The application of structured light for external subsea pipeline inspection based on the underwater dry cabin

Abstract

This study addresses the critical challenge of inspecting subsea pipelines in the highly turbid waters of the East China Sea, where visibility significantly hinders conventional methods. To overcome these limitations, we developed an advanced unmanned submarine light-scanning system that leverages structured light technology within a large-scale underwater dry cabin. This innovative setup enables high-precision, in-situ external inspections of pipelines by ensuring comprehensive scanning coverage even in poor visibility conditions. The core components of our system include the shipboard-controlled structured light scanning driving system (SLSDS) for precise motion control, enabling seamless full-pipeline coverage in a single deployment, and the shipboard electric control subsystem (SECS), which integrates power supply, sensing, communication, and control functionalities. Applied in the Zhoushan sea area, the dry-cabin scanning system demonstrated a 50–66.7 % reduction in inspection time and a tenfold improvement in data resolution over traditional technologies. These results highlight the system's effectiveness, efficiency, and safety advantages, offering a robust solution for pipeline inspections in offshore environments with compromised visibility. The system's capability to significantly enhance inspection accuracy and operational efficiency underscores its potential for broader application in similar high-turbidity settings.