Elastic Effect of Variable-Length Flexible Cables Axially Moving in Underwater Tunnel

Optimal design and autonomous control of the Remotely Operated Vehicle (ROV) system involves precise modelling of the variable-length cable attached considering the elastic effect and predicting the transient motion of the system when it moves through the long underwater tunnels. This paper presents a novel flexible cable model for the ROV system with application in the underwater tunnel detection considering mass flow from the winch. The thin or slender cable is based on the Absolute Nodal Coordinate Formulation (ANCF) element in the framework of Arbitrary Lagrange-Euler (ALE). The presented multibody dynamic model for this problem consists of the flexible cable, the ROV, the winch, and the interaction of the cable with the fluid and the tunnels. Hertz contact model is utilized to model the normal contact interaction between the cable and the underwater tunnel and the velocity-based friction model is applied to model the tangential friction interaction. The accuracy and validity of the model and solution are verified by a 30-m cable case, which can be solved as a rigid body analytically. Numerical simulation reveals that the velocity responses near the ROV and winch has a noteworthy time lag effect when the cable attached goes over a certain length and thus, the elastic effect should be considered for the ROV system when it works in the underwater tunnels.