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Publications

Publications by CRIIS

2026

Prototyping of a Customised Automated Water Sampling System for Quality Monitoring

Authors
Gonçalves, J; Batista Coelho, JA; Alvarez, M; Brancalião, L; Matos, P; Coelho, JP;

Publication
ICARA

Abstract
This paper presents the development of an automated water sampling system designed to enhance quality control in water treatment facilities. The system is built around a mechanical structure that houses a watertight box containing all electronic components. A display inside the box allows users to program sampling schedules, including parameters such as the day, time, number of samples, sample volume, and intervals between samples. A balance integrated into the structure holds a bottle that collects the water samples, while a reservoir at the bottom accumulates water to ensure an adequate supply. A water pump connected to the structure enables controlled sample collection. The design ensures that all components are compactly integrated, while a non-invasive method is used to measure the volume of the sampled water, thereby avoiding direct contact between the sensors and the sample. A Project-Based Learning (PBL) approach, coupled with direct industry collaboration, has reinforced the effectiveness of active learning methodologies in engineering education.

2026

Micro-ROS Multi-Board Control for a Robotic Leg

Authors
Gomes, DF; Costa, P; Gonçalves, J; Pinto, VH;

Publication
IEEE ACCESS

Abstract
This paper explores an innovative distributed real-time control system for a 3D-printed robotic leg. The system is constructed on a modular multi-board architecture that seamlessly integrates with ROS2 and micro-ROS, demonstrating the use of 3D printing for rapid prototyping and customized solutions. A notable feature of this robotic leg is its 360-degree rotating joint, which extends its range of motion, enabling intricate and versatile movements. Incorporating a shoulder joint further facilitates sideways mobility, augmenting its operational capabilities. A multi-board architecture is designed to ensure efficient communication, ease of component interchangeability, and robust scalability for future development. Additionally, advanced control techniques, including tuning of proportional-integral-derivative (PID) controllers, ensure responsive joint actuation tailored to the unique properties of 3D-printed materials. Experimental validation indicates low latency and stable operation, underscoring the system's effectiveness for real-time robotic applications.

2026

Quantifying Latency and Jitter in Distributed Mobile Robotics Control: A Dual-Core RP2350 and Micro-ROS Ethernet Multicast Analysis

Authors
Gomes D.F.; Costa P.; Gonçalves J.; Silva R.; Gonçalves G.; Teixeira G.; Pinto V.H.;

Publication
IEEE International Conference on Autonomous Robot Systems and Competitions Icarsc

Abstract
The transition from centralized to distributed control architectures in mobile robotics introduces the challenge of "Temporal Coherence"- the requirement that physically separated actuators execute commands simultaneously. This paper presents a validation of standard Ethernet Multicast to achieve Soft Real-Time synchronization suitable for dynamic locomotion. An "Inertial Filtering Condition"is proposed, positing that if network jitter (sc) is negligible relative to the robot's mechanical time constant (tmech), the system becomes functionally deterministic. Using a Dual-Core SMP architecture on RP2350 microcontrollers, this study demonstrates that standard Layer 2 Ethernet switches serve as effective hardware synchronizers. Experimental results show a packet-arrival reliability of 99.92% for a 1 kHz control loop and a network jitter standard deviation of s ˜65 µs. Furthermore, a Virtual Hardware-in-the-Loop (HIL) stress test confirmed that inter-leg actuation skew is reduced to ˜ 275 µs, representing a 32x improvement over the 9 ms latency bottleneck observed in previous USB-Serial architectures. Finally, it is concluded that standard Ethernet transport provides sufficient statistical determinism for coordinated gait stability without requiring complex hard real-time protocols.

2026

Augmented Reality and Deep Learning-Based Framework for Defect Detection in Reflective Parts

Authors
Nascimento, RC; Martins, JG; Gonzalez, DG; Silva, MF; Filipe, V; Petry, MR; Rocha, LF;

Publication
ICARA

Abstract
Inspecting reflective parts is challenging due to strong specular reflections that conceal small porosities and reduce defect visibility. This work presents a framework that combines augmented reality with a deep learning detector. An augmented reality headset is used to capture multi-view images under natural illumination, enabling the operator to adjust the viewpoint and obtain angles that reduce glare. The collected data form a 640 × 480 dataset used to train a yolov8 detection model, integrated into a Robot Operating System 2 architecture for real-time processing. Testing on an independent set of unseen parts yields a precision of 86.70 %, a recall of 87.26 %, and an F1-score of 86.97 %. Additional qualitative examples confirm that the model can identify low-contrast porosities despite reflective surfaces. The results demonstrate the feasibility of AR-assisted acquisition combined with deep learning for real-time inspection of machined aluminum components in a laboratory case study.

2026

Linear Parameter-Varying Dynamic Modeling of Agricultural Robots on Variable-Friction Soils

Authors
Santos Neto, AFd; Petry, MR; Moreira, AP; Mercorelli, P;

Publication
ICARA

Abstract
Accurate dynamic modeling of ground robots (Unmanned Ground Vehicles - UGVs) is essential for robust control and navigation in agricultural environments, where variations in soil friction and rolling resistance significantly affect system dynamics. This work proposes a Linear Parameter-Varying (LPV) model parameterized by the friction coefficient, identified under different soil conditions using two excitation strategies: Amplitude-Pseudo-Random Binary Sequence (APRBS) and standard maneuvers (SM). A simulated ground robot - the Clearpath Husky - was used under multiple soil friction scenarios within the ROS 2 and Gazebo simulation environment. The results show that the LPV model effectively captures the influence of soil friction, with both LPV APRBS and LPV SM yielding similar RMSE values across scenarios. The results also highlight the feasibility of using SM-based excitation for identifying the robot dynamics.

2026

Bounding Box-Based 3D Mapping with UGV-UAV Collaboration for Precision Agriculture

Authors
Santos Neto, AFd; Couto, MB; Petry, MR; Moreira, AP; Mercorelli, P;

Publication
ICARA

Abstract
Building 3D maps in agricultural environments is challenging due to dense vegetation, irregular terrain, lack of landmarks, and unreliable GPS. This paper proposes a Bounding Box-Based 3D Mapping method using collaboration between an Unmanned Ground Vehicle (UGV) and an Unmanned Aerial Vehicle (UAV). The method simplifies crop rows and tree canopies by enclosing their point clouds in 3D bounding boxes, fused with original UAV and UGV data, producing compact maps that preserve essential structures for autonomous navigation and trajectory planning. Evaluation in a simulated Orchard scenario shows that the method could reduce map size by up to 60% while maintaining 83.6% coverage. Multi-robot collaboration proved crucial, with the UGV contributing 74% and the UAV 26% of the merged map. Overall, the proposed method demonstrates potential and deserves further investigation in more complex agricultural scenarios.

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