Optimizing autonomous underwater vehicle routes with the aid of high resolution ocean models

Abstract

In underwater vehicle operations in areas such as estuaries, vehicles may face currents with magnitudes equal to or exceeding the vehicle's maximum forward speed. We propose a method which generates vehicle routes taking into account ocean current forecasts from high resolution ocean models, in order to both take advantage of the ocean current velocity and avoid its negative effects. We formulate the problem in an optimal control setting and derive the associated Hamilton-Jacobi-Bellman partial differential equation (PDE). We solve this PDE using a parallelized C++ implementation of a numerical method which allows us to obtain the solution in a few minutes on a mainstream computer. After obtaining the solution of the PDE, optimal trajectories with any initial condition can be computed efficiently. The method is illustrated using data from highresolution ocean models of the Sado river estuary in Portugal. Two mission scenarios are analyzed, which highlight the influence of ocean currents on optimal trajectories and the benefits of considering ocean current forecasts in mission planning.

Minimal time delivery of multiple robots

“…The resulting variational inequalities are solved numerically to find the solution in the form of a set of value functions. This computationally expensive operation is efficiently performed by our parallel implementation of a solver [1]. Given the desired time and location of departure of the carrier, those value functions can then be used to determine approximations of the optimal trajectory for this vehicle, along with the deployment times and locations for all AUVs.…”

“…Miguel Aguiar 1 , Jorge Estrela da Silva 2 and João Borges de Sousa 1 Abstract-Consider a set of autonomous vehicles, each one with a preassigned task to start at a given region. Due to energy constraints, and in order to minimize the overall task completion time, these vehicles are deployed from a faster carrier vehicle.…”

“…In the examples below we use our open-source parallel implementation 1 of the fast sweeping method (FSM) [13,9,1] to compute an approximate solution of (6). The FSM is an iterative method which can be combined with several different discretization methods.…”

“…All of these vehicles are subject to time-varying currents. The approach builds on DP methods applied to a hybrid-state model and on an efficient solver [1] of the Hamilton-Jacobi-Bellman partial differential equation resulting from the application of the DPP to this model.…”

Integrated Autonomous Underwater Vehicle Path Planning and Collision Avoidance Algorithms

“…There have been numerous studies on AUV path planning, mostly using graph searching-type, sampling-based, and potentially, field-based algorithms (An, et al, 2023). For example, Aguiar et al propose AUV route optimization through the use of high-resolution ocean models (Aguiar, et al, 2019). This involves the acceleration and speed of the AUV, which are optimized by means of more accurate ocean models which allow currents or other environmental effects to be considered during path planning.…”