  Self-assembly enables multi-robot systems to merge diverse capabilities and
accomplish tasks beyond the reach of individual robots. Incorporating varied
docking mechanisms layouts (DMLs) can enhance robot versatility or reduce
costs. However, assembling multiple heterogeneous robots with diverse DMLs is
still a research gap. This paper addresses this problem by introducing CuBoat,
an omnidirectional unmanned surface vehicle (USV). CuBoat can be equipped with
or without docking systems on its four sides to emulate heterogeneous robots.
We implement a multi-robot system based on multiple CuBoats. To enhance
maneuverability, a linear active disturbance rejection control (LADRC) scheme
is proposed. Additionally, we present a generalized parallel self-assembly
planning algorithm for efficient assembly among CuBoats with different DMLs.
Validation is conducted through simulation within 2 scenarios across 4 distinct
maps, demonstrating the performance of the self-assembly planning algorithm.
Moreover, trajectory tracking tests confirm the effectiveness of the LADRC
controller. Self-assembly experiments on 5 maps with different target
structures affirm the algorithm's feasibility and generality. This study
advances robotic self-assembly, enabling multi-robot systems to collaboratively
tackle complex tasks beyond the capabilities of individual robots.
