Experimental Study on Compressibility Modulus of Pressure Compensation Oil for Underwater Vehicle

Abstract

: In order to determine the appropriate volume of the a pressure compensator of deep seabed mining robots, this paper reports on an experimental test for oil volume change in an oil-filled box. At the design stage of underwater robots, it is crucial to determine the capacity of the hydraulic compensator which is replenished as much as the contracted oil volume of the robots. A pilot mining robot, MienRo was designed to work under 6,000 m in the deep sea. The hydraulic actuating oil and pressure compensating oil of MineRo may be exposed at a hydrostatic pressure environment of 600 bar. Although the oil can be assumed to be incompressible, its volume is actually changed under high pressure conditions due to air contained in the oil and oil contraction. To determine the capacity of the pressure compensator, the oil contraction rate should be verified through an experimental test using a hyperbaric chamber.

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

“…Some industrial companies such as Schilling Robotics, Hydro-Lek and ISE, have already realized deep-sea hydraulic manipulator industrialization, the normally designed depth rating is 6000 meters or less. However, the high hydrostatic pressure (about 115MPa in 11000m depth) in deepsea environment will make the kinematic viscosity of the oil significantly increased leading to the hydraulic manipulator too sluggish to operate, which will be a great technical challenge for the 11000m depth hydraulic manipulator design and control [7,8].Nowadays, the increasing demands on underwater operational ease require the implementation of manipulator system which can maintain similar dynamic and tracking performance in different working conditions [9,10]. Therefore, research on the performance at different ambient pressures is essential to realize the response consistency of hydraulic manipulator at any ocean depth.…”

DOREP: An Educational Experiment Platform for Robot Control Based on MATLAB and the Real-Time Controller

“…However, there are still challenges existing in the hadal scientific expedition equipment, especially the hydraulic manipulator. The high hydrostatic pressure (about 115 MPa in 11000 m depth) in the hadal environment will make the kinematic viscosity of the oil significantly increase, which will affect the performance of the manipulator [10,11]. It is difficult to maintain similar dynamic and tracking performance in different working conditions for an underwater hydraulic manipulator [12].…”