  Harmful marine spills, such as algae blooms and oil spills, damage ecosystems
and threaten public health tremendously. Hence, an effective spill coverage and
removal strategy will play a significant role in environmental protection. In
recent years, low-cost water surface robots have emerged as a solution, with
their efficacy verified at small scale. However, practical limitations such as
connectivity, scalability, and sensing and operation ranges significantly
impair their large-scale use. To circumvent these limitations, we propose a
novel asymptotic boundary shrink control strategy that enables collective
coverage of a spill by autonomous robots featuring customized operation ranges.
For each robot, a novel controller is implemented that relies only on local
vision sensors with limited vision range. Moreover, the distributedness of this
strategy allows any number of robots to be employed without inter-robot
collisions. Finally, features of this approach including the convergence of
robot motion during boundary shrink control, spill clearance rate, and the
capability to work under limited ranges of vision and wireless connectivity are
validated through extensive experiments with simulation.
