Computer-Aided Control Systems Design

4.6.3    Hydrodynamic Damping Forces

Matrix D is the hydrodynamic damping matrix [61–62] consisting of both linear and quadratic terms. This hydrodynamic damping is caused by the potential damping due to linear skin friction (linear damping) drag and vortex shedding (quadratic or nonlinear damping). The sum of these individual components gives the overall hydrodynamic damping effect on the ROV.

Since the ROV is designed to be self-stabilizing in the roll and pitch angle, the magnitude of these angles, especially the pitch angle, is very small. Hence, for such small pitch angle (or angle of attack), there is no cross-flow separation and no boundary layer separation, and the flow remains attached. Therefore, the nonlinear part of the forces and ...