Attitude control for a pectoral fin actuated bio-inspired robotic fish

In this work we present a dynamic model for a pectoral fin driven robotic fish, simple yet precise enough to be successfully implemented on a Bio-inspired Underwater Vehicle with multiple fins, modeled after the Ostracion Meleagris, a coral reef dweller well known for its surprising maneuverability and dynamic stability. The control algorithm relies on a robust and computationally efficient sensory feedback, based on a complementary filter fusing data from different Inertial Measurement Unit (IMU) sensors. The almost global stability of the attitude estimator guarantees convergency and robustness to noise and parameters uncertainties, showing good performance of the vehicle in steering plane maneuvering. First, the controller was implemented to do point-to-point tracking of a desired roll angle while the robot was tethered. It was then implemented in a freely swimming robot to do trajectory tracking of a desired sinusoidal roll angle. Finally, to demonstrate the effectiveness of the combined roll/yaw coupling on the maneuveribility of the robot, the freely swimming robot was controlled to perform banked turns to circle the tank in loops.