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Publicações

Publicações por CRAS

2018

A Personal Robot as an Improvement to the Customers’ In- Store Experience

Autores
Santos, J; Campos, D; Duarte, F; Pereira, F; Domingues, I; Santos, J; Leão, J; Xavier, J; Matos, Ld; Camarneiro, M; Penas, M; Miranda, M; Morais, R; Silva, R; Esteves, T;

Publicação
Service Robots

Abstract

2018

The secrets of Segway revealed to students: revisiting the inverted pendulum

Autores
Azevedo Perdicoulis, TPA; Lopes dos Santos, PL;

Publicação
2018 13TH APCA INTERNATIONAL CONFERENCE ON CONTROL AND SOFT COMPUTING (CONTROLO)

Abstract
This article revisits the inverted pendulum-in particular, analyses a simplified model of a Segway, with a view to exploring its capabilities in Control Systems Engineering education. The integration between the theoretic and practical side is achieved through simulation, and in particular by using MathWorks software. We also present a structure for the work to be done in the Laboratory class and propose a solution for the problem.

2018

An extended instrument variable approach for nonparametric LPV model identification

Autores
Lima, MML; Romano, RA; dos Santos, PL; Pait, F;

Publicação
IFAC PAPERSONLINE

Abstract
Linear parameter varying models (LPV) have proven to be effective to describe non-linearities and time-varying behaviors. In this work, a new non-parametric estimation algorithm for state-space LPV models based on support vector machines is presented. This technique allows the functional dependence between the model coefficients and the scheduling signal to be "learned" from the input and output data. The proposed algorithm is formulated in the context of instrumental (IV) estimators, in order to obtain consistent estimates for general noise conditions. The method is based on a canonical state space representation and admits a predictor form that has shown to be suitable for system identification, as it leads to a convenient regression form. In addition, this predictor has an inherent filtering feature. In the context of vector support machines, such filtering mechanism leads to two-dimensional data processing, which can be used to decrease the variance of estimates due to noisy data. The performance of the proposed approach is evaluated from simulated data subject to different noise scenarios. The technique was able to reduce the error due to the variance of the estimator in most of the analyzed scenarios.

2018

An Iterative MOLI-ZOFT Approach for the Identification of MISO LTI Systems

Autores
Saraiva, PG; dos Santos, PL; Pait, F; Romano, RA; Perdicoulis, TP;

Publicação
2018 13TH APCA INTERNATIONAL CONFERENCE ON CONTROL AND SOFT COMPUTING (CONTROLO)

Abstract
In this paper, a new system identification algorithm is proposed for linear and time invariant systems with multiple input and single output. The system is described by a state-space model in the canonical observable form and represented by a Luenberger observer with a known state matrix. Thence, the identification problem is reduced to the estimation of the system input matrix and the observer gain which can be performed by a simple Least Square Estimator. The quality of the estimator depends on the observer state matrix. In the proposed algorithm, this matrix is found by an iterative process where, in each iteration, a state matrix called curiosity is generated. A weight depending on the value of the Least Square Cost is associated to each curiosity. The optimal state matrix is the barycenter of the curiosities. This iterative process is a free derivative optimization algorithm with its roots in non-iterative barycenter methods previously introduced to solve adaptive control and system identification problems. Although the Barycenter iterative version was recently proposed as an optimization method, here it will be implemented in an identification algorithm for the first time.

2018

A note on Nash equilibrium with wave dynamics and boundary control: controllability, observability and stabilizability considerations

Autores
Azevedo-Perdicoúlisr T.P.; Jank G.; Lopes dos Santos P.;

Publicação
International Journal of Control

Abstract
In this paper, the gas dynamics within the pipelines is written as a wave repetitive process, and modified in a way that the dynamics is driven by the boundary conditions. We study controllability of the system through boundary control and every agent, as well as observability of the system being steered by initial and boundary data. Next, we obtain sufficient criteria for the existence and uniqueness of boundary equilibrium controls. From the point of view of some applications, e.g. in high pressure gas pipeline management, it seems to make sense to consider boundary data controls. The same problem is then extended to its infinite counterpart since it may run infinitely and, in this case, we become interested in studying its stabilisation.

2018

A note on Nash equilibrium with wave dynamics and boundary control: controllability, observability and stabilizability considerations

Autores
Azevedo Perdicoúlis, TP; Jank, G; dos Santos, PL;

Publicação
Int. J. Control

Abstract

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