A Dispatching Strategy of Autonomous Robotic Charger Boats for Charging Electric Vessels

Autonomous robotic boats equipped with chargers or swappable batteries can serve as Mobile Energy Disseminators (MED) and proactively maintain the State-of-Charge of electric vessels. However, previous methods are either incapable of keeping the vessels continuously driving without recharge downtime, or not directly applicable for the scheduling of chargers on city-scale transportation networks. We propose RoboCharger: a Robotic Charger boat scheduling system that adaptively determines the number of serving MEDs, and the optimal routes of the MEDs according to vessel traffic. We studied a metropolitan-scale vessel mobility dataset provided by MarineTraffic and analyzed the spatial-temporal characteristics of vessel movements in Amsterdam's canals. Based on the analysis insights, we developed a MinHash and spatial-temporal similarity comparison based method for vessel traffic estimation, a Chinese Postman Problem based method for determining the cruising routes of the MEDs, and formulated and solved a multi-objective optimization problem to determine the number of serving MEDs, the driving route of each MED and maintain the SoC of the vessels above zero. Our trace-driven experiments demonstrate that compared with previous methods, RoboCharger increases the average SoC of vessels over all time slots throughout a day by almost 42%, and the number of charges of vessels by almost 53%.