D. Bibbo | Roma Tre University, Rome, Italy (original) (raw)

Papers by D. Bibbo

Human Movement Science, 2004

IRBM

Abstract Background The assessment of the force exerted during a gesture in human motion analysis... more Abstract Background The assessment of the force exerted during a gesture in human motion analysis can provide direct and indirect information regarding the expended energy, especially during the execution of a sport gesture. In this field, assessment and improvement of the performance can be supported by instrumented devices able to measure and process mechanical quantities. In cycling, strain gauges-based instrumented pedals represent one of the last innovations in the sector, because they can provide data about the power exerted (produced) during training and the pedal efficiency. Optimization of the strain-gauges positioning is thus required to improve accuracy in the exerted force estimation. Methods A new technique to give a support for evaluating the best compromise between maximum sensitivity and ease of assembly was developed in the present work, based on a Finite Element Model (FEM) and a parametric analysis of the strain field at different sensor placements. Optimal positions were identified as those combining high sensitivity and low dependence from positioning inaccuracies. Results Parametric strain-load trends obtained from the developed model show a linear behavior of strain gauges pairs and confirm that there is a good sensitivity of the adopted sensors if they are mounted in handy positions of the developed load cell. Discussion The conducted analysis enables to calculate the sensitivity of the load cell to the exerted forces, and evaluates its dependence to the positioning of strain gauges, and makes it possible to appropriately choose strain gauges positioning in areas where border effects are minimized. The strain distributions obtained by the FEM analysis in the presented load cells gives useful indications for all the situations where small strain gauges are requested to be mounted on a reduced offered area.

During cycling, the measurement of forces exerted on the pedal is used to monitor the level of tr... more During cycling, the measurement of forces exerted on the pedal is used to monitor the level of training and to maximize the efficiency of pedaling. In rehabilitation, the force measurement can be used to monitor the functional recovery of a patient during a therapy. In these situations, it is useful to quantify with high resolution these variables. In this work a solution to remove the DC offset at the input of an AD converter for force measurement systems, based on strain gauges load cells, is presented. This circuit has been integrated into a device used in sports and in rehabilitation contexts, that relies on a couple of cycling instrumented pedals. The system designed in this work aims at obtaining these results in a simple way and with its complete integration into the control circuit of the instrumented pedals.

IFMBE Proceedings, 2014

ABSTRACT Several studies have shown the effect of visual biofeedback (VBF) on postural control wi... more ABSTRACT Several studies have shown the effect of visual biofeedback (VBF) on postural control with real-time presentation of centre of pressure (CoP). However, up to now no study has yet focussed on the effect that a predictive VBF could have on postural control. The aim of this study is thus to determine whether the Time-to-Boundary function (TtB) could be used as an efficacious VBF in static posturography. The CoP coordinates were extracted from force plate data and elaborated to calculate TtB in real-time. Two groups of six healthy young subjects executed the protocol in two different sequences composed of the following conditions: noVBF-VBF1 (real-time presentation of CoP) and noVBF-VBF2 (real-time TtB presentation). Each condition was repeated three times. The effect of the two VBFs was studied by five parameters extracted directly from CoP coordinates (sway area, sway path, mean amplitude, frequency bandwidth that contains 95% of the power spectral density of antero-posterior and medio-lateral displacement) and two parameters by fraction Brownian motion model (exponential radial terms Hrs and Hrl corresponding to the short-term and long-term region Hurst exponents). The comparison between the VBF conditions didn’t show significant differences in the studied parameters. This evidence suggests that the participants react in similar way in both conditions, and it opens the possibility of using a predictive VBF as a tool to facilitate postural control in upright stance.

Biomedical Engineering / 817: Robotics Applications, 2014

This paper investigates how different window sizes for feature extraction and classification affe... more This paper investigates how different window sizes for feature extraction and classification affect the accuracy of daily living locomotors activity recognition through accelerometers. A comprehensive data set was collected from 9 healthy subjects performing walk, stair descending and stair ascending while carrying an accelerometer on the waist. Nearest neighbor based classification has been used because of its simplicity and flexibility. The findings show that, by increasing window length, the system accuracy increases, but it produces delays in real time detection/alert of the activity. From the experiments it is concluded that a 2 seconds (2 s) time window may represent a trade-off for the detection of these mentioned activities in a real-time scenario, as it produces 91.7 percent of accuracy.

Algorithms, 2014

This paper documents the research towards the development of a system based on Artificial Neural ... more This paper documents the research towards the development of a system based on Artificial Neural Networks to predict muscle force patterns of an athlete during cycling. Two independent inverse problems must be solved for the force estimation: evaluation of the kinematic model and evaluation of the forces distribution along the limb. By solving repeatedly the two inverse problems for different subjects and conditions, a training pattern for an Artificial Neural Network was created. Then, the trained network was validated against an independent validation set, and compared to evaluate agreement between the two alternative approaches using Bland-Altman method. The obtained neural network for the different test patterns yields a normalized error well below 1% and the Bland-Altman plot shows a considerable correlation between the two methods. The new approach proposed herein allows a direct and fast computation for the inverse dynamics of a cyclist, opening the possibility of integrating such algorithm in a real time environment such as an embedded application.

Frontiers in Physiology, 2013

Finding an optimum for the cycling performance is not a trivial matter, since the literature show... more Finding an optimum for the cycling performance is not a trivial matter, since the literature shows the presence of many controversial aspects. In order to quantify different levels of performance, several indexes have been defined and used in many studies, reflecting variations in physiological and biomechanical factors. In particular, indexes such as Gross Efficiency (GE), Net Efficiency (NE) and Delta Efficiency (DE) have been referred to changes in metabolic efficiency (Eff Met), while the Indexes of Effectiveness (IE), defined over the complete crank revolution or over part of it, have been referred to variations in mechanical effectiveness (Eff Mech). All these indicators quantify the variations of different factors [i.e., muscle fibers type distribution, pedaling cadence, setup of the bicycle frame, muscular fatigue (MFat), environmental variables, ergogenic aids, psychological traits (Psych Tr)], which, moreover, show high mutual correlation. In the attempt of assessing cycling performance, most studies in the literature keep all these factors separated. This may bring to misleading results, leaving unanswered the question of how to improve cycling performance. This work provides an overview on the studies involving indexes and factors usually related to performance monitoring and assessment in cycling. In particular, in order to clarify all those aspects, the mutual interactions among these factors are highlighted, in view of a global performance assessment. Moreover, a proposal is presented advocating for a model-based approach that considers all factors mentioned in the survey, including the mutual interaction effects, for the definition of an objective function E representing the overall effectiveness of a training program in terms of both Eff Met and Eff Mech .

Frontiers in Computational Neuroscience, 2013

Recent studies have reported evidence that the motor system may rely on a modular organization, e... more Recent studies have reported evidence that the motor system may rely on a modular organization, even if this behavior has yet to be confirmed during motor adaptation. The aim of the present study is to investigate the modular motor control mechanisms underlying the execution of pedaling by untrained subjects in different biomechanical conditions. We use the muscle synergies framework to characterize the muscle coordination of 11 subjects pedaling under two different conditions. The first one consists of a pedaling exercise with a strategy freely chosen by the subjects (Preferred Pedaling Technique, PPT), while the second condition constrains the gesture by means of a real time visual feedback of mechanical effectiveness (Effective Pedaling Technique, EPT). Pedal forces, recorded using a pair of instrumented pedals, were used to calculate the Index of Effectiveness (IE). EMG signals were recorded from eight muscles of the dominant leg and Non-negative Matrix Factorization (NMF) was applied for the extraction of muscle synergies. All the synergy vectors, extracted cycle by cycle for each subject, were pooled across subjects and conditions and underwent a 2-dimensional Sammon's non-linear mapping. Seven representative clusters were identified on the Sammon's projection, and the corresponding eight-dimensional synergy vectors were used to reconstruct the repertoire of muscle activation for all subjects and all pedaling conditions (VAF > 0.8 for each individual muscle pattern). Only 5 out of the 7 identified modules were used by the subjects during the PPT pedaling condition, while 2 additional modules were found specific for the pedaling condition EPT. The temporal recruitment of three identified modules was highly correlated with IE. The structure of the identified modules was found similar to that extracted in other studies of human walking, partly confirming the existence of shared and task specific muscle synergies, and providing further evidence on the modularity of the motor system.

Computational and Mathematical Methods in Medicine, 2013

Two approaches to the classification of different locomotor activities performed at various speed... more Two approaches to the classification of different locomotor activities performed at various speeds are here presented and evaluated: a maximum a posteriori (MAP) Bayes’ classification scheme and a Support Vector Machine (SVM) are applied on a 2D projection of 16 features extracted from accelerometer data. The locomotor activities (level walking, stair climbing, and stair descending) were recorded by an inertial sensor placed on the shank (preferred leg), performed in a natural indoor-outdoor scenario by 10 healthy young adults (age 25–35 yrs.). From each segmented activity epoch, sixteen features were chosen in the frequency and time domain. Dimension reduction was then performed through 2D Sammon’s mapping. An Artificial Neural Network (ANN) was trained to mimic Sammon’s mapping on the whole dataset. In the Bayes’ approach, the two features were then fed to a Bayes’ classifier that incorporates an update rule, while, in the SVM scheme, the ANN was considered as the kernel function ...

During exercise the concomitant increase of arterial pressure and heart rate indicates that arter... more During exercise the concomitant increase of arterial pressure and heart rate indicates that arterial baroreflex control of the heart period is modified. It has been shown that during dynamic exercise heart rate increases are due to both a parasympathetic withdrawal and ...

ABSTRACT Every athlete aims to establish the best performances in his sport activities. This can ... more ABSTRACT Every athlete aims to establish the best performances in his sport activities. This can be reached by means of indications to the athlete on specific parameters to check during his training and so optimizing the effectiveness of the athletic gesture. The present study is developed within a research project on the evaluation, validation and application of efficiency indexes of the athletic gesture in cycling, by means of the measurements of the effective force to the pedal carried on by an Instrumented Pedal (iPed) and displaying measurement results in real time: the final aim is to provide a feedback to the athlete, on the basis of some efficiency indexes, in order to improve the efficiency of the sport performance. The specific goal of this contribution deals with the set-up of the measurement chain and with the implementation of the system calibration. In particular, calibration was performed with known dead weights. During calibration the crosstalk effects between measurement channels have been evaluated and modeled with a cross sensitivity matrix. Accuracy on force measurement is between 3% and 5%. Also angle and power measurements underwent a calibration procedure with a relative uncertainty between 8% and 15% of the measured value. The obtained results validate the iPed and the measurement chain and open wide scenarios for the system applicability. A cycloergometer embedded with an aerodynamic brake has been used for some tests on the efficiency indexes as obtained by athletes during different training sessions. Preliminary evaluations of efficiency indices under controlled conditions are encouraging and seem to confirm the validity of the method.

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 2012

In this study we investigate the muscle coordination underlying the execution of a pedaling exerc... more In this study we investigate the muscle coordination underlying the execution of a pedaling exercise across different biomechanical demands, by using the muscle synergies paradigm. 9 non professional subjects performed a cycling exercise using their preferred pedaling strategy (Preferred Strategy, PS) and then, through the use of a feedback based on the presentation of a real-time index of mechanical efficiency determined by means of instrumented pedals, they were helped to optimize their pedaling technique (Effective Strategy, ES). EMG activity was recorded from 8 muscles of the dominant leg. Nonnegative Matrix Factorization was applied for the extraction of muscle synergies. 4 modules were sufficient to reconstruct the repertoire of muscle activations for all the subjects during PS condition, and these modules were found consistent across all the subjects (correlation > 83%). 5 muscle synergies were necessary for the characterization in ES condition; 4 out of these modules were shared with PS condition, and the resulting additional module appeared subject-specific. These preliminary results support the existence of a modular motor control in humans.

Gait & Posture, 2009

[1] Bao L, et al. Activity recognition from user-annotated acceleration data. Pervasive 2004;3001... more [1] Bao L, et al. Activity recognition from user-annotated acceleration data. Pervasive 2004;3001:1-17.

Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2006

In this paper different estimation techniques are evaluated for the assessment of Electromechanic... more In this paper different estimation techniques are evaluated for the assessment of Electromechanical Delay (EMD). The following techniques are compared for benchmarking purposes: envelope estimation and thresholding, with different subjective combinations of filters and thresholds, and a double threshold statistical detector (DTD). Performance are compared in terms of bias, standard deviation and erroneous detections of the estimations. DTD showed higher robustness and repeatability of results, guaranteed by the objective settings based on the statistical characteristics of the algorithm.

IFMBE Proceedings, 2008

In cycling, instrumented devices providing a quantitative assessment of the task execution could ... more In cycling, instrumented devices providing a quantitative assessment of the task execution could facilitate the functional evaluation and the training organization generally carried on by sport trainers. To this purpose, this work deals with the design and the implementation of a system able to evaluate the pedaling efficiency. The system is based on an Instrumented Pedal (IPed) that measures the components of the force (ie the perpendicular to the load plane and the tangential to the motion direction) exerted during pedaling and the angle ...

Medical Imaging 2005: Physiology, Function, and Structure from Medical Images, 2005

During contraction and stretching, muscles change shape and size, and produce a deformation of sk... more During contraction and stretching, muscles change shape and size, and produce a deformation of skin tissues and a modification of the body segment shape. In human motion analysis, it is indispensable to take into account this phenomenon and thus approximating body limbs to rigid structures appears as restrictive. The present work aims at evaluating skin and muscular deformation, and at modeling body segment elastic behavior by analysing video sequences that capture a sport gesture. The soft tissue modeling is accomplished by using triangular meshes that automatically adapt to the body segment during the execution of a static muscle contraction. The adaptive triangular mesh is built on reference points whose motion is estimated by using the technique based on Gauss Laguerre Expansion. Promising results have been obtained by applying the proposed method to a video sequence, where an upper arm isometric contraction was present. * goffredo@uniroma3.it, phone +39 06 5517-7305; fax. +39 06 5517-7026; http://www.dea.uniroma3.it/biolab