AUV navigation around jacket structures II: map based path-planning and guidance

Abstract

This paper proposes a path-planning and guidance strategy for an autonomous underwater vehicle (AUV) to perform detailed inspections of jacket structures such as the support legs of offshore platforms. Inspections of such structures are important for maintenance, security, and environmental assessment. These tasks can be carried out at a less cost by using AUVs than through conventional methods. The path-planning method generates a set of waypoints to facilitate the complete coverage of the surface of the target from a constant distance based on the given information about the configurations of both the target and the vehicle. The guidance method actually controls the vehicle such that it follows the waypoints, under the assumption that the position and attitude of the vehicle are being estimated in real time with adequate accuracy. By combining these methods with the localization method we had previously proposed (Maki et al., J Mar Sci Technol [1]) an AUV can perform a fully autonomous observation of jacket structures with prior knowledge of only their configuration. The performance of the method was verified though tank experiments using the AUV Tri-Dog 1. A simple model of a jacket was installed in a test tank, and the vehicle succeeded in inspecting the target.