  Optimal maintenance of sensor nodes in a Wireless Rechargeable Sensor Network
(WRSN) requires effective scheduling of power delivery vehicles by solving the
Charging Scheduling Problem (CSP). Deploying Unmanned Aerial Vehicles (UAVs) as
mobile chargers has emerged as a promising solution due to their mobility and
flexibility. The CSP can be formulated as a Mixed-Integer Non-Linear
Programming problem whose optimization objective is maximizing the recharged
energy of sensor nodes within the UAV battery constraint. While many studies
have demonstrated satisfactory performance of heuristic algorithms in
addressing specific routing problems, few studies explore online updating
(i.e., mission re-planning `on the fly') in the CSP context. Here we present a
new offline and online mission planner leveraging a first-principles power
consumption model that uses real-time state information and environmental
information. The planner, namely Rapid Online Metaheuristic-based Planner
(ROMP), supplements solutions from a Guided Local Search (GLS) with our
Context-aware Black Hole Algorithm. Our results demonstrate that ROMP
outperforms GLS in most cases tested. We developed and proposed FastROMP to
speed up the online mission (re-)planning algorithm by introducing a new online
adjustment operator that uses the latest state information as input,
eliminating the need for re-initialization. FastROMP not only provides a better
quality route, but it also significantly reduces computational time. The
reduction ranges from 39.57% in sparse deployment to 93.3% in denser
deployments.
