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Publicações

Publicações por CRIIS

2010

Fuzzy Reasoning in Fractional-Order PD Controllers

Autores
Barbosa, RS; Jesus, IS; Silva, MF;

Publicação
NEW ASPECTS OF APPLIED INFORMATICS, BIOMEDICAL ELECTRONICS AND INFORMATICS AND COMMUNICATION

Abstract
In this paper, we incorporate fuzzy reasoning in fractional-order PD controllers. The resulting fuzzy fractional PD controller is investigated in terms of its digital implementation and robustness. The combined features of both algorithms will result in a better control system performance. Also, the effectiveness and robustness of the new methodology is illustrated through an application example.

2010

Comparative study on the use of network services in robotic work-cells

Autores
Veiga, G; Malaca, P; Pires, JN;

Publicação
ICINA 2010 - 2010 International Conference on Information, Networking and Automation, Proceedings

Abstract
The vertical integration of the manufacturing equipments within the information infrastructure of companies is a growing demand. The use of service-oriented standard interfaces and the upcoming trend of cloud computing technologies both deserve careful attention. This paper makes a comparison of remote database access times made through service-oriented interfaces, both for a cloud computing solution and for a local server data base. The results are analyzed not only in terms of the interface used (REST or SOAP) but also within the context of a laboratorial industrial robot work-cell evaluating the effective impact of these results when compared with other automation operations. © 2010 IEEE.

2010

Petri Net Robotic Task Plan Representation: Modelling, Analysis and Execution

Autores
Costelha, H; Lim, P;

Publicação
Autonomous Agents

Abstract

2010

Multi-criteria Manipulator Trajectory Optimization Based on Evolutionary Algorithms

Autores
Pires, EJS; Oliveira, PBD; Machado, JAT;

Publicação
SOFT COMPUTING MODELS IN INDUSTRIAL AND ENVIRONMENTAL APPLICATIONS

Abstract
This paper proposes a method, based on a genetic algorithm, to generate smoth manipulator trajectories in a multi-objective perspective. The method uses terms proportional to the integral of the squared displacements in order to eliminate the jerk movement. In this work, the algorithm, based on NSGA-II and maximin sorting schemes, considers manipulators of two, three and four rotational axis (2R, 3R, 4R). The efficiency of the algorithm is evaluated, namely the extension of the front and the dispersion along the front. The effectiveness and capacity of the proposed approach are shown through simulations tests.

2010

Greenhouse Heat Load Prediction Using a Support Vector Regression Model

Autores
Coelho, JP; Cunha, JB; Oliveira, PD; Pires, ES;

Publicação
SOFT COMPUTING MODELS IN INDUSTRIAL AND ENVIRONMENTAL APPLICATIONS

Abstract
Modern greenhouse climate controllers are based on models in order to simulate and predict the greenhouse environment behaviour. These models must be able to describe indoor climate process dynamics, which are a function of both the control actions taken and the outside climate. Moreover, if predictive or feedforward control techniques are to be applied, it is necessary to employ models to describe and predict the weather. From all the climate variables, solar radiation is the one with greater impact in the greenhouse heat load. Hence, making good predictions of this physical quantity is of extreme importance. In this paper, the solar radiation is represented as a time-series and a support vector regression model is used to make long term predictions. Results are compared with the ones achieved by using other type of models, both linear and non-linear.

2010

Maximin Spreading Algorithm

Autores
Solteiro Pires, EJS; Mendes, L; Lopes, AM; de Moura Oliveira, PBD; Tenreiro Machado, JAT; Vaz, J; Rosario, MJ;

Publicação
2010 IEEE CONGRESS ON EVOLUTIONARY COMPUTATION (CEC)

Abstract
This paper presents a genetic algorithm to optimize uni-objective problems with an infinite number of optimal solutions. The algorithm uses the maximin concept and epsilon-dominance to promote diversity over the admissible space. The proposed algorithm is tested with two well-known functions. The practical results of the algorithm are in good agreement with the optimal solutions of these functions. Moreover, the proposed optimization method is also applied in two practical real-world engineering optimization problems, namely, in radio frequency circuit design and in kinematic optimization of a parallel robot. In all the cases, the algorithm draws a set of optimal solutions. This means that each problem can be solved in several different ways, all with the same maximum performance.

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