Low-Cost Underwater In-Pipe Centering and Inspection Using a Minimal-Sensing Robot

2026-02-05

AI Summary

This study addresses the challenge of autonomous inspection in submerged pipelines, where confined spaces, turbid conditions, and the absence of reliable localization cues hinder conventional approaches. The authors propose a lightweight perception system that relies solely on an IMU, a pressure sensor, and two sonars—a single-beam and a 360° rotating sonar. By efficiently estimating range from single-beam sonar intensity data and employing a closed-form geometric model to compute the pipe center in real time, the system enables robust navigation. A confidence-weighted proportional-derivative (PD) controller is further designed to achieve adaptive centering. Requiring neither complex sensors nor high computational resources, the method successfully accomplishes stable traversal through an entire 46-cm-diameter submerged pipeline, demonstrating strong robustness and practicality under structural deformations and environmental disturbances.

Technology Category

• Intelligent Robots: Localization, Mapping, and Navigation
• Planning, Routing, and Scheduling: Activity and Plan Recognition
• Search and Optimization: Learning to Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Responsible Web: Machine-in-the-loop, human agency and autonomy
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation

Abstract

Autonomous underwater inspection of submerged pipelines is challenging due to confined geometries, turbidity, and the scarcity of reliable localization cues. This paper presents a minimal-sensing strategy that enables a free-swimming underwater robot to center itself and traverse a flooded pipe of known radius using only an IMU, a pressure sensor, and two sonars: a downward-facing single-beam sonar and a rotating 360 degree sonar. We introduce a computationally efficient method for extracting range estimates from single-beam sonar intensity data, enabling reliable wall detection in noisy and reverberant conditions. A closed-form geometric model leverages the two sonar ranges to estimate the pipe center, and an adaptive, confidence-weighted proportional-derivative (PD) controller maintains alignment during traversal. The system requires no Doppler velocity log, external tracking, or complex multi-sensor arrays. Experiments in a submerged 46 cm-diameter pipe using a Blue Robotics BlueROV2 heavy remotely operated vehicle demonstrate stable centering and successful full-pipe traversal despite ambient flow and structural deformations. These results show that reliable in-pipe navigation and inspection can be achieved with a lightweight, computationally efficient sensing and processing architecture, advancing the practicality of autonomous underwater inspection in confined environments.

Problem

• underwater inspection
• in-pipe navigation
• autonomous robot
• confined environments
• localization

Innovation

• minimal-sensing
• underwater pipe inspection
• sonar-based localization
• adaptive PD control
• autonomous underwater robot