Claudia Lescano - Academia.edu (original) (raw)

Uploads

Papers by Claudia Lescano

Research on Biomedical Engineering, 2022

Purpose The precise control of an active ankle–foot orthosis (AAFO) based on a pneumatic artifici... more Purpose The precise control of an active ankle–foot orthosis (AAFO) based on a pneumatic artificial muscle (PAM) is a key aspect in gait rehabilitation applications. This brings the challenge of describing a priori the complex dynamics of the entire robotic system, highly dependent on both, the purely nonlinear behaviour of the PAM and the typical variable external load conditions throughout a gait cycle. The literature shows that this double dependence has been scarcely modelled for this system. To solve this difficulty and based on their predictive capacities, we propose to explore the use of artificial neural network models, such as the nonlinear autoregressive models with exogenous inputs (NLARX) and the Hammerstein-Wiener (HW) structures. Considering this, the objectives of this paper are first, to develop models describing the nonlinear dynamics of this type of gait rehabilitation robotic system under the load conditions considered in a gait cycle, and second, to evaluate the performance of these models. Methods The NLARX and HW structures were used to model the dynamics of an experimental prototype of AAFO driven by a PAM from the recording of input and output data. These models were then validated by comparing the simulated data and the experimental data. Results A comparison of the results of the two models evaluated in the highest demand condition within the gait cycle showed that the HW model describes more precisely the dynamics of the robotic system considered. Conclusions The HW model constitutes a valid alternative for the future design of a model-based control scheme and the evaluation of its performance as a gait-rehabilitation robotic system.

Converging Clinical and Engineering Research on Neurorehabilitation III, 2018

The aim of this two-part paper is to find clues for designing a rehabilitation protocol for robot... more The aim of this two-part paper is to find clues for designing a rehabilitation protocol for robot-assisted gait training, based on the principles of “assisting patient movements only when necessary” and “eliciting a normative sensory input to improve motor output”, applied through neurorehabilitation techniques to facilitate the functional recovery of gait in spinal cord lesion patients.

Journal of Physics: Conference Series, 2016

The strength and usefulness of a rating scale for describing disease evolution relies on the accu... more The strength and usefulness of a rating scale for describing disease evolution relies on the accurate determination of variations representing clinically relevant changes. In this sense, the habitually used Hoehn-Yahr (HY) Scale for Parkinson Disease (PD) in its modified version distinguishes between the 2 and 2.5 stages to explain if the bilateral involvement is or is not accompanied by body balance impairment. Nevertheless, this scaling does not allow for differentiating the symptoms and signs associated with each stage accurately. Considering this difference, this work aims at analyzing some gait parameters-stance and swing phase times and magnitude of the vertical component of ground reaction force during the gait cycle-of PD patients classified as HY=2 and HY=2.5 in contrast with healthy subjects (HY=0), with the purpose of assessing whether there is a statistically significant difference among all these HY categories. For all gait parameters evaluated, the results indicated significant differences between HY=0 and HY=2.5. However, only the magnitude of the vertical component of ground reaction force presented relevant differences between HY=2 and 2.5. As expected, therefore, these results show the potential of such parameter to clinimetrically identify the level of gait impairment/disability in PD patients on the Hoehn-Yahr Scale.

Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2016

Journal of Physics: Conference Series, 2013

ABSTRACT The training of lower limbs with robotic exoskeletons or active orthoses has proven to b... more ABSTRACT The training of lower limbs with robotic exoskeletons or active orthoses has proven to be an effective tool to help patients with various types of neurological movement disorders, to recover their functional ambulation capacity. A key component to achieve this purpose is the type of active element used to compensate for muscle weakness, typically observed in such locomotor disorders. Based on these considerations, this paper presents the results of an experimental test developed for calibration, tuning and behavioral identification of a commercial pneumatic artificial muscle Festo ®, with view to its application as active element of an active ankle – foot orthosis prototype for human gait rehabilitation. It is expected that such prototype would enable to recover the ankle joint function in patients with Myelomeningocele. The actuator performance analysis from the achieved tests, as well as the study of gait patterns in persons with Myelomeningocele, evidence the potentiality of this actuator as an active element of a robotic exoskeleton applied to human gait rehabilitation.

Revista Brasileira de Engenharia Biomédica, 2012

Breast cancer has the second highest world's incidence rate, according to the Brazilian National ... more Breast cancer has the second highest world's incidence rate, according to the Brazilian National Cancer Institute (INCa). Clinical examination and mammography are the best methods for early diagnosis. Computer-aided detection (CADe) and computer-aided diagnosis (CADx) systems are developed to improve mammographic diagnosis. Basically, CADx systems have three components: (i) segmentation, (ii) parameters extraction and selection, (iii) lesion classifi cation. The fi rst step for a CADx system is segmentation. Methods: A microcalcifi cation segmentation method is proposed, based on morphological operators, Otsu's Method and radiologists' knowledge. Pre-processing with top-hat operators improves contrast and reduces background noise. The Otsu's method automatically selects the best grey-level threshold to segment microcalcifi cations, obtaining binary images. Following, inferior reconstruction and morphological dilatation operators are applied to reconstruct lost structure details and fi ll small fl aws in the segmented microcalcifi cations. Finally, the Canny edge detection is applied to identify microcalcifi cations contour candidates for each region-of-interest (ROI). Two experienced radiologists intervene in this semi-automatic method, fi rstly, selecting the ROI and, then, analyzing the segmentation result. The method was assessed in 1000 ROIs from 158 digital images (300 dpi, 8 bits). Results: Considering the radiologists opinion, the rates of ROIs adequately segmented to establish a diagnosis hypothesis were 97.8% for one radiologist and 97.3% for the other. Using the Area Overlap Measure (AOM) and the 2136 microcalcifi cations delineated by an experienced radiologist as gold standards, the method achieved an average AOM of 0.64±0.14, being 0.56±0.09 for small microcalcifi cations and 0.66±0.13 for the large ones. Moreover, AOM was 0.64±0.13 for the benign and 0.64±0.14 for the malignant lesions with no statistical differences between them. Conclusion: Based on these fi ndings, the proposed method could be used to develop a CADx system that could help early breast cancer detection.

We propose an unsupervised approach to map motor unit action potential (MUAP) trains to hand kine... more We propose an unsupervised approach to map motor unit action potential (MUAP) trains to hand kinematics. To quantify the spatio temporal information in MUAP trains, we develop a novel complex principal component analysis (CPCA) representation that includes muscle synergies for antagonistic movements in a single dimension, so it makes the direct control of each motor of a bionic hand straightforward by a simple dimensionality reduction. We further explore the importance of a linear transformation (rotation) in the projection space that best aligns the PCA subspace with the canonical projection space of the bionic hand degrees of freedom. We perform some experiments to estimate hand flexion-extension from MUAP trains identified during voluntary movements, with promising preliminary results.

Esta bien establecido que la cuantificacion de la distribucion de las presiones plantares provee ... more Esta bien establecido que la cuantificacion de la distribucion de las presiones plantares provee informacion valiosa acerca de la estructura y funcion de las articulaciones del pie y del tobillo, que puede ser utilizada como una herramienta clinica y de investigacion importante en el analisis de la locomocion humana. Considerando estos antecedentes, el objetivo de este trabajo fue optimizar un dispositivo prototipo para el registro dinamico de presiones plantares, previamente desarrollado en base a una plantilla instrumentada con sensores piezoelectricos. Tal optimizacion consistio en el procesamiento digital de las senales adquiridas mediante integracion numerica de la senal de entrada, sin necesidad de utilizar la etapa de amplificacion electrometrica, lo cual no solo simplifica el hardware implementado, sino tambien la etapa de calibracion estatica y dinamica requerida. Los resultados obtenidos fueron comparables con los logrados en base al dispositivo original.

IFMBE proceedings

ABSTRACT