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Show HN: I made a new sensor out of 3D printer filament for my PhD

paulbupejr.com

111–120 of 138 posts

Re: Show HN: I made a new sensor out of 3D printer filament for my PhD

#111

This is really neat—thanks for sharing! I love the general idea of making materials more "self-aware" or inspectable. It's very sci fi! The research I did before my current job touched ever so slightly on this too, so even cooler to see it on the front page. What we were doing was using complex valued neural nets to learn the transmission matrix of an optical fibre. It was previously done in the optics community by p…

could it detect a twist instead of a bend?

Re: Show HN: I made a new sensor out of 3D printer filament for my PhD

#112
It seems to me that the refractive index plays a role: couldn't you increase resolution by replacing air by another medium every other cut? Say air, water, air, etc.

My reasoning is that you'd increase the resolution without adding too much technical complexity.

My maths is too rusty to evaluate how it would mess with the gray code though.

Very nice idea

Re: Show HN: I made a new sensor out of 3D printer filament for my PhD

#113

> also be doable in 3 years I would like to add more color to this. 3 year PhD is very possible for a motivated individual at, what I'll call, the low end of R1 universities. That doesn't mean you cannot do good research (the OP is a counterexample) but that there is a fundamental difference between the program that the OP went to and top-tier universities. Think Harvard, Berkeley, Stanford, etc. It is normally prett…

In my experience in computer engineering in the academic systems of the USA, New Zealand, and Australia, a very large proportion of students will write their first paper in their first year. It is field dependent, but when I was a postdoc at a top US R1, 100% of the students I interacted with had their first paper in their first year. These even included students working on LLMs :-)

Also, top non-US universities often graduate their engineering students within 3-4 years of commencing, with 3-4 papers being a very common international expectation as well.

If you want to finish a PhD in 3 years and are interested in academia, in addition to following the path the OP has laid out you may also look to good international universities and then get your next 3-4 papers as a postdoc.

Re: Show HN: I made a new sensor out of 3D printer filament for my PhD

#115
post #75
post #51

What an absolutely amazing idea, great work! Your sensor data seems to have quite large "dead zones" - those should be trivially fixable by reducing the inter-sensor distance, right? Would it be useful to sense the direction of the bend? I reckon this might be possible by dividing the tube like a Mercedes logo, and having three sets of the sensor in one outer tube. Is there a way to sense multiple bends? With the cur…

Great ideas! Even though I haven't implemented it fully it is possible to sense multiple bends because each bend will always have the same relative attenuation (across the strands) so it would just be a matter of matching on the relative deltas from one reading to another. The catch, though, is at that at some point no light will reach the end if every joint bends a lot. There are ways to mitigate that, but my commen…

Could you increase power output through the fibre in response to a loss of signal, or one that falls below a given threshold? Using reasonable bounds to account for errors where attenuation isn’t the cause of no signal being received.

Re: Show HN: I made a new sensor out of 3D printer filament for my PhD

#116

Isn't this just the same tech as the first Nintendo Power Glove had? https://www.youtube.com/watch?v=3g8JiGjRQNE They put light down a tube and then measured the light to trigger a key press. That's why bending your fingers/hand did anything. The revised the mechanism in the later generations.

I think at least one novelty here is that there's multiple "bend points" it can detect without needing a fiber for each bend point.

Re: Show HN: I made a new sensor out of 3D printer filament for my PhD

#117
post #103

I don't understand what happens when the sensor is bent in more than one location. At the beginning you mention a ToF sensor, which made me think that you're looking at reflections from the bends and measuring distance to them, but this seems not to be the case. ISTM that if you bend the sensor in two places, you'll simply get the sum of the logattenuations from both. If we assume that the "strength" of the bend cont…

In the paragraph "Visualization of the OptiGap Sensor System" looks like the gap pattern from multiple sensors is providing a unique signature that can be translated into the exact location on the length of the sensors. The mechanism for translating the wave forms to actual location seems to be based on a bayesian model, according to the "Realtime Machine Learning on a Microcontroller" paragraph.

Re: Show HN: I made a new sensor out of 3D printer filament for my PhD

#118
post #97
post #76

Earlier quoted context omitted.

I can die happy if I never have to work with libgnipgnop again

But have you used the new 3.6 release which uses pfnaphell integration to stochastically pre-convolute the tertiary nodes? It's a game-changer!

lol v3.6.7845 doesn’t even self calibrate. Most people are on v3.6.8002a except Mac users and people using a venv. Works perfectly under newer plan9 emulators. I just use Albus mode in Emacs (trunk) and avoid a lot of those problems. If you forget to use trunk the mouse is disabled for some reason…

Re: Show HN: I made a new sensor out of 3D printer filament for my PhD

#119
post #113

> also be doable in 3 years I would like to add more color to this. 3 year PhD is very possible for a motivated individual at, what I'll call, the low end of R1 universities. That doesn't mean you cannot do good research (the OP is a counterexample) but that there is a fundamental difference between the program that the OP went to and top-tier universities. Think Harvard, Berkeley, Stanford, etc. It is normally prett…

In my experience in computer engineering in the academic systems of the USA, New Zealand, and Australia, a very large proportion of students will write their first paper in their first year. It is field dependent, but when I was a postdoc at a top US R1, 100% of the students I interacted with had their first paper in their first year. These even included students working on LLMs :-) Also, top non-US universities ofte…

I appreciate adding data for the crowd but "a very large proportion of students will write their first paper in their first year" is simply not true when talking about the whole population. My department, albeit not CS but stats/ML, the first year is dedicated to doing courses and preparing for the qualifying exams. Some students would publish a paper. A few more might be coauthors with an upper year student (read, very little involvement). Pretty close to half would not even have an advisor until the summer. I studied at, supposedly to US News, a top 10 in the US for CS.

Typically, non-US universities have 3 year undergrads and 2 year masters prior to PhD. End-to-end, you are looking at the same time. There are, of course, exceptions. UK I think shaves off a year by integrating undergrad and masters.

Hiding the years or a PhD by doing an extended postdoc is barely the point of the exercise. The median time for a CS PhD in the US is 7 years [1]. Subtract 2 years for good students but add a year postdoc and I think you have a realistic 5-6 years from start of PhD to first academic position for the top decile.

[1] - https://ncses.nsf.gov/pubs/nsf22300/report/path-to-the-docto...

Re: Show HN: I made a new sensor out of 3D printer filament for my PhD

#120

This is really neat—thanks for sharing! I love the general idea of making materials more "self-aware" or inspectable. It's very sci fi! The research I did before my current job touched ever so slightly on this too, so even cooler to see it on the front page. What we were doing was using complex valued neural nets to learn the transmission matrix of an optical fibre. It was previously done in the optics community by p…

could it detect a twist instead of a bend?

Interesting! I'm not sure to be honest. I imagine in practice it's hard to get a pure twist without any bending, and if the system can't detect any difference with a twist then the need to detect it is also nullified as it is effectively the same system.
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