Positional assembly kinematic loop

Look at a 3D printer or some subtractive manufacturing machine like a CNC mill. There is:

• a workpiece holder of some sort
• a tooltip holder of some sort
• a frame connecting the two somehow
• actuators within that frame facilitating controlled motion that is minimally cross coupled

This sequence forms a kinematic chain.
And once the tooltip contacts-onto and presses-into the workpiece a loop is closed.

A progression in "expanding the loop"?

See also page: Expanding the kinematic loop

Regarding the bootstrapping of advanced atomically precise manufacturing
one idea along the incremental path is to introduce a positional assembly loop quite early on and then scale it up.

Progression:

• Existing natural enzymatic proteins as example
• Catalysis construction kit approach (which includes the less ambitious functional block construction kit approach)
• Printer approach (See: Foldamer printer) (and less so robotic AP block handling approach)
• Full on advanced productive nanosystems

This "expanding the positional kinematic loop" approach pushes
the material capability technology levels pretty hard pretty early on.
So it's a quite direct side of the incremental path.

Closing the loop too early on the incremental path

Going left too early in this diagram can and will cause problems for R&D efforts. (1) hitting the fat finger problem too hard (defeatingly) (2) hitting the Positional assembly redundancy blockade too hard (defeatingly).

When pushing too early and/or too hard towards better material capabilities (i.e. higher technology levels)
or catalytic capabilities or even just small molecule sensing capabilities which are related (all leftwards in the diagram).
E.g. aiming for an active core modular de-novo foldamer assembly. Then there can be and will be issues.

When the kinematic loop is still small and one is still (too) early … – … then the kinematic loop is is still not yet good (enough) in separation of concerns (competing design constraints of foldamer side chains). => Thus one is in for hitting hard the fat finger problem. (technical blockade) – … then while the kinematic loop may manage with high effort to solve certain problems/tasks these problems/tasks may be (are) achievable much more easily & cheaply (in various metrics) via self-assembly only solution => Thus one is in for hitting hard the positional assembly redundancy blockade. (economical blockade)

Detours to larger kinematic loops for easier walkeable pathways

For averting both of the fat finger problem and the positional assembly redundancy blockade
one needs to navigate around them by first improving on hierarchical selfassembly and (important!) termination control.
(rightwards in the chart) and only then go leftwards.

Once the next higher technology level capabilities (leftwards in chart) become available
They will start with a regression on hierarchical selfassembly
(or by then called "convergent assembly", just a different term for the same ting in positional assembly).
This is to ok and to be expected (arrows going sorta backwards to the left in the diagram).

The foldamer printer goes quite a bit further up the right side in the diagram compared to a
ultra basic active core modular de-novo foldamer assembly as a most primitive possible kinematic loop.
But it is still very direct. (And as of 2025 ahead of its time. Still few (no) protein researchers will take it seriously.)

The foldamer robot approach (incremental path) is fully focused on scaling hierarchical assembly levels
shifting the problem of getting to better materials and mechanosynthesis like capabilities entirely to later.

Modular molecular composite nanosystems kinda combine the
foldamer robot approach (incremental path) with existing natural molecular machinery (e.g. enzymes) or
(so far it works despite the aforementioned issues active core modular de-novo foldamer assembly)
they cold even integrate foldamer printer like structures evetually at some point.

Mixed path systems where modular molecular composite nanosystems make for the structural matrix
would also integrate crystolecules as stiff cores.

Related

• Expanding the kinematic loop

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• Incremental path
• Foldamer printer

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• Positional assembly redundancy blockade
• Fat finger problem

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• Introduction of total positional control

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• General: Functional block construction kit approach
• Specific: Active core modular de-novo foldamer assembly

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• General: Separation of concerns
• Specific: Competing design constraints of foldamer side chains

External links

• https://en.wikipedia.org/wiki/Kinematic_chain