Publications by Philippe Robert

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Introduction: A reliable measurement of the physical activity in everyday life should allow a better assessment of the utility and the relevance of a number of medical treatments. Continuous 24-h recordings of posture and motion can be generally useful in behaviour assessment. Categorising body postures (sitting, standing and lying) and locomotion (walking) based on only one miniature kinematic sensor has been studied [1]. The purpose of this study is to improve the accuracy of that system and to provide ot

In this study we describe an ambulatory system for estimation of spatio-temporal parameters during long periods of walking. This original method based on wavelet analysis is proposed to compute the values of temporal gait parameters from the angular velocity of lower limbs. Based on a mechanical model, the medio-lateral rotation of the lower limbs during stance and swing, the stride length and velocity are estimated by integration of the angular velocity. Measurement's accuracy was assessed using as a crite

The time of sit-stand and stand-sit transition and its duration were measured using a miniature gyroscope on the chest and a portable recorder on the waist Based on a simple model and wavelet analysis, three parameters related to postural transition, namely the average and standard deviation of transition duration and the occurrence of abnormal successive transition, were provided for evaluating the falling risk. The comparison between two groups of elderly subjects (i.e. fallers and non-fallers) shows that

A new method of evaluating the characteristics of postural transition (PT) and their correlation with falling risk in elderly people is described. The time of sit-to-stand and stand-to-sit transitions and their duration were measured using a miniature gyroscope attached to the chest and a portable recorder placed on the waist. Based on a simple model and the discrete wavelet transform, three parameters related to the PT were measured, namely, the average and standard deviation of transition duration and the

A new system, Physilog, for ambulatory monitoring of movement is proposed and its applications in orthopaedic, physiology, angiology and quality of life are presented. Body accelerations were recorded by a portable measuring device. Significant parameters of body motion, namely, movement coordination, temporal parameters, speed, incline, distance covered, kind of physical activity and its duration, are extracted from the subject accelerations in its daily environment. The accuracy of these parameters guaran

A new real-time ergometric system, ERGORAT, for measuring the energy expenditure due to muscular activity of small mammals is described. The method is based on measuring the vibrations induced by a freely moving rat to a platform on which it is living. Six accelerometers placed on the platform detect all the vibrations produced by the rat. The co-ordinates of the centre of mass of the animal are located by an optoelectronic device. This location and the six accelerations are fed to a microprocessor-based da

The objective of this feasibility study is to evaluate the use of the 'Physilog' device, an ambulatory physical- activity recorder based on acceleration measurement, for the monitoring of daily physical activities. Accelerations measured at the level of the chest and the thigh are recorded by Physilog over a period of 1 h in five normal subjects. A specially designed studio-like room allowing the performance of most usual activities of everyday life is used. A video film synchronised with the Physilog is ob

A new method of physical activity monitoring is presented, which is able to detect body postures (sitting, standing, and lying) and periods of walking in elderly persons using only one kinematic sensor attached to the chest. The wavelet transform, in conjunction with a simple kinematics model, was used to detect different postural transitions (PTs) and walking periods during daily physical activity. To evaluate the system, three studies were performed. The method was first tested on 11 community-dwelling el

Spatial and temporal parameters of gait have clinical relevance in the assessment of motor pathologies, particularly in orthopaedics. A new gait analysis system is proposed which consists of (a) an ambulatory device (Physilog(R)) including a set of miniature gyroscopes and a portable datalogger, and (b) an algorithm for gait analysis. The aim of this study was the validation of this system, for accuracy and clinical applicability. Eleven patients with coxarthrosis, eight patients with total hip arthroplasty

Body accelerations during human walking were recorded by a portable measuring device. A new method for parameterizing body accelerations and finding the pattern of walking is outlined. Two neural networks were designed to recognize each pattern and estimate the speed and incline of walking. Six subjects performed treadmill walking followed by self- paced walking on an outdoor test circuit involving roads of various inclines. The neural networks were first ''trained'' by known patterns of treadmill walking.

The objective of this study is to present a new method of physical activity monitoring, able to detect body postures (sitting, standing and lying) from only one kinematic sensor attached on the chest. Wavelet analysis in conjunction with a simple kinematics model is used to recognize different posture transitions during daily physical activity. The postures observed with this technique matched those obtained with a reference optical motion system. Accurate results were also obtained during real-life testing

Falls are the leading cause of injury-related morbidity and mortality among elderlypersons and are associated with significant adverse psychological andphysical consequences [1].Evaluating fall risk is important because it allows better targeting for preventiveand assistive interventions to at risk subjects. Most falls occur during walkingand several studies have demonstrated an association between changes in gaitand risk of falling in older adults [2]. Despite these findings, fall risk is mainlyassessed by

A new method for the detection of gait cycle phases using only two miniature accelerometers together with a light, portable digital recorder is proposed. Each subject is asked to walk on a walkway at his/her own preferred speed. Gait analysis was performed using an original method of computing the values of temporal parameters from accelerometer signals. First, to validate the accelerometric method, measurements are taken on a group of healthy subjects. No significant differences are observed between the re

Comprehensive gait analysis usually includes kinematics, kinetics, and electromyography. A complex instrumentation is thus required that only can be installed in a dedicated laboratory. These techniques are valuable to support clinical decisions and to evaluate the results. However, in several instances, a simplified analysis, concentrated on few selected gait parameters, can be valuable as well. One problem, however, is to ascertain that the computed parameters are correct and correspond to what could be m

Osteoarthritis is the most frequent joint pathology throughout the world. Obtaining objective, dynamic and quantified data allowing the evaluation of patients’ progress before and after hip arthroplasty is crucial. Gait analysis can be used for evaluating improvement in such patients, since walking is the principal human physical activity. Comprehensive gait analysis usually includes kinematics, kinetics, and electromyography. A complex instrumentation is thus required that only can be installed in a dedica

The aim of this paper is to demonstrate that wavelet denoising processing is extremely attractive for efficient source separation of strong noisy mixtures. Systematic numerical simulations using source separation algorithms after wavelet de-noising are used to provide quantitative evaluations of the efficiency of the method. The cases of correlated Gaussian and non-Gaussian noise are investigated, which open the way to various practical applications.

Spinal cord stimulation (i.e. the electrical stimulation of the dorsal columns of the spinal cord) isincreasingly used for the treatment of intractable pain syndromes due to vascular or neurogenicdisorders. Despite well-established safety and efficacy in properly selected cases, the use of SCS is stilllimited and its acceptance by the medical community remains somewhat restricted. This is due toseveral factors including an unclear mechanism of action and difficulties in determining objective endpointsto ass

Polarization dispersion is one of the effect which can give rise to data rate limitation. An actual optical link can be installed using different appended fibres, manufactured by different producers, processing techniques or batches. Knowing the polarization dispersion of each individual fibre, it could be difficult to forecast the overall dispersion of such an heterogeneous link. Fortunately recent models make the prediction of the global polarization dispersion possible. An experimental verification of th

This paper addresses the source separation in strong noisy mixtures by wavelet de-noising processing. Experiments include the cases of white/correlated Gaussian and non- Gaussian noise, which correspond to various applications. The performance of BSS/ICA algorithms after wavelet de- noising is quantitatively investigated, and points out the efficiency of the method.

A portable data logger is designed to record body accelerations during human walking, Five subjects walk first on a treadmill at various speeds on the level, and at positive and negative inclines. Then, the subjects performed a self-pace walking on an outdoor test circuit involving roads of various inclines, The recorded signals are parameterized, and the pattern of walking at each gait cycle is found. These patterns re presented to two neural networks which estimate the incline and the Speed of walking. Th

Philippe Robert

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ESMAC-SIAMOC 2001 Joint Congress: Body Postures and Walking Period Estimation Using a Kinematic Sensor: Application for Long Term Monitoring of Physical Activity in Elderly Subjects

Spatio-temporal parameters of gait measured by an ambulatory system using miniature gyroscopes

Falling risk evaluation in elderly using miniature gyroscope

Measurement of stand-sit and sit-stand transitions using a miniature gyroscope and its application in fall risk evaluation in the elderly

Motion analysis in clinical practice using ambulatory accelerometry

Real-Time Measurement of the Contribution of the Muscular- Activity to the Metabolic-Rate in Freely Moving Rats

Physical activity monitoring based on accelerometry: validation and comparison with video observation

Ambulatory system for human motion analysis using a kinematic sensor: Monitoring of daily physical activity in the elderly

Evaluation of an ambulatory system for gait analysis in hip osteoarthritis and after total hip replacement

Incline, Speed, and Distance Assessment During Unconstrained Walking

A new method for body posture detection using a kinematic sensor

Falling Risk Evaluation in Elderly Using Miniature Gyroscope: Relation Between Gait and Risk of Falling

Temporal feature estimation during walking using miniature accelerometers: an analysis of gait improvement after hip arthroplasty

ESMAC-SIAMOC 2001 Joint Congress: Gait Events in Hip Osteoarthritis and Total Hip Replaced Patients Evaluated by Two different Gait Analysis Systems

Gait Features Assessment in Hip Osteoarthritis and Total Hip Replaced Patients Based on an ambulatory System (Physilog)

Wavelet de-noising for highly noisy source separation

Accurate physical mobility analysis of patients treated by neuromodulation

Overall polarization dispersion after propagation through different fibres

Source separation in strong noisy mixtures: A study of wavelet de-noising pre-processing

Estimation of Speed and Incline of Walking Using Neural- Network