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Navigation Method of Multiple AUVs with Velocity Control for Stable Positioning and Communication among AUVs

This paper proposes a navigation method of multiple autonomous underwater vehicles (AUVs) with velocity control based on a single high-performance AUV which can estimate self-state (position and pose) accurately without any support. To understand the environment of the seafloor, photo and acoustic mapping by AUVs have been conducted. Since the AUVs cannot obtain GPS data directly in underwater environment, it is difficult to estimate self-state. In the proposed method, AUVs consist of two types of AUVs: a parent AUV and child AUVs where the former has high-grade navigational sensors and acts as a positioning reference; the latter has only low-cost navigational sensors. The child AUVs realize high positioning accuracy thanks to acoustic positioning relative to the parent AUV. However, positioning accuracy depends on distance between the parent and child AUVs. There is a risk that the positioning accuracy may degrade due to the child AUV moves away from the parent AUV. For that reason, the parent AUV transmits its own position and destination to the child AUVs, and each child AUV accelerates or decelerates its ground velocity based on its position and above information received from the parent AUV. As a result, each child AUV can realize seafloor observation while maintain its position relative to the parent AUV. Thanks to the proposed method, child AUVs can realize stable and accurate positioning relative to the parent AUV.