Development and Experiments of an Electrothermal Driven Deep-Sea Buoyancy Control Module

Abstract

Due to the extremely high pressures in the deep sea, heavy ballast tanks and pressure compensating hydraulic tanks are typically required to support the operation of classic buoyancy controls. Buoyancy control systems driven by phase-change materials (PCM) have unique advantages over conventional hydraulically actuated buoyancy control systems, including high adaptability for deep-sea exploration and simple, lightweight, and compact structures. Inspired by this, a buoyancy control module (BCM) was designed with flexible material as the shell. Instead of a conventional mechanical system, the device uses an electric heating drive to control buoyancy by heating and cooling the PCM. Based on the principle of pressure compensation, this device can adjust the buoyancy of a small underwater vehicle in a deep-sea high-pressure environment. The BCM successfully adjusts the buoyancy to lift itself up and down in the South China Sea at a depth of 3223 m. The performance of the phase-change BCM to control buoyancy under high pressure is validated by systematic experiments and theoretical analysis. Our work proposes a flexible scheme for the design of a deep-sea phase-change-driven BCM and highlights its potential application in deep-sea micro-mechanical systems, especially soft robots.

Design and Performance Study for Electrothermally Deep-Sea Drive Microunits Using a Paraffin Phase Change Material

“…The deep-sea environment has high corrosion and high electrical conductivity. The experiments in South China Sea show that the bonding of 704-silicone rubber can be applied to the deep-sea environment, which can ensure that the wrapped metal electrode is not negatively affected by seawater [ 30 ]. Given the refraction of laser in water, the micro-laser displacement sensor cannot effectively and accurately measure the displacement characteristics of the deep-sea drive microunit in water.…”

“…Hou et al developed an electrothermally driven deep-sea buoyancy control module, which has been successfully verified at 3223 m to the seabed of the South China Sea. This device also uses the volume change generated by paraffin in the process of phase transformation [ 30 ].…”

Recent Advances on Underwater Soft Robots

“…This mechanism could facilitate the replacement of traditional, physically larger buoyancy regulation systems, such as pistons and pressurized tanks, and enable miniaturization of autonomous underwater vehicles. Jiaoyi Hou et al [ 239 ] designed a phase‐change buoyancy control module (BCM) with flexible material as the shell, which has great potential for application in small deep‐sea robots, especially in the buoyancy regulation of deep‐sea flexible electronic fish.…”

Depth Control of an Oil Bladder Type Deep-Sea AUV Based on Fuzzy Adaptive Linear Active Disturbance Rejection Control

“…The main characteristics and differences of the three types of VBS are compared in Table 1. Besides, a new VBS type based on the phase change of paraffin with the advantages of silence and miniaturization appears, but it is still under study [27,28]. Due to the advantages of oil bladder VBS, this paper proposes a deep-sea AUV using an oil bladder VBS with an electro-hydraulic proportional valve to achieve high depth control performance.…”