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Publications

Publications by CRIIS

2024

A MQTT-based infrastructure to support Cooperative Online Learning Activities

Authors
Mendonça, HS; Zambelli, C; Alves, JC;

Publication
2024 39TH CONFERENCE ON DESIGN OF CIRCUITS AND INTEGRATED SYSTEMS, DCIS

Abstract
Teaching the processes of designing digital electronic systems is becoming an increasingly challenging task. Design methodologies and tools have evolved to cope with the ever-growing complexity and density, raising the abstraction level of the source design far away from the logic circuit. However, it is of paramount importance that fresh students start by understanding the fundamental concepts of Boolean algebra, design, and optimization of combinational and sequential gatelevel circuits, before moving to higher abstract concepts and tools. For this, hands-on practice with simple real digital circuits is essential to understanding the essentials of the operation of digital circuits and how digital data is propagated and transformed from block to block. In this paper we present a distributed infrastructure based on the network protocol MQTT to support the deployment of distributed digital systems built with parts located in different physical locations. Thus, promoting the implementation of collaborative online learning/teaching activities will be one of our main goals. Experimental results show latencies between remote sites in the range of a few tens of milliseconds, which is acceptable for running simple digital systems at low speeds, which is necessary for being perceived and understanded by people.

2024

Collaborative learning using open-source FPGA-based under water ultrasonic system

Authors
Lemaire, E; Busseuil, R; Chemla, J; Certon, D; Zambelli, C; Cruz de la Torre, C; Gardel Vicente, A; Bravo, I; Mendonça, H; Alves, JC;

Publication

Abstract
The Digital electronics collaborative enhanced learning (DECEL) project has recently developed an international collaborative education course. Its main objective is to enhance the digital electronics skills of international students by working on a complex, multidisciplinary applied problem using a mixed digital architecture. We have developed a logic level synthesis and dedicated software layers on the Red Pitaya FPGA platform. The diversity of digital concepts to be implemented, from hardware description language (HDL) to high-level languages such as Python or Matlab, forced the students to work together and rapidly improve their skills. Their motivation was fueled by the curiosity of controlling an ultrasound probe to obtain ultrasound signatures. This particular physics, little known to the students, was an additional source of curiosity. The goal of forming an image in a liquid medium was an additional motivating factor for them. The students reported that they learned a lot from the experiment. Thus, the technical parts and pedagogical results are documented in this work for reproducibility.

2024

Image and Command Transmission Over the 5G Network for Teleoperation of Mobile Robots

Authors
Levin, TB; Oliveira, JM; Sousa, RB; Silva, MF; Parreira, BS; Sobreira, HM; Mendonça, HS;

Publication
2024 7TH IBERIAN ROBOTICS CONFERENCE, ROBOT 2024

Abstract
Human oversight can benefit scenarios with complex tasks, such as pallet docking and loading and unloading containers, beyond the current capabilities of autonomous systems without any failures. Furthermore, teleoperation systems allow remote control of mobile ground robots, especially with the surge of 5G technology that promises reliable and low latency communication. Current works research on exploring the latest features from the 5G standard, including ultra-Reliable Low-Latency Communication (uRLLC) and network slicing. However, these features may not be available depending on the Internet Service Provider (ISP) and communication devices. Thus, this work proposes a network architecture for the teleoperation of ground mobile robots in industrial environments using commercially available devices over the 5G Non-Standalone (NSA) standard. Experimental results include an evaluation of the network and End-to-End (E2E) latency of the proposed system. The results show that the proposed architecture enables teleoperation, achieving an average E2E latency of 347.19 ms.

2024

Vision-Based Smart Sprayer for Precision Farming

Authors
Deguchi, T; Baltazar, AR; dos Santos, FN; Mendonça, H;

Publication
ROBOT 2023: SIXTH IBERIAN ROBOTICS CONFERENCE, VOL 2

Abstract
Since the advent of agriculture, humans have considered phytopharmaceutical products to control pests and reduce losses in farming. Sometimes some of these products, such pesticides, can potentially harm the soil life. In the literature there is evidence that AI and image processing can have a positive contribution to reduce phytopharmaceutical losses, when used in variable rate sprayers. However, it is possible to improve the existing sprayer system's precision, accuracy, and mechanical aspects. This work proposes spraying solution called GraDeS solution (Grape Detection Sprayer). GraDeS solution is a sprayer with two degrees of freedom, controlled by a AI-based algorithm to precisely treat grape bunches diseases. The experiments with the designed sprayer showed two key points. First, the deep learning algorithm recognized and tracked grape bunches. Even with structure movement and bunch covering, the algorithm employs several strategies to keep track of the discovered objects. Second, the robotic sprayer can improve precision in specified areas, such as exclusively spraying grape bunches. Because of the structure's reduced size, the system can be used in medium and small robots.

2024

Hierarchical Reinforcement Learning and Evolution Strategies for Cooperative Robotic Soccer

Authors
Santos, B; Cardoso, A; Ledo, G; Reis, LP; Sousa, A;

Publication
2024 7TH IBERIAN ROBOTICS CONFERENCE, ROBOT 2024

Abstract
Artificial I ntelligence ( AI) a nd M achine Learning are frequently used to develop player skills in robotic soccer scenarios. Despite the potential of deep reinforcement learning, its computational demands pose challenges when learning complex behaviors. This work explores less demanding methods, namely Evolution Strategies (ES) and Hierarchical Reinforcement Learning (HRL), for enhancing coordination and cooperation between two agents from the FC Portugal 3D Simulation Soccer Team, in RoboCup. The goal is for two robots to learn a high-level skill that enables a robot to pass the ball to its teammate as quickly as possible. Results show that the trained models under-performed in a traditional robotic soccer two-agent task and scored perfectly in a much simpler one. Therefore, this work highlights that while these alternative methods can learn trivial cooperative behavior, more complex tasks are difficult t o learn.

2024

Using Deep Learning for 2D Primitive Perception with a Noisy Robotic LiDAR

Authors
Brito, A; Sousa, P; Couto, A; Leao, G; Reis, LP; Sousa, A;

Publication
2024 7TH IBERIAN ROBOTICS CONFERENCE, ROBOT 2024

Abstract
Effective navigation in mobile robotics relies on precise environmental mapping, including the detection of complex objects as geometric primitives. This work introduces a deep learning model that determines the pose, type, and dimensions of 2D primitives using a mobile robot equipped with a noisy LiDAR sensor. Simulated experiments conducted in Webots involved randomly placed primitives, with the robot capturing point clouds which were used to progressively build a map of the environment. Two mapping techniques were considered, a deterministic and probabilistic (Bayesian) mapping, and different levels of noise for the LiDAR were compared. The maps were used as input to a YOLOv5 network that detected the position and type of the primitives. A cropped image of each primitive was then fed to a Convolutional Neural Network (CNN) that determined the dimensions and orientation of a given primitive. Results show that the primitive classification achieved an accuracy of 95% in low noise, dropping to 85% under higher noise conditions, while the prediction of the shapes' dimensions had error rates from 5% to 12%, as the noise increased. The probabilistic mapping approach improved accuracy by 10-15% compared to deterministic methods, showcasing robustness to noise levels up to 0.1. Therefore, these findings highlight the effectiveness of probabilistic mapping in enhancing detection accuracy for mobile robot perception in noisy environments.

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