Search Results (798)

Wearable inertial measurement units (IMUs) offer an accessible alternative to optical motion capture (MoCap) gait analysis, but their performance in Progressive Supranuclear Palsy (PSP) requires validation. We assessed the concurrent validity of IMU-derived versus MoCap-derived gait metrics and static postural sway in 30 patients with PSP using Bland–Altman analysis, Intraclass Correlation Coefficients (ICC), and Spearman rank correlations. Finally, we assessed equivalence using the Two one-sided tests (TOST) procedure. Multivariable linear regression was used to determine whether clinical severity, as measured by the PSP Rating Scale (PSPRS), independently predicted absolute IMU measurement error while controlling for patient age and gait velocity. IMUs demonstrated excellent between-system agreement for parameters such as cadence (100.76 ± 11.42 vs. 100.52 ± 11.59) and cycle time (1.21 ± 0.15 vs. 1.22 ± 0.15; ICC > 0.98), despite a systematic underestimation of gait velocity (p < 0.05). Agreement significantly diminished for micro-phases (e.g., single/double support times) and spatial asymmetry. Interestingly, the TOST procedure revealed that only sagittal and transverse trunk kinematics were equivalent between systems, with all other measures failing to find equivalency. For static sway, the IMU demonstrated strong rank-order correspondence for tracking relative postural instability (ρ = 0.82, p < 0.05). Multivariable analysis revealed that higher PSPRS scores are independently associated with greater between-system discrepancies in support phases and pelvic and trunk kinematics (p < 0.05), irrespective of reduced gait speed. These findings highlight the need to develop disease-specific algorithms, rather than relying on normative commercial models, to establish reliable digital biomarkers for monitoring progressive motor decline. Full article

This study maps the dynamic response of the IEA 15 MW reference wind turbine mounted on the UMaine VolturnUS-S semi-submersible platform across seven wave headings, spanning $\beta$ = 0–180°. A fully coupled aero–hydro–servo–elastic OpenFAST model with lumped-mass catenary mooring is simulated over three environmental groups: below-rated operation, a severe sea state at rated wind, and a parked extreme, combined with seven wave headings and supplemented by a 77-case operational envelope sweep across hub wind speeds of 4–24 m/s. Responses are analyzed through time-domain and frequency-domain statistics, drift kinematics, and exceedance curves. At operating states, the maximum side-to-side moment rises from 80.44 to 273.60 MNm between following and beam seas, while the maximum fore–aft moment reduces from 566.90 MNm to 485.23 MNm, respectively. The parked extreme LC-C maximum pitch response (2.77° at following seas, 2.59° at beam seas) is roughly half that of the severe operating LC-B (6.29° and 5.38°, respectively). This directional coupling is robust across environmental severities. In the parked group, the lateral motions (sway, roll) are amplified, as feathering reduces the rotor’s aerodynamic contribution to lateral damping. The developed wind speed misalignment response atlas condenses the aforementioned data, providing a compact basis for rapid early screening of ultra-large floating offshore wind turbines. Full article

Bilateral vertical ground reaction force (vGRF) plates are the dominant sensor for field-deployed neuromuscular monitoring in athletes, with the countermovement jump (CMJ) being the dominant test. Detecting movement onset on the vGRF trace is a single decision that propagates through impulse–momentum integration to bias jump height. Existing onset method comparisons used fewer than 100 athletes, and bilateral weight rocking, a form of pre-jump postural sway during quiet standing, has not been characterized at scale as a method-specific source of disagreement. We analyzed 32,952 NCAA Division I CMJ trials from 579 athletes across 15 teams recorded on bilateral vGRF plates. Five hypotheses were pre-specified, and a per-trial decision rule was developed under leave-one-athlete-out cross-validation. Pooled, 45.89% of trials showed false-early firing on at least one of five non-first-derivative onset methods, relative to a rate-of-change reference, at a 30 ms threshold. On the rocking-amplified subset, a bidirectional body weight band method overestimated jump height by 0.943 cm versus the reference. The decision rule reached an area under the receiver operating characteristic curve of 0.71 with near-perfect calibration. It is a per-trial screening flag, not a deterministic classifier, and deployment should anchor on balanced-accuracy or high-precision operating points, holding the onset method constant across an athlete’s monitoring timeline. Full article

In automated dry bulk terminal operations, accurate perception of the spatial pose of portal crane wire ropes is important for grab positioning and can provide geometric information for subsequent anti-sway control research. Vision-based measurements may be affected by metallic reflections, illumination variation, and dust occlusion, whereas inertial or mechanically coupled measurements may be affected by vibration and dynamic coupling. This study proposes a LiDAR-based method for wire rope point cloud segmentation and pose estimation using an improved PointNet++. Dual-LiDAR point clouds are aligned and filtered using a kinematic constraint-based Region of Interest (ROI) to reduce background redundancy. A Spatial Self-Attention (SSA) module is introduced to combine long-range semantic dependencies with local spatial weighting, improving the representation of sparse and fragmented wire rope points. The segmented wire rope points are separated by t–k-means clustering and fitted with spatial lines for pose estimation. The complete acquisition comprises 11,348 annotated frames: a 9458-frame model development dataset from 1000 complete operating cycles, and a separately retained 1890-frame independent engineering test set from 200 condition-specific operating sequences. The development dataset was divided into mutually exclusive training and validation partitions at the level of complete operating cycles, and checkpoint selection was performed only on the validation set. Three independent training runs with fixed random seeds were conducted. On the independent test set, PointNet++ achieved an F1-score of 87.5 ± 0.2% and an mIoU of 79.0 ± 0.2%, whereas the complete proposed method achieved an F1-score of 92.8 ± 0.2% and an mIoU of 86.6 ± 0.2%. These results characterize performance on independent operating sequences collected from the crane and sensor configurations represented in the dataset. The standalone segmentation stage achieved 111.9 FPS, whereas the complete processing pipeline required slightly more than 2 s per frame because of frame-by-frame KD-ICP fine registration. Full article

Dedicated platforms for floating vertical-axis wind turbines (VAWTs) require an in-depth understanding of their strongly unsteady coupled dynamics, yet the effects of platform configuration on motion stability, aerodynamic loading, and wake recovery remain insufficiently clarified. This study develops a high-fidelity aero-hydro-mooring coupled framework base on computational fluid dynamics (CFD) to compare Φ-type floating VAWTs supported by semi-submersible and spar platforms under identical wind–wave excitation. The results show that the semi-submersible configuration, owing to its larger structural scale near the free surface, experiences stronger wave interaction and more pronounced wave-frequency heave, surge, and pitch responses. The spar configuration reduces wave-frequency hydrodynamic excitation because of its deep-draft slender structure, but it is more prone to mean pitch offset and sway–roll–yaw coupling. Mooring responses are governed by mean surge drift, mean pitch inclination, and wave-frequency motions, with the semi-submersible system exhibiting stronger tension fluctuations and the spar system showing a more uneven load distribution among the mooring lines. Under the examined wind–wave condition, the spar configuration exhibits larger fluctuations in instantaneous power, thrust and single-blade torque than the semi-submersible configuration. Wake analysis indicates that the semi-submersible system maintains stronger wake coherence, while the spar system enhances vortex breakdown, turbulent mixing, and velocity-deficit recovery. These findings support platform selection, load control, and array layout optimization for floating VAWTs. Full article

Background: Quantitative assessment of dynamic balance remains challenging in clinical practice. Wearable inertial measurement unit (IMU)-based technologies offer an objective and accessible approach for monitoring postural control. This study aimed to develop and preliminarily validate a wearable IMU-based trunk sway monitoring system (SwayTracker) and investigate trunk sway characteristics in stroke patients walking with and without arm sling support. Methods: A sternum-mounted IMU system was developed to quantify dynamic trunk sway during walking. Fifteen healthy adults and fourteen stroke patients participated. The healthy participants established normative reference values, whereas the stroke patients completed walking trials with and without arm sling support. Trunk sway was quantified using anteroposterior (AP) and mediolateral (ML) deviations and a polar-coordinate-based sway model. Results: The healthy reference cohort exhibited a mean trunk sway magnitude (radius) of 8.20 ± 3.16°. The stroke patients demonstrated greater sway during unsupported (15.36 ± 5.83°) and sling-assisted walking (15.35 ± 4.59°). Although overall sway magnitude remained unchanged, the mean sway direction shifted from 69.49° to 110.20°, indicating a redistribution of trunk sway from the anterior-right toward the anterior-left quadrant. Forward sway remained the dominant AP component, whereas ML sway shifted from predominantly rightward to leftward with sling use. Conclusions: SwayTracker provides a feasible method for objective assessment of dynamic trunk sway during walking. The stroke patients exhibited increased sway magnitude and altered directional organization compared with healthy individuals. Arm sling use primarily modified ML postural compensation patterns rather than reducing overall trunk sway, highlighting the potential of wearable trunk sway monitoring for gait and balance assessment in neurological rehabilitation. Full article

This paper presents a positioning control method for underactuated unmanned surface vehicles (USVs) subject to environmental disturbances and wave-contaminated measurements. In underactuated dynamic positioning, surge motion and yaw motion can be directly regulated by the propulsion system, whereas sway motion cannot be directly controlled by an independent lateral thrust. Therefore, the lateral environmental-force component is utilized to induce the vehicle’s dynamic response to sway. To achieve this objective, a position-keeping guidance system taking into account the desired heading and the lateral positioning error is introduced in this paper. With this guidance mechanism, the lateral environmental-force component can drive the USV to reduce the cross-track error, thereby enabling underactuated positioning. A rotated coordinate system is established around the desired position, and the positioning error is decomposed into along-track and cross-track components. To improve the transient response, an error-rate feedback term is introduced into the rotated-angle update law for yaw-heading guidance design, which enhances the damping of the cross-track dynamics. Meanwhile, a wave-filtering observer is designed to make low-frequency position and velocity estimates for feedback control. Simulation results under multiple operating conditions show that the proposed observer reduces the amplitude and high-frequency variation of the control signals compared with the existing wave-filtering observer, and the proposed positioning control method achieves smaller positioning errors than the existing nonlinear positioning control (NPC). The comparative results also indicate that the proposed method is suitable for position keeping under constant or slowly varying environmental loads, moderate model uncertainty, and wave-contaminated measurements, whereas rapidly varying load directions may degrade the positioning accuracy. Full article

Background/Objectives: After menopause, hormonal, age-related, and lifestyle factors may adversely affect physical functioning and psychological well-being. This study compared immediate changes in physical function, psychological health, and health-related quality of life following a five-day Combined Marine Treatment Program (CMTP) with those observed under a usual-routine control condition. Methods: A parallel-group randomized controlled trial was conducted with 62 postmenopausal women allocated equally to the CMTP and control groups. The CMTP included coastal walking, resistance exercises, mindfulness meditation, and visits to local natural attractions. Participants in the control group continued their customary daily activities. The co-primary outcomes were the Timed Up and Go test and the Short Form-36. Secondary outcomes were grip strength, pinch strength, static balance, the 10-item Perceived Stress Scale, and the Beck Depression Inventory-II. Mixed repeated-measures analysis of variance was used to test whether temporal changes differed between groups. Trial registration was completed through the Clinical Research Information Service of the Republic of Korea (KCT0009741). Results: Changes over time differed significantly between groups for the Timed Up and Go test, grip strength, pinch strength, eyes-open sway area, eyes-closed sway area, eyes-closed sway velocity, and all self-reported outcomes. Post-intervention values differed significantly between groups for the Timed Up and Go test, pinch strength, both eyes-closed balance measures, and all self-reported outcomes. No adverse events were reported during the trial. Conclusions: Relative to the usual-routine condition, the five-day CMTP was associated with immediate changes in selected performance-based physical outcomes and broader changes across self-reported psychological and health-related quality-of-life outcomes. Brief multicomponent coastal health programs therefore warrant further study in postmenopausal women. Full article

Ultra-wideband (UWB) and inertial measurement unit (IMU) fusion is an effective scheme for train and rail-guided target localization because UWB provides absolute ranging results and the IMU provides high-rate motion prediction. In practical rail transportation systems, UWB anchors are usually deployed along the track with large longitudinal intervals and limited lateral separation to reduce installation and maintenance costs. This anchor deployment leads to a large condition number of the observation matrix, so slight ranging errors caused by non-line-of-sight (NLoS) propagation may be amplified into large localization errors. To mitigate LoS/NLoS interference, this article proposes a propagation reliability estimation method for track-constrained UWB/IMU fusion localization. First, rail transportation localization along a narrow path is formulated as a one-dimensional track-constrained problem, and each UWB ranging result is converted into a candidate longitudinal coordinate on the known track centerline. Second, the reliability of each anchor–target propagation is estimated in a sliding window by comparing the motion increments solved by UWB observations with the motion prediction by the IMU. Third, the estimated reliability is incorporated into a reliability-weighted track-domain update before a closed-loop position–velocity Kalman correction. The simulation results show that, under the mixed LoS/NLoS scenario, the proposed method achieves an NLoS-interval RMSE of 0.0090 m. Compared with Track-EKF, Track-Gauss-AUKF, Track-Adaptive KF, and Track-SW-FGO, the proposed method reduces the NLoS-interval RMSE by 92.9%, 62.1%, 92.8%, and 92.6%. A supplementary real-data stress test on the public STAR-loc dataset demonstrates an average longitudinal RMSE of 0.0555 m under a strict online calibrated-range protocol, supporting the algorithm’s practical applicability against real-world lateral sway and asynchronous sensor noise. Full article

This study examined the post-exercise window of vulnerability in static postural control after submaximal treadmill exercise in adults with sedentary behavior and evaluated sex differences in balance impairment and recovery. Thirty-four adults with sedentary behavior (17 women, 17 men) performed the Modified Bruce Protocol. Postural sway was assessed at baseline (Pre), immediately post-exercise (Post0), and at 5 (Post5) and 10 (Post10) minutes of recovery using center-of-pressure metrics (sway area, total sway distance, anterior–posterior excursion, medial–lateral excursion). Blood lactate and heart rate were recorded concurrently. Postural sway and blood lactate were analyzed with a two-way mixed ANOVA (time × sex): heart rate and RPE, with stage-wise independent-sample t-tests. Blood lactate increased markedly post-exercise and remained elevated throughout the 10 min recovery window (p < 0.001, η²_p = 0.797), with higher levels in men across all time points (main effect of sex, p = 0.006, η²_p = 0.215). Heart rate was higher in men at rest and throughout recovery (all p < 0.001; women higher only at Stage 4), returning near resting level in both sexes by Post10. All four postural sway parameters showed significant main effects of time (all p < 0.001, except total sway distance, p = 0.001) without statistically significant sex × time interactions, and all remained significantly elevated above baseline at Post10, indicating that postural recovery was incomplete within the 10 min observation window. Submaximal treadmill exercise induces acute postural control impairment in sedentary adults that persists into early recovery along specific CoP axes. Despite higher lactate in men, postural and metabolic recovery did not dissociate within the 10 min observation window, defining a post-exercise vulnerability window of at least 10 min that may warrant heightened attention to postural stability in this population. Full article

Background: Physical activity plays a vital role in caring for people with multiple sclerosis (MS). Yet, challenges like fatigue, mobility impairment, fall risk, symptom fluctuation, and poor access to rehabilitation often make sustained participation difficult. Adhering to physical activity programmes is tough. Artificial intelligence (AI) may transform wearable, smartphone, clinical, and patient-reported data into interpretable information for monitoring, prediction and individualized support. Objective: Building on the identified need for individualized support, this scoping review mapped original AI-based studies relevant to physical activity, gait, mobility, ambulation, fatigue, fall risk, and real-world functioning in people with MS. Methods: The review followed PRISMA-ScR principles. Search covered records published from 1 January 2016 to 14 May 2026 across biomedical, rehabilitation, technology-oriented, trial registry, and citation-searching sources. Eligible studies included MS or MS-specific data, an explicit AI/ML or model-derived predictive analytics component, and an activity-related clinical domain. Results: The search identified 332 records/reports. After removing 127 duplicates, 205 records were screened, 45 full texts were assessed, and 21 original AI studies met the eligibility criteria. These addressed inertial sensor deep learning, wearable gait speed estimation, postural sway fall risk prediction, connected device prediction of fatigue and health state, smartphone-based ambulation characterization, treadmill or walkway gait classification, chair stand fall status prediction, daily life gait/turning fall prediction, fear-of-falling detection, sensor-derived fatigue prediction, mobile/wearable modelling of MS, and physical activity prediction. Conclusions: AI can extract clinically relevant patterns from gait, wearable, smartphone, connected device, clinical, and patient-reported data in MS. However, evidence does not yet show that AI-supported systems improve physical activity, adherence, fatigue burden, fall risk, quality of life, or functional independence. AI is therefore promising but early, and prospective, externally validated, human-supervised, fatigue-aware, safety-sensitive studies are needed to support clinically meaningful, patient-centred MS rehabilitation and activity planning. Full article

This paper presents a constrained robust procedure for synthesizing fixed positive input shapers for a trolley–pendulum crane that accounts for motor dynamics, actuator lag, and PD trajectory tracking. Rope length L and payload mass m are treated as uncertain parameters within a prescribed operating domain, while remaining constant during each maneuver. The method searches offline for a single impulse sequence that can be used across the entire (L,m) domain without online retuning. The impulse amplitudes and delays are obtained from a linearized closed-loop electromechanical model. Mean and worst-case peak payload sway are evaluated during synthesis, while residual RMS sway, terminal-position error, peak motor current, and peak actuator voltage are imposed as feasibility constraints. The resulting shapers are tested on a dense nonlinear validation grid and compared with nominal classical shapers, frequency-robust references, and pointwise-retuned benchmarks. The synthesized four-impulse robust shaper yields the lowest worst-case peak sway among the tested fixed shapers and satisfies all imposed feasibility limits over the validation domain. A frequency-robust reference retains a lower mean peak sway, a shorter shaping horizon, and lower drive demand. The proposed shaper is better suited to applications in which limiting the maximum payload excursion is the primary design objective. Full article

Background/Objectives: Postural control in elite athletes may reflect sport- and side-related balance demands. Conventional Centre of Pressure (CoP) path length alone offers only limited information about directional and frequency-domain sway characteristics. This cross-sectional study described CoP path length, mediolateral/anteroposterior (ML/AP) directionality, and power spectral density (PSD)-derived frequency-domain descriptors in elite athletes from sports with distinct movement demands. Methods: A total of 116 asymptomatic elite athletes from volleyball, football, short track, ice hockey, and field hockey were assessed during single-leg stance. CoP path length, the ML/AP index, and PSD outcomes were analysed. PSD was calculated in LabVIEW using a fast Fourier transform (FFT) routine from the complete 60 s trial acquired at 1 kHz after removal of the DC component. Spectra were not normalised and are reported as absolute spectral-density values in mm²/Hz. PSD outcomes were summarised in low-frequency (0.02–0.6 Hz) and higher-frequency (1–5 Hz) windows, and the PSD quotient was defined as PSD 0.02–0.6 Hz/PSD 1–5 Hz. Results: Observed sport–sex groups differed in subject-averaged CoP path length (F(5,110) = 22.26, p < 0.001, eta_p² = 0.503), ML/AP index (F(5,110) = 4.07, p = 0.002, eta_p² = 0.156), PSD 0.02–0.6 Hz (F(5,110) = 38.67, p < 0.001, eta_p² = 0.637), PSD 1–5 Hz (F(5,110) = 4.83, p < 0.001, eta_p² = 0.180), and the exploratory PSD quotient (F(5,110) = 3.33, p = 0.008, eta_p² = 0.132). Paired-side comparisons showed greater right-side CoP path length, greater right-side PSD 0.02–0.6 Hz, and a higher right-side ML/AP index, whereas PSD 1–5 Hz and the PSD quotient did not differ significantly between sides. Conclusions: The combined analysis of CoP path length, ML/AP directionality, and PSD-derived descriptors characterised sport-, sex-, and side-specific postural-control profiles in this cohort. Mechanistic interpretations of segmental neuromuscular control remain tentative because the study was cross-sectional and did not include electromyography, kinematics, or prospective injury data. Full article

(1) Background: The effects of posterior parietal cortex (PPC)-targeted transcranial direct current stimulation (tDCS) on postural stability and cortical activity remain unclear. Therefore, this study aimed to investigate and compare changes in cortical activity and postural stability before and following tDCS conditions. (2) Methods: Eight right-handed adults completed a baseline assessment followed by three stimulation sessions: left-anodal/right-cathodal (L-A/R-C), left-cathodal/right-anodal (L-C/R-A), and sham on the PPC. The sessions were administered in a randomized Latin square design with a minimum 4-day washout period between each. At baseline and following each tDCS session, cortical activity was measured using functional near-infrared spectroscopy, and postural stability during a tandem stance was assessed utilizing the Balance Error Scoring System (BESS) and a force platform. (3) Results: Compared with the baseline measurements, significant deactivation in the right middle temporal gyrus (MTG) was observed following L-C/R-A stimulation. Furthermore, postural stability measures revealed significantly higher BESS error scores and greater sway length following L-C/R-A stimulation compared to both the baseline and L-A/R-C conditions. (4) Conclusions: Bilateral tDCS over the PPC differentially influences cortical activity and postural control depending on the stimulation polarity. Specifically, L-C/R-A stimulation was associated with impaired visual–vestibular integration and postural stability. These preliminary findings highlight the critical role of interhemispheric parietal balance in posture regulation and suggest that polarity-specific tDCS protocols may be important considerations for the future. Full article

With the continuous advancement of urban renewal and the renovation and utilization of existing buildings, a large number of existing reinforced concrete slender columns face challenges in capacity evaluation. Quick and accurate calculation of their stability capacity, which represents the upper limit of member capacity, holds significant importance. These columns often exhibit plastic characteristics such as concrete cracking and steel yielding. Moreover, the bracing restraint provided by adjacent columns typically falls between that of a sway frame and a non-sway frame, classifying them as elastically restrained sway frame columns. Current design codes lack appropriate effective length factor tables for such columns, while the stiffness degradation induced by material nonlinearity is difficult to quantify accurately. To address these issues, the frame column is isolated from the overall structure and modeled as a rigid compression member system with three springs. The influence of bracing stiffness on the column’s critical load is revealed, leading to a formula for the elastic critical load of elastically restrained sway frame columns. Based on tests of reinforced concrete columns under compression, the influence mechanisms of eccentricity ratio and longitudinal reinforcement ratio on flexural stiffness degradation are elucidated. The obtained elastoplastic stiffness is then integrated into the stability calculation framework for elastically restrained sway frame columns, resulting in a method for determining the elastoplastic stability capacity of reinforced concrete columns that accounts for both geometric and material nonlinearities. This method avoids solving complex transcendental equations and offers a straightforward calculation process, providing a simple and practical hand-calculation tool for evaluating the stability capacity of reinforced concrete columns in existing buildings. Full article