  Providing a higher level of decision autonomy and accompanying prompt changes
of an uncertain environment is a true challenge of AUVs autonomous operations.
The proceeding approach introduces a robust reactive structure that
accommodates an AUV's mission planning, task-time management in a top level and
incorporates environmental changes by a synchronic motion planning in a lower
level. The proposed architecture is developed in a hierarchal modular format
and a bunch of evolutionary algorithms are employed by each module to
investigate the efficiency and robustness of the structure in different mission
scenarios while water current data, uncertain static-mobile/motile obstacles,
and vehicles Kino-dynamic constraints are taken into account. The motion
planner is facilitated with online re-planning capability to refine the
vehicle's trajectory based on local variations of the environment. A small
computational load is devoted for re-planning procedure since the upper layer
mission planner renders an efficient overview of the operation area that AUV
should fly thru. Numerical simulations are carried out to investigate
robustness and performance of the architecture in different situations of a
real-world underwater environment. Analysis of the simulation results claims
the remarkable capability of the proposed model in accurate mission
task-time-threat management while guarantying a secure deployment during the
mission.
