Genetic Algorithms
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`vbgraphix
`Genetic Algorithms
`January 11, 2009 04:35AM
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`Advanced
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`Registered: 15 years ago
`Posts: 8
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`I'm wondering what applications Genetic Algorithms could have in improving RepRap.
`
`It shouldn't be too hard to use software-based optimizers that can improve our circuits, designs,
`etc.
`
`Thoughts?
`
`nophead
`Re: Genetic Algorithms
`January 11, 2009 05:38AM
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`Posts: 7,881
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`I doubt software could improve the design any better than 1000's of people making Repraps and
`tweaking the design as they go. That is really gathering momentum this year. It is like genetic
`evolution in so much as the best design aspects survive and the things that don't work get dropped
`but the mutations are not random, they are hopefully intelligent design.
`
`[www.hydraraptor.blogspot.com]
`
`Forrest Higgs
`Re: Genetic Algorithms
`January 11, 2009 08:45AM
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`Posts: 1,915
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`I've written genetic algorithms in my day job in years past. The question isn't one of whether they
`could improve outcomes. They definitely could. The question is more one of who wants to invest
`the man-hours to apply the method to these particular applications. It's not something I have time
`for.
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
`1
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`Shenzhen Tuozhu 1010
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`

`

`Genetic Algorithms
`
`-------------------------------------------------------
`
`Hell, there are no rules here - we're trying to accomplish something.
`
`Opportunity is missed by most people because it is dressed in overalls and looks like work.
`
`Thomas A. Edison
`
`nophead
`Re: Genetic Algorithms
`January 11, 2009 08:50AM
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`Plus somebody would have to be a slave to the genetic software, building and testing the variants,
`unless the software had a brilliant physics simulator in it. As most of the random mutations would
`be no hope dead ends it would be a lot of work, most of it pointless.
`
`[www.hydraraptor.blogspot.com]
`
`Forrest Higgs
`Re: Genetic Algorithms
`January 11, 2009 08:54AM
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`Reply Quote
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`Admin
`Registered: 17 years ago
`Posts: 1,915
`
`>>
`
`unless the software had a brilliant physics simulator in it.
`
`>Y
`
`eah, I should have mentioned that bit. Unless you have an evaluation function, you can't have
`genetic algorithms. I don't think that we have any that can be reduced to pseudocode.
`
`-------------------------------------------------------
`
`Hell, there are no rules here - we're trying to accomplish something.
`
`Opportunity is missed by most people because it is dressed in overalls and looks like work.
`
`Thomas A. Edison
`
`Batist
`Re: Genetic Algorithms
`January 11, 2009 09:24AM
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
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`Registered: 16 years ago
`Posts: 32
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`2
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`

`

`Genetic Algorithms
`
`There are some brilliant physics simulators available...
`For example [www.bulletphysics.com] (C++ & Java)
`Or [www.ode.org] (C++)
`
`However, it doesn't solve the evaluation function problem...
`
`---
`[www.coded.be]
`
`nophead
`Re: Genetic Algorithms
`January 11, 2009 09:34AM
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`They might be brilliant but I would be very surprised if you could input a 3D model including its
`materials and simulate the extruder building an object, predicting all the defects like stringing and
`warping and working out how long it would take for things to wear out. Sounds like science fiction
`to me.
`
`[www.hydraraptor.blogspot.com]
`
`Forrest Higgs
`Re: Genetic Algorithms
`January 11, 2009 09:38AM
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`Posts: 1,915
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`There have been some very science fictiony things done with genetic algorithms. I've done one or
`two.
` I fear, though, that the app proposed here is simply too fuzzily defined to yield useful
`results.
`
`-------------------------------------------------------
`
`Hell, there are no rules here - we're trying to accomplish something.
`
`Opportunity is missed by most people because it is dressed in overalls and looks like work.
`
`Thomas A. Edison
`
`Samuel
`Re: Genetic Algorithms
`January 12, 2009 06:45PM
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
`Reply Quote
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`Registered: 17 years ago
`Posts: 82
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`3
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`

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`Genetic Algorithms
`
`I'd be interested in hearing about your experiences with GA, Forrest. Unfortunately, it probably isn't
`related enough to reprap to post here. Got any better ideas?
`
`On a more topic related note: Yes, the extruder physics stuff would be hard to do with GA, but the
`suggestion about circuit boards would be more approachable.
`
`Maybe you could use it to come up with a better slicing/filling algorithm for the software, or use GA
`to design better corner brackets that use less material, but are just as strong. That should be
`possible to simulate without a fancy filament warping function.
`
`Do you think any of those physics sims could tell us how far apart our fill threads can be without
`sagging too much? Saving on material and build time is certainly a worthy goal, even without
`achieving higher accuracy in model shape.
`
`VDX
`Re: Genetic Algorithms
`January 13, 2009 03:25AM
`
`Hi Forrest,
`
`Reply Quote
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`Admin
`Registered: 17 years ago
`Posts: 13,988
`
`actual working GA-samples would be interesting for me too.
`
`20 years ago i made some 'traveling salesmen'-optimisation with a neural-network-chain for CNC-
`drilling PCB's on my Atari-ST and hoped to develop a 'self-trained' perfect 3D-CNC-controller, but
`then my diploma examinations went hot and i somehow lost contact ...
`
`Viktor
`
`Forrest Higgs
`Re: Genetic Algorithms
`January 13, 2009 07:34AM
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`Admin
`Registered: 17 years ago
`Posts: 1,915
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`I doubt that my GA samples would be of much use to the effort contemplated. The major effort I
`undertook was to simulate heritable IQ drift over several centuries in traditionalRussian Jewish
`Shtetl and Nguni kraals.
`
`-------------------------------------------------------
`
`Hell, there are no rules here - we're trying to accomplish something.
`
`Opportunity is missed by most people because it is dressed in overalls and looks like work.
`
`Thomas A. Edison
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
`4
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`

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`Genetic Algorithms
`
`VDX
`Re: Genetic Algorithms
`January 13, 2009 07:40AM
`
`... aiii
`
`Reply Quote
`
`Admin
`Registered: 17 years ago
`Posts: 13,988
`
`By the way ... could you prove true the effect of IQ-multiplying when two long time separated
`genetic lines recombine?
`
`Viktor
`
`Forrest Higgs
`Re: Genetic Algorithms
`January 13, 2009 10:19AM
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`Reply Quote
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`Admin
`Registered: 17 years ago
`Posts: 1,915
`
`VDX Wrote:
`-------------------------------------------------------
`> ... aiii
`>
`> By the way ... could you prove true the effect of
`> IQ-multiplying when two long time separated
`> genetic lines recombine?
`>
`I'd need a clearer statement of the proposition that I think that you are making. Got any prior art or
`links you can point me at?
`
`-------------------------------------------------------
`
`Hell, there are no rules here - we're trying to accomplish something.
`
`Opportunity is missed by most people because it is dressed in overalls and looks like work.
`
`Thomas A. Edison
`
`VDX
`Re: Genetic Algorithms
`January 13, 2009 10:49AM
`
`Hi Forrest,
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
`Reply Quote
`
`Admin
`Registered: 17 years ago
`Posts: 13,988
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`5
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`

`

`Genetic Algorithms
`
`... no links ... i read this somewhere and was interested if it's true that crossbreeded animals (or
`people too) between long time separated genetic lines are significantly shrewder than their parents
`
`Viktor
`
`Nil Einne
`Re: Genetic Algorithms
`January 13, 2009 11:08AM
`
`Reply Quote
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`Registered: 16 years ago
`Posts: 84
`
`Your thinking of hybrid vigour [en.wikipedia.org] . However it's not really applicable here since it's
`most evident when the parents are highly inbred, usually in artifical selection cases where people
`have been inbreeding the plants/animals for years. I doubt any of the RepRap stuff qualifies and in
`any case, to work you'd need to actually have some sort of genetic algorythm at work in the
`background which we don't. Taking the best features from each model out there is not the same
`thing (even if it may be a good strategy.)
`
`Also whether it has any real application to humans is also quite controversial. Sure if you're talking
`about highly inbred populations outbreeding has clear advantages but it may not make so much
`difference with humans since despite what the KKK et al want us to believe humans are actually a
`(mostly) incredibly mixed population.
`
`Edited 1 time(s). Last edit at 01/13/2009 11:09AM by Nil Einne.
`
`Forrest Higgs
`Re: Genetic Algorithms
`January 13, 2009 11:44AM
`
`Reply Quote
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`Admin
`Registered: 17 years ago
`Posts: 1,915
`
`With generational genetic drift in a more or less homogeneous population you have some fairly
`well-understood statistical mechanisms. The most usual one you see says that the IQ of children of
`a couple will fall within a fairly narrow distribution curve the mean of which can be taken to be the
`average of the parents' respective IQ's.
`
`I modeled two situations, the first was a Jewish Shtetl in which bright males were identified quite
`early in life and encouraged to undertake rabbinic studies. Socially, such males, on completing
`their studies were considered prized marriage material by the Shtetl and pretty much had their pick
`of eligible young women. The rabbi's family was also expected to be large and the children thereof
`were similarly considered to be prized marriage material.
`
`The question that I posed was one of accepting this social mechanism for encouraging bright
`males to have large families who were married back into the community, how long would it take for
`the mean IQ of the Stetl to exhibit the 10 point IQ advantage that Jewish populations consistently
`show over other european populations. The answer came out to about 250 years. I ran about a
`dozen variations on the scenario and found that the time frame only deviated from 250 years by
`about +/-20 to 30 years.
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
`6
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`Genetic Algorithms
`
`Against that I modeled a the marriage and child rearing customs common in southern African
`Nguni kraal where families accumulate capital over generations and the family patriarch is able to
`purchase multiple wives which aid him in capital accumulation. My genetic models of that
`mechanism typically showed an extremely gentle downward drift of population IQ. The drift that I
`detected was so small that I wouldn't vouch for it even existing. The IQ drift for Jewish Shtetl,
`however, was very pronounced and much stronger than I would have guessed before the modeling
`exercise.
`
`The problem with the crossbreeding, as it were, of human populations with respect to IQ is that
`most of the information that we have comes from the 20th century. During that period the Flynn
`Effect complicates separating out IQ drift resulting from other factors.
`
`Someday, if I am spared for long enough, I hope to revisit that exploration and maybe get a handle
`on why the Flynn Effect set off the massive upwards IQ drift that it did in the 20th century in the
`industrialised world. Knowing the hows and whys of the Flynn Effect would be VERY interesting.
`
`-------------------------------------------------------
`
`Hell, there are no rules here - we're trying to accomplish something.
`
`Opportunity is missed by most people because it is dressed in overalls and looks like work.
`
`Thomas A. Edison
`
`Forrest Higgs
`Re: Genetic Algorithms
`January 13, 2009 11:54AM
`
`Reply Quote
`
`Admin
`Registered: 17 years ago
`Posts: 1,915
`
`Nil Einne Wrote:
`-------------------------------------------------------
`>
`> Also whether it has any real application to humans
`> is also quite controversial. Sure if you're
`> talking about highly inbred populations
`> outbreeding has clear advantages but it may not
`> make so much difference with humans since despite
`> what the KKK et al want us to believe humans are
`> actually a (mostly) incredibly mixed population.
`
`>D
`
`NA surveys consistently indicate that genetic variation amongst humans not originating from
`subSaharan Africa is extremely slight, less by several magnitudes for all five billion of us than what
`you'd encounter in the average Chimpanzee troop.
`
`Not to put too fine a point on it, we're (the Euroasians amongst us, that is) are as inbred as a
`bunch of rough collies. That could go a long way towards explaining the average 30 point
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
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`7
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`Genetic Algorithms
`
`difference between Euroasian and subsaharan African populations. Genetically, subSaharan
`Africans are humanity's root stock, to use a good horticultural term. Most of humanity's DNA
`variation is found amongst those who never left Africa. We should guard that treasure house of
`DNA very carefully. You never know when we might really, really need it.
`
`-------------------------------------------------------
`
`Hell, there are no rules here - we're trying to accomplish something.
`
`Opportunity is missed by most people because it is dressed in overalls and looks like work.
`
`Thomas A. Edison
`
`Nil Einne
`Re: Genetic Algorithms
`January 13, 2009 03:29PM
`
`Forrest Higgs Wrote:
`-------------------------------------------------------
`> DNA surveys consistently indicate that genetic
`> variation amongst humans not originating from
`> subSaharan Africa is extremely slight, less by
`> several magnitudes for all five billion of us than
`> what you'd encounter in the average Chimpanzee
`> troop.
`
`Reply Quote
`
`Registered: 16 years ago
`Posts: 84
`
`But that's precisely my point. Given the low variation and the fact that what variation does exist has
`been shown to be not strongly linked to the concept of race, it doesn't make sense that hybrid
`vigiour would be observed. The simple fact is, as much as certain groups would like to claim
`otherwise, there is no such thing (generally speaking) as all these pure races that shouldn't mix. In
`fact, most of what we think as races don't really exist on a genetic level. So it's unlikely your going
`to get hybrid vigour and mixing or not doesn't really matter since by and large, humans are already
`mixed.
`
`> Not to put too fine a point on it, we're (the
`> Euroasians amongst us, that is) are as inbred as a
`> bunch of rough collies. That could go a long way
`> towards explaining the average 30 point difference
`> between Euroasian and subsaharan African
`> populations. Genetically, subSaharan Africans are
`> humanity's root stock, to use a good horticultural
`> term. Most of humanity's DNA variation is found
`> amongst those who never left Africa. We should
`> guard that treasure house of DNA very carefully.
`> You never know when we might really, really need
`> it.
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
`8
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`

`

`Genetic Algorithms
`
`Nil Einne
`Re: Genetic Algorithms
`January 13, 2009 04:13PM
`
`Reply Quote
`
`Registered: 16 years ago
`Posts: 84
`
`Forrest Higgs Wrote:
`-------------------------------------------------------
`> With generational genetic drift in a more or less
`> homogeneous population you have some fairly
`> well-understood statistical mechanisms. The most
`> usual one you see says that the IQ of children of
`> a couple will fall within a fairly narrow
`> distribution curve the mean of which can be taken
`> to be the average of the parents' respective
`> IQ's.
`>
`> I modeled two situations, the first was a Jewish
`> Shtetl in which bright males were identified quite
`> early in life and encouraged to undertake rabbinic
`> studies. Socially, such males, on completing
`> their studies were considered prized marriage
`> material by the Shtetl and pretty much had their
`> pick of eligible young women. The rabbi's family
`> was also expected to be large and the children
`> thereof were similarly considered to be prized
`> marriage material.
`>
`> The question that I posed was one of accepting
`> this social mechanism for encouraging bright males
`> to have large families who were married back into
`> the community, how long would it take for the mean
`> IQ of the Stetl to exhibit the 10 point IQ
`> advantage that Jewish populations consistently
`> show over other european populations. The answer
`> came out to about 250 years. I ran about a dozen
`> variations on the scenario and found that the time
`> frame only deviated from 250 years by about +/-20
`> to 30 years.
`
`I would like to know how you came out with those figures. The genetic basis for IQ is rather poorly
`understood. There is definitely an inherited component but how large it is remains an open
`question. Even if it's true "IQ of children of a couple will fall within a fairly narrow distribution curve
`the mean of which can be taken to be the average of the parents' respective IQ's" which I'm
`somewhat doubtful (most studies I've seen suggest the correlation with parental IQ is far from
`clear) this doesn't prove a genetic basis since amongst other things contrary to what some people
`claim, IQ isn't purely inate. Of course, if the correlation is there, it's possible/likely? it would
`increase whatever the cause but I would suggest that's far from certain.
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
`9
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`

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`Genetic Algorithms
`
`For that matter, IQ is poorly understood. All it actually measures is your ability to do IQ tests. There
`appears to be some correlation with what we call 'intelligence' but it's at best only a loose one.
`
`Also it doesn't sound to me like you study considered the IQ of the female partner. The fact that
`the male had the pick doesn't mean they choose the ones with the higher IQ. It's easily possible to
`imagine that they choose the ones with the IQ 10 points lower on average therefore likely
`cancelling out any advantage their higher IQ had presuming your theory of IQs holds true. Also,
`even though their children could may have been high up in the social scale, having large families
`means you can afford to devote less attention/resources to the children you have. For humans,
`having large families is not necessarily the most effective evolutionary strategy. It could easily lead
`to a lower IQ of the children and a lower chance of evolutionary success of the children which the
`social (and genetic?) advantage they have due to their parents may not be enough to make up for.
`
`Indeed there are other factors to consider. Just because the parents are encouraged to have more
`children doesn't mean they do or are able to. It may be that the high IQ is correlated with other
`factors which reduce evolutionary success. For example, if the Father is more likely to die young.
`Or for that matter beyond having more children is less able to raise the children effectively. Indeed
`even social factors could come into play. Does the increase pressure on the father to perform
`according to societal expectations lead to a lower median age at death or negatively effect the way
`they raise their children?
`
`Bringing the female into it again, regardless of the fact the father has the pick of the crop or the IQ
`of the female they select, there's no guarantee they will select the most evolutionarily successful
`females. Given the societal factors at play, it's possible that the females they pick are not the best
`choice. Perhaps for example, the females are more prone to infidelity (whose effect is going to be
`even more difficult to quantify) or has similar problems to those I raise for the father.
`
`Of course sexual selection will likely come into play. The fact that they choose the females and
`they had the pick of the crop means that whatever the traits they must be those considered most
`important amongst their community and therefore whatever inherited component of these traits
`that's passed to the children would give them an advantage even if they paradoxically also give
`them a disadvantage. (The same of course for the father.) This of course plays back into the
`societal edge the children have. But again, rather extra fitness component they have must be
`weighed against any negative effect on fitness it may also have.
`
`BTW, I would avoid the term 'drift' when talking about evolution. Drift usually refers to genetic drift
`which is random and doesn't seem to be what you're referring to. It does have to be considered in
`any calculation of evolutionary rates though.
`
`P.S. A bit tired so apologise if any of that didn't make sense. I think I covered the basics though.
`Since this is OT and not really something of great interest to me, I'll probably stop there. I have
`some background in biology so know calculating evolutionary rates is an extremely complicated
`thing. And working out how a trait will change in a certain situation even more so given the near
`infinite number of variables many of which can have a fairly large effect. Particularly in a beast as
`complicated as humans. If you haven't already, I suggest you consult an evolutionary biologist
`(which I'm guessing your not) preferbly one with a background in statistics/biometry who could
`advise you further on your calculations. I think you may not have quite understood the complexity
`of the calculations.
`P.P.S. In case I was wrong about how far you went, were any of those calculations published in a
`peer-reviewed journal?
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
`10
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`

`

`Genetic Algorithms
`
`Edited 2 time(s). Last edit at 01/13/2009 04:21PM by Nil Einne.
`
`VDX
`Re: Genetic Algorithms
`January 13, 2009 04:32PM
`
`... now, that's the real spirit
`
`Reply Quote
`
`Admin
`Registered: 17 years ago
`Posts: 13,988
`
`I found some similarities with breeding pets, cultural/social relationships between long time
`separated folks (eg. eastern and western europeans after breakdown of the Sowjet Union) and
`developing repraps/repstraps with different strategies ...
`
`Maybe there are some significant patterns we can use for faster 'rep-volution'?
`
`Viktor
`
`Forrest Higgs
`Re: Genetic Algorithms
`January 13, 2009 05:21PM
`
`Reply Quote
`
`Admin
`Registered: 17 years ago
`Posts: 1,915
`
`Nil Einne Wrote:
`-------------------------------------------------------
`
`>>
`
` There is definitely an inherited component but how large it is remains an
`> open question.
`
`> M
`
`ostly it's a politically explosive question the possible answers to which fly in the face of a half-
`century of social orthodoxy.
`
`Thank you for your review of the genetic programming project I undertook.
`
`I mentioned the content of what I did mostly in reply to Viktor's query, not from any desire to spark
`a debate about IQ or the vexed IQ vs race question. After I got my PhD in 1990 I undertook a
`number of explorations using various techniques mostly to satisfy my own curiosity and relax. This
`was one of them. One of the others was slowly, painfully working my way through the proofs of
`Kurt G
`
`Edited 1 time(s). Last edit at 01/13/2009 05:30PM by Forrest Higgs.
`
`-------------------------------------------------------
`
`Hell, there are no rules here - we're trying to accomplish something.
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
`11
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`

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`Genetic Algorithms
`
`Opportunity is missed by most people because it is dressed in overalls and looks like work.
`
`Thomas A. Edison
`
`Samuel
`Re: Genetic Algorithms
`January 13, 2009 07:47PM
`
`Fascinating.
`
`How were G
`
`Forrest Higgs
`Re: Genetic Algorithms
`January 13, 2009 07:58PM
`
`Reply Quote
`
`Registered: 17 years ago
`Posts: 82
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`Reply Quote
`
`Admin
`Registered: 17 years ago
`Posts: 1,915
`
`I used the old Nagel and Newman explication of G
`
`Edited 1 time(s). Last edit at 01/13/2009 11:41PM by Forrest Higgs.
`
`-------------------------------------------------------
`
`Hell, there are no rules here - we're trying to accomplish something.
`
`Opportunity is missed by most people because it is dressed in overalls and looks like work.
`
`Thomas A. Edison
`
`Colecoman1982
`Re: Genetic Algorithms
`January 14, 2009 01:47PM
`
`Hi,
`
`Reply Quote
`
`On the topic of applying GA (or, more generally, self-learning iterative algorithms) to reprap, my
`suggestion is that is might be more feasible than you think. You don
`
`Forrest Higgs
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
`
`Reply Quote
`
`Admin
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`12
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`Genetic Algorithms
`
`Re: Genetic Algorithms
`January 14, 2009 02:53PM
`
`Registered: 17 years ago
`Posts: 1,915
`
`Colecoman: The problem with that approach is that it presumes a very high rate of interactive
`dataflow between the PC and the reprap machine. That's not happening at the present time. Right
`now, reprap machines are either stand alone or more or less peripherals to your PC.
`
`-------------------------------------------------------
`
`Hell, there are no rules here - we're trying to accomplish something.
`
`Opportunity is missed by most people because it is dressed in overalls and looks like work.
`
`Thomas A. Edison
`
`vbgraphix
`Re: Genetic Algorithms
`January 14, 2009 03:34PM
`
`Reply Quote
`
`Registered: 15 years ago
`Posts: 8
`
`I really love the camera idea. Though, scanning may not require anything as complex as a camera.
`A camera might bring the cost up too much. A simple light detector or laser of some sort may do
`the trick.
`
`As for data flow, it shouldn't be too hard to hack together a bunch of open source monitoring
`devices to record data like temperature, speed, vibration, etc. I think that would be a very
`constructive thing to do.
`
`Wade
`Re: Genetic Algorithms
`January 14, 2009 04:10PM
`
`Reply Quote
`
`Registered: 16 years ago
`Posts: 536
`
`Hm, I don't look forward to trying to code up a vision system from scratch....
`
`but, an accelerometer on the write head might be useful. Keep an eye on the RMS power of the
`vibration the head experiences; that might be able to detect the next time I have an all-night long
`series of head collisions due to a bad programming job.
`
`A strain gauge on the extruder mount would do that as well, and it could do a few other things as
`well, like finding the bed height automatically. Could take some time though.
`
`Wade
`
`Reply Quote
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`Genetic Algorithms
`
`Mr. Seeker
`Re: Genetic Algorithms
`January 14, 2009 05:02PM
`
`Wade Wrote:
`-------------------------------------------------------
`> but, an accelerometer on the write head might be
`> useful. Keep an eye on the RMS power of the
`> vibration the head experiences; that might be able
`> to detect the next time I have an all-night long
`> series of head collisions due to a bad programming
`> job.
`
`Registered: 16 years ago
`Posts: 96
`
`Why dont you get a shock absorber? Foam works pretty well for this kind of problems
`
`The accelerometer wont be very useful if you have lots of vibration because when you want to fill a
`gap quickly, the "vibrations" will shut the machine off. Try to look at [forums.parallax.com] from
`parallax, there is shown how their X-Y accelerator works.
`
`Also thinking about the strain gauge... You could also use it to calibrate the Z-axis, but its also
`possible with IR or ultrasonic sensors... Or in the case of "money is not a problem" a webcam?
`
`Edited 2 time(s). Last edit at 01/14/2009 05:15PM by Mr. Seeker.
`
`Wade
`Re: Genetic Algorithms
`January 14, 2009 05:29PM
`
`Reply Quote
`
`Registered: 16 years ago
`Posts: 536
`
`Well, I figured that the rms power of the vibration will be much higher for stuck head situation,
`where the stepper is jumping steps at high speed. It's certainly noisy as hell when it happens!
`Should be easy to set a limit that will pass a zig zag path, but fail multiple head collisions. A single
`head collision would be more difficult to detect without a strain gauge.
`
`I prefer the Analog Devices ADXL series, but I haven't used them for a few years. Even so, my
`webcam only cost me $10 new; I'd be hard pressed to put together an accelerometer monitoring
`system for less than that. Still, it could be fun.
`
`I wonder, does anyone make a sort of instrumented bolt for a reasonable price? The extruder
`mount could use a pair of bolts with strain gauges, and you could watch the change in bolt tension
`when you run into something. Probably cost as much as the RepRap.
`
`Wade
`
`edit - the neat thing about strain gauge vs optical measurements is that the strain gauge will tell
`you how much your extruder has elongated due to heating, warping, or in my special case,
`catastrophic failure.
`
`https://reprap.org/forum/read.php?1,20208,page=1[12/31/2024 1:28:00 PM]
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`Genetic Algorithms
`
`Edited 1 time(s). Last edit at 01/14/2009 05:31PM by Wade Bortz.
`
`VDX
`Re: Genetic Algorithms
`January 15, 2009 03:30AM
`
`Reply Quote
`
`Admin
`Registered: 17 years ago
`Posts: 13,988
`
`... the camera could do a better scanning job when treating with photogrammetry - take two
`picrures from different positions and calculate the displacement of some relevant edges or
`previous placed colour-dots ...
`
`Even GA or NeuralNetwork-simulation could help a lot - i knew someone who built high-speed-3D-
`scanners with two cameras that acts like the human brain with image-recognition ... extremely fast,
`super precise but extremely expensive too
`
`Maybe an open source approach and some clever people can do the same?
`
`Viktor
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`Genetic Algorithms
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`Genetic Algorithms
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`Larry_Pfeffer
`Re: Genetic Algorithms (now instrumented bolts/load cells)
`January 15, 2009 07:37AM
`
`Wade Wrote:
`-------------------------------------------------------
`
`> I wonder, does anyone make a sort of instrumented
`> bolt for a reasonable price? The extruder mount
`> could use a pair of bolts with strain gauges, and
`> you could watch the change in bolt tension when
`> you run into something. Probably cost as much as
`> the RepRap.
`
`Wade, et al,
`
`If we had such a sensor (crash/no-crash), how would it be used? Stop everything and wait for
`help? Or is some more complicated, automatic recovery envisioned?
`
`Generally, strain gauges (particularly applying them) is labor intensive (read fussy work) and in
`consequence usually not cheap. The signals from foil strain gauges are small, so one needs high
`amplification (with low time & thermal drift) to get a usable signal.
`
`Metals have much lower failure strains (order of 1e-3) than plastics (10 -- 1000x as a WAG), so
`instrumenting a plastic "bolt" or other structure would be easier -- except that plastics are terrible
`heat conductors, and have much higher thermal coefficients of expansion, which makes it difficult
`to match coefficients, such that one can measure mechanically-induced strain, separately.
`Plastics generally creep, if you strain them long and hard. And some are virtually impossible to
`glue strain gauges (or anything else!) to them.
`
`However, there may be a way to skin this cat.... I did some preliminary experiments (read, played
`around with) some conductive-plastic fiber I got a sample of, and it serves as a pretty good strain
`gage, and well matched to plastic, because it is plastic. Since it has high intrinsic resistance
`(compared to foil gauges), it develops a larger signal, with minimal resistive heating.
`(The mfgr. didn't seem very interested in this aspect -- may have been too far out of their area of
`expertise....)
`
`https://reprap.org/forum/read.php?1,20208,page=2[12/31/2024 1:38:28 PM]
`
`16
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`

`Genetic Algorithms
`
`Typically, bolts aren't the best shape for instrumenting, even if one turns down the thread for a flat
`surface (and smaller section to increase the strain) because bolts are usually strained mainly in
`tension. Load-cell structures are typically designed to strain the instrumented areas in bending,
`torsion (or sometimes shear), to get us usably large strains. I don't have a darwin, and I'm a bit
`hazy on the attachment of the extruder to the cartBot. If you (or anybody else) can post some
`photos (or sketch w/dimensions) of the attachment, I might be able to come up with a mod that'd
`serve as a load-cell structure and try putting some of my "strain gauges" on it.
`
`I know we'd *like* three forces and three moments, resolved about a common point, e.g. the
`extruder tip. However, a 6-DOF load cell is usually a complicated (hard to machi