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Publicações

Publicações por José Lima

2022

Combined Optimization and Regression Machine Learning for Solar Irradiation and Wind Speed Forecasting

Autores
Amoura, Y; Torres, S; Lima, J; Pereira, AI;

Publicação
OPTIMIZATION, LEARNING ALGORITHMS AND APPLICATIONS, OL2A 2022

Abstract
Prediction of solar irradiation and wind speed are essential for enhancing the renewable energy integration into the existing power system grids. However, the deficiencies caused to the network operations provided by their intermittent effects need to be investigated. Regarding reserves management, regulation, scheduling, and dispatching, the intermittency in power output become a challenge for the system operator. This had given the interest of researchers for developing techniques to predict wind speeds and solar irradiation over a large or short-range of temporal and spatial perspectives to accurately deal with the variable power output. Before, several statistical, and even physics, approaches have been applied for prediction. Nowadays, machine learning is widely applied to do it and especially regression models to assess them. Tuning these models is usually done following manual approaches by changing the minimum leaf size of a decision tree, or the box constraint of a support vector machine, for example, that can affect its performance. Instead of performing it manually, this paper proposes to combine optimization methods including the bayesian optimization, grid search, and random search with regression models to extract the best hyper parameters of the model. Finally, the results are compared with the manually tuned models. The Bayesian gives the best results in terms of extracting hyper-parameters by giving more accurate models.

2023

Modelling of a Vibration Robot Using Localization Ground Truth Assisted by ArUCo Markers

Autores
Matos, D; Lima, J; Rohrich, R; Oliveira, A; Valente, A; Costa, P; Costa, P;

Publicação
ROBOTICS IN NATURAL SETTINGS, CLAWAR 2022

Abstract
Simulators have been increasingly used on development and tests on several areas. They allow to speed up the development without damage and no extra costs. On realistic simulators, where kinematics play an important role, the modelling process should be imported for each component to be accurately simulated. Some robots are not yet modelled, as for example the Monera. This paper presents a model of a small vibration robot (Monera) that is acquired in a developed test-bed. A localisation ground truth is used to acquire the position of the Monera with actuating it. Linear and angular speeds acquired from real experiments allow to validate the proposed methodology.

2023

Hybrid Legged-Wheeled Robotic Platforms: Survey on Existing Solutions

Autores
Moreira, J; Soares, IN; Lima, J; Pinto, VH; Costa, P;

Publicação
ROBOTICS IN NATURAL SETTINGS, CLAWAR 2022

Abstract
This survey analyses and compares ten different robots capable of hybrid locomotion in an attempt to elucidate the readers on several aspects of importance when designing and implementing a legged-wheeled vehicle. With this purpose in mind, the robots are compared based on their goals, kinematic configurations, joint specifications and overall performance. In this text, their variety and versatility is presented, justifying their use in real-world scenarios.

2023

Multi-robot Coordination for a Heterogeneous Fleet of Robots

Autores
Pereira, D; Matos, D; Rebelo, P; Ribeiro, F; Costa, P; Lima, J;

Publicação
ROBOT2022: FIFTH IBERIAN ROBOTICS CONFERENCE: ADVANCES IN ROBOTICS, VOL 2

Abstract
There is an increasing need for autonomous mobile robots (AMRs) in industrial environments. The capability of autonomous movement and transportation of items in industrial environments provides a significant increase in productivity and efficiency. This need, coupled with the possibility of controlling groups of heterogeneous robots, simultaneously addresses a wide range of tasks with different characteristics in the same environment, further increasing productivity and efficiency. This paper will present an implementation of a system capable of coordinating a fleet of heterogeneous robots with robustness. The implemented system must be able to plan a safe and efficient path for these different robots. To achieve this task, the TEA* (Time Enhanced A*) graph search algorithm will be used to coordinate the paths of the robots, along with a graph decomposition module that will be used to improve the efficiency and safety of this system. The project was implemented using the ROS framework and the Stage simulator. Results validate the proposed approach since the system was able to coordinate a fleet of robots in various different tests efficiently and safely, given the heterogeneity of the robots.

2022

A realistic simulation environment as a teaching aid in educational robotics

Autores
Lima, J; Kalbermatter, RB; Braun, J; Brito, T; Berger, G; Costa, P;

Publicação
2022 LATIN AMERICAN ROBOTICS SYMPOSIUM (LARS), 2022 BRAZILIAN SYMPOSIUM ON ROBOTICS (SBR), AND 2022 WORKSHOP ON ROBOTICS IN EDUCATION (WRE)

Abstract
The experimental component is an essential method in Engineering education. Sometimes the availability of laboratories and components is compromised, and the COVID19 pandemic worsened the situation. Resorting to an accurate simulation seems to help this process by allowing students to develop the work, program, test, and validate it. Moreover, it lowers the development time and cost of the prototyping stages of a robotics project. As a multidisciplinary area, robotics requires simulation environments with essential characteristics, such as dynamics, connection to hardware (embedded systems), and other applications. Thus, this paper presents the Simulation environment of SimTwo, emphasizing previous publications with models of sensors, actuators, and simulation scenes. The simulator can be used for free, and the source code is available to the community. Proposed scenes and examples can inspire the development of other simulation scenes to be used in electrical and mechanical Engineering projects.

2023

Position Estimator for a Follow Line Robot: Comparison of Least Squares and Machine Learning Approaches

Autores
Matos, D; Mendes, J; Lima, J; Pereira, AI; Valente, A; Soares, S; Costa, P; Costa, P;

Publicação
ROBOTICS IN NATURAL SETTINGS, CLAWAR 2022

Abstract
Navigation is one of the most important tasks for a mobile robot and the localisation is one of its main requirements. There are several types of localisation solutions such as LiDAR, Radio-frequency and acoustic among others. The well-known line follower has been a solution used for a long time ago and still remains its application, especially in competitions for young researchers that should be captivated to the scientific and technological areas. This paper describes two methodologies to estimate the position of a robot placed on a gradient line and compares them. The Least Squares and the Machine Learning methods are used and the results applied to a real robot allow to validate the proposed approach.

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