A Floating Cable-Driven Robotic Manipulator in a Marine Environment

A cable-driven platform is designed, manufactured and tested in a water tank. The platform is operated by four cables anchored to the tank corners and controlled by actuators mounted on a cylindrical floating structure. Labview based experiments are conducted on the floating cable-driven parallel manipulator to measure tensions in the cables as it moves within its workspace. The platform is analyzed, in parallel, as a three degrees of freedom system within the framework of rigid-body dynamics, taking the influence of the surrounding water on the mass, stiffness, and damping matrices. A numerical model is established to calculate the tension in the cables as a function of the platform pose. Theoretical prediction and experimental results are found to agree fairly well.