Nonlinear Dynamics Modeling and Analysis of Underwater Mud-Penetrator Steering System

Adopting underwater mud-penetrator to thread the steel wire is one of the important steps in the current wreck salvage process, which is safer and more efficient than threading with manpower by the diver. This paper first establishes the kinematics model of the underwater mud-penetrator in the inertial coordinate system and discussed the drill steering mechanism and force characteristics under the nonlinear coupling interaction between drill bit, drill pipe, and seabed geology. Based on the Newton-Eulerian method, the nonlinear dynamic model of mud-penetrator is established, and the influence of guiding angle, geological features, and propelling force on steering process is analyzed through simulation. The simulation results show that the steering process of underwater mud-penetrator is the compound movement of the drill bit translation and deflection. The reduction of the guiding angle and the increase of the propulsive force can effectively improve the guiding ability of the non-excavation drill bit. As the guiding angle decreases pi/12-pi/15, the deflection angle of the drill bit is increased by 2°-3°, and as propulsion increases 500 N, the deflection angle of the drill bit is increased by 3°. The area of the guiding plate also has a great influence on the guiding ability of the drill bit, and the deflection angle is inversely proportional to the area of the drill guiding plate. The deflection angle is more sensitive to soft geological changes. The simulation results are of great significance help to understand the process of drilling guidance process for wrecking and salvaging, and it can help to improve the threading success rate and salvage efficiency.