Kinematic Analysis Research Articles

Batoids achieve remarkable swimming efficiency through adaptive speed modulation. While previous studies have preliminarily linked pectoral fin kinematics to swimming speed in cownose rays (Rhinoptera javanica), the dynamic relationship between fin motion patterns and propulsive performance has remained unclear. By integrating kinematic analysis with hydrodynamic experiments, this study establishes a consistent framework that reveals their unique propulsion mechanism. Kinetically, we found that fin velocity exhibits a linear relationship with swimming speed via coordinated amplitude-frequency modulation. The Strouhal number (St) decreases with increasing speed, with most values falling within the optimal range of 0.2-0.4. A bio-inspired robot successfully replicated the figure-eight motion of biological pectoral fins. Hydrodynamic experiments demonstrated that the fins generate comparable instantaneous thrust during both upstroke and downstroke, with thrust in each half-stroke following a unimodal pattern-increasing to a peak before declining. A parameter equivalence law was identified: when the product of frequency and amplitude (fA) is held constant, different kinematic combinations yield consistent mean thrust, and thrust shows a significant positive correlation with fA. This confirms that the rays dynamically regulate swimming speed through fin velocity while maintaining high efficiency across conditions. These findings not only advance the understanding of cownose ray propulsion but also provide a theoretical basis for motion control in bio-inspired underwater robots.

The relevance of the work lies in the need for reliable and non-invasive tools to assess the functional state of athletes and to correct the training process. The goal is to develop a methodology for assessing the characteristics of the locomotor system in speed rock climbers during training using an experimental sample of a contact LED track (CLT). Methods and participants of the study included kinematic analysis of jumping exercises using the CLT; with speed rock climbers participating, including men (n = 9), with master of sport (6 people) and candidate master of sport (3 people). Results of the study showed correlations between the height of the seated jump (r = -0.85), counter-movement jump with arm swing (r = -0.87), index of reactive strength (r = -0.75), specific height of jump (r = -0.76), and competition time during the passage of a standard route for speed rock climbers. Conclusions. The results obtained suggest that in speed climbing, athletes with high maximum strength and the ability to achieve peak power faster than their opponents have an advantage. The speed-climbing work of athletes is characterized by a pronounced strength-speed nature. Athletes with a high strength gradient, able to significantly increase power at a fast pace and create the necessary conditions for taking off and performing effective jumps, may have an advantage in long-distance climbing. The method developed for assessing the characteristics the locomotor system characteristics using CLT is a mobile, objective, and informative method for promptly monitoring and optimizing of the speed-strength potential of athletes.

ABSTRACT Flexible pressure sensors hold transformative potential in personalized healthcare and motion‐aware electronics. However, constrained by a single conduction mechanism, current sensors still face significant challenges in simultaneously achieving high sensitivity, wide range, and robust stability. Herein, a gradient doping hierarchical microstructure flexible piezoresistive sensor with multi‐path conduction mechanisms is developed. The synergistic combination of micro‐engineered surfaces and spatially graded doping enables significant resistance variation at low pressures, yielding a high sensitivity of 101.1 kPa −1 . Multi‐path conduction mechanisms (including surface resistance, interlayer electrode resistance, interlayer contact resistance, interlayer tunneling resistance, and bulk resistance) enable tunable resistivity under high loads, extending the sensing range from 0.32 Pa to 3.6 MPa (a span of seven orders of magnitude). Moreover, the integrated full‐carbon nanotubes/polydimethylsiloxane design shows high stability, durability (over 5000 cycles), and fast response/recovery time (10/58 ms). As a proof of concept, the sensor's application for broad‐range biomechanical monitoring has been validated, spanning from subtle pulse waveform detection to high‐intensity plantar pressure monitoring. This work advances next‐generation wearables for simultaneous high‐fidelity physiological tracking and extreme‐force kinematic analysis.

A knowledge graph-based post-stroke gait assessment system: A pilot study.

Technical field-evaluation of exoskeleton-assisted overhead work among carpenters.

Abstract - This paper presents the computer-aided design (CAD) methodology and documentation strategy for a modular, hydraulically-damped transfemoral prosthetic lower limb system. Using SolidWorks, individual components—including the polycentric knee joint, hydraulic damping mechanism, protective leg case, and energy-storing foot—were modelled with detailed, dimensioned drawings to ensure manufacturability and precise assembly. The resulting CAD assembly demonstrates a fully constrained, functional model suitable for kinematic analysis and production planning. The design emphasizes modularity for adjustable height and component replacement. Key Words: Prosthetic lower limb, SolidWorks, CAD design, hydraulic.

The flat-spectrum radio quasar (FSRQ) is a bright and highly variable radio and We aim to pinpoint the location of the region within its jet in order to derive strong constraints on models for blazar jets. We use radio and data obtained with the Atacama Large Millimeter/submillimeter Array ( the Owens Valley Radio Observatory ( the Submillimeter Array ( and the Large Area Telescope on board the Fermi Gamma-ray Space Telescope to study the cross-correlation between multifrequency radio light curves. Moreover, we employ Very Long Baseline Array (ľba) observations at 43 over a period of around nine years to study the parsec-scale jet kinematics of To pinpoint the location of the region, we use a model in which outbursts shown in the radio light curves are produced when moving jet components pass through the and the radio core regions. We find two bright and compact newly ejected jet components that are likely associated with a high activity period visible in the different radio light curves. The kinematic analysis of the ľba,observations leads to a maximum apparent jet speed of β_ app =19±10 and an upper limit on the viewing angle of phiłesssim4 Furthermore, we determine the power law indices that are characterizing the jet geometry, brightness temperature distribution, and core shift to be l=0.974±0.098, s=-3.31±0.31, and k_ r =1.09±0.17, respectively, which are all in agreement with a conical jet in equipartition. A cross-correlation analysis shows that the radio light curves follow the curve. We pinpoint the location of the region with respect to the jet base to the range of $2.6 pc łeq d_ mathrmγ łeq20 pc Our observational limits places the location of in beyond the expected extent of the broad-line region (BLR) and therefore challenges blazar-emission models that rely on inverse Compton up-scattering of BLR seed photons.

ABSTRACT In tennis, athletes’ technique, influenced by biomechanical characteristics, plays a key role in success. Forehand groundstroke is the most used technique during a match. This study analysed the relationship between forehand stroke duration and shot accuracy. Sixteen skilled young tennis players (National Class: 3.11 ± 0.43) were evaluated before and after 6-week off-season training. The test involved 15 forehands with maximal acceleration from a standing position. Each stroke was video recorded for movement duration analysis, while accuracy was based on whether the ball landed in or out of the designed area. Total duration was divided into two phases: backswing to impact (initial) and impact to follow-through (final). A significant reduction in total duration suggested improved efficiency. However, no significant changes were observed in accuracy. A significant negative correlation emerged between accuracy and the duration of the final phase. This study showed that, in youth players, improved forehand accuracy is significantly associated with shorter follow-through times. Findings suggest efficiency and control of the follow-through phase play a key role in shot precision, even without explicit changes in accuracy. From a practical perspective, coaches may benefit from emphasising post-impact control and efficient deceleration, as these elements appear linked to greater accuracy in young athletes.

With the popularization of robots in various manufacturing and assembly plants, robots are gradually replacing humans in complex and dangerous work situations, playing an increasingly important role. However, in narrow working terrain, the performance of six-degree-of-freedom robots is significantly limited. This essay put forward a seven DOF robotic arm to solve this problem, which uses redundant degrees of freedom to solve the problem of limited robot use under complex working conditions and narrow terrain conditions. Then, the Denavit-Hartenberg parameter method is applied to analyze the positive kinematic model of the robotic arm by mathematical modeling, and the MATLAB software is used to verify the obtained positive kinematic model. In the end, the trajectory planning of the robotic arm is made in a straight line, and the relationship between position, velocity and acceleration with time is obtained, which proves that the structural rationality of the robotic arm is in line with expectations.

Pallidal deep brain stimulation (DBS) for dystonia can induce bradykinesia. We analyzed retrospective (n = 55) and prospective (n = 11) cohorts to identify risks and anatomical substrates for this side effect. Bradykinesia was prevalent (60–72%), with female sex, older dystonia onset, shorter disease duration, and crucially, stimulation pulse width identified as key predictive factors. Probabilistic mapping isolated a posterolateral globus pallidus internus “sour spot” for bradykinesia, which was spatially distinct from therapeutic “sweet spots” and demonstrated patient-level predictive power in cross-validation (R² = 0.16, p = 0.0013). Kinematic analysis showed reducing stimulation selectively improved movement frequency without altering amplitude. The effect appears mediated by local grey-matter modulation, not major white matter tracts. These findings suggest programming strategies using shorter pulse widths while avoiding the identified sour spot can mitigate bradykinesia without sacrificing antidystonic benefit.

Vaginal pessaries are a cost-effective, nonsurgical treatment for pelvic organ prolapse (POP), but limited understanding of pessary biomechanics and the inability of static MRI analyses to capture continuous device-tissue interactions hinder design innovation. While dynamic magnetic resonance imaging (MRI) offers insights into pelvic floor biomechanics, conventional analyses rely on static frame comparisons and cannot capture continuous device-tissue interactions. This study aimed to apply a validated, automated motion-tracking framework to dynamic MRI for frame-by-frame analysis of pessary kinematics and evaluate correlations between pessary displacement and changes in hiatus dimensions. In this prospective pilot study, six individuals with anterior vaginal wall-predominant POP successfully using a ring pessary with support underwent dynamic 3D pelvic MRI at rest and during maximal Valsalva. A previously validated optical flow-based tracking algorithm was employed to quantify frame-by-frame motion of defined mid-sagittal regions of interest (ROIs), including pessary rims, perineal body, and anorectal angle. These regions of interest were chosen for their biomechanical relevance in capturing the interaction between the pessary and the structures that define the urogenital and levator hiatus size, key determinants of pessary retention. Pearson correlation was used to evaluate the relationship between distal pessary displacement and changes in urogenital and levator hiatus dimensions. The median age was 66.5years (range 52-76) and median pessary use was 3years (range 2-4); all patients used a size 3 or 4 ring pessary and performed self-maintenance. Two of six reported occasional prolapse of the pessary, and all achieved successful retention. Resting MRI showed the pessary positioned posterior and inferior to the pubic bone with elevation of both anterior and posterior vaginal walls in all patients, as compared to resting MRI without the pessary in situ. Automated tracking was successful for all participants. Frame-by-frame analysis demonstrated strong correlations between distal pessary translation and enlargement of the urogenital hiatus (r = 0.96 [95% CI 0.94-0.97]) and levator hiatus (r = 0.86 [0.81-0.91]). Correlations were stronger than those observed using start-to-end frame comparisons. This pilot study demonstrates the feasibility of automated frame-by-frame motion to quantify pessary-pelvic floor interactions during physiologic loading. This proof-of-concept establishes a foundation for larger studies to explore patient- and device-specific determinants of pessary function and failure, with the ultimate goal of informing personalized device design and improving clinical outcomes.

Multiple sclerosis (MS) is the disabling neurological disease that currently most affects young people. Changes in gait significantly impact the functionality and independence of these individuals. This study aimed to differentiate between patients in the early stages of MS and healthy controls using machine learning in angular gait variables. This cross-sectional observational study included 38 participants, 19 with MS and 19 in the healthy control group (without neurological or orthopedic diseases). For movement analysis, a three-dimensional gait examination was conducted on patients with EDSS (Expanded Disability Status Scale) scores below 3.5 and healthy volunteers during normal gait and while performing a dual task (walking and performing a working memory task). An elastic net regression model was utilized to classify patients and healthy controls based on the kinematic variables. Our model achieved an AUC (area under the curve) of the ROC plot = 0.77 ± 0.21 using the average, an AUC of 0.94 ± 0.09 using the average and standard deviation, and AUC = 0.95 ± 0.09 when incorporating only the standard deviation of kinematic variables. The study suggests that utilizing angular gait analysis with machine learning methods is an effective approach to categorizing individuals with early-stage multiple sclerosis and healthy controls.

This work stems from the curiosity stimulated by a paper by Yttrup and Abramsson, which appeared in the journal Australian Geomechanics in 2003. Their work proposes a kinematic limit analysis method to compute the ultimate strength of steel screw piles in sand when first the bending and then the plastic collapse of the pile helix occurs. It is accompanied by insightful comments drawn from geotechnical design experience. The paper has both academic and professional impact as it is cited in scientific journals and used in engineering practice in Australia and New Zealand. However, the original paper is quite brief in its exposition. Here, Yttrup and Abramsson’s model is critically reconstructed, providing guidance that can help avoid potential pitfalls in its application. A variation of the model is proposed. Then, the calculated results are discussed and compared with experimental results, starting with those of the original paper. This work hopes to contribute to enhancing the appraisal, adoption, and utility of Yttrup and Abramsson’s model in design practice and in subsequent studies.

ObjectiveTo analyze the effects of different hard pull actions on lumbar joint movement and dynamics in weightlifting and evaluate their contribution to the risk of lumbar spine injury.MethodThe study recruited eight national second level and above weightlifters as volunteers, and conducted detailed kinematic and dynamic analysis of different hard pull actions through exercise experiments and finite element analysis (FEA).ResultThe lumbar flexion angles of traditional hard pull and hexagonal barbell hard pull were 58° and 55°, respectively, while the lumbar flexion angle of straight leg hard pull was 90°. The first peak torque of straight leg hard pull was 893 N∙m, significantly higher than the traditional hard pull of 749 N∙m and the hexagonal barbell hard pull of 640 N∙m. In terms of stress distribution, the peak stress of straight leg hard pull at the L5 vertebral body was 997 MPa, and the peak stress of L5 trabecular bone was 3.3 MPa, both higher than traditional hard pull and hexagonal barbell hard pull. The peak stress of the lumbar intervertebral disc was also highest in straight leg tension, with the peak stress of the L4–5 lumbar intervertebral disc being 45.6 MPa.ConclusionStraight leg hard pull causes greater damage to the lumbar spine due to its larger lumbar flexion angle and higher peak stress. The damage to the L5 vertebral body during weightlifting is much higher than that of other lumbar vertebrae. Therefore, it is recommended to reduce straight leg hard pull during weightlifting training and strengthen protective measures for the L5 vertebral body to reduce lumbar spine injury.

Understanding vehicle acceleration behavior during intersection departures is critical for advancing traffic safety, sustainable mobility, and intelligent transport systems. This study presents a high-resolution kinematic analysis of 714 vehicle departures from signalized intersections, encompassing straight crossings, left turns, and right turns, and involving a diverse sample of internal combustion engine (ICE), hybrid electric (HEV), and battery electric vehicles (BEV). Using synchronized Micro Electro-Mechanical Systems (MEMS) accelerometers and Real-Time Kinematic (RTK)-GPS systems, the study captures longitudinal acceleration and velocity profiles over fixed distances. Results indicate that BEVs exhibit significantly higher acceleration and final speeds than ICE and HEV vehicles, particularly during straight crossings and longer left-turn maneuvers. Several mathematical models—including polynomial, arctangent, and Akçelik functions—were calibrated to describe acceleration and velocity dynamics. Findings contribute by modeling jerk and delay propagation, supporting better calibration of AV acceleration profiles and the optimization of intersection control strategies. Moreover, the study provides validated acceleration benchmarks that enhance the accuracy of forensic engineering and road accident reconstruction, particularly in scenarios involving intersection dynamics, and demonstrates that BEVs accelerate more rapidly than ICE and HEV vehicles, especially in straight crossings, with direct implications for traffic simulation, ADAS calibration, and urban crash analysis.

In ski jumping, studying to determine a reasonable run-up posture can effectively reduce air resistance during the run-up phase, thereby increasing sliding speed. However, most current research focuses on kinematic analysis from video perspectives, with fewer studies examining dynamics. Therefore, this paper proposes a maximum speed take-off model based on particle swarm optimization and ODE solver from a dynamic perspective. First, a dynamic model is established using Newtonian mechanics principles, incorporating dynamic factors for attitude control and determining relevant initial parameters. Then, the sliding process is simulated using an ODE solver, and the optimal attitude control parameters are determined using particle swarm optimization. The final model concludes that squatting during the run-up significantly reduces resistance and increases take-off speed. By further considering aerodynamic effects and refining the model by introducing real-time dynamic data, this model can become a core tool for training in winter sports research.

ABSTRACT The Southeast Yunnan Arcuate Structural Belt, a complex tectonic region at the southeastern margin of the Tibetan Plateau, has been significantly influenced by the India – Eurasia collision. The debates regarding its Cenozoic deformation history and the intricate dynamics between crustal deformation and mantle processes remain ongoing. Employing an innovative integrative approach, this study offers a multidimensional analysis of crustal kinematics and stress fields through the integration of geological surveys, stress field inversion, and 3D numerical simulation. Our results indicate that the central and southern segments of the Red River Fault (RRF) exhibit oblique slip motion, suggesting that the region is in a transtensional stress state. The stress field inversion results reveal southeastward compression and southwestward extension. The principal stress axes and the stress shape factor R indicate that the region is characterized by a strike-slip stress regime and a relatively tensile stress state. Fault slip tendency analysis reveals high activity in specific fault types, underscoring their potential to trigger seismic events. Numerical simulations emphasized the significant role of the lithospheric mantle in surface deformation, supporting the concept of strong crust‒mantle coupling. This integrated approach provides additional insights into the tectonic dynamics and seismic hazards in the area.

Bradykinesia is the hallmark sign of parkinsonism. We recently proposed redefining bradykinesia as a complex of motor abnormalities, each reflectingseparate pathophysiological elements. To analyze the 'bradykinesia complex' in Parkinson's disease (PD) and healthy elderly individuals. We conducted a finger-tapping kinematic analysis in 350 individuals (192 PD patients OFF medication and 158 healthy controls). A subsample of 129 patients was also tested ON medication. Group comparisons were followed by unsupervised clustering. Receiver operating characteristic (ROC) analyses defined optimal kinematic cut-offs to detect individual motor abnormalities. We then quantified the prevalence and combinations of these features per subject. Using Bayes' theorem, we estimated the probability of PD based on the observed combination of bradykinesia features. Regression analyses served to identify predictors of kinematic alterations. Patients exhibited reduced velocity and amplitude as well as altered rhythm and sequence effect compared with controls (all P-values < 0.001). Cluster analysis revealed substantial group overlap. ROC analyses showed that bradykinesia (movement slowness) was the most common and accurate feature for distinguishing PD, with its diagnostic power improving when combined with other motor abnormalities (hypokinesia, dysrhythmia, sequence effect). The likelihood of correctly identifying PD increased with the number of observed abnormalities, reaching up to 95% when all features were present. Levodopa improved motor performance, but the motor abnormality patterns remained unchanged. The detailed bradykinesia features assessment was crucial for differentiating PD individuals from controls. Diagnostic accuracy requires considering multiple motor abnormalities together, irrespective of the specific combination. Advancing our understanding of the 'bradykinesia complex' has clinical and pathophysiological implications. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Most of the current soft pipeline robots are capable of crawling and climbing motions but are relatively poor at steering motions and adapting to different pipe diameters. Although peristaltic soft pipeline robots can adapt to different pipe diameters, the complexity of the structure limits the minimum working pipe diameter that can be adapted by itself. Therefore, this paper proposes a worm-like soft pipeline robot. According to the motion mechanism of the worm, the idea of modular design is applied to the axial actuator and radial actuator to complete the overall structural design of the pipeline robot. The kinematic analysis of these two actuators is accomplished using the segmented constant curvature model with the D-H method. The optimization of the structural parameters through simulation resulted in better kinematic performance of the two actuators. In the experiments, the robot crawled at a speed of 4.96 mm/s in the small pipe diameter motion mode and 3.52 mm/s in the large pipe diameter motion mode. In addition, the pipe robot can accomplish 90° steering movement. The soft worm-like pipeline robot demonstrates adaptability to various pipe diameters and exhibits excellent movement performance.

In the context of collisional orogenic belts, the importance of lateral extrusion lies in the dissipation of energy accumulated by tectonically driven crustal thickening. The present study characterizes lateral extrusion across a newly reported (in this study) pre-detachment shear zone (PDSZ) in the Garhwal Tethyan Himalayan Sequence (THS), India, and highlights its significance in the Middle–Late Oligocene tectonothermal evolution of the Himalaya–Tibetan orogen. Integrated structural, microstructural and kinematic vorticity analyses suggest crustal overthickening in the THS, due to thrusting in the ductile regime. Increased overburden ( c . 24 km) on the lower THS (deformed and metamorphosed at c . 500–620°C) facilitated extrusion. However, the greater uplift rate of the Greater Himalayan Sequence (GHS, south of the THS), compared to that of the THS, obstructed frontal extrusion and triggered orogen-parallel lateral tectonic escape of the THS. Lateral tectonic escape was dominated by dextral shearing in a general shear regime. Thrusting-dominated deformation in a general shear regime characterizes the southern boundary of the PDSZ. The study suggests that in the Garhwal Himalaya, the southern boundary of the PDSZ represents the tectonic front separating the domain of lateral extrusion (northwards into the Tibetan crust) from the domain of frontal extrusion and thrusting prevalent in the GHS during the Oligocene–Miocene.