Robust Maneuverability of a Miniature, Low-Cost Underwater Robot Using Multiple Fin Actuation

In this letter, we present the design of a miniature (100 mm) autonomous underwater robot that is low-cost ($ 100), easy to manufacture, and highly maneuverable. A key aspect of the robot design that makes this possible is the use of low-cost magnet-in-coil actuators, which have a small profile and minimal sealing requirements. This allows us to create a robot with multiple flapping fin propulsors that independently control robot motions in surge, heave, and yaw. We present several results on the robot, including 1) quantified open-loop swimming characteristics; 2) autonomous behaviors using a pressure sensor and an inertial measurement unit (IMU) to achieve controlled swimming of prescribed trajectories; 3) feedback from an optic sensor to enable homing to a light source. The robot is designed to form the basis for underwater swarm robotics testbeds, where low cost and ease of manufacture are critical, and three-dimensional (3-D) maneuverability allows testing complex coordination inspired by natural fish schools. Individually, miniature and low-cost underwater robots can also provide a platform for the study of 3-D autonomy and marine vehicle dynamics in educational and resource-constrained settings.