Apm: added {{RepRec}}

2024-08-11T12:27:59Z

added {{RepRec}}

← Older revision		Revision as of 14:27, 11 August 2024
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			{{RepRec}}
	== Definition ==		== Definition ==

Apm at 12:27, 11 August 2024

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	★ Locomotion … rotative — vs — translative<br>		★ Locomotion … rotative — vs — translative<br>
	★ Location of the motors … [[RepRec motor backpack]] on base or on tip of [[RepRec positioner]]<br>		★ Location of the motors … [[RepRec motor backpack]] on base or on tip of [[RepRec positioner]]<br>
	★ Crawler interdependence … one crawler or more than one crawler that only can replicate as a complete set (~~borromean~~ crawlers)<br>		★ Crawler interdependence … one crawler or more than one crawler that only can replicate as a complete set (Borromean crawlers)<br>

	Yes, there are also other less motion limiting approaches.<br>		Yes, there are also other less motion limiting approaches.<br>

Apm: moved dons = Pre APM-wiki page history =

2024-08-11T12:26:52Z

moved dons = Pre APM-wiki page history =

← Older revision		Revision as of 14:26, 11 August 2024
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	~~= Crawler =~~
	~~Created 2020-01-03 Friday<br>~~
	~~Review 2022-11-24<br>~~
	~~– [[AssemblyCrawler]] (redirects here)<br>~~
	== Definition ==		== Definition ==

	A crawler or "assembly crawler" is a robotic pick and place manipulation platform<br>		A crawler or "assembly crawler" is a robotic pick and place manipulation platform<br>
	permanently attached to a [[RepRec Base Truss]] such that<br>		permanently attached to a [[RepRec Base Truss]] such that<br>
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	– Elastomechanical battery drive: Recharging internal springs (how long can that last when operating efficiently?)<br>		– Elastomechanical battery drive: Recharging internal springs (how long can that last when operating efficiently?)<br>
	– Chemomechanical battery drive: Gathering and dumping bond-zipper energy storage capsules (complex & very big?)<br>		– Chemomechanical battery drive: Gathering and dumping bond-zipper energy storage capsules (complex & very big?)<br>

			= Pre APM-wiki page history =

			Created 2020-01-03 Friday, review 2022-11-24
			[[RepRec assembly crawler]] (shall redirect here)<br>

	= Related =		= Related =

Apm: /* Alternative approaches */ added new section === Subsystem transporter ===

2024-08-11T12:24:55Z

Alternative approaches: added new section === Subsystem transporter ===

@@ Line 72: / Line 72: @@
 – One of them is rotation around truss beams and moving brachiatingly through the base-truss.<br>
 More on that below ...<br>
 == Brachiating ==

Apm: basic page (migrated and brushed up form local desktop wiki)

2024-08-11T12:15:24Z

basic page (migrated and brushed up form local desktop wiki)

New page

= Crawler =
Created 2020-01-03 Friday 
Review 2022-11-24 
– [[AssemblyCrawler]] (redirects here) 
== Definition ==
A crawler or "assembly crawler" is a robotic pick and place manipulation platform 
permanently attached to a [[RepRec Base Truss]] such that 

– it has boundless (or at least sufficient) mobility on that [[RepRec Base Truss]] in at least one dimension 
– it can boundless (or at least sufficient) extend the basetruss 
A crawler may be dysfunctional without a [[RepRec Base Truss]] because 
the motion across the basetruss may be depended on for positioning parts in pick and place operations. 

== Why crawlers on base-truss rather than self-contained replicators? ==

The same reason as for the [[RepRec Base Truss]]. 
Crawlers and base-truss go together, they are mutually dependent for self-replicative capability. 
In essence: To have an extensible system that as a whole remains in [[GMT/MachinePhase]]. 
Disjoint self-replicating units (crawling or swimming around) would need some fancy things 
(like possibly even image recognition) to seek out and dock with other disconnected parts of the system 
in order to make larger scale products. 
Replication is only a means to the target of productivity not "the end goal". 
''At the nanoscale one can go for self-assembly. But that's only useful for early foldamer based systems. Very useful there though.'' 

Crawlers on base-truss match quite well as a [[RepRec Second Assembly Level]] in the [[gemstone metamaterial on chip factory]] concept. 
Self contained replicators match the (now obsolete) [[Molecular Assembler]] 

== Example approach (Moses2014) ==

In [[Moses2014]] the crawlers have a Cartesian gantry crane geometry and 
move on a 2D square grid of racetracks ( a 2D [[BaseTruss]] ) 
All crawlers are restricted to motion along a linear track in one dimension only. 
To get 2D extendability crawlers assemble further crawlers in a 90° rotated state on 90° rotated track seeds. 
Designing [[RepRec Crawlers]] for motion along a 1D track can simplify the design complexity notably. 
As demonstrated in [[Moses2014]]. 

== Restriction to one DOF only, and how to deal with it ==

In the case of 3D [[RepRec base truss]], 2D-tracks are replaced by 3D channels. 
For reducing system complexity crawlers can be restricted to just one single base-truss channel. 
Just like in the 2D example case in (Moses2014) RepRec Crawlers 
restricted to a single base-truss channel must be able to assemble 
"offspring" replicas that feature rotated orientations, such that 
all the six orientations of the [[Octet truss channels]] (not counting sign thus not 12) are accessible 
either via one or several [[stage rotations via replication]]. 
More formally: '''Replication operation rotations need to span the whole mathematical rotation group.''' 

'''See: [[RepRec crawler replication rotation group]]''' 

== Mass ==

When putting more and more complexity from the systems products, the [[BaseTruss]] and other static parts 
into the mobile [[#Crawler]] then mobility may be come harder and harder to justify. 

'''Possible alternative:''' 
Having the manipulator static and moving an assembly strip (like a conveyor belt) back and forth within the [[BaseGrid]] 
But assembling a replication of the assembly mechanism on that moving strip what one gets essentially is a mobile 
manipulator. One is back at the [[RepRec crawler]] 

== Alternative approaches ==

'''Design space parameters:''' 
★ Complexity balance … 
– Crawler can replicate in multiple orientations(places/spaces) but cannot go anywhere — vs — 
– Crawler can go anywhere but replicate only in one orientation(place/space) 
★ Locomotion … rotative — vs — translative 
★ Location of the motors … [[RepRec motor backpack]] on base or on tip of [[RepRec positioner]] 
★ Crawler interdependence … one crawler or more than one crawler that only can replicate as a complete set (borromean crawlers) 

Yes, there are also other less motion limiting approaches. 
– One of them is turning on the tracks (nontrivial) 
– One of them is rotation around truss beams and moving brachiatingly through the base-truss. 
More on that below ... 

== Brachiating ==

Issue: Locomotion by brachiating through the base-truss gets more impractical with bigger more sophisticated crawlers, 
as likely for crawlers in nanoscale systems with [[Mechanical through joint threading]] 
Also at the macroscale gravitative mass becomes a problem leading to: 
– no longer ignoreable downward deflections (aka sagging) needing nontrivial software compensation 
– need for high forces due to high mechanical (dis)advantage => stronger heavier motors, a vicious cycle 
– potentially damaging load on the truss 
=> thus this approach will not be taken here (for macroscale prototypes) 
There are examples of existing prototype systems taking this approach (The [[Center For Bits And Atoms]] is working on this) 
Note that the complex crawlers there are fully pre-produced. They do not assemble other crawlers from more fundamental base-parts. 
Maybe (likely?) suitable for space-tech context, but not suitable for nanoscale-tech. 

== Toothed racks –vs– brachiating ==

Racks are a much faster mode of motion than brachiating. A [[RepRec base truss]]es 
3D printed racks are probably less accurate than ''properly designed'' 3D printed rotative bearings (??). 
But given that the accuracy requirements here are not at the level of a 3D printer it should be ok. 

Motion by racks either locks [[RepRec crawler]]s into a specific motion axis (e.g. a specific octet truss channel) 
or require complex means to switch between them (does not seem worth the effort ??) 
''(In an octet truss there are three channels in a truss layer and six channels in full 3D space).'' 

'''More complex math:''' 
A brachiating mode of locomotion changes assembly coordinates in quite complicated ways 
if assembly is meant to be allowed not just in a few special positions but in all positions . 
And the double usage of the locomotion DOF as assembly DOF is desirable. 

For continuous racks the nodes of the [[RepRec base truss]] are in the way. 
In an octet truss rack crossings are probably worse than in a square grid like the one in [[Moses2014]]. 

== Alternative names ==

– Crawler … troublesome and misleading bio-assozialtin (crawling proliferating out of control bug infestation) 
– IncompRec … making it more clear that this is not a complete RepRec without its [RepRec base truss]] 
– MobileUnit … bland & inconvenient & too unspecific 
'''Note:''' [[RepRec poser]] and [[repRec positioner]] are 
not applicable as names because these are 
sub and sub-sub systems respectively. 

= Ideas =

Macroscale: If rotations of big/heavy motors are involved: 
Maybe its possible to rotate motors almost around their center of gravity ?? 

'''Regarding driving a crawler (all scales):''' 
[[RepRec mechanical demultiplexing]] could be done to use the same motors 
for the motion of the [[RepRec crawler]] crawler as are used for the [[RepRec poser]]. 
Not advisable though if the motion of the [[RR/Crawler]] serves as one of the axes of the [[RR/Poser]] as in [[Moses2013]]. 

'''Regarding energy supply for a crawler (macroscale specific)''' 
The energy supply for the [[RepRec crawler]] could be a strapped on battery and data can be transmitted wirelessly. 
This way there is no requirement for … 
★ either threading mechanical motion across all of the [[BaseTruss]], See: [[Mechanical through joint threading]] 
★ or cheating with … 
– either free floating flexing electrical coil-spring cables or 
– or electrical sliding contacts 

'''Regarding energy supply for the driving of a crawler (nanoscale specific)''' 
★ If motors are kept static in the base-truss then [[Mechanical through joint threading]] 
becomes even more of a headache. Requiring base-truss to crawler threading and long range transmission along 
some changing length of base-truss struts/tracks. 
★ If motors get integrated into crawlers (may make sense for big crawlers!) 
– Wired electric drive: Graphene sliding or rolling contacts. 
– Elastomechanical battery drive: Recharging internal springs (how long can that last when operating efficiently?) 
– Chemomechanical battery drive: Gathering and dumping bond-zipper energy storage capsules (complex & very big?) 

= Related =

* [[RepRec base truss]]
* [[Mechanical through joint threading]]

Base Truss Crawler - Revision history

Apm: added {{RepRec}}

Apm at 12:27, 11 August 2024

Apm: moved dons = Pre APM-wiki page history =

Apm: /* Alternative approaches */ added new section === Subsystem transporter ===

Apm: basic page (migrated and brushed up form local desktop wiki)