Cross-Track Formation Control of Underactuated Autonomous Underwater Vehicles

Abstract

Summary. The problem of 3D cross-track control for underactuated 5-degrees-of-freedom (5-DOF) autonomous underwater vehicles (AUV) is considered. The proposed decentralized controllers make the AUVs asymptotically constitute a desired formation that follows a given straight-line path with a given forward speed profile. The proposed controllers consist of two blocks. The first block, which is based on a Line of Sight guidance law, makes every AUV asymptotically follow straight line paths corresponding to the desired formation motion. The second block manipulates the forward speed of every AUV in such a way that they asymptotically converge to the desired formation and move with a desired forward speed profile. The results are illustrated with simulations. IntroductionFormationc ontrol of marine vessels is an enabling technology foranumber of interesting applications. Afl eet of multiple autonomous underwaterv ehicles (AUVs) moving together in ap rescribed patternc an form an efficientd ataa cquisitionn etwork forsurveying at depths where neither diversnor tethered vehiclescan be used, andinenvironments toorisky formanned vehicles. Thisincludes forinstance oceanographic surveying at deeps ea,o perationsu nder icef or explorationo fA rctic areas ande fficientm onitoring sub-seao il installations.In this paperwestudythe problem of 3D cross-trackformation controlfor underactuated 5-DOF AUVs that arei ndependently controlledi ns urge,p itch andy aw. Roughly speaking,t his problemc an be formulateda sf ollows: givenastraight line path, ad esired formationp attern, andadesireds peed profile, c ontrol the AUVs such thata symptotically they constitute the desiredf ormationw hicht hen moves alongthe givenp athw ith thed esired speed. Ther elevance of such af ormation control problemi sj ustified by thef actt hatadesired path fora utonomousv ehicles is usually givenb ys traightlinesi nterconnecting way-points,see, e.g., [ 9].A tt he same time, thes peed profile of an autonomous vehicle is often specified independently of the desired path. This makesi tp ossible to decouple them issionp lanning into two stages:ageometricp athp lannings tage andadynamics peed assignments tage.

Straight line path following for formations of underactuated underwater vehicles

“…For fully actuated marine vehicles the formation control problem has been considered in [9], [10] and [11]. For underactuated marine vehicle this problem has been considered in [12] for the case of two vehicles with planar motion, in This [13] for an arbitrary number of surface vessels and in [14], [15] for the 3D case of autonomous underwater vehicles.…”

Straight line path following for formations of underactuated surface vessels under influence of constant ocean currents

“…The sway dynamics (7b) is assumed to be inherently stable, with its boundedness properties captured by an assumption in the next section. The terms w ⊤ * (ψ)ρ are the corresponding components of the vector M −1 Dν c , with ν c given in (3). In what follows we will use the reformulated model (6)- (7) with (τ u , τ r ) as control inputs and with the current vector ρ = [ρ x ρ y ] ⊤ ∈ R 2 as unknown parameters.…”

“…Yet for marine vessels, especially in the underactuated case, one cannot simply put together general results on formation control (which are usually formulated on the kinematics level) and results on the path following problem for a single vehicle (studied both on the kinematics and dynamics level). Such a combination requires careful overall analysis due to the highly nonlinear dynamics of the systems involved, as pointed out in [3]. In [15] this analysis is done for the case of two cooperating vessels, and in [1], [4] it is performed for an arbitrary number of surface vessels.…”

Path following for formations of underactuated marine vessels under influence of constant ocean currents

“…The problem of path following control of formations of marine vehicles is studied in [16]- [21]. In [19] path following of two underwater vehicles is investigated.…”

“…In [16]- [18] straight-line path following for formations of marine vehicles is considered. In particular, in [16]- [18] LOS guidance is used to make each vehicle in the formation follow a desired path, whilst a formation control term is added to the velocity control to achieve a desired inter-agent distance and formation. However, in all the formation control approaches discussed above the effects of ocean currents are not taken into account.…”