A novel simplified algorithm for calculating the mooring line based on lumped-mass method

Abstract

As an important component in Anchor Handling Simulator(AHS), the mooring system’s modeling and simulation have great impact on the AHS’s physical realism, behavioural realism and operating environment. We built the mooring line’s dynamics model based on Lumped-Mass Method (LMM) and used 4th order Runge-Kutta to solve it; However, the huge amounts of calculation in the model’s solving seriously hindered its application in AHS. To speed up the model’s solving process and realize the real-time simulation, we analysed the variables’ variation rates in the governing equation, identified the invariants, fast variables and slow variables, then proposed a novel simplified algorithm by adopting different time steps for their calculation. Experimental results show that, our simplified algorithm can reduce more than 64.5% of the calculating time on the premise of assuring the accuracy and numerical stability.