Self-Replicating Hierarchical Modular Robotic Swarms
Abdel-Rahman et al. (MIT CBA, 2022) demonstrate a discrete modular material-robot system capable of serial, recursive, and hierarchical assembly (bib).
Key contributions
- A single robot can build copies of itself from the same modular blocks it uses to build the target structure — self-replication as a construction strategy, not just a biological curiosity.
- Self-replicated robots can build larger robots from the same blocks, enabling hierarchical assembly where each scale carries bigger payloads over longer distances.
- The combination of self-replication and hierarchy achieves exponential throughput scaling — O(2^N) — matching biological self-assembly (ribosomes).
- The system is a material-robot system: robot and structure are composed of the same discrete modular blocks, making them indistinguishable.
Scaling comparison
| Strategy | Assembly time | Throughput scaling |
|---|---|---|
| Gantry (serial) | O(2^4N) | decreasing |
| Carrier robot (serial) | O(2^4N) | decreasing |
| Self-replicating swarm | O(2^3N) | constant |
| Hierarchical only | O(2^3N) | constant |
| Recursive + hierarchical | O(2^2N) | O(2^N) — increasing |
| Biological (ribosomal) | — | O(2^log(E)) — increasing |
Implications for continuous assembly
This paper provides evidence that physical assembly can scale like software deployment — not through bigger machines, but through more and smarter small ones (xettel). It directly supports the continuous assembly thesis that the physical world can be treated as a build target.