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Publications

Publications by CRIIS

2023

Model-Free VRFT-Based Tuning Method for PID Controllers

Authors
Vrancic, D; Oliveira, PM; Bisták, P; Huba, M;

Publication
MATHEMATICS

Abstract
The main objective of this work was to develop a tuning method for PID controllers suitable for use in an industrial environment. Therefore, a computationally simple tuning method is presented based on a simple experiment on the process without requiring any input from the user. Essentially, the method matches the closed-loop response to the response obtained in the steady-state change experiment. The proposed method requires no prior knowledge of the process and, in its basic form, only the measurement of the change in the steady state of the process in the manually or automatically performed experiment is needed, which is not limited to step-like process input signals. The user does not need to provide any prior information about the process or any information about the closed-loop behavior. Although the control loop dynamics is not defined by the user, it is still known in advance because it is implicitly defined by the process open-loop response. Therefore, no exaggerated control signal swings are expected when the reference signal changes, which is an advantage in many industrial plants. The presented method was designed to be computationally undemanding and can be easily implemented on less powerful hardware, such as lower-end PLC controllers. The work has shown that the proposed model-free method is relatively insensitive to process output noise. Another advantage of the proposed tuning method is that it automatically handles the tuning of highly delayed processes, since the method discards the initial process response. The simplicity and efficiency of the tuning method is demonstrated on several process models and on a laboratory thermal system. The method was also compared to a tuning method based on a similar closed-loop criterion. In addition, all necessary Matlab/Octave files for the calculation of the controller parameters are provided online.

2023

Ant-Balanced Multiple Traveling Salesmen: ACO-BmTSP

Authors
Pereira, SD; Pires, EJS; Oliveira, PBD;

Publication
ALGORITHMS

Abstract
A new algorithm based on the ant colony optimization (ACO) method for the multiple traveling salesman problem (mTSP) is presented and defined as ACO-BmTSP. This paper addresses the problem of solving the mTSP while considering several salesmen and keeping both the total travel cost at the minimum and the tours balanced. Eleven different problems with several variants were analyzed to validate the method. The 20 variants considered three to twenty salesmen regarding 11 to 783 cities. The results were compared with best-known solutions (BKSs) in the literature. Computational experiments showed that a total of eight final results were better than those of the BKSs, and the others were quite promising, showing that with few adaptations, it will be possible to obtain better results than those of the BKSs. Although the ACO metaheuristic does not guarantee that the best solution will be found, it is essential in problems with non-deterministic polynomial time complexity resolution or when used as an initial bound solution in an integer programming formulation. Computational experiments on a wide range of benchmark problems within an acceptable time limit showed that compared with four existing algorithms, the proposed algorithm presented better results for several problems than the other algorithms did.

2023

Pocket Labs as a STEM Learning Tool and for Engineering Motivation

Authors
Cardoso, A; Oliveira, PM; Sa, J;

Publication
LEARNING IN THE AGE OF DIGITAL AND GREEN TRANSITION, ICL2022, VOL 1

Abstract
Teaching and learning are processes that must accompany the digital transition, which is one of the biggest challenges we currently face, along with the green transition. The digital transition in education is a process with several challenges that must count on the involvement and collaboration of all stakeholders, contributing to the schools of the future. For this, technology plays a decisive role, and must be integrated into classes as a relevant tool to develop and implement different types of experiments, motivating the students towards STEM areas. In this context, a project financed by IFAC made it possible to use pocket laboratories in different high schools, encouraging teachers to prepare activities supported by this equipment, stimulating students to be interested in engineering topics. This article presents the approach followed in one high school and discusses the results obtained, highlighting the usefulness and opportunity of using pocket labs, and low-cost equipment in general, in school activities, which can promote the STEM areas and, in particular, the engineering courses.

2023

Investigating the Effectiveness of Process Control Didactics Kits in Engineering Education

Authors
Silva, V; Oliveira, PM; Leao, P; Soares, F; Lopes, H; Machado, J;

Publication
2023 5th International Conference of the Portuguese Society for Engineering Education, CISPEE 2023

Abstract
This paper deliberates some of the motivations for contemplating Kits in the theoretical-practical class of a Curricular Unit of Process Control to first year students of a Master Degree in Mechanical Engineering, alongside their purpose. Also, the perceptions of these students about the use of these kits in their learning process are discussed based on an online questionnaire developed for that purpose. According to students' feedback, gathered by an anonymous online questionnaire, it was possible to investigate the effectiveness of the use of didactics kits in the learning of Process Control topics. The obtained results from the students perception are clearly positive and motivating to further uses of this type kit as portable laboratories. © 2023 IEEE.

2023

Comparative Analysis of Windows for Speech Emotion Recognition Using CNN

Authors
Teixeira, FL; Soares, SP; Pio Abreu, JL; Oliveira, PM; Teixeira, JP;

Publication
Optimization, Learning Algorithms and Applications - Third International Conference, OL2A 2023, Ponta Delgada, Portugal, September 27-29, 2023, Revised Selected Papers, Part I

Abstract

2023

Temperature Control Laboratory (TCLab): Demonstration of Use in Portugal

Authors
Oliveira, PM; Cardoso, A; Soares, FO; Machado, J; Sá, J; Lopes, H; Silva, V;

Publication
2023 6th Experiment@ International Conference (exp.at'23), Évora, Portugal, June 5-7, 2023

Abstract
Low-cost, small-sized portable laboratories, or take-home laboratories, have been increasing in popularity worldwide. One example of such a successful Arduino-based kit is the Temperature Control Laboratory (TCLab), originally proposed by [1]. This kit has been used in Portugal for control engineering education since 2018. This paper proposes a TCLab demo session, reflecting the use of this kit in Portugal across different educational contexts. © 2023 IEEE.

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