Sequences from the engineers’ hand-designed robotic self-reproduction. New Molecubes are deposited from the top, and each cube has the ability to swivel. Image credit: Zykov, et al. ©IEEE 2007.
The set-up of the manual process resembles a 3D Tetris game, where a dispenser drops cubic modules, called “Molecubes,” to a machine consisting of a line of connected cubes that can pick up, hold, and drop other cubes, as well as swivel to place a cube in a different location. Ultimately, the original machine can be programmed to build a copy of itself, which in turn can copy itself, ideally through several generations.
Each Molecube is identical: a 10 cm3, 625-gram module that can swivel along its long diagonal axis. On two of the cube’s sides, connectors can attach to other cubes’ connectors. A servo motor within each cube drives the swiveling mechanism.
The goal of the second part of the project was to find out whether or not it is possible to artificially evolve simple modular 2D self-reproducing machines with 2D Molecubes. First, the genetic algorithm searches for a specific shape of a 2D machine. The desired shape should enable the robot to pick up available modules around itself, swivel to a target location, and, by sequentially dropping the modules off one by one in the right places, form an exact 2D replica of itself.