Simulation Analysis of Passive Heave Compensation Device for Heavy-duty Underwater Robot

Abstract

At present, the simulation model of heave compensation device is usually highly complex, which is not conductive for intuitive understanding of its dynamic characteristics and performance mechanism. Therefore, this paper focuses on a swing-arm and gas-liquid mixed passive heave compensation (PHC) device that is applicable for launching and recovering of deep-sea heavy-duty underwater robots. The complex compensation process and nonlinear dynamic characteristics of the device are analyzed. By establishing reasonable modeling assumptions to reduce modeling complexity, simplified mathematical models of system dynamics and kinematics are derived, and corresponding numerical simulation software is developed. Model-based stability and dynamic simulation analyses are conducted, and the main factors that may affect the passive compensation performance are identified, including accumulator capacity, initial nitrogen charging pressure and nitrogen pressure after oil filling. By simulating the heave compensation performance of the heave compensation device with different design parameters and system states under the condition of still sea surface and degree-3 sea state, and comparing the main factors that affect compensation performance through simulations, the compensation performance of the PHC device in terms of compensation movement range and sensitivity to variations of umbilical cable tension, and the effectiveness of the algorithm model are verified. Based on the simulation results, some suggestions are proposed to improve the performance of the PHC through adjusting accumulator volume and nitrogen pressure.

Keywords

• passive heave compensation (phc)
• accumulator
• launch and recovery system (lars)
• simulation
• underwater robot