Embodimetrics: A Principal Component Analysis Study of the Combined Assessment of Cardiac, Cognitive and Mobility Parameters.

There is a growing body of literature investigating the relationship between the frequency domain analysis of heart rate variability (HRV) and cognitive Stroop task performance. We proposed a combined assessment integrating trunk mobility in 72 healthy women to investigate the relationship between cognitive, cardiac, and motor variables using principal component analysis (PCA). Additionally, we assessed changes in the relationships among these variables after a two-month intervention aimed at improving the perception-action link. At baseline, PCA correctly identified three components: one related to cardiac variables, one to trunk motion, and one to Stroop task performance. After the intervention, only two components were found, with trunk symmetry and range of motion, accuracy, time to complete the Stroop task, and low-frequency heart rate variability aggregated into a single component using PCA. Artificial neural network analysis confirmed the effects of both HRV and motor behavior on cognitive Stroop task performance. This analysis suggested that this protocol was effective in investigating embodied cognition, and we defined this approach as "embodimetrics".

On the OCRA Measurement: Automatic Computation of the Dynamic Technical Action Frequency Factor.

OCRA (OCcupational Repetitive Action) is currently one of the most widespread procedures for assessing biomechanical risks related to upper limb repetitive movements. Frequency factor of the technical actions represents one of the OCRA elements. Actually, the frequency factor computation is based on workcycle video analysis, which is time-consuming and may lead to up to 30% of intra-operator variability. This paper aims at proposing an innovative procedure for the automatic counting of dynamic technical actions on the basis of inertial data. More specifically, a threshold-based algorithm was tested in four industrial case studies, involving a cohort of 20 workers. Nine combinations of the algorithm were tested by varying threshold values related to time and amplitude. The computation of frequency factor showed an average relative error lower than 5.7% in all industrial-based case studies after the appropriate selection of the time and amplitude threshold values. These findings open the possibility to use the threshold-based algorithm proposed here for the automatic computation of OCRA frequency factor, avoiding the time efforts in video analysis.

1RM prediction: a novel methodology based on the force-velocity and load-velocity relationships.

PURPOSE: This study aimed to evaluate the accuracy of a novel approach for predicting the one-repetition maximum (1RM). The prediction is based on the force-velocity and load-velocity relationships determined from measured force and velocity data collected during resistance-training exercises with incremental submaximal loads. 1RM was determined as the load corresponding to the intersection of these two curves, where the gravitational force exceeds the force that the subject can exert. METHODS: The proposed force-velocity-based method (FVM) was tested on 37 participants (23.9 ± 3.1 year; BMI 23.44 ± 2.45) with no specific resistance-training experience, and the predicted 1RM was compared to that achieved using a direct method (DM) in chest-press (CP) and leg-press (LP) exercises. RESULTS: The mean 1RM in CP was 99.5 kg (±27.0) for DM and 100.8 kg (±27.2) for FVM (SEE = 1.2 kg), whereas the mean 1RM in LP was 249.3 kg (±60.2) for DM and 251.1 kg (±60.3) for FVM (SEE = 2.1 kg). A high correlation was found between the two methods for both CP and LP exercises (0.999, p < 0.001). Good agreement between the two methods emerged from the Bland and Altman plot analysis. CONCLUSION: These findings suggest the use of the proposed methodology as a valid alternative to other indirect approaches for 1RM prediction. The mathematical construct is simply based on the definition of the 1RM, and it is fed with subject's muscle strength capacities measured during a specific exercise. Its reliability is, thus, expected to be not affected by those factors that typically jeopardize regression-based approaches.

Ambulatory assessment of shoulder abduction strength curve using a single wearable inertial sensor.

The aim of the present article was to assess the reliability of strength curves as determined from tridimensional linear accelerations and angular velocities measured by a single inertial measurement unit (IMU) fixed on the upper arm during a shoulder abduction movement performed holding a 1 kg dumbbell in the hand. Within-subject repeatability of the task was assessed on 45 subjects performing four trials consisting of one maximal shoulder abduction-adduction movement. Intraclass correlation coefficient (ICC) was computed on the average movement angular velocity (VEL) and range of movement (ROM) across the four trials. Within-subject repeatability of torque curves was assessed in terms of waveform similarities by computing the coefficient of multiple determination (CMD). Accuracy of the estimated ROM was assessed using an isokinetic dynamometer. High ICC values of ROM (0.955) and VEL (0.970) indicated a high within-subject repeatability of the task. A high waveform similarity of torque curves was also found between trials (CMD = 0.867). Accuracy with respect to isokinetic dynamometer in estimating ROM was always <1 degree (p = 0.37). This study showed the effectiveness of using a single wearable IMU for the assessment of strength curve during isoinertial movements in a way that complies with the needs of clinicians in an ambulatory setting.

Providing time-discrete gait information by wearable feedback apparatus for lower-limb amputees: usability and functional validation.

Here we describe a novel wearable feedback apparatus for lower-limb amputees. The system is based on three modules: a pressure-sensitive insole for the measurement of the plantar pressure distribution under the prosthetic foot during gait, a computing unit for data processing and gait segmentation, and a set of vibrating elements placed on the thigh skin. The feedback strategy relies on the detection of specific gait-phase transitions of the amputated leg. Vibrating elements are activated in a time-discrete manner, simultaneously with the occurrence of the detected gait-phase transitions. Usability and effectiveness of the apparatus were successfully assessed through an experimental validation involving ten healthy volunteers.

First-episode psychosis and migration in Italy (PEP-Ita migration): a study in the Italian mental health services.

BACKGROUND: It has been frequently reported a higher incidence of psychotic disorders in immigrants than in native populations. There is, however, a lack of knowledge about risk factors which may explain this phenomenon. A better understanding of the causes of psychosis among first-generation migrants is highly needed, particularly in Italy, a country with a recent massive migration. METHODS/DESIGN: The "Italian study on first-episode psychosis and migration (PEP-Ita)" is a prospective observational study over a two-year period (1 January 2012-31 December 2013) which will be carried out in 11 Italian mental health centres. All participating centres will collect data about all new cases of migrants with first-episode psychosis. The general purpose ("core") of the PEP-Ita study is to explore the socio-demographic and clinical characteristics, and the pathways to care of a population of first-episode psychosis migrants in Italy. Secondary aims of the study will be: 1) to understand risk and protective factors for the development of psychotic disorders in migrants; 2) to evaluate the correlations between psychopathology of psychotic disorders in migrants and socio-demographic characteristics, migration history, life experiences; 3) to evaluate the clinical and social outcomes of first-episode psychoses in migrants. DISCUSSION: The results of the PEP-Ita study will allow a better understanding of risk factors for psychosis in first-generation migrants in Italy. Moreover, our results will contribute to the development of prevention programmes for psychosis and to the improvement of early intervention treatments for the migrant population in Italy.

A wireless flexible sensorized insole for gait analysis.

This paper introduces the design and development of a novel pressure-sensitive foot insole for real-time monitoring of plantar pressure distribution during walking. The device consists of a flexible insole with 64 pressure-sensitive elements and an integrated electronic board for high-frequency data acquisition, pre-filtering, and wireless transmission to a remote data computing/storing unit. The pressure-sensitive technology is based on an optoelectronic technology developed at Scuola Superiore Sant'Anna. The insole is a low-cost and low-power battery-powered device. The design and development of the device is presented along with its experimental characterization and validation with healthy subjects performing a task of walking at different speeds, and benchmarked against an instrumented force platform.

Automated detection of gait initiation and termination using wearable sensors.

This paper presents algorithms for detection of gait initiation and termination using wearable inertial measurement units and pressure-sensitive insoles. Body joint angles, joint angular velocities, ground reaction force and center of plantar pressure of each foot are obtained from these sensors and input into supervised machine learning algorithms. The proposed initiation detection method recognizes two events: gait onset (an anticipatory movement preceding foot lifting) and toe-off. The termination detection algorithm segments gait into steps, measures the signals over a buffer at the beginning of each step, and determines whether this measurement belongs to the final step. The approach is validated with 10 subjects at two gait speeds, using within-subject and subject-independent cross-validation. Results show that gait initiation can be detected timely and accurately, with few errors in the case of within-subject cross-validation and overall good performance in subject-independent cross-validation. Gait termination can be predicted in over 80% of trials well before the subject comes to a complete stop. Results also show that the two sensor types are equivalent in predicting gait initiation while inertial measurement units are generally superior in predicting gait termination. Potential use of the algorithms is foreseen primarily with assistive devices such as prostheses and exoskeletons.

A flexible sensor technology for the distributed measurement of interaction pressure.

We present a sensor technology for the measure of the physical human-robot interaction pressure developed in the last years at Scuola Superiore Sant'Anna. The system is composed of flexible matrices of opto-electronic sensors covered by a soft silicone cover. This sensory system is completely modular and scalable, allowing one to cover areas of any sizes and shapes, and to measure different pressure ranges. In this work we present the main application areas for this technology. A first generation of the system was used to monitor human-robot interaction in upper- (NEUROExos; Scuola Superiore Sant'Anna) and lower-limb (LOPES; University of Twente) exoskeletons for rehabilitation. A second generation, with increased resolution and wireless connection, was used to develop a pressure-sensitive foot insole and an improved human-robot interaction measurement systems. The experimental characterization of the latter system along with its validation on three healthy subjects is presented here for the first time. A perspective on future uses and development of the technology is finally drafted.

A modular sensorized mat for monitoring infant posture.

We present a novel sensorized mat for monitoring infant's posture through the measure of pressure maps. The pressure-sensitive mat is based on an optoelectronic technology developed in the last few years at Scuola Superiore Sant'Anna: a soft silicone skin cover, which constitutes the mat, participates in the transduction principle and provides the mat with compliance. The device has a modular structure (with a minimum of one and a maximum of six sub-modules, and a total surface area of about 1 m2) that enables dimensional adaptation of the pressure-sensitive area to different specific applications. The system consists of on-board electronics for data collection, pre-elaboration, and transmission to a remote computing unit for analysis and posture classification. In this work we present a complete description of the sensing apparatus along with its experimental characterization and validation with five healthy infants.

An enhanced estimate of initial contact and final contact instants of time using lower trunk inertial sensor data.

This study introduces a new method of extracting initial and final contact gait time events from vertical acceleration, measured with one waist mounted inertial measurement unit, by means of continuous wavelet transforms. The method was validated on 18 young healthy subjects and compared to two others available in the literature. Of the three methods investigated, the new one was the most accurate at identifying the existence and timing of initial and final contacts with the ground, with an average error of 0.02±0.02 s and 0.03±0.03 s (approximately 2% and 3% of mean stride duration), respectively.

An optimized Kalman filter for the estimate of trunk orientation from inertial sensors data during treadmill walking.

The aim of this study was the fine tuning of a Kalman filter with the intent to provide optimal estimates of lower trunk orientation in the frontal and sagittal planes during treadmill walking at different speeds using measured linear acceleration and angular velocity components represented in a local system of reference. Data were simultaneously collected using both an inertial measurement unit (IMU) and a stereophotogrammetric system from three healthy subjects walking on a treadmill at natural, slow and fast speeds. These data were used to estimate the parameters of the Kalman filter that minimized the difference between the trunk orientations provided by the filter and those obtained through stereophotogrammetry. The optimized parameters were then used to process the data collected from a further 15 healthy subjects of both genders and different anthropometry performing the same walking tasks with the aim of determining the robustness of the filter set up. The filter proved to be very robust. The root mean square values of the differences between the angles estimated through the IMU and through stereophotogrammetry were lower than 1.0° and the correlation coefficients between the corresponding curves were greater than 0.91. The proposed filter design can be used to reliably estimate trunk lateral and frontal bending during walking from inertial sensor data. Further studies are needed to determine the filter parameters that are most suitable for other motor tasks.

Bio-inspired mechanical design of a tendon-driven dexterous prosthetic hand.

This paper presents the preliminary design of a new dexterous upper-limb prosthesis provided with a novel anthropomorphic hand, a compact wrist based on bevel gears and a modular forearm able to cover different levels of upper-limb amputations. The hand has 20 DoFs and 11 motors, with a dexterous three fingered subsystem composed by a fully actuated thumb, and an hybrid index and middle fingers to enable dexterous manipulation and enhance grasp performance.

Non-invasive assessment of superficial soft tissue local displacements during movement: a feasibility study.

In the movement analysts community, the assessment of the displacement of skin photogrammetric markers relative to the underlying bone (soft tissue displacement, STD) is considered to be a priority. The aim of this study is to present a non-invasive method that allows for the characterization of STD for any marker location, subject, and motor task. In particular, this method provides an estimate of the STD vector in a bone-embedded frame. The body segment under analysis is endowed with the largest possible number of skin markers located over all areas of interest. Any given STD vector is observed from all the marker cluster frames that can be built by suitably combining all the available markers. A subset of the latter frames is identified that is made of frames endowed with uncorrelated local movements. The estimate of a given STD vector is determined through the coherent average of the vectors reconstructed using the above-mentioned independent frames. This estimate is affected by a 180 degrees phase indeterminacy. The proposed method and the underlying hypotheses were validated using markers located on the thighs of two female subjects treated for a total knee replacement. The relevant STD estimates, STDm, were compared with those directly observed using photogrammetry combined with 2D fluoroscopic projections and the prosthesis CAD model (STDf). Recordings were made while the volunteers performed step up/down motor tasks. The root mean square value of STDm was found in the range 2.5-23.0 mm and was consistent with the RMS values of STDf and with other results reported in the literature and obtained in similarly unconstrained conditions. Moreover, STDm and STDf showed a pattern similarity measured by a correlation coefficient equal to 0.83 (+/-0.13) and by a normalised root mean square distance equal to 27% (+/-16%). The described estimate of the STD pattern and magnitude, even with the above-mentioned indeterminacies, constitutes valuable information when aiming at optimal marker placement and is an indispensable prerequisite for bone pose estimator design and assessment.

Hip joint centre location: an ex vivo study.

The human hip joint is normally represented as a spherical hinge and its centre of rotation is used to construct femoral anatomical axes and to calculate hip joint moments. The estimate of the hip joint centre (HJC) position using a functional approach is affected by stereophotogrammetric errors and soft tissue artefacts. The aims of this study were (1) to assess the accuracy with which the HJC position can be located using stereophotogrammetry and (2) to investigate the effects of hip motion amplitude on this accuracy. Experiments were conducted on four adult cadavers. Cortical pins, each equipped with a marker cluster, were implanted in the pelvis and femur, and eight skin markers were attached to the thigh. Recordings were made while an operator rotated the hip joint exploiting the widest possible range of motion. For HJC determination, a proximal and a distal thigh skin marker cluster and two recent analytical methods, the quartic sphere fit (QFS) method and the symmetrical centre of rotation estimation (SCoRE) method, were used. Results showed that, when only stereophotogrammetric errors were taken into account, the analytical methods performed equally well. In presence of soft tissue artefacts, HJC errors highly varied among subjects, methods, and skin marker clusters (between 1.4 and 38.5 mm). As expected, larger errors were found in the subject with larger soft tissue artefacts. The QFS method and the distal cluster performed generally better and showed a mean HJC location accuracy better than 10mm over all subjects. The analysis on the effect of hip movement amplitude revealed that a reduction of the amplitude does not improve the HJC location accuracy despite a decrease of the artefact amplitude.

Anatomical frame identification and reconstruction for repeatable lower limb joint kinematics estimates.

The quantitative description of joint mechanics during movement requires the reconstruction of the position and orientation of selected anatomical axes with respect to a laboratory reference frame. These anatomical axes are identified through an ad hoc anatomical calibration procedure and their position and orientation are reconstructed relative to bone-embedded frames normally derived from photogrammetric marker positions and used to describe movement. The repeatability of anatomical calibration, both within and between subjects, is crucial for kinematic and kinetic end results. This paper illustrates an anatomical calibration approach, which does not require anatomical landmark manual palpation, described in the literature to be prone to great indeterminacy. This approach allows for the estimate of subject-specific bone morphology and automatic anatomical frame identification. The experimental procedure consists of digitization through photogrammetry of superficial points selected over the areas of the bone covered with a thin layer of soft tissue. Information concerning the location of internal anatomical landmarks, such as a joint center obtained using a functional approach, may also be added. The data thus acquired are matched with the digital model of a deformable template bone. Consequently, the repeatability of pelvis, knee and hip joint angles is determined. Five volunteers, each of whom performed five walking trials, and six operators, with no specific knowledge of anatomy, participated in the study. Descriptive statistics analysis was performed during upright posture, showing a limited dispersion of all angles (less than 3 deg) except for hip and knee internal-external rotation (6 deg and 9 deg, respectively). During level walking, the ratio of inter-operator and inter-trial error and an absolute subject-specific repeatability were assessed. For pelvic and hip angles, and knee flexion-extension the inter-operator error was equal to the inter-trial error-the absolute error ranging from 0.1 deg to 0.9 deg. Knee internal-external rotation and ab-adduction showed, on average, inter-operator errors, which were 8% and 28% greater than the relevant inter-trial errors, respectively. The absolute error was in the range 0.9-2.9 deg.

Enhanced anatomical calibration in human movement analysis.

The representation of human movement requires knowledge of both movement and morphology of bony segments. The determination of subject-specific morphology data and their registration with movement data is accomplished through an anatomical calibration procedure (calibrated anatomical systems technique: CAST). This paper describes a novel approach to this calibration (UP-CAST) which, as compared with normally used techniques, achieves better repeatability, a shorter application time, and can be effectively performed by non-skilled examiners. Instead of the manual location of prominent bony anatomical landmarks, the description of which is affected by subjective interpretation, a large number of unlabelled points is acquired over prominent parts of the subject's bone, using a wand fitted with markers. A digital model of a template-bone is then submitted to isomorphic deformation and re-orientation to optimally match the above-mentioned points. The locations of anatomical landmarks are automatically made available. The UP-CAST was validated considering the femur as a paradigmatic case. Intra- and inter-examiner repeatability of the identification of anatomical landmarks was assessed both in vivo, using average weight subjects, and on bare bones. Accuracy of the identification was assessed using the anatomical landmark locations manually located on bare bones as reference. The repeatability of this method was markedly higher than that reported in the literature and obtained using the conventional palpation (ranges: 0.9-7.6 mm and 13.4-17.9, respectively). Accuracy resulted, on average, in a maximal error of 11 mm. Results suggest that the principal source of variability resides in the discrepancy between subject's and template bone morphology and not in the inter-examiner differences. The UP-CAST anatomical calibration could be considered a promising alternative to conventional calibration contributing to a more repeatable 3D human movement analysis.