.

> It appears that evolution made use of some physical property of these cells--possibly a capacitive effect or electromagnetic inductance--to influence a signal passing nearby. Somehow, it seized on this subtle effect and incorporated it into the solution.

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