Autonomous shape and structure formation is an important problem in the
domain of large-scale multi-agent systems. In this paper, we propose a 3D
structure representation method and a distributed structure formation strategy
where settled agents guide free moving agents to a prescribed location to
settle in the structure. Agents at the structure formation frontier looking for
neighbors to settle act as beacons, generating a surface gradient throughout
the formed structure propagated by settled agents. Free-moving agents follow
the surface gradient along the formed structure surface to the formation
frontier, where they eventually reach the closest beacon and settle to continue
the structure formation following a local bidding process. Agent behavior is
governed by a finite state machine implementation, along with potential
field-based motion control laws. We also discuss appropriate rules for
recovering from stagnation points. Simulation experiments are presented to show
planar and 3D structure formations with continuous and discontinuous
boundary/surfaces, which validate the proposed strategy, followed by a
scalability analysis.Comment: 8 pages, 6 figures, accepted for publication in IROS 2023. A link to
the simulation videos is provided under the Validation sectio