View source for RepRec pick-and-place robots (GemGum)

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'''In general context''' RepRec systems are (per definition) a class of [[self replication|self replicating]] pick and place robotic systems ...
* that do not produce their own parts but instead use parts pre-produced by a different process
* that do assemble copies (and improvements) of themselves from the same types of parts that they are themselves composed out of.

'''In the specific context of advanced [[atomically precise manufacturing]]''' i.e. <br> 
[[gemstone metamaterial technology]] RepRec systems ...
* constitute the [[second assembly level]] in a [[gemstone metamaterial on chip factory]]
* are much more amenable to prototyping at the macroscale for the nanoscale. <br>See: [[Applicability of macro 3D printing for nanomachine prototyping]]

Closest currently existing project is: <br>
'''"An architecture for universal construction via modular robotic components"''' by Matt Moses et.al. 
[https://rpk.lcsr.jhu.edu/wp-content/uploads/2014/08/Moses13_An-Architecture.pdf] <br>
There are quite some major differences though to make it work in the context of nanoscale physics with [[crystolecules]] as building blocks. <br>
More on that further below.

== Huge differences to diamondoid molecular assembler concept ==

The self-replicative capability in RepRec systems is not to confuse with <br>
the ultra compact self-contained selfreplicativity in the <br>
outdated concept of [[molecular assembler]]s where self replication <br>
is a necessary prerequisite for the [[bootstrapping]] of the technology. <br>

In RepRec systems the situation is reversed. <br>
Self-replicative capability is more an eventual consequence of [[bootstrapping]] towards <br>
[[advanced productive nanosystem]] systems without having self-replicative capability yet.

There is no "proto (diamondoid) RepRec" concept like <br>
there is the "proto(diamondoid) molecular assembler" concept.

Unlike molecular assemblers '''crystolecular RepRec systems''' ...
* do not need to be ultra compact to be buildable via [[positional assembly]] nigh atom by atom in reasonable timescales.
* do depend on pre-produced parts that is: [[Crystolecules]] ... (some caveats here)
* do constitute only a part of an eventual [[advanced productive nanosystem]]
* do have a modular static (but reconfigurable) scaffolding frame system an integral non-removable part of their system
* may even depend of multiple different semi-mobile units to achieve full selfreplicativity (disributed selfreplicativity)

== Advantages of reasonable compact selfrepicative capability ==

Remaining reasonable compactness of selfreplicativity in RepRec seems like a strong and good driver to <br>
highly reusable/recyclable general purpouse parts and components. <br>
Remaining compactness of self-replicativity in RepRec systems involves:
* a nanofactory chips "pixel" being fully self-replicative not needing the whole chip
* the [[second assembly level]] alone being having self-replicative capability not needing the [[third assembly level]] for it (not a strong constraint) 

The results from such constraints may be well designed systematic sets component parts. <br>
In a sense similarly to standard electrical components just for mechanical systems <br>
<small> (and thus richer as mechanical voltages aka forces come as vectors rather than scalars).<br>

Standard mechanical components for generality and reusability rarely make sense at the macroscale as the overhead is to high. <br>
Macroscale mechanical systems (like clockworks and transmission gearboxes) are small scale one off solutions amenable to heavy optimization. <br>
Like a very specialized analog circuit in electronics. <br>
Prototyping with legotechnic (which is not at all good system for the nanoscale for various reasons btw) may be one exception. 

Standard mechanical components for generality and reusability do make a lot of sense for nanosystems <br>
where the complexity approaches the one on that is present on the computer chips of today (2023).

= Base block materials the design is aimed at =

== Reusable crystolecules ==

The design is: 
* particularly targeted towards reusable fully passivated [[crystolecule]]s as the pre-produced base parts. 
* not targeted towards partially passivated [[crystolecule]]s that get [[Seamless covalent welding|irreversibly welded]] together to bigger [[microcomponents]]. 

== Foldamer parts? ==

Pre self-assembled foldamer parts with high geometry might eventually work too as base parts. <br>
Given they are stiff enough. But this is questionable. If it works it will be quite a bit bigger than in the crystolecule case.<br>
Unfortunately the parts that [[structural DNA nanotechnology]] can make are almost certainly not stiff enough. 

== Macroscale prototypes ==

For prototyping functionality at the macroscale FDM 3D printing or resin 3D printing are possible options. <br>
Of course one needs to keep an eye on: [[Applicability of macro 3D printing for nanomachine prototyping]] <br>
Look at [[mechanical property transposition]] for comparability.

Eventual macroscopic use cases of the system (as home device beside a RepRap or as a device for truss construction in space) <br>
can't be excluded but optimization for those applications is definitely not the design goal here. <br>
heavy chains instead of drive belts and other design choices might make the system quite sub-optimal for those alternate application cases.

= Key properties =

Same as the [[ReChain frame systems]] that may serve as a basis. 

== Narrow range of part sizes == 

All parts are in a narrow size range. <br>
There is not a range from very small connectors to very big plates. <br>
Instead bigger parts are made up out of many smaller parts <br>
This allows to keep all assembly activity to just a single (the second) assembly level.

== No dependence on friction based self holding ==

A dedicated nanoscale friction element: 
* is solely used for deliberate energy dissipation 
* can not beused for friction self holding
* is more like a tuning fork in vacuum that after being plugged (see: [[snapback]]) distributes its excitation into overtones and eventually the mounting surface. <br>This "flowout" called dissipation (to more degrees of freedom) and is driven by the forks anharmonicity ~ deviation from linearity of the restoring force.

There is no friction at the nanoscale between atomically precise surfaces in the way as there is friction at the macroscale. <br>
So screws won't hold in the same way as they do at the macroscale. <br>
Matching up atomic surface waviness can hold things in place, yes, but that's an energetic barrier rather than static friction.

== Bulky design ==

There are a few reasons for bulky design.
* To compensate for the low stiffness of all materials at the nanoscale. Necessary only for suppressing deflections from thermal motion. <br>Deflections from machine accelerations at the proposed speeds of a few mm/s are very much insignificant.
* To make sure all the parts can be handled with robotics of only one (the second) assembly level. Giving a narrow size range between smallest and biggest parts.
* The design happening at the lower end of the physically possible size scales. Details see below.

=== On bulkiness originating from designing on the lowermost physically possible size limit ===

When the functional [[crystolecule]] pieces are already at the lower end of what physics allows for, <br>
then pieces for connecting parts together cannot by yet smaller since this would make them smaller than an atom.  <br>
This pushes the size of the connection mechanisms and similar up into the size scale of the parts they connect.  <br>
This is very much unlike the macroscale where e.g. large pieces are often held together by screws, <br>
splint rings or other means that are really quite small in relation.

= A note on selfreplicativity = 

While with "[[second assembly level self replication]]" there is a medium compact form of self replication present <br>
the self replicative capability is not as compact as in the case of the [[molecular assembler]]s approach. <br>
[[Molecular assembler]]s are outdated because of too compact self-replications and the consequences thereof.

= Choice of name =

The name RepRec was chosen in analogy to the name RepRap (Replicating Rapid Prototyper) <br>
that refers to partially self replicating 3D printers.

The name "RepRec" is:
* a shorthand for "Replicating Recomposers".
* a name for a whole class of robotic systems (akin to RepRap not referring to one specific 3D printer but a whole class of them)

= Related =

* [[ReChain frame systems]] – A factored our sub-projects
* [[Second assembly level self replication]]
* [[Applicability of macro 3D printing for nanomachine prototyping]]
* [[Self replication]]

= External Links =

'''[https://reprap.org/wiki/RepRec_Pick_%26_Place_Robots RepRec pick and place robots – on the RepRap wiki]''' <br>
There more kept in the context of usage at home in conjunction with a RepRap <br>
which is actually not the primary design target.
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'''Remotely related:''' <br>
Project Quine:
* https://projectquine.substack.com/
* https://www.youtube.com/channel/UCWmAvYrypYI8u_w5nJGb_CA/featured
* https://twitter.com/ProjectQuine
Ambots:
* http://ambots.net
* https://www.youtube.com/c/AMBOTS3D
Replimat:
* https://wiki.replimat.org/wiki/Main_Page
* https://reprap.org/wiki/RBS_Overview