A Nonlinear Observer for Remotely Operated Vehicles with Cable Effect in Ocean Currents

Xiang Li,Min Zhao,Tong Ge

doi:10.3390/app8060867

Abstract

A nonlinear observer for a remotely operated vehicle (ROV) is investigated, and a four-degree-of-freedom nonlinear sliding state observer is designed in this study. An ocean current model and a simplified umbilical cable disturbing force model of ROVs were set up; the simplified cable force model characterized the cable disturbing force. The velocity information and the cable force were observed and estimated both online and in real time. We proved that the observation error was uniformly ultimately bounded. The modeling of the disturbing force and the compensation for the observer was an effective method to improve the observation precision and to reduce the chattering of the observer outputs.

Highlights

The improvement of marine resources exploitation technology has become important for the development of the marine industry
The results presented in this paper are based on the Sea Dragon remotely operated vehicle (ROV)
The inertial measurement unit (IMU); Depth sensor: 6000 m rating, 0.01% accuracy; Doppler

Summary

Introduction

The improvement of marine resources exploitation technology has become important for the development of the marine industry. The design and development of new types of marine engineering equipment to enhance the technological level of the ocean engineering industry is of considerable significance. Unmanned underwater vehicles, including remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), and underwater gliders, have been extensively and increasingly used in marine environments for exploration, inspection, and engineering operations [1]. They can provide safe and effective access to deep sea and hadal environments without physically entering them. With advantages like functional diversity, strong operational ability, and a high safety factor, ROVs have been widely used and have become important technical equipment in areas such as ocean resource development, exploration, marine scientific research, and underwater engineering [2]

Methods

Results

Conclusion