- Biomedical Engineering, Gait and Balance, Rehabilitation Engineering, Parkinson's Disease, Deep Brain Stimulation, Wearable Technologies, and 20 moreBiomedical signal and image processing, Wearable Inertial Sensors, Elderly Falls (Geriatrics), Postural Control, Vestibular Disorders: Diagnosis/Treatment, Pattern Recognition, Gait Biomechanics, EEG Biofeedback, Personal Health Cloud, Mobile Computing and Wireless Communications, Information Security and Privacy, Digital Enterprises, Digital Governments, Digital Health., Neurofeedback, Nonlinear dynamics, Ambient Assisted Living, Human Movement Science, Motor Control and Rehabilitation (Health Sciences), Human Gait Analysis, Gerontechnology, Biofeedback, Cognitive Neuroscience, and Audiological Sciences(Biomedical signal and image processing, Wearable Inertial Sensors, Elderly Falls (Geriatrics), Postural Control, Vestibular Disorders: Diagnosis/Treatment, Pattern Recognition, Gait Biomechanics, EEG Biofeedback, Personal Health Cloud, Mobile Computing and Wireless Communications, Information Security and Privacy, Digital Enterprises, Digital Governments, Digital Health., Neurofeedback, Nonlinear dynamics, Ambient Assisted Living, Human Movement Science, Motor Control and Rehabilitation (Health Sciences), Human Gait Analysis, Gerontechnology, Biofeedback, Cognitive Neuroscience, and Audiological Sciences)edit
Abstract The surface electrocardiogram (ECG) is an established diagnostic tool for the detection of abnormalities in the electrical activity of the heart. The interest of the ECG, however, extends beyond the diagnostic purpose. In recent... more
Abstract The surface electrocardiogram (ECG) is an established diagnostic tool for the detection of abnormalities in the electrical activity of the heart. The interest of the ECG, however, extends beyond the diagnostic purpose. In recent years, studies in cognitive psychophysiology have related heart rate variability (HRV) to memory performance and mental workload.
Abstract—The SMILING project is aimed at providing a technological solution to motor problems, particularly related to gait and balance such as the risk of falling, occurring in the elderly population. The contribution of the present... more
Abstract—The SMILING project is aimed at providing a technological solution to motor problems, particularly related to gait and balance such as the risk of falling, occurring in the elderly population. The contribution of the present paper is to provide an insight on the SMILING system prototype with a particular focus on the User Control Unit, that is a portable, wireless device designed to assist the user during training and to control the interaction with the different parts of the system.
Abstract A new method for the estimation of multi-link angular kinematics in the sagittal plane, using one single-axis accelerometer (SAA) per segment, is presented in this paper. A preliminary calibration, using SAAs and a reference... more
Abstract A new method for the estimation of multi-link angular kinematics in the sagittal plane, using one single-axis accelerometer (SAA) per segment, is presented in this paper. A preliminary calibration, using SAAs and a reference system (encoder or stereo-photogrammetry), allows the estimation of sensors position and orientation and segment lengths. These parameters are then used to predict the chain kinematics using the SAAs only.
Background Self-reported gait unsteadiness is often a problem in neurological patients without any clinical evidence of ataxia, because it leads to reduced activity and limitations in function. However, in the literature there are only a... more
Background Self-reported gait unsteadiness is often a problem in neurological patients without any clinical evidence of ataxia, because it leads to reduced activity and limitations in function. However, in the literature there are only a few papers that address this disorder. The aim of this study is to identify objectively subclinical abnormal gait strategies in these patients.
Abstract To separate the atrial (AA) from the ventricular (VA) electrical activity in surface ECG recordings of atrial fibrillation (AF), various methods have been proposed, such as QRS-T cancellation by beat-averaged template... more
Abstract To separate the atrial (AA) from the ventricular (VA) electrical activity in surface ECG recordings of atrial fibrillation (AF), various methods have been proposed, such as QRS-T cancellation by beat-averaged template subtraction, and blind source separation (BSS). Although QRS-T cancellation is computationally more efficient than BSS, and allows the preservation of spatial information, it is sensitive to morphology changes, which produce large residuals in AA, biasing the frequency analysis.
The Timed Up and Go (TUG) is a clinical test to assess balance, mobility and fall risk. The traditional outcome of this test is its duration. Since this single measure cannot provide insight on subtle differences in test performances,... more
The Timed Up and Go (TUG) is a clinical test to assess balance, mobility and fall risk. The traditional outcome of this test is its duration. Since this single measure cannot provide insight on subtle differences in test performances, instrumented Timed Up and Go tests (iTUG) have been recently proposed [1]. Quantitative evaluation of TUG may be especially important, eg, in early stages of Parkinson's Disease (PD) when balance and gait problems are not clinically evident but still may be detected by instrumented analysis [1].
In motor rehabilitation, the use of biofeedback for improving postural sway and balance control is common. In most cases, the biofeedback is provided by a clinician or by an electronic system, and assists the subject with visual, oral or... more
In motor rehabilitation, the use of biofeedback for improving postural sway and balance control is common. In most cases, the biofeedback is provided by a clinician or by an electronic system, and assists the subject with visual, oral or tactile information. Specifically, center of pressure (CoP) information has been used in many studies to provide visual biofeedback to patients with neurological diseases while standing on a force plate [1].
Background In clinical gait assessment, the correct interpretation of gait kinematics and kinetics has a decisive impact on the success of the therapeutic programme. Due to the vast amount of information from which primary anomalies... more
Background In clinical gait assessment, the correct interpretation of gait kinematics and kinetics has a decisive impact on the success of the therapeutic programme. Due to the vast amount of information from which primary anomalies should be identified and separated from secondary compensatory changes, as well as the biomechanical complexity and redundancy of the human locomotion system, this task is considerably challenging and requires the attention of an experienced interdisciplinary team of experts.
Abstract Background: Good balance depends on accurate and adequate information from the senses. One way to substitute missing sensory information for balance is with biofeedback technology. We previously reported that audio-biofeedback... more
Abstract Background: Good balance depends on accurate and adequate information from the senses. One way to substitute missing sensory information for balance is with biofeedback technology. We previously reported that audio-biofeedback (ABF) has beneficial effects in subjects with profound vestibular loss, since it significantly reduces body sway in quiet standing tasks.
Abstract Background: High-density surface electromyography (HD-SEMG) has recently emerged as a potentially useful tool in the evaluation of amyotrophic lateral sclerosis (ALS). This study addresses a practical constraint that arises when... more
Abstract Background: High-density surface electromyography (HD-SEMG) has recently emerged as a potentially useful tool in the evaluation of amyotrophic lateral sclerosis (ALS). This study addresses a practical constraint that arises when applying HD-SEMG for supporting the diagnosis of ALS; specifically, how long the surface EMG should be recorded before one can be confident that fasciculation potentials (FPs) are absent in a muscle being tested.
Background Stroke is the most common cause of disability in the developed world and can severely degrade walking function. Robot-driven gait therapy can provide assistance to patients during training and offers a number of advantages over... more
Background Stroke is the most common cause of disability in the developed world and can severely degrade walking function. Robot-driven gait therapy can provide assistance to patients during training and offers a number of advantages over other forms of therapy. These potential benefits do not, however, seem to have been fully realised as of yet in clinical practice.
Background Eye Gaze Tracking Systems (EGTSs) estimate the Point Of Gaze (POG) of a user. In diagnostic applications EGTSs are used to study oculomotor characteristics and abnormalities, whereas in interactive applications EGTSs are... more
Background Eye Gaze Tracking Systems (EGTSs) estimate the Point Of Gaze (POG) of a user. In diagnostic applications EGTSs are used to study oculomotor characteristics and abnormalities, whereas in interactive applications EGTSs are proposed as input devices for human computer interfaces (HCI), eg to move a cursor on the screen when mouse control is not possible, such as in the case of assistive devices for people suffering from locked-in syndrome.
Background Previous studies demonstrated that stroke survivors have a limited capacity to increase their walking speeds beyond their self-selected maximum walking speed (SMWS). The purpose of this study was to determine the capacity of... more
Background Previous studies demonstrated that stroke survivors have a limited capacity to increase their walking speeds beyond their self-selected maximum walking speed (SMWS). The purpose of this study was to determine the capacity of stroke survivors to reach faster speeds than their SMWS while walking on a treadmill belt or while being pushed by a robotic system (ie “push mode”). Methods Eighteen chronic stroke survivors with hemiplegia were involved in the study.
Background Virtual reality (VR) technology along with treadmill training (TT) can effectively provide goal-oriented practice and promote improved motor learning in patients with neurological disorders. Moreover, the VR+ TT scheme may... more
Background Virtual reality (VR) technology along with treadmill training (TT) can effectively provide goal-oriented practice and promote improved motor learning in patients with neurological disorders. Moreover, the VR+ TT scheme may enhance cognitive engagement for more effective gait rehabilitation and greater transfer to over ground walking.
Falls are not an inevitable consequence of aging. The risk and rate of falls can be reduced. Recent improvements in smartphone technology enable implementation of a wide variety of services and applications, thus making the smartphone... more
Falls are not an inevitable consequence of aging. The risk and rate of falls can be reduced. Recent improvements in smartphone technology enable implementation of a wide variety of services and applications, thus making the smartphone more of a digital companion than simply a communication tool. This paper presents the results obtained by the FARSEEING project where smartphones are one example of intervention in a population-based scenario. The applications developed take advantage of the smartphone-embedded inertial sensors and require that subjects wear the smartphone by means of a waist belt. The uFall Android application has been developed for monitoring the user’s motor activities at home. The application does not require any direct interaction with the user and it is also capable of running a real-time fall-detection algorithm. uTUG is a stand-alone application for instrumenting the Timed Up and Go test, which is a test often included in fall risk assessment protocols. The application acts like a pocket-sized motion laboratory, since it is capable not only of recording the trial but also of processing the data and immediately displaying the results. uTUG is designed to be self-administrable at home. Stürze sind keine notwendige Folge des Alterns, sie können verhindert werden. Die jüngsten Entwicklungen der Smartphonetechnologie ermöglichen eine Vielzahl von Anwendungen und Applikationen, wodurch das Gerät nicht nur als Kommunikationswerkzeug, sondern zunehmend als digitaler Alltagsbegleiter dient. In diesem Artikel werden Ergebnisse des FARSEEING-Projekts präsentiert, bei dem Smartphones ein Interventionsbeispiel in einem populationsbezogenen Szenario sind. Die hier vorgestellten Applikationen nutzen die im Gerät integrierten Inertialsensoren. Das Smartphone wird dabei mit einem Hüftgurt getragen. Die uFall-Applikation dient zur innerhäuslichen Beobachtung der körperlichen Aktivität des Nutzers und ermöglicht eine algorithmusbasierte Echtzeitsturzerkennung. Die uTUG-Applikation instrumentalisiert den Timed-up-and-go(TUG)-Test (Zeit bis zum Aufstehen und Gehen), welcher häufig zur Messung des Sturzrisikos verwendet wird. Dieses „miniaturisierte Bewegungslabor“ erlaubt nicht nur die Durchführung einzelner Messungen, sondern stellt auch prozessierte Daten zur direkten Auswertung bereit. Die Applikationen ermöglichen die Eigenanwendung und erfordern keine direkte Interaktion des Nutzers mit dem Gerät.
Research Interests: Web 2.0, Signal Processing, Elderly Falls (Geriatrics), Mobile Technology, Business Intelligence, and 21 moreFall prevention, E Health, Telemedicine, Mobile Computing, Healthcare, Mobile Health, Mhealth, Business Development, Business Models, Older people, Mobile Computing and Wireless Communications, Information Security and Privacy, Digital Enterprises, Digital Governments, Digital Health., Wireless Computing, Image Procesing, Mobile Devices, Health IT, Falls, Smartphone apps, Fall Prevention Interventions, Homecare, Enginnerig, and Community Creation(Fall prevention, E Health, Telemedicine, Mobile Computing, Healthcare, Mobile Health, Mhealth, Business Development, Business Models, Older people, Mobile Computing and Wireless Communications, Information Security and Privacy, Digital Enterprises, Digital Governments, Digital Health., Wireless Computing, Image Procesing, Mobile Devices, Health IT, Falls, Smartphone apps, Fall Prevention Interventions, Homecare, Enginnerig, and Community Creation)
(Fall prevention, E Health, Telemedicine, Mobile Computing, Healthcare, Mobile Health, Mhealth, Business Development, Business Models, Older people, Mobile Computing and Wireless Communications, Information Security and Privacy, Digital Enterprises, Digital Governments, Digital Health., Wireless Computing, Image Procesing, Mobile Devices, Health IT, Falls, Smartphone apps, Fall Prevention Interventions, Homecare, Enginnerig, and Community Creation)
Falls are by far the leading cause of fractures and accidents in the home environment. The current Cochrane reviews and other systematic reviews report on more than 200 intervention studies about fall prevention. A recent meta-analysis... more
Falls are by far the leading cause of fractures and accidents in the home environment. The current Cochrane reviews and other systematic reviews report on more than 200 intervention studies about fall prevention. A recent meta-analysis has summarized the most important risk factors of accidental falls. However, falls and fall-related injuries remain a major challenge. One novel approach to recognize, analyze, and work better toward preventing falls could be the differentiation of the fall event into separate phases. This might aid in reconsidering ways to design preventive efforts and diagnostic approaches. From a conceptual point of view, falls can be separated into a pre-fall phase, a falling phase, an impact phase, a resting phase, and a recovery phase. Patient and external observers are often unable to give detailed comments concerning these phases. With new technological developments, it is now at least partly possible to examine the phases of falls separately and to generate new hypotheses. The article describes the practicality and the limitations of this approach using body-fixed sensor technology. The features of the different phases are outlined with selected real-world fall signals. Stürze sind die mit Abstand häufigsten Ursachen von Frakturen und häuslichen Verletzungen im Alter. In den Cochrane Reviews und anderen systematischen Analysen wurden mehr als 200 randomisierte Interventionsstudien zur Sturzprävention erfasst. Eine neue Metaanalyse liegt für die Risikofaktoren von Stürzen vor. Dennoch bleiben Stürze und sturzbedingte Verletzungen eine große Herausforderung. Ein neuer Ansatz zur Erkennung, Analyse und Prävention von Stürzen ist es, Stürze in Abschnitte aufzuteilen. Dies könnte bei der Erstellung diagnostischer und präventiver Ansätze helfen. Phänomenologisch ist offenkundig, dass es eine Vorphase, Fallphase, Aufprallphase, Ruhephase und mögliche Erholungsphase gibt. Patienten und Fremdbeobachter sind allerdings nicht in der Lage, hierzu exakte Angaben zu machen. Durch technologische Neuentwicklungen ist es nunmehr möglich, diese Abschnitte zumindest teilweise zu beurteilen und daraus erste Hypothesen abzuleiten. Der Artikel beschreibt dabei die Praktikabilität und Beschränkungen der Verwendung von am Körper getragenen Sensoren. Die Sturzphasen werden anhand von Fallbeispielen verdeutlicht.
Research Interests: Elderly Falls (Geriatrics), Wearable Technologies, Fall prevention, Wearable Inertial Sensors, Older people, and 8 moreQualitative, Falls and Slips Biomechanics, Health Professionals, Dementia and Falls, Falls, Fall Prevention Interventions, Uptake of Fall Prevention Interventions, and Fall Prevention Intervention
In 2004, a videotape of a fall by Fidel Castro, then Cuban President, gained extensive press coverage and elicited a range of reactions. 1 The sequence captured a key shot for researchers who study falls. In the film, Castro, after one of... more
In 2004, a videotape of a fall by Fidel Castro, then Cuban President, gained extensive press coverage and elicited a range of reactions. 1 The sequence captured a key shot for researchers who study falls. In the film, Castro, after one of his exhausting speeches and probably dazzled by lights, misses a step, starts falling after an unsuccessful stepping attempt, and turns in the air to reduce the impact of his head on the ground at the expense of an upper limb; the fall resulted in a broken should...
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Object Difficulty with step initiation, called "start... more
Object Difficulty with step initiation, called "start hesitation," is related to gait bradykinesia and is an early hallmark of gait freezing in Parkinson disease (PD). Authors of this study investigated the effects of deep brain stimulation (DBS) and levodopa on step initiation before and 6 months after DBS surgery in 29 patients with PD who were randomized to either the bilateral subthalamic nucleus (STN) or globus pallidus internus (GPi) as the DBS site. Methods The authors measured the amplitude and duration of anticipatory postural adjustments (APAs), the feed-forward postural preparation that precedes the onset of voluntary step initiation, based on center-of-pressure displacements on a force plate. They also measured the length and velocity of the first step using a motion analysis system to study kinematics. Some of the patients (22) were from a large, multicenter, double-blind clinical trial, and all patients in the study (29, PD-DBS group) were randomized to DBS in either the bilateral STN (15 patients) or bilateral GPi (14 patients). Differences in step initiation were investigated in 2 conditions before surgery (off/on levodopa) and in 4 conditions after surgery (off/on levodopa combined with off/on DBS). Twenty-eight elderly healthy control volunteers (CTRL group) were also tested, and 9 control volunteers with PD who met the criteria for DBS (PD-C group) were tested at baseline and 6 months later. Results Patients in the PD-DBS group had smaller amplitudes and longer durations of APAs compared with those in the 28 healthy control volunteers in all conditions. Before surgery, APAs improved with levodopa. After surgery, the APAs were significantly worse than in the best-treatment state before surgery (DOPA condition), and responsiveness to levodopa decreased. No differences in APAs were detected between the STN and GPi groups. A comparison with PD control volunteers who did not undergo DBS surgery confirmed that a deterioration in step preparation was not related to disease progression. Step length and velocity were smaller in the PD-DBS group than in controls in all conditions. Before surgery, levodopa improved the length and velocity of the first step. Both step length and velocity were unchanged in the best-treatment state before surgery (DOPA condition) as compared with after surgery (DBS+DOPA), with only step velocity in the STN group getting worse after surgery. Conclusions Six months of DBS in the STN or GPi impaired anticipatory postural preparation for step initiation, the opposite effect as with levodopa. Deep brain stimulation disrupted postural preparation more than step execution, suggesting independent motor pathways for preparation and execution of gait. Although turning the stimulators on after surgery combined with levodopa benefited the postural preparation to step, a comparison of pre- and postsurgery conditions suggests that either the surgery itself or 6 months of continuous stimulation may lead to an alteration of circuits or plastic changes that impair step initiation.
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This paper proposes a 2D functional evaluation tool for estimating subject-specific body segment parameters, which uses a simple motor task (repeated sit-to-stand, rSTS), recorded with one single-axis accelerometer (SAA) per segment and a... more
This paper proposes a 2D functional evaluation tool for estimating subject-specific body segment parameters, which uses a simple motor task (repeated sit-to-stand, rSTS), recorded with one single-axis accelerometer (SAA) per segment and a force plate (FP). After this preliminary estimation, the accelerometer alone is used to make quasi-real-time predictions of ground reaction force (anterior/posterior, F X , and vertical, F Z , components), center of pressure (CoP) and center of mass (CoM), during rSTS and postural oscillation in the sagittal plane. These predicted dynamic variables, as well as those obtained using anthropometric parameters derived from De Leva, were compared to actual FP outputs in terms of root mean-squared errors (RMSEs). Using De Leva’s parameters in place of those estimated, RMSEs increase from 12 to 21 N (F X ), from 21 to 24 N (F Z ), and from 21.1 to 55.6 mm (CoP) in rSTS; similarly, RMSEs increase from 3.1 to 3.3 N (F X ) and from 5.5 to 6.6 mm (CoP) in oscillatory trials. A telescopic inverted pendulum model was adopted to analyze the balance control in rSTS using only predicted CoP and CoM. Results suggest that one SAA per segment is sufficient to predict the dynamics of a biomechanical model of any degrees of freedom.
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Objective measures of postural control that are sensitive to Parkinson's disease (PD) progression would improve patient care and accelerate clinical trials. Although measures of postural sway during quiet stance in untreated PD have been... more
Objective measures of postural control that are sensitive to Parkinson's disease (PD) progression would improve patient care and accelerate clinical trials. Although measures of postural sway during quiet stance in untreated PD have been shown to differ from age-matched control subjects, it is not known if sway measures change with disease progression in early PD. In this pilot study, we asked whether accelerometer-based metrics of sway could provide a practical tool for monitoring progression of postural dyscontrol in people with untreated or newly treated PD.We examined 13 subjects with PD and 12 healthy, age-matched control subjects. The PD subjects had been recently diagnosed and had not started any antiparkinsonian medications at the baseline session. All subjects were tested 3–6 months and 12 months after the baseline session. Subjects were asked to stand quietly for two minutes while wearing an inertial sensor on their posterior trunk that measured trunk linear acceleration.Our results suggested that objective sway measures deteriorated over one year despite minimal changes in UPDRS motor scores. Medio-lateral (ML) sway measures were more sensitive than antero-posterior sway measures in detecting progression. The ML JERK was larger in the PD group than the control group across all three testing sessions. The ML sway dispersion and ML sway velocity were also significantly higher in PD compared to control subjects by the 12-month evaluation. It is feasible to measure progression of PD prior to onset of treatment using accelerometer-based measures of quiet standing.► Objective sway measures deteriorated over one year. ► UPDRS motor scores did not show significant changes over one year. ► Medio-lateral (ML) sway measures were more sensitive than antero-posterior sway measures in detecting progression.
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The Timed Up and Go (TUG) is one of the most widely used clinical tests to assess balance and mobility. An instrumented Timed Up and Go (iTUG) makes use of a specialized measurement system (e.g. an accelerometer) to identify and evaluate... more
The Timed Up and Go (TUG) is one of the most widely used clinical tests to assess balance and mobility. An instrumented Timed Up and Go (iTUG) makes use of a specialized measurement system (e.g. an accelerometer) to identify and evaluate specific mobility skills. Nowadays a Smartphone (SP) comes with a large set of embedded sensors, including an accelerometer. An SP is a user-friendly device able to perform ubiquitous sensing with a variety of connectivity options. In this study we evaluate the validity of an SP for instrumenting the TUG. We examined 49 subjects (59 ± 16 years old), without defining any inclusion criteria, using both an SP and a McRoberts Dynaport Hybrid, a device specifically designed for movement analysis. The statistical agreement between the two measurement systems is good for some of the parameters described in literature, which are of clear clinical value. Inter-rater reliability is often excellent and intra-rater reliability has been assessed in a subgroup of 25 subjects finding the same results for the two devices. In conclusion we found evidence that the SP is capable of becoming a pervasive and low-cost tool for the quantitative analysis of balance and mobility.► We compare a Smartphone-embedded accelerometer with a commercial ambulatory monitoring device. ► We evaluate the Smartphone validity on Timed Up and Go test parameters already used in the literature. ► We find good statistical agreement in most cases. ► It is crucial to define an appropriate pre-processing of Smartphone signals. ► Smartphones can provide suitable solutions for pervasive movement analysis.
Research Interests: Signal Processing, Privacy, Mobile Technology, Security, E Health, and 15 moreTelemedicine, Mobile Computing, Mobile Health, Android, Mhealth, Business Development, Mobile Computing and Wireless Communications, Information Security and Privacy, Digital Enterprises, Digital Governments, Digital Health., Smartphones, Wireless Computing, Image Procesing, Mobile Devices, Health IT, Smartphone, Homecare, and Enginnerig(Telemedicine, Mobile Computing, Mobile Health, Android, Mhealth, Business Development, Mobile Computing and Wireless Communications, Information Security and Privacy, Digital Enterprises, Digital Governments, Digital Health., Smartphones, Wireless Computing, Image Procesing, Mobile Devices, Health IT, Smartphone, Homecare, and Enginnerig)
(Telemedicine, Mobile Computing, Mobile Health, Android, Mhealth, Business Development, Mobile Computing and Wireless Communications, Information Security and Privacy, Digital Enterprises, Digital Governments, Digital Health., Smartphones, Wireless Computing, Image Procesing, Mobile Devices, Health IT, Smartphone, Homecare, and Enginnerig)
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The paper provides a new technique based on a least-squares approach for the accurate estimation of a force platform calibration matrix using simple manual procedures, when the direction of the applied loads cannot be perfectly aligned... more
The paper provides a new technique based on a least-squares approach for the accurate estimation of a force platform calibration matrix using simple manual procedures, when the direction of the applied loads cannot be perfectly aligned with the axes of the platform. This new procedure can be applied to all force platforms and allows the combined application of vertical and horizontal forces, both static and time-varying. The robust calibration method includes the angular errors in the least-squares parameter vector, thus reducing the bias in the estimated calibration matrix parameters. The performance of the robust method was compared with the conventional one, using a numerical simulation approach starting from a known calibration matrix. With the conventional approach, in noiseless conditions, the maximum error due to load misalignment (SD = 3 degrees) was 6% for the direct terms and over 10% for the cross-talk terms. With the robust method, these errors reduced to zero and were always below 0.4%, even when realistic noise was superimposed on the measures. With perfectly aligned loads and realistic output noise, the confidence intervals of the calibration matrix parameters were very similar for the two methods, demonstrating that the increased number of parameters did not affect the reliability of the estimate.
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Most of the knowledge on falls of older persons has been obtained from oral reports that might be biased in many ways. Fall simulations are widely used to gain insight into circumstances of falls, but the results, at least concerning fall... more
Most of the knowledge on falls of older persons has been obtained from oral reports that might be biased in many ways. Fall simulations are widely used to gain insight into circumstances of falls, but the results, at least concerning fall detection, are not convincing. Variation of acceleration and maximum jerk of 5 real-world backward falls of 4 older persons (mean age 68.8 years) were compared to the corresponding signals of simulated backward falls by 18 healthy students. Students were instructed to “fall to the back as if you were a frail old person” during experiment 1. In experiment 2, students were instructed not to fall, if possible, when released from a backward lean. Data acquisition was performed using a tri-axial acceleration sensor. In experiment 1, there was significantly more variation within the acceleration signals and maximum jerk was higher in the real-world falls, compared to the fall simulation. Conversely, all values of acceleration and jerk were higher for the fall simulations, compared to real-world falls in experiment 2.The present findings demonstrate differences between real-world falls and fall simulations. If fall simulations are used, their limitations should be noted and the protocol should be adapted to better match real-world falls.
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Posture analysis in quiet standing is a key component of the clinical evaluation of Parkinson's disease (PD), postural instability being one of PD's major symptoms. The aim of this study was to assess the feasibility of using... more
Posture analysis in quiet standing is a key component of the clinical evaluation of Parkinson's disease (PD), postural instability being one of PD's major symptoms. The aim of this study was to assess the feasibility of using accelerometers to characterize the postural behavior of early mild PD subjects. Twenty PD and 20 control subjects, wearing an accelerometer on the lower back, were tested in five conditions characterized by sensory and attentional perturbation. A total of 175 measures were computed from the signals to quantify tremor, acceleration, and displacement of body sway. Feature selection was implemented to identify the subsets of measures that better characterize the distinctive behavior of PD and control subjects. It was based on different classifiers and on a nested cross validation, to maximize robustness of selection with respect to changes in the training set. Several subsets of three features achieved misclassification rates as low as 5%. Many of them included a tremor-related measure, a postural measure in the frequency domain, and a postural displacement measure. Results suggest that quantitative posture analysis using a single accelerometer and a simple test protocol may provide useful information to characterize early PD subjects. This protocol is potentially usable to monitor the disease's progression.
Research Interests: Engineering, Algorithms, Artificial Intelligence, Biomechanics, Feature Selection, and 21 moreDiscriminant Analysis, Humans, Female, Male, Accelerometers, Feature Extraction, Cross Validation, Acceleration, Time Frequency Analysis, Posture, Aged, Middle Aged, Accelerometer, Reproducibility of Results, Disease Progression, Frequency Conversion, Logistic Models, Time measurement, Parkinson Disease, Frequency Domain, and Clinical evaluation(Discriminant Analysis, Humans, Female, Male, Accelerometers, Feature Extraction, Cross Validation, Acceleration, Time Frequency Analysis, Posture, Aged, Middle Aged, Accelerometer, Reproducibility of Results, Disease Progression, Frequency Conversion, Logistic Models, Time measurement, Parkinson Disease, Frequency Domain, and Clinical evaluation)
(Discriminant Analysis, Humans, Female, Male, Accelerometers, Feature Extraction, Cross Validation, Acceleration, Time Frequency Analysis, Posture, Aged, Middle Aged, Accelerometer, Reproducibility of Results, Disease Progression, Frequency Conversion, Logistic Models, Time measurement, Parkinson Disease, Frequency Domain, and Clinical evaluation)
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Research Interests: Algorithms, Biomedical Engineering, Linear Algebra, Wavelet Analysis, Humans, and 10 moreStandard Deviation, Wavelet Transform, Root-Mean Square Error, Cardiac Arrhythmias, Electrocardiogram, Arrhythmia, Sensitivity and Specificity, Floating Point, Positive predictive value, and Automatic Annotation
While several studies have shown that subjects with advanced Parkinson’s disease (PD) exhibit abnormalities in sway parameters during quiet standing, abnormalities of postural sway associated with untreated PD have not been reported.... more
While several studies have shown that subjects with advanced Parkinson’s disease (PD) exhibit abnormalities in sway parameters during quiet standing, abnormalities of postural sway associated with untreated PD have not been reported. Although not clinically apparent, we hypothesized that spontaneous sway in quiet stance is abnormal in people with untreated PD.We examined 13 subjects, recently diagnosed with PD, who were not yet taking any anti-parkinsonian medications and 12 healthy, age-matched control subjects. Postural sway was measured with a linear accelerometer on the posterior trunk (L5 level) and compared with traditional force plate measures of sway. Subjects stood for 2 min under two conditions: eyes open (EO) and eyes closed (EC).One of the most discriminative measures of postural changes in subjects with untreated PD was the increased ‘JERK’ of lower trunk in the EO condition, measured with the accelerometer. Root mean square and the frequency dispersion of postural sway in the EO condition also discriminated sway in untreated PD subjects compared to control subjects.We conclude that accelerometer-based sway metrics could be used as objective measures of postural instability in untreated PD. Accelerometer-based analysis of spontaneous sway may provide a powerful tool for early clinical trials and for monitoring the effects of treatment of balance disorders in subjects with PD.
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Research Interests: Biomedical Engineering, Quality of life, Postural Control, Humans, Female, and 13 moreMale, Aged, Geriatric Depression Scale, Middle Aged, Pilot study, Adverse Event, Neurodegenerative Disease, Disease Progression, Postural Balance, Non parametric statistics, Pilot Projects, Neurosciences, and Parkinson Disease
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Research Interests: Mechanical Engineering, Photogrammetry, Knowledge sharing, Adipose tissue, Clinical Practice, and 16 moreHumans, Movement, Measurement Errors, Artifacts, Clinical Sciences, Gait and Posture, Rigid Body, Human Movement, Error Propagation, Lower limb, Soft Tissue, Joints, Numerical Solution, Experiment Design, Biomechanical Phenomena, and Statistics as Topic
Research Interests: Mechanical Engineering, Photogrammetry, Knowledge sharing, Adipose tissue, Clinical Practice, and 16 moreHumans, Movement, Measurement Errors, Artifacts, Clinical Sciences, Gait and Posture, Rigid Body, Human Movement, Error Propagation, Lower limb, Soft Tissue, Joints, Numerical Solution, Experiment Design, Biomechanical Phenomena, and Statistics as Topic
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Research Interests: Engineering, Carbon Dioxide, Nonlinear dynamics, Humans, Anoxia, and 15 moreComputer Simulation, Time Delay, Lung, Steady state, Adult, Respiratory System, Theoretical Framework, Cardiac Output Monitoring, Nonlinear Model, Reference Values, Experimental Data, Simulation Model, Hypercapnia, Pulmonary Gas Exchange, and Acid-Base Equilibrium
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Abstract Step and stride regularity were assessed in three transfemoral amputees and two control subjects by autocorrelation analysis of wearable inertial sensor signals. Autocorrelation parameters from acceleration were markedly lower in... more
Abstract Step and stride regularity were assessed in three transfemoral amputees and two control subjects by autocorrelation analysis of wearable inertial sensor signals. Autocorrelation parameters from acceleration were markedly lower in amputees than in control subjects during a 40 m rectilinear path (P≪ 0.0015). That may allow the development of a Virtual Gait Trainer based on biofeedback.
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With the objective to release solutions which can be easily manageable by their final users, including older users, we worked to design methods and devices which rely on a minimal set-up for monitoring and rehabilitation of balance and... more
With the objective to release solutions which can be easily manageable by their final users, including older users, we worked to design methods and devices which rely on a minimal set-up for monitoring and rehabilitation of balance and mobility. A single inertial sensing unit, typically worn on the trunk, was hence engineered to accomplish for activity monitoring and event detection (including fall detection), tremor rejection, instrumented clinical tests (e.g. stabilometry, Timed-Up and Go), and sensory biofeedback (audio, visual or tactile). The sensing unit is wirelessly connected with a processing unit, which can in turn act as a gateway to remote applications or caregivers. Promising results were obtained, which may pave the way to novel intensive and pervasive neurorehabilitation strategies.
Research Interests:
The Timed Up and Go is a clinical test to assess mobility in the elderly and in Parkinson's disease. Lately instrumented versions of the test are being considered, where inertial sensors assess motion. To improve the pervasiveness, ease... more
The Timed Up and Go is a clinical test to assess mobility in the elderly and in Parkinson's disease. Lately instrumented versions of the test are being considered, where inertial sensors assess motion. To improve the pervasiveness, ease of use, and cost, we consider a smartphone's accelerometer as the measurement system. Several parameters (usually highly correlated) can be computed from the signals recorded during the test. To avoid redundancy and obtain the features that are most sensitive to the locomotor performance, a dimensionality reduction was performed through principal component analysis (PCA). Forty-nine healthy subjects of different ages were tested. PCA was performed to extract new features (principal components) which are not redundant combinations of the original parameters and account for most of the data variability. They can be useful for exploratory analysis and outlier detection. Then, a reduced set of the original parameters was selected through correlation analysis with the principal components. This set could be recommended for studies based on healthy adults. The proposed procedure could be used as a first-level feature selection in classification studies (i.e. healthy-Parkinson's disease, fallers-non fallers) and could allow, in the future, a complete system for movement analysis to be incorporated in a smartphone.
Research Interests: Algorithms, Geriatrics, Movement analysis, Biomechanics, Principal Component Analysis, and 23 moreCell Phones, Feature Selection, Humans, Movement, Outlier detection, Feature Extraction, Motion, Acceleration, Aged, Middle Aged, Adult, Correlation Analysis, Time Factors, Reproducibility of Results, Ambulatory BP monitoring, Ease of Use, Inertial Sensor, Exploratory Analysis, Healthy Subjects, Equipment Design, Quantitative Evaluation, Parkinson Disease, and Measurement System(Cell Phones, Feature Selection, Humans, Movement, Outlier detection, Feature Extraction, Motion, Acceleration, Aged, Middle Aged, Adult, Correlation Analysis, Time Factors, Reproducibility of Results, Ambulatory BP monitoring, Ease of Use, Inertial Sensor, Exploratory Analysis, Healthy Subjects, Equipment Design, Quantitative Evaluation, Parkinson Disease, and Measurement System)
(Cell Phones, Feature Selection, Humans, Movement, Outlier detection, Feature Extraction, Motion, Acceleration, Aged, Middle Aged, Adult, Correlation Analysis, Time Factors, Reproducibility of Results, Ambulatory BP monitoring, Ease of Use, Inertial Sensor, Exploratory Analysis, Healthy Subjects, Equipment Design, Quantitative Evaluation, Parkinson Disease, and Measurement System)
This paper introduces a portable audio-biofeedback (ABF) system that encodes the signals provided by a linear accelerometric sensor into a stereo sound. This sound is relayed to the subjects via headphones and can enhance the ability of... more
This paper introduces a portable audio-biofeedback (ABF) system that encodes the signals provided by a linear accelerometric sensor into a stereo sound. This sound is relayed to the subjects via headphones and can enhance the ability of subjects to perceive trunk accelerations. We tested this system on nine healthy subjects while they stood in three conditions listening to the ABF representation of their trunk accelerations. The ABF significantly improved the subjects' balance in all three conditions. The subjects reported that they were comfortable wearing and using the ABF device. Results suggest that devices such as this ABF system may be used for balance training and balance rehabilitation therapy.
Research Interests:
Abstract A simple model of the chemical acid-base regulation in blood is formulated and analysed. The model incorporates only two interacting buffers representing bicarbonate and non-bicarbonate (mainly hemoglobin and plasma proteins)... more
Abstract A simple model of the chemical acid-base regulation in blood is formulated and analysed. The model incorporates only two interacting buffers representing bicarbonate and non-bicarbonate (mainly hemoglobin and plasma proteins) buffers. The results obtained show that, in spite of its simplicity, this model represents accurately a large set of relationships between CO 2 concentration and partial pressure, pH, base excess (BE) within the physiological range of variables
Page 1. 2688 IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, VOL. 56, NO.
Abstract Spectral analysis of heart rate variability was used to study the different reactions to hypovolemia in patients under chronic hemodialytic treatment. Autoregressive power spectra of the RR signal were calculated in twenty uremic... more
Abstract Spectral analysis of heart rate variability was used to study the different reactions to hypovolemia in patients under chronic hemodialytic treatment. Autoregressive power spectra of the RR signal were calculated in twenty uremic patients during the hemodialytic sessions. Patients were earlier classified as hemodynamically stable or unstable on the basis of their historical propensity to hypotension.
Abstract The Timed Up and Go test (TUG) is a clinical test to assess mobility in Parkinsons disease (PD). It consists of rising from a chair, walking, turning, and sitting. Its total duration is the traditional clinical outcome. In this... more
Abstract The Timed Up and Go test (TUG) is a clinical test to assess mobility in Parkinsons disease (PD). It consists of rising from a chair, walking, turning, and sitting. Its total duration is the traditional clinical outcome. In this study an instrumented TUG (iTUG) was used to supplement the quantitative information about the TUG performance of PD subjects: a single accelerometer, worn at the lower back, was used to record the acceleration signals during the test and acceleration-derived measures were extracted from the recorded signals.
Even though several diagnostic and therapeutic instruments and methodologies have never had a proper scientific validation, they are recognised as valid tools and regularly used in clinics. Our aim is to validate instrumental... more
Even though several diagnostic and therapeutic instruments and methodologies have never had a proper scientific validation, they are recognised as valid tools and regularly used in clinics. Our aim is to validate instrumental posturography as for instruments and methodologies which are widely used in motor rehabilitation. A model was proposed in 1983 by Kapteyn et al. to standardise their use, but no adequate models have been implemented up to now.
Abstract: The present study addresses the challenge of identifying the features of the centre of pressure (CoP) trajectory that are most sensitive to postural performance, to progress in the process of transforming CoP data into useful... more
Abstract: The present study addresses the challenge of identifying the features of the centre of pressure (CoP) trajectory that are most sensitive to postural performance, to progress in the process of transforming CoP data into useful information and to promote standardization in quantitative posturography.
Abstract An analytic solution of the variable volume double-pool urea kinetics model and its application to the estimation of urea distribution volume and generation rate during dialysis, are presented. The estimation of these clinically... more
Abstract An analytic solution of the variable volume double-pool urea kinetics model and its application to the estimation of urea distribution volume and generation rate during dialysis, are presented. The estimation of these clinically relevant parameters starting from only three blood samples requires the assumption of constant values for the diffusion coefficient and the intra-extracellular volume ratio.
Journal of Biomechanics, Volume 39, Issue null, Pages S510, 2006, Authors:A. Cedraro; L. Chiari; A. Cappello.
Abstract Much is known about the sit-to-stand (STS) and its biomechanics. Currently, however, there is little opportunity for instrumented quantification of the STS as part of screening or diagnosis in clinical practice. The objectives of... more
Abstract Much is known about the sit-to-stand (STS) and its biomechanics. Currently, however, there is little opportunity for instrumented quantification of the STS as part of screening or diagnosis in clinical practice. The objectives of the present study were to describe the feasibility of using an automated approach for quantifying the STS using one sensor location and to start testing the discriminative validity of this approach by comparing older and younger adults.
A device for conditioning the balance and motor co-ordination of a user (2) comprises a system (3) for acquisition of information relative to the kinematics of at least one part (4) of the body of the user (2), a processing interface (9)... more
A device for conditioning the balance and motor co-ordination of a user (2) comprises a system (3) for acquisition of information relative to the kinematics of at least one part (4) of the body of the user (2), a processing interface (9) connected to the acquisition system (3) to encode the information in a signal, a pair of earphones (12, 13) operating between the processing interface (9) and the user (2), to feed the user the signal suitably defined by a stereophonic sound which can be transmitted in an audio channel.
Gait & Posture, Volume 30, Issue null, Pages S55-S56, October 2009, Authors:L. Palmerini; S. Mellone; L. Rocchi; F. Valzania; L. Chiari.
Gait & Posture, Volume 30, Issue null, Pages S6-S7, October 2009, Authors:F. Bagalà; VL Fuschillo; L. Chiari; A. Cappello.
The study of posture control is relevant in many areas of medical research and clinical application. Investigating balance disorders and postural reactivity to perturbations, as well as the innovative field of muscular stimulation and... more
The study of posture control is relevant in many areas of medical research and clinical application. Investigating balance disorders and postural reactivity to perturbations, as well as the innovative field of muscular stimulation and sensory augmentation/substitution involved in the design of functional prostheses or virtual reality interfaces, are typical examples of such a wide spectrum of applications.
1. Med Eng Phys. 1998 Jun;20(4):315-8. Estimation of parameters in a two-pool urea kinetic model for hemodialysis. Cappello A, Avanzolini G, Chiari L. Comment on Med Eng Phys. 1997 Jan;19(1):69-76. PMID: 9728683 [PubMed - indexed for... more
1. Med Eng Phys. 1998 Jun;20(4):315-8. Estimation of parameters in a two-pool urea kinetic model for hemodialysis. Cappello A, Avanzolini G, Chiari L. Comment on Med Eng Phys. 1997 Jan;19(1):69-76. PMID: 9728683 [PubMed - indexed for MEDLINE]. Publication Types: Comment; Letter. MeSH Terms. Biometry; Humans; Kinetics; Models, Biological; Renal Dialysis*; Urea/metabolism*. Substances. Urea.
The improvement of balance ability and consciousness is an important point for reducing falls and increasing the quality of life. Increased body awareness and position sense is necessary to compensate functional limitation in balance... more
The improvement of balance ability and consciousness is an important point for reducing falls and increasing the quality of life. Increased body awareness and position sense is necessary to compensate functional limitation in balance disorders but also to maximize sport performance. Balance improvements may be achieved by adding artificial sensory information (sensory augmentation or substitution) that enlightens the brain about actual body posture and movements.
Abstract: A nonlinear dynamic model of oxygen and carbon dioxide exchange, transport and storage in the adult human is presented, which has satisfactory performances under different physiological conditions. The model includes three... more
Abstract: A nonlinear dynamic model of oxygen and carbon dioxide exchange, transport and storage in the adult human is presented, which has satisfactory performances under different physiological conditions. The model includes three compartments related to lungs, tissues and brain, with a respiratory controller that adjusts alveolar ventilation and cardiac output in order to keep gas tensions close to their normal values.
A mathematical model of solute kinetics oriented to improve hemodialysis treatment is presented. It includes a two-compartment description of the main solutes (K+, Na+, Cl-, urea, HCO3-, H+, CO2), acid-base equilibrium through two buffer... more
A mathematical model of solute kinetics oriented to improve hemodialysis treatment is presented. It includes a two-compartment description of the main solutes (K+, Na+, Cl-, urea, HCO3-, H+, CO2), acid-base equilibrium through two buffer systems (bicarbonate and non-carbonic buffers) and a three-compartment model of body fluids (plasma, interstitial and intracellular).
Abstract The aim of this study is to develop a system for investigating human falls and mobility based on a Smartphone platform. We have designed and tested a set of software applications building on the inertial data captured from the... more
Abstract The aim of this study is to develop a system for investigating human falls and mobility based on a Smartphone platform. We have designed and tested a set of software applications building on the inertial data captured from the tri-axial accelerometer sensor embedded in the Smartphone.
Abstract A simplified model of carbon dioxide respiratory control is formulated and analysed. The model includes three compartments set of CO 2 store (lungs, extracellular and intracellular fluids), a dynamic respiratory controller and a... more
Abstract A simplified model of carbon dioxide respiratory control is formulated and analysed. The model includes three compartments set of CO 2 store (lungs, extracellular and intracellular fluids), a dynamic respiratory controller and a new realistic model of acid-base chemical regulation. The results obtained show that, in spite of its simplicity, the proposed model accurately reproduces steady state and transient physiological data measured during hypercapnic experiments.
Journal of Biomechanics, Volume 39, Issue null, Pages S113, 2006, Authors:A. Cedraro; L. Chiari; A. Cappello.
A modeling approach for on-line estimation of urea kinetics from continuous measurement of urea concentration in the effluent dialysate stream (DUN) is presented. On-line identification of urea kinetics response parameters is used to... more
A modeling approach for on-line estimation of urea kinetics from continuous measurement of urea concentration in the effluent dialysate stream (DUN) is presented. On-line identification of urea kinetics response parameters is used to predict and update dialysis adequacy during the treatment. Dialysis adequacy can be quantified in several ways, but its strict dependence on final urea concentration is a major fact.
1. Short-term autonomic response to haemodialysis-induced hypovolaemia was studied in 30 patients undergoing chronic haemodialysis by analysing power spectra of heart-period variability. Patients were classified as haemodynamically stable... more
1. Short-term autonomic response to haemodialysis-induced hypovolaemia was studied in 30 patients undergoing chronic haemodialysis by analysing power spectra of heart-period variability. Patients were classified as haemodynamically stable (15 patients) and unstable (15 patients) according to their past history of cardiovascular collapse during the treatment. Blood volume, systolic arterial pressure and heart period were measured during sessions that ended without the occurrence of collapse. 2.