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Publicações

Publicações por Miguel Velhote Correia

2014

Unsupervised flow-based motion analysis for an autonomous moving system

Autores
Pinto, AM; Correia, MV; Paulo Moreira, AP; Costa, PG;

Publicação
IMAGE AND VISION COMPUTING

Abstract
This article discusses the motion analysis based on dense optical flow fields and for a new generation of robotic moving systems with real-time constraints. It focuses on a surveillance scenario where an especially designed autonomous mobile robot uses a monocular camera for perceiving motion in the environment. The computational resources and the processing-time are two of the most critical aspects in robotics and therefore, two non-parametric techniques are proposed, namely, the Hybrid Hierarchical Optical Flow Segmentation and the Hybrid Density-Based Optical Flow Segmentation. Both methods are able to extract the moving objects by performing two consecutive operations: refining and collecting. During the refining phase, the flow field is decomposed in a set of clusters and based on descriptive motion properties. These properties are used in the collecting stage by a hierarchical or density-based scheme to merge the set of clusters that represent different motion models. In addition, a model selection method is introduced. This novel method analyzes the flow field and estimates the number of distinct moving objects using a Bayesian formulation. The research evaluates the performance achieved by the methods in a realistic surveillance situation. The experiments conducted proved that the proposed methods extract reliable motion information in real-time and without using specialized computers. Moreover, the resulting segmentation is less computationally demanding compared to other recent methods and therefore, they are suitable for most of the robotic or surveillance applications.

2014

An I2C Based Mixed-Signal Test and Measurement Infrastructure

Autores
Salazar Escobar, AJS; da Silva, JM; Correia, M;

Publicação
2014 19TH INTERNATIONAL MIXED-SIGNALS, SENSORS AND SYSTEMS TEST WORKSHOP (IMS3TW)

Abstract
The framework being proposed addresses the test and measurement of circuits and systems populated with varying types of sensors and functional blocks, among which one can find embedded test instruments. Its conceptual functionality is based on four types of operations: setup, capture, process, and scan (SCPS), and aims to provide a unifying methodology for managing and synchronizing test operations and instruments. The generalized physical structure and examples of operating commands are described. An application illustrates its use in a particular case.

2017

Analysis and quantification of upper-limb movement in motor rehabilitation after stroke

Autores
Silva, RM; Sousa, E; Fonseca, P; Pinheiro, AR; Silva, C; Correia, MV; Mouta, S;

Publicação
Biosystems and Biorobotics

Abstract
It is extremely difficult to reduce the relations between the several body parts that perform human motion to a simplified set of features. Therefore, the study of the upper-limb functionality is still in development, partly due to the wider range of actions and strategies for motor execution. This, in turn, leads to inconsistent upper-limb movement parameterization. We propose a methodology to assess and quantify the upper-limb motor execution. Extracting key variables from different sources, we intended to quantify healthy upper-limb movement and use these parameters to quantify motor execution during rehabilitation after stroke. In order to do so, we designed an experimental setup defining a workspace for the execution of the action recording kinematic data. Results reveal an effect of object and instruction on the timing of upper-limb movement, indicating that the spatiotemporal analysis of kinematic data can be used as a quantification parameter for motor rehabilitation stages and methods. © Springer International Publishing AG 2017.

2013

Wearable monitoring system for locomotion rehabilitation

Autores
Catarino, A; Rocha, AM; Abreu, MJ; da Silva, JM; Ferreira, JC; Tavares, VG; Correia, MV; Zambrano, A; Derogarian, F; Dias, R;

Publicação
OCCUPATIONAL SAFETY AND HYGIENE

Abstract
Human motion capture systems are used by medical staff for detecting and identifying mobility impairments, early stages of certain pathologies and can also be used for evaluation of the effectiveness of surgical or rehabilitation intervention. Other applications may involve athlete's performance, occupational safety, among others. Presently there is a considerable number of solutions available, however these systems present some drawbacks, as they are often expensive, considerably complex, difficult to wear and use in a daily basis, and very uncomfortable for the patient. With the purpose of solving the above mentioned problems, a new wearable locomotion data capture system for gait analysis is under development. This system will allow the measurement of several locomotion-related parameters in a practical and non-invasive way, comfortable to the user, which will also be reusable that can be used by patients from light to severe impairments or disabilities. The present paper gives an overview of the research that is being developed, regarding the design of the wearable equipment, textile support, and communications.

2017

Consistency of surface electromyography assessment at lower limb selected muscles during vertical countermovement

Autores
Rodrigues, C; Correia, M; Abrantes, JMCS; Nadal, J; Benedetti Rodrigues, MAB;

Publicação
Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS

Abstract
Given the difficulty of invasive methods to assess muscle action during natural human movement, surface electromyography (sEMG) has been increasingly used to capture muscle activity in relation to kinesiological analysis of specific tasks. Isolated isometric, concentric and eccentric forms of muscle action have been receiving the most attention for research purposes. Nevertheless natural muscle action frequently involves the use of a preceding eccentric muscle action as a form of potentiation of immediate muscle concentric action, in what is designated as muscle stretch-shortening cycle (SSC). The most frequently applied protocols for the evaluation of SSC on vertical jumps are by virtue of their reproducibility and control of experimental conditions, squat jump (SJ) without countermovement (CM), countermovement jump (CMJ) with long CM and drop jump (DJ) with short CM. The methods used to extract information and relationship of the captured signals also present a high diversity, with the question about the consistency of the methods and obtained results. The objective of this study is to evaluate the consistency of the analysis and results by applying different EMGs signal analysis techniques related to strategic muscle groups of the lower limbs at different countermovement evaluated in vertical jumps. Raw sEMG signals of 5 lower limb muscles of 6 subjects during SJ, CMJ and DJ were rectified, filtered and obtained their envelope, and then correlated (CR) for detection of synergistic, agonist and antagonist activity, applied principal component analysis (PCA) for the detection of uncorrelated components explaining maximum variability and normalized cross-correlation (CCRN) for detection of maximum correlations and time lag. CR of EMG envelopes presented higher coactivities (CoA) in DJ relative to SJ and these CoA superior to CMJ with greater synergy in DJ relative to SJ and CMJ that present several loop cycles corresponding to time lag of activity. CCRN of the EMG envelopes presented also higher CoA in DJ when compared to SJ and both higher CoA to CMJ. PCA allowed to detect a principal component (PC) explaining 92.2% of the variability of EMG in DJ, 90.6% in SJ and 78.7% in CMJ, the second PC responsible for the explanation of 4.9% variability in DJ, 6.7% in SJ and 15.3% in CMJ. © 2017 IEEE.

2013

Wearable sensors for the prophylaxis of lower limb pathologies

Autores
Abreu, MJ; Catarino, A; Rocha, AM; Derogarian, F; Dias, R; Da Silva, JM; Ferreira, JC; Tavares, VG; Correia, MV;

Publicação
Fiber Society Spring 2013 Technical Conference

Abstract
In this paper a new wearable locomotion data capture system for gait analysis is presented. The system under development intends to help clinicians to detect and identify mobility impairments as well as to evaluate the effectiveness of surgical or rehabilitation intervention. The proposed system allows the measurement of kinematic and biomechanical parameters in a practical and comfortable weft knitted legging, in which the sensors are incorporated.

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