Nonlinear Adaptive Tracking Of Surface Vessels With Exogenous Disturbances

Braga²,

2019

Front. Robot. AI

This work presents the results of an experimental verification of a coordinated path following strategy for underactuated marine vehicles. The coordinated path following strategy is presented, and is then experimentally verified using three autonomous underwater vehicles. The vehicles are required to coordinate their motion along spatially separated straight-line paths to obtain a desired formation. The vehicles are steered to the paths using an integral line-of-sight guidance approach that allows the vehicles to reject constant ocean currents. Simultaneously, the coordination is achieved by adjusting the velocity based on the along-path distance. First, simulation results are presented, which serve as benchmarks for the experimental results. Furthermore, the simulations are used to show the effect of changing different parameters. The simulation results are performed using high-fidelity hardware simulation models. The results obtained from experiments in the harbor of Porto are then presented and compared with the results of the simulation.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Verification of a Coordinated Path-Following Strategy for Underactuated Marine Vehicles

Braga²,

2019

Front. Robot. AI

“…The vessels are underactuated, but no environmental disturbances are considered. In [5] underway replenishment between fully actuated vessels is investigated and adaptive backstepping controllers are designed to reject exogenous disturbances.…”

Section: Introductionmentioning

confidence: 99%

Underactuated leader-follower synchronisation for multi-agent systems with rejection of unknown disturbances

2015 American Control Conference (ACC)

2015

Abstract-In this paper leader-follower synchronization is considered for underactuated followers in an inhomogeneous multi-agent system. The goal is to synchronise the motion of a leader and an underactuated follower. Measurements of the leader's position and velocity are available, while the dynamics and trajectory of the leader is unknown. The leader velocities are used as input for a constant bearing guidance algorithm to assure that the follower synchronises its motion to the leader. It is also shown that the proposed leader-follower scheme can be applied to multi-agent systems that are subjected to unknown environmental disturbances. Furthermore, the trajectory of the leader does not need to be known. The stability properties of the complete control scheme and the unactuated internal dynamics are analysed using nonlinear cascaded system theory. Simulation results are presented to validate the proposed control strategy.

“…In the marine systems literature work leader-follower synchronisation has played an important part in research on underway replenishment of ships, see for instance [15], [19], and [24]. For these operations the supply-ship is usually responsible for synchronising its motion with the ship it is supplying.…”

Section: Introductionmentioning

confidence: 99%

“…The vessels are underactuated, but no analysis of the underactuated internal dynamics are given. In [15] underway replenishment between fully actuated vessels is investigated and adaptive backstepping controllers are designed to reject exogenous disturbances.…”

Section: Introductionmentioning

confidence: 99%

Leader–Follower Synchronisation for a Class of Underactuated Systems

2016

Nonlinear Systems

In this work leader-follower synchronization is considered for underactuated followers in an inhomogeneous multi-agent system. The goal is to synchronise the motion of a leader and an underactuated follower. Measurements of the leader's position, velocity, acceleration, and jerk are available, while the dynamics of the leader is unknown. The leader velocities are used as input for a constant bearing guidance algorithm to assure that the follower synchronises its motion to the leader. It is also shown that the proposed leader-follower scheme can be applied to multi-agent systems that are subjected to unknown environmental disturbances. Furthermore, the trajectory of the leader does not need to be known. The closed-loop dynamics are analysed and it is shown that under certain conditions all solutions remain bounded and the synchronisation error kinematics are shown to be integral input-to-state stable with respect to changes in the unactuated sway velocity. For straight-line motions, i.e. where the desired yaw rate and sway velocity go to zero, synchronisation is achieved. Simulation results are presented to validate the proposed control strategy.