Assembly line orienting stage

One axis goniometer stage (Zaber Technologies Inc.). Assembly line orienting stages for tooltips could feature a somewhat similar stiff geometry (with a very different drive). Main design constrain is that there may not be any parts so small that they are no longer approximable due to atomic granularity. – Unlike in macroscppic goniometers like this, stacking two nanoscale goniometer stages will require some additional complexity due to the then needed through joint mechanical motion threading.

An assembly line orienting stage:

• is a a stiff robotic stage mechanism for orienting tooltips for piezomechanosynthesis (or crystolecule fragment workpieces).
• is meant to geometrically oppose an assembly line positioning stage froming an positional assembly kinematic loop and thus a (moving) mechanosynthesis core.
• is (unlike an assembly line positioning stage) not depicted in the concept visualization video "Productive Nanosystems From molecules to superproducts".

Why a virtual center of rotation

Ideally the assembly line orienting stage mechanism rotates around the tip of the tooltip as a virtual center of rotation such that
there is no need for movement of the opposing assembly line positioning stage to keep the center of rotation statically non-moving in the frame of reference of the workpiece.

Additional cams for compensating movements of rotation centers (using pre-compurted reverse kinematics) seem quite undesirable.
(Compensation with live general purpose re-programmable positioning is totally out of the question since as this lowest size-scale motions absolutely need to be hard-coded in efficient systems.)

As the tip of the tooltip is typically near point like. It seems desirable to:

• put the assembly line orienting stage on the tooltip side and to
  
• put the assembly line positioning stage on the side of the build platform and growing workpiece.

Putting both stages (positioning and orienting) on one side as serial robotics (like a robotic arm)
is not desirable as stuff on an assembly line should preferably be compact and rugged.
And serial robotics at this scale wouldn't be compact and rugged because ...
Details in next section.

Why not serial robotics to avoid the need for a virtual rotation center

Serial robotics would make mechanisms way bigger since at the scale of assembly level 1
only (nontrivial and bigger) mechanical through joint threading is an option.
Local moving electric motors would be way too big and wires problematic due to ballistic electron transport, undesired tunneling, size of rolling contacts.
Unlike in macroroboitics the problem of larger robotics is not moving mass. proposed assembly speeds are rather low (~1mm/s) and materials very stiff (flawless diamond)
What makes size problematic is rather rather the too low spacial density density of active sites of piezomechanosynthesis.
And possibly the lower geometric stiffness for suppressing placement errors from thermal motions.

Stiffness

As thermal motions need to be sufficiently restrained to keep placement error rates low
a geometry that derives stiffness from its design is desirable.
Many classical gimbals and wrist mechanisms are quite filigree and thus may be a poor choice.

Inspiring sources for design

Stiff goniometer stages used in camera equipment may be usable as good inspiration source.
Adding the design constraint of no filigree parts (tat would be smaller than atoms at this scale)

Related

• assembly line positioning stage
• positional assembly kinematic loop
• Machine elements, List of machine elements

External links

• https://commons.wikimedia.org/wiki/File:Positioning_goniometer_stage.jpg