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

Abstract

Abstract-In this paper the straight line path following problem is considered for formations of underactuated marine vessels. The vessels are affected by a constant ocean current that is bounded, and irrotational with respect to the inertial frame. A Line-of-Sight (LOS) guidance law with two feedback linearising controllers is used to achieve path following of each individual vessel. Integral action is added to the LOS guidance law to compensate the effects of the ocean current acting on each vessel. In addition to the individual geometric task of path convergence, the vessels must also achieve the formation control task. More specifically, the vessels have to move along the desired path with a specified relative inter-vessel distance and with a constant desired velocity. This task is accomplished using a nonlinear formation control law. The closed-loop dynamics are analysed using theory for feedbackinterconnected cascaded systems. It is shown that the origin of the closed-loop error dynamics of the combined path following dynamics and formation dynamics is uniformly globally asymptotically stable. Simulation results are presented in a case study.

Path following with disturbance rejection for inhomogeneous formations with underactuated agents

“…The approach in [12] requires knowledge or estimation of the side-slip angle, while this is not necessary in the integral LOS guidance developed in [13] that is used in this work. This A path-following control strategy for formations of underactuated marine vehicles in the presence of ocean currents is presented in [14]. The vehicles in [14] are controlled to a desired path using integral LOS guidance ( [13], [15]) to reject the disturbance and a decentralised formation controller is used to synchronise the alongpath position using only locally available information.…”

“…This A path-following control strategy for formations of underactuated marine vehicles in the presence of ocean currents is presented in [14]. The vehicles in [14] are controlled to a desired path using integral LOS guidance ( [13], [15]) to reject the disturbance and a decentralised formation controller is used to synchronise the alongpath position using only locally available information. However, in [14] it is assumed that the current for each vessel is the same, which is typically not the case if vessels are far apart or if one is shielding the other from the current.…”

“…The vehicles in [14] are controlled to a desired path using integral LOS guidance ( [13], [15]) to reject the disturbance and a decentralised formation controller is used to synchronise the alongpath position using only locally available information. However, in [14] it is assumed that the current for each vessel is the same, which is typically not the case if vessels are far apart or if one is shielding the other from the current. Moreover, the path following controller cannot be tuned considering individual vessel dynamics and limitations but should be the same for each vessel in the formation.…”

“…The main contribution in this work is to extend the work in [14] by removing the most limiting assumption. More, specifically, in [14] it is assumed that all the vessels are disturbed by the same current, which is necessary because the vessels are controlled to a constant desired relative velocity.…”

Leader–Follower Synchronisation for a Class of Underactuated Systems

“…In [4] formation control of underactuated systems is considered, and straight-line path following in formation is achieved for underactuated marine vessels under the influence of constant ocean currents. Straight-line target tracking for underactuated unmanned surface vessels is investigated in [8].…”