Development and Experimental Validation of an Underwater Manipulator Hydrodynamic Model

Abstract

Hydrodynamic forces can be large, and hence have a significant effect on the dynamic performance of underwater manipulation sys tems. This paper investigates these forces for a cylindrical single- link arm undergoing motions that are characteristic of a robotic manipulator. Based on flow visualization, theoretical analysis, and experimental measurements, a new model is developed that describes these forces. This model differs from previous models in that the drag and added mass coefficients are state-dependentfunctions that depend on the distance traveled by the arm. A factor of four improve ment in accuracy is demonstrated over standard constant-coefficient models.