A guidance and control system proposal for autonomous pipeline inspections

Abstract

This paper describes a guidance and control method, used to guide an autonomous underwater vehicle (AUV) in the task of locating and tracking underwater pipeline and cables. The article also gives details about the simulation and experimental results of the AUV’s navigation when searching for simulated pipelines on the seabed in shallow waters. Sonar based pipeline detection and tracking starts by the acquisition of the sonar image and further realtime processing to distinguish the pipeline from the seabed. Depending on the success of detection, an artificial intelligence (AI) based dynamic path planner must decide the next actions: a search, a skip, an obstacle avoidance or a track process. For instance, pipeline searching involves a series of zig zag explorations of the area where the pipeline is presumably located. Pipeline tracking involves keeping the navigation at fixed distance from the pipe. The path following method proposed in this article is based on a combination of a Lyapunov technique and a PI controller acting over two horizontal thrusters dual torpedo AUV. The article finally reports some of the stages involved in the detection of the pipeline using a sonar, the guidance and control method used for the generation of a smooth path following trajectory, the main aspects of dynamic mission re-planning, and the results, both in computer simulation as well as sea trial experiments for a search process of a simulated pipeline in shallow waters.