Large area navigation method of multiple AUVs based on mutual measurements

In this paper, we propose a large area navigation method of multiple AUVs for accurate seafloor mapping over large area. The key idea of the method is alternating roles of the AUVs between “Moving and Measuring Role (MMR)” and “Landmark Role (LR)”. AUVs in the MMR move based on the AUVs in the LR. On the other hand, AUVs in the LR keep their stations to act as landmarks for the moving AUVs. By alternating their roles, the two groups of AUVs can observe a large area. AUV position is estimated by mutual measurements of distance and direction among them. These measurements are fused with other on-board sensors such as DVL, angular rate gyro and depth sensor by particle filter, a probabilistic state estimator, in order to realize stable positioning robust against sensor noises and lack of measurements. We verified the performance of the method through simulation based on data obtained during various experiments performed in pool and at sea. Through the simulation, we demonstrated that the proposed method achieves a positioning error considerably smaller than dead reckoning and thus a stable navigation over an area larger than achieved by a single AUV.