Self reproducing machines

1. Self reproducing machines Victor Zykov, EfstathiosMytilinaios, Bryant Adams,Hod Lipson, Nature, 2005. 2010. 3.22 이영설

2. 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

3. Space application of a modular robotics

4. 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

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

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

7. 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 • 36 = 729 possible states (in the experiment, only two faces in each cube) • Machine control • Using a sequence of swiveling and bond-state switching commands

8. 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

9. 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

10. Experimental result for 4 module robot

11. Experimental result for 3 module robot

12. Summary • Demonstration of self-reproducing machines with modular robots • 1020amino-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