Development of a Novel Underwater Robotic Platform with Rotating Thrusters for Hovering *

There are many harmful marine organisms, such as starfishes, in underwater environments. Underwater task to eliminate such organisms by divers is dangerous and inefficient. This paper proposes a novel remotely operated vehicle (ROV) platform for a robotic application to capture harmful marine organisms. The proposed underwater robotic platform has four rotatable thrusters for hovering motion against ocean current and reaction force of manipulator. Design procedure is presented and a prototype based on the design is assembled. Dynamic model is derived and a nonlinear controller based on backstepping algorithm is synthesized. Simulation results show possibility of hovering motion that can maintain static position and orientation of robot against ocean current.