Robotics question (well, not too technical of course)...

[Kyriakos]

I asked something similar in the Science forum here...

Generally only need to fill in some gaps for a possible short-story plot. The main idea is that someone is operating (not certain) a robotic/machine object which attacks other humans and virtually erases all trace of the victim, yet it leaves behind any bank-notes intact (cause the end-game was to rob them).

So, assuming the robotic enemy can have sensors which identify elements such as the rare earth 'Europium' found in banknotes, and assuming (?) the latter is plausibly spread out enough in the banknote to cause the robot to not attack any of it, anyone got an idea how such a sensor would work?

Ie:

Would the censor have to use UVC (UV lighting, which reveals the red glow of the europium to a human eye), and have some built-in system to then prevent attack on a radius of that europium

OR

would it be more likely/doable that the robot just has a sensor that identifies the europium without any use of UVC at all, eg through identifying its chemical properties directly?

The idea is that the europium is not going to exist in other parts of the victim's clothing, nor his/her skin, so only the banknotes would remain. Which is why i could not model this on less rare stuff the banknotes have (eg fibers also found on cloth, etc).

PS: trust me, this is for a story. I am not making any such thing. And a recent disappearence in this city is not tied to that either.

 

[Manfred Belheim]

Would it not just make more sense for the robot to have some rudimentary (in sci-fi terms) intelligence and object recognition skills? That way it could just kill the target, root through his clothes for banknotes, put them in a neat pile off to the side, then vaporise the body? Or is that too boring...

 

[Zelig]

Would it not just make more sense for the robot to have some rudimentary (in sci-fi terms) intelligence and object recognition skills? That way it could just kill the target, root through his clothes for banknotes, put them in a neat pile off to the side, then vaporise the body? Or is that too boring...

Same as I was going to say, standard image recognition works pretty well.

 

[warpus]

How about a fleet of nanobots that jumps onto the body of the victim and atom-by-atom decomposes the body, leaving the bills behind. All you'd need for that would be image recognition as well, I think. That could be done from the central body of the main robot, which could also scan the body of the victim for hidden bills, so that it could relay that information to the nanobots.

I have literally spent 5 seconds thinking about this scenario, but I'm throwing it out there, maybe you'll find some use for it in your story.

 

[Kyriakos]

Meh

It won't work with tricks of the variety "some special tech enabled this" nor with "nano-robots do this and that". For two reasons:

a) it is a bit of a drool scifi trope, but far more importantly:
b) it is not certain this has happened. Maybe the robot doesn't exist at all. So the method of seperating the victim from his/her money will have metaphorical meaning as well in that case.

And re 'image identification', would that be plausible when those notes may be tilted, or pressed upon more notes, or not in perfect condition, or in many different places? I think that if the robot/thing has theoretically excellent ability to be specific in how it cuts then it makes sense to just use some chemical substance identification (the europium mentioned being an option here i am leaning towards), and so i asked how some machine which alters a material based on substances there to be altered or kept as are would operate...! Any info on that?

 

[Kyriakos]

Given i am likely going to begin the story in the next week, any other view re the OP questions?

 

[GarLuna]

The discussion is looking pretty nice and i want to know about the robotics in your work.
What kind of robots do you use in your work? Also what kind of the hardware of electronics and mechanical it use?
Is it use any kind of MCU and the other elctronic components?

pcb prototyping

 

[Kyriakos]

Hi GarLuna

Well i am not familiar with robotics, i am just trying to not be unrealistic in what would be presented in the short story...

So if you have any ideas, do share!

 

[Valka D'Ur]

How about a fleet of nanobots that jumps onto the body of the victim and atom-by-atom decomposes the body, leaving the bills behind. All you'd need for that would be image recognition as well, I think. That could be done from the central body of the main robot, which could also scan the body of the victim for hidden bills, so that it could relay that information to the nanobots.

I have literally spent 5 seconds thinking about this scenario, but I'm throwing it out there, maybe you'll find some use for it in your story.

Don't nanomachines work by programming them to interact a specific way with specific atoms? Nanobots could be programmed to interact a certain way with Europium atoms, and ignore all others (or vice versa).

Admittedly I'm going by Ben Bova's take on nanotech in his Grand Tour series. The Moon War/Asteroid Wars books are especially focused on nanotechnology and how it can be both one of the most useful inventions mankind ever had or if misused, can be the most gruesome murder weapon... depending on how you program the machines to deal with carbon atoms (for example).

@Kyriakos: If you have some time, I'm going to recommend that you read Moonrise and Moonwar, by Ben Bova. They're part of the Grand Tour series, but can be read on their own - you don't need to have read any other books in the series to enjoy these. The books address nanotech, both in terms of the science involved and the social issues involved (ie. is it ethical to use nanotech to basically make yourself immortal).

And besides that, they're examples of the best kind of space opera - good adventure stories that make an effort to have plausible science.

 

[uppi]

Would the censor have to use UVC (UV lighting, which reveals the red glow of the europium to a human eye), and have some built-in system to then prevent attack on a radius of that europium

OR

would it be more likely/doable that the robot just has a sensor that identifies the europium without any use of UVC at all, eg through identifying its chemical properties directly?

I see multiple options to detect the Eu IV in the banknotes:
- Use the UV light and a spectrometer
- nuclear magnetic resonance: would require the robot to apply a strong magnetic field and then measure the absorption of a radio frequency signal.
- Infrared spectroscopy. The europium should have a transition in the fine structure at 27 micrometer wavelength in the infrared but being in a banknote might shift that a bit (and the banknote would have to be somewhat transparent at this wavelength, I do not know whether it is).
- I would have liked to add hyperfine spectroscopy, but I fear the Europium is too hot for that.

Using the chemical properties would most likely require to destroy the banknote (at least partially).

I think using the UV method or NMR are probably the best options. Which one to use would depend on how your robot is engineered and at what distance the banknotes should be detected.

 

[Kyriakos]

^Wow, thanks Uppi

Well, partially destroying some notes (or all) isn't that problematic as long as they can realistically be used (and i don't mean having them be accepted at a bank ).

Also there is simply zero care in the story about how appalling the pain and death of the human will be. The sole care is to extract the notes safely [also i must note that the robot doesn't have to carry them itself, it just has to destroy the rest (so to be able to discern what is note and what is non-note)-- at worst the main character will be sticking around to take the loot].

Would the NMR have better result than the UV+spectrometer? Cause both of those (UV+spectrometer) are realistic for one to just buy (i suppose the spectrometer too).

I think a 'realistic' way to go about it would be for the robot to first render the human both immobile and unable to make a sound, ie attack his/her head with one blow, and then just extract the notes, destroying everything else entirely (then again i may just go around that, by having the robot collect the victim as well, although in a rather... compressed... state)...

 

[uppi]

Would the NMR have better result than the UV+spectrometer? Cause both of those (UV+spectrometer) are realistic for one to just buy (i suppose the spectrometer too).

UV+spectrometer would indeed be easier (yes, you can just buy spectrometers) but has the disadvantage that almost nothing is transparent in the UV (and clothes tend to be not transparent in the visible, either), so you could only detect the banknote once you removed anything on top of it.
NMR is used in medicine because it can image things inside the body, so you could could in principle detect the europium even if you ate it. But you would need a much bigger device.

 

[Kyriakos]

NMR sounds a lot more like what could make sense story-wise... Any article i could read for a very general idea of what it is like, and what sort of device could create such a field? (i suppose it is those massive hospital machines, but maybe i can work around that--- if all else fails this can be at a hospital anyway, although with a sinister twist ).

 

[uppi]

You would need electromagnetic coils to generate the necessary field. Those devices at the hospital are that big, because they are supposed to scan a whole human. If you want to scan a smaller volume, you would need less big coils, they would need less current and everything gets easier.

 

[Kyriakos]

Ok...

I have more questions (general again, of course, but i am not sure if i will be able to use this info...)

-Which isotope of Europium is used in euro notes? Apparently there is EU with atomic mass nearing 152, but also 151 and 153

-Why is the atomic mass a non-integer? (is it obvious i have forgotten most of highschool chemistry? )

-I suppose that all of EU 152, 151 and 153 atomic mass have (approximation/techinically) odd numbers of both protons and neutrons? I know their number of protons is odd, 63 (cause i read that is needed for them to present an effect with a magnetic field created by the NMR, due to spin properties existing then). Moreover, would it be enough if just number of protons OR neutrons was odd so that an element would have a spin and thus work in this manner in a magnetic field of the type NMR creates?

-The images of NMR machines i found are both massive and sinister (and a bit like the painting, 'the elephant-Celebes ). What if the robot only needs the property to create such a field, but then very linearly ruin/remove anything not sending back a signal in the specific frequency (?) ? WHICH BRINGS US TO THE MOST IMPORTANT QUESTION:

-What frequency would the NMR use for a field to pick up effect/existence of a Europium isotope?

 

[uppi]

-Which isotope of Europium is used in euro notes? Apparently there is EU with atomic mass nearing 152, but also 151 and 153

Most probably 48% Eu-151 and 52% Eu-153, like europium in nature. In principle they could have altered the ration, but that would be much too expensive. Eu-152 is not found in nature and would be too radioactive to on banknotes (Fun fact: Eu-151 is also radioactive, but with a half-life much longer than the age of the universe)

-Why is the atomic mass a non-integer? (is it obvious i have forgotten most of highschool chemistry? )

The mass defect. A nucleus has less total energy than its constituent parts, as you need energy to break it up into those part (the binding energy). By the formula E=m c^2, this means that the nucleus is also lighter by m=E/c^2, where E is the binding energy.

-I suppose that all of EU 152, 151 and 153 atomic mass have (approximation/techinically) odd numbers of both protons and neutrons? I know their number of protons is odd, 63 (cause i read that is needed for them to present an effect with a magnetic field created by the NMR, due to spin properties existing then). Moreover, would it be enough if just number of protons OR neutrons was odd so that an element would have a spin and thus work in this manner in a magnetic field of the type NMR creates?

Easy to calculate: the isotope number is the total number of protons and neutrons combined, so 63 protons means 151-63 = 88 neutrons for Eu-151
Yes, it works if only one number is odd, which is good for NMR, because there are only 4 non-radioactive nuclei that have both numbers odd (another fun fact: Eu-152 is radioactive exactly because it has an odd number of protons and neutrons). Both Eu-151 and Eu-153 have a spin of 5/2, so NMR works

-The images of NMR machines i found are both massive and sinister (and a bit like the painting, 'the elephant-Celebes ). What if the robot only needs the property to create such a field, but then very linearly ruin/remove anything not sending back a signal in the specific frequency (?) ? WHICH BRINGS US TO THE MOST IMPORTANT QUESTION:

You could just build it smaller and just feed the NMR device small chunks. In principle you could also do it like you suggest, but you need to able to apply a strong and controlled magnetic field and then pick up enough signal to detect the resonance. How to engineer such a thing, I have no idea - I ahve never actually worked with NMR.

-What frequency would the NMR use for a field to pick up effect/existence of a Europium isotope?

That depends on how much magnetic field you apply.
Apparently it is 10.559 MHz/T for Eu-151 and 4.662 MHz/T for Eu-153

 

[Kyriakos]

Thanks again, Uppi!

Well, i might still try using some of that. Not sure, cause currently it likely will be more work to have some over-general info if i actually make it elegant in the story itself. So maybe i'll just go the HP Lovecraft way and use merely tiny bits of chemistry/ physics info here and there.