André Filipe Pinto

Abstract
This paper leverages image processing techniques, including edge detection and feature extraction, to identify and perform pose tracking of cylindrical-like structures within underwater scenes. Examples of these cylindrical-shaped objects are pipes typically used in offshore oil and gas, pillars of bridge structures, or mooring line cables when their sag angle is near zero, making them approximately flat and thus can be approximated as rectilinear. In addition to the pipe's contour identification, this algorithm provides relative distance and bearing to the vision sensor to enable a convergence framework between the structure and any vehicle equipped with this sensor. Furthermore, the algorithm proposed was tested in a pollsimulated scene with a digital twin of the actual vision sensor, onboard an in-house developed ROV prototype. Additionally, the effects of common underwater challenges, such as lighting variability, shadows, turbidity, and visual noise from the pool's geometric structure, were all analyzed to describe the algorithm's performance and robustness fully. Performance was evaluated for distances, bearing angles, FOV, turbidity, camera resolutions, and algorithm processing complexity. © 2025 Marine Technology Society.

Abstract
Wireless communication over the ocean surface is challenged by the absence of infrastructure, dynamic propagation conditions, variations in node position and orientation, and signal degradation from reflections, scattering, and absorption. To evaluate the feasibility of long-range, low-power communication in such environments, field trials were conducted using LoRa's Chirp Spread Spectrum (CSS) modulation with E22-900T22S modules operating at 868 MHz. Tests were performed over nearshore ocean water using omnidirectional antennas. One antenna was mounted on a buoy close to the surface, and the other on a movable station, while varying transmission power, bit rate, and distance. Performance was assessed through signal quality, Packet Delivery Ratio (PDR), and throughput measurements, with results indicating that a log-distance Received Signal Strength Indicator (RSSI) model, with fitted parameters showing high correlation, can describe the observed behavior across configurations. LoRa achieved up to 1.7 km range with over 60% PDR at 10 dBm and 2.4kbs-1, demonstrating its potential for ocean-surface communication and aiding in optimal configuration for maritime applications. © 2025 Marine Technology Society.

Abstract
In the present paper, we propose a control approach to perform docking of an autonomous surface vehicle (ASV) while avoiding surrounding obstacles. This control architecture is composed of two sequential controllers. The first outputs a feasible trajectory between the vessel's initial and target state while avoiding obstacles. This trajectory also minimizes the vehicle velocity while performing the maneuvers to increase the safety of onboard passengers. The second controller performs trajectory tracking while accounting for the actuator's physical limits (extreme actuation values and the rate of change). The method's performance is tested on simulation, as it enables a reliable ground truth method to validate the control architecture proposed.

Abstract
This paper describes a system designed to collect water samples, from the surface down to a configurable depth, and with configurable profiles of vertical velocity. The design was intended for the analysis of suspended sediments, therefore the sampling can integrate water flow for a given depth profile, or at a specific depth. The system is based on a catamaran-shaped platform, from which a towfish is lowered to collect the water samples. The use of a surface vehicle ensures a permanent link between the operator and the full system, allowing for a proper mission supervision. All components can be remotely controlled from the control station, or programmed for fully autonomous operation. Although the main intended use is for the analysis of suspended sediments in rivers, it can easily be extended to collect water samples in other water bodies.

Abstract
As humanity progresses and globalization advances, humanized environment and associated systems increase in complexity and size. In earth systems, oceans represent an essential element of equalization and normal functioning. Ocean-atmospheric interactions are nowadays believed to be at the heart of all earth vital signs and climatic behaviours, and therefore are essential to accurate monitoring and understanding of earth systems. The work presented is a preliminary result of the K2D- Knowledge and Data from the Deep to Space, project which addresses the challenge of creating underwater network nodes to provide power and communication to land through the submarine fiber optic cable repeaters. The N2ODE system will consist of a set of subsystems that will allow continuous monitoring and interaction with fixed and mobile underwater devices.