Catastrophe of submarine near-surface motion

To study the mechanism for losing stability, the nonlinear submarine near-surface motion model under wave disturbances was established. The bifurcation and catastrophe theory methodology was adapted to analyze the motion stability. The equations of submarine were reduced to the lower system which contained all dynamic properties of original system by utilizing center manifold theory. The status catastrophe caused by static bifurcation was discussed. The numerical simulation results in MATLAB/Simulink program validate that the transcritical bifurcation occurred in submarine operating motion with lowspeed under wave disturbances in dive plane which would lead to status catastrophe at bifurcation points. These catastrophe phenomena reveal the effect of wave disturbances and nonlinear terms in submarine dynamic model, and provide necessary theoretical basis for submarine maneuvering control system designing.