Victor Zykov, Efstathios Mytilinaios, Bryant Adams,Hod Lipson, Nature, 이영설 Self reproducing machines

Self-replication Definition –A process for a physical system is capable of producing another autonomous, functional system Motivation –Understanding of one of the basic tenets of biological life –Studying long-term sustainability and evolutionary adaptation in nature Self-repair, self-reproduction Related works –In early 1980s, physical self-reproduction for remote lunar colonization Abandoned due to many unresolved technical difficulties –Kinematic self-replication A paradigm for both long-term self-sustaining and self-repairing robotic ecologies Space and hazardous applications –Artificial physical self-replication by Penrose Stochastic tumbling blocks with special geometries and latching mechanisms

Space application of a modular robotics

Concepts for self-replication Self-replicability –(1) amount of information needed to reproduce an inaccurate copy of a machine –(2) amount of information necessary to produce more exact duplicate (1) < (2) → 복제에 필요한 정보량은 대상의 복잡도와 환경에 대한 영향으로 결정 Domain-independent metric R of self-replicability – : relative replicability of system over the period of time – : the probability of emergence of system in environment – : environment where system was not present a priori –Avoidance of the difficulties of Von Neumann’s “binary” definition –Providing a graded value that can serve as a basis for comparison of self- reproducing systems

Robot conceptual design for self-replication Conceptual design in 3-D grid Comparison of modular robot concepts Only one that enables a single module to perform out-of-plane configuration

Robot design for self-replication Swiveling –Swiveling one half of cube relative to another half –Three possible swivel states : 120, 240, 360

Robot design for self-replication Module connector –Electromagnetic bonding : attract, repel or insert Switching “north”, “south”, “off” states –Six faces in each cube with connectors 3 6 = 729 possible states (in the experiment, only two faces in each cube) Machine control –Using a sequence of swiveling and bond-state switching commands

Possible modes of self-replication Direct reproduction –A machine reconfigures to pick cubes from a dispenser and place them in a new location, gradually building a copy from the ground up Multi-parent reproduction –Multiple machines are required to produce a single copy –One machine may place cubes, while the other reorients the constructed machine Self-assisted reproduction –The machine being constructed reconfigures during the construction process to facilitate its own construction Multi-stage reproduction –Intermediate constructions are required before the target machine can be made –The intermediate machine (or scaffold) is then discarded as waste, or can be reused to catalyze the production of additional machines

Experimental result for self-replication Physical self-replication process –Spanning about 2.5 min –Reproduction process without human intervention Except for replenishing building blocks at two “feeding” locations

Experimental result for 4 module robot

Experimental result for 3 module robot

Summary Demonstration of self-reproducing machines with modular robots –10 20 amino-acid combinations of roughly 20 amino-acid types for animals Very low for our robots (four modules of one complex type) –Quantification, comparison and systematically improvement of self-reproduction –Rank by comparing properties such as number of basic building blocks used compared with the number of building-block types and their complexity