Mechanical computing systems using only links and rotary joints
arxiv.org
arxiv.org
They need to fabricate something, anything, to validate that they can get those devices to work at that scale. Things are not Newtonian down there.
It's really disappointing that rather key aspects of this are more or less ignored. There's not much of an analysis of things like what force propagation looks like, gate delay issues, mechanical energy losses due to heat, etc. I'm surprised there isn't anything like an analysis of macro-scale linkages to try to estimate what these things looked like if they were shrunk down to scale (even though, as you say, things don't work at that scale like they do at the macroscale).
Realistically, you need a demand side on this sort of work for functional and realistic solutions to take hold (iterate and improve). Right now Moore's Law has driven semiconductor logic to the point where very little else can economically compete. Thus there's little investment of resources... or even accurate determination of markets. At the same time many people view nano (and micro) machining through Moore's lens, when in reality the low dimensionality, isolation, and fault tolerance of electrical/digital solutions allows for much more design independence/flexibility and complex system development.
Imagine the vibratory harmonics of a mechanical computing system. There would be literally millions or billions of coupled oscillators. What about stiction/frictional losses due to surface chemistry/tension? What about limiting thermal noise effects? It's complicated and there's no money in it :^)
Ralph has done a bunch of work on mechanical flexure computing stuff that works entirely through vibratory harmonics, as you probably know but might not be thinking about at the moment.
p.s. always glad to discuss cap-sensors... a field I never thought I'd end up in.
In any case, the extremely precise machining in large quantities required for any reasonable mechanical computer means that it's not a low-tech or high-reliability replacement for electronic computers, it's a very high-tech future solution to the limitations of current electronic devices. We can't make such devices now, we'll hopefully be barely able to make them in the future, but in the case of infrastructure collapse we'll lose the capability to make these advanced mechanical devices before losing digital devices.
And nowadays computing is so ubiquitous, that every horrible scenario would still leave us with huge amounts of computing power lying around. Soldering together devices out of scrap electronic components is a much more reasonable way of doing post-apocalyptic computation than any of this mechanical computing tech; If there was a real need, nowadays you could extract a dozen usable processors from a crashed car or modern kitchen - even excluding computers and smartphones, so many modern devices have random processor(s) that are more powerful than what people used as their primary computers some decades ago. Things like wireless headphones and washing machines have chips that could be sufficient for so many computing needs. Apple's Lightning to HDMI cable has a powerful ARM processor inside. etc, etc.
If something like that happens all you will want is clean water, some basic food, and a weapon to defend yourself, your family, and small, closely-knit community you will not have a chance of survival without. And yes, you will quickly forget about "space com."
I do agree that it's something you should worry about once your basic survival, shelter, and community needs are secure. However given you would need a reasonable technology base to manufacture mechanical computers, I think the "dependency management" would naturally sort itself out.
This also assumes that the satellites haven't been shot down during whatever disaster caused the complete failure of electrical computing, and that you can actually build a mechanical computer that can receive the broadcast and usefully render the images.
Reading https://www.swpc.noaa.gov/impacts/satellite-drag, I get the impression that involves ground control (because of those complicated models that get updated all the time)
So, how long will these satellites stay up there without ground control?
That said, the imaging sensors have a limited lifetime (the satellite platform is designed to be good for ~15 years but the sensor package limits the mission lifetime to 8 years).
If the ball is at the center of the disk it doesn't move, if it moves positive the ball spins up, if it moves negative the ball spins down. The overall rotation of the ball is essentially the integral. You can also do almost this to make multipliers by varying the speed of the disk. These mechanical computers were used until the mid 1900s.
> There is linear stress problems that can occur, a single "activation" line (clock signal through a train of locks) can eventually reach a point that the mechanism will be unable to move at all.
You can see an example of that long single activation line in this gif http://www.merkle.com/images/4_phase_shift_register_v4.gif and described in more detail in this part of the video: https://youtu.be/yVX9Ob4SjGA?t=769. I was surprised this wasn't explicitly addressed in the talk. Transistors aren't just powerful because they can be off or on (switch) but also because they can amplify signals (a lever).
Edit: The paper does address this in section 4.5, saying that "The method for dealing with scaling is to isolate individual cells in a shift register (or more generally, individual clocked logic elements, such as Fredkin gates) by using the four-phase clock. That is, forces along signal lines cannot move beyond two cells before encountering a locked lock, preventing any accumulation of forces over long distances. At any point in time, a cell is either blocked from transmitting forces to adjacent cells, or can transmit forces only to one other cell (either the predecessor or the successor)" and "Force accumulation in link logic systems can be mitigated because each lock acts as a mechanical amplifier, with a small force controlling a much larger one."
> I'm really loving the idea of mechanical logic gates and computers... it's far easier to produce in 3D print, which will be vital in space exploration and colonization.
Question is, what additional primitives are needed to construct all the primitives (locks and balances) from a bin of links and rotors? Maybe a "lifter" that raises a hinge pin out of 2D plane so it can be placed in a rotor.
There are some hints that a Canadian company called CBN Nanotechnologies is working with them (they bought all of Merkle and Freitas’ patents), but who knows.