Experimental Results of Ship-free Underwater Survey Method of Multiple Autonomous Underwater Vehicles

This paper reports on the latest results of experiments of an underwater survey method of a single high-performance parent AUV and a group of child AUVs. In the proposed method low-cost AUVs (child AUVs) estimate their self-states including their position, yaw angle, and horizontal moving velocity accurately thanks to the parent AUV without any external support such as a ship. Since the child AUVs have only simple navigational sensors, positioning performance is not enough. The parent AUV, on the other hand, can conduct accurate self-state estimation using high-grade navigational sensors without any external support. The parent AUV supports the child AUVs through all processes of deployment, surveying, recovery, and surfacing. All the child AUVs have acoustic positioning and communication devices and cameras; hence, they build a parent-centered wireless positioning and communication network. The proposed method was implemented on AUVs Tri-Dog 1, Tri-TON, Blue AUV, and Tri-TON 2. To verify the performance of the proposed method, sea and tank experiments with these AUVs were conducted. Through the results from the experiments, it was verified that low-cost child AUVs can realize stable state estimation.