Influence of Ambient Pressure on Performance of a Deep-sea Hydraulic Manipulator

Abstract

Deep-sea hydraulic manipulator is the most commonly used operation equipment for executing subsea operations in different applications. The increasing demands on underwater operational ease require the implementation of manipulator system which can maintain similar dynamic performance in different working conditions Considering the variations of seawater properties at different ocean depths, especially high hydrostatic pressure in deep-sea environment will make the kinematic viscosity of oil obviously increased, which has a significant influence on the performance of deep-sea hydraulic manipulator. The viscosity-pressure characteristics of working medium is tested. A detailed nonlinear mathematical model and related simulations considering the significant slender pipelines between valves and actuators due to the increased oil viscosity are conducted to analyze the ambient pressures against varying depths affecting the manipulator performance. The 115MPa online pressure experimental results indicate the joint response characteristics at different ambient pressures, which provides basis for response consistency control of deep-sea hydraulic manipulator. Keywords-Deep-sea hydraulic manipulator, Viscosity-pressure characteristics, Nonlinear mathematical model, 11000m on-line pressure experimentI.

Working Performance of the Deep-Sea Valve-Controlled Hydraulic Cylinder System under Pressure-Dependent Viscosity Change and Hydrodynamic Effects

“…The pressure compensator introduces the ambient pressure P am into the hydraulic system. According to the effective area on both sides of the hydraulic cylinder expressed by Equation ( 25), it can be known that the hydraulic cylinder has an output force of πd 2 h P am 4, which equals the ambient pressure load expressed by Equation (27). Then, it can be known that the ambient pressure load is inherently balanced and does not need to be considered.…”

“…Therefore, for the VCHCS working in deep-sea conditions with high seawater ambient pressure, pipeline pressure loss cannot be directly ignored since it increases significantly with the change in viscosity. Tian et al [27] proposed a detailed nonlinear model of a deep-sea hydraulic manipulator, in which the viscosity change of the hydraulic oil caused by the ambient pressure in the deep sea is considered. With this model, the simulation of the deep-sea hydraulic manipulator has been conducted.…”

“…The work of Tian et al [27] indicated that the output movement delay of the deepsea VCHCS is caused by the increase in pipeline pressure loss relating to the viscosity change of hydraulic oil. However, there is something that can be further deepened and improved.…”

Extended State Observer-Based Fuzzy Adaptive Backstepping Force Control of a Deep-Sea Hydraulic Manipulator with Long Transmission Pipelines

“…where u i is the parameter obtained from the output of the fuzzy self-tuner; and ∆k i = k i f max − k i f min and k i f max , k i f min are the maximum and minimum values of k i f determined from Equation (37) and the experiments, respectively.…”

Kinematic Viscosity Prediction of Polyalkylene Glycol in a Deep-Sea Environment from Molecular Dynamics

“…Solutions to EHL lubrication problems require data on pressure and temperature dependence. , The demand for such data has grown in recent years. In hydraulic systems, the fluid viscosity also affects the starting efficiency of the motor, the pressure loss of the pipes, the control accuracy of the solenoid valves, and so on. − The present reports on PAGs are focused on their ability to achieve ultralow friction lubrication in aqueous solutions, , and there are no reports of PAGs about their viscosity. In many situations, it is prohibitive to obtain these properties experimentally due to safety issues or economic factors .…”