  The emerging field of passive macro-scale tile-based self-assembly (TBSA)
shows promise in enabling effective manufacturing processes by harnessing
TBSA's intrinsic parallelism. However, current TBSA methodologies still do not
fulfill their potentials, largely because such assemblies are often prone to
errors, and the size of an individual assembly is limited due to insufficient
mechanical stability. Moreover, the instability issue worsens as assemblies
grow in size. Using a novel type of magnetically-bonded tiles carried by
bristle-bot drives, we propose here a framework that reverses this tendency;
i.e., as an assembly grows, it becomes more stable. Stability is achieved by
introducing two sets of tiles that move in opposite directions, thus zeroing
the assembly net force. Using physics-based computational experiments, we
compare the performance of the proposed approach with the common orbital
shaking method, proving that the proposed system of tiles indeed possesses
self-stabilizing characteristics. Our approach enables assemblies containing
hundreds of tiles to be built, while the shaking approach is inherently limited
to a few tens of tiles. Our results indicate that one of the primary
limitations of mechanical, agitation-based TBSA approaches, instability, might
be overcome by employing a swarm of free-running, sensorless mobile robots,
herein represented by passive tiles at the macroscopic scale.
