Inter-Platform Coordination for Estimating Oceanic Velocity Gradients Using Lagrangian Floats

This article introduces an estimation–coordination framework that couples oceanic velocity gradient estimation with floats coordination, leveraging interplatform displacement measurements for mutual performance improvement. Framed as a nonlinear estimation problem, the paper considers an extended system with velocity-gradient coefficients as states and examines its observability by linking the approximation’s physical structure to the geometry of relative displacement. The proposed method employs a particle filter to perform the estimation of the coefficients. To enable the estimation, a robust control law on depth for pairwise coordination is applied. The estimation and coordination strategy’s performance is evaluated through numerical simulations and further validated in a synthetic replay experiment using processed data from an open-sea trial in the Atlantic Ocean.