An Autonomous Charging System for a Robotic Fish

The use of autonomous underwater vehicles is often hampered by stringent power constraints that limit the duration of their deployment. Here, we present a novel autonomous underwater charging system for robotic fish. The system features a charging station designed with form-fit claws to facilitate the robotic fish docking. A controller is implemented externally to monitor the battery level of the robotic fish, swimming autonomously in two dimensions. When the battery level is low, the controller commands the robotic fish to approach the charging station using video feedback from an overhead camera. The approach angle of the robotic fish to the charging station is optimized through a series of experiments, assessing the success of both docking and electrical contact, as well as the time to approach the charging station. To demonstrate the feasibility of the autonomous charging system, the robotic fish is monitored as it cycles through periods of charging and discharging while swimming in the tank. The proposed system is expected to find application in laboratory and educational settings, where robotic fish should operate with minimal supervision and assistance from technical staff over extended time periods.