3D Motion Research Articles

Quantitative comparison of 2D and 3D monitoring dimensions in fish behavior analysis.

To improve the accuracy and efficiency of fish behavior assessment, this paper focuses on quantitatively exploring the variations and relationships between different monitoring dimensions. A systematic comparison was conducted between 3D and 2D behavioral factors using an infrared tracing system, during both day and night. Significant differences in swimming distance were observed among the different monitoring methods, as determined by two-way ANOVA and Tukey's test. A correction was applied to account for the disparities observed in 2D swimming distance, ensuring accurate measurements. These findings present a cost-effective and efficient approach for obtaining precise 3D distance data. Additionally, a kinematic factor called the "number of U-turns" was proposed to provide a more intuitive characterization of directional changes in fish swimming. Significant differences were observed between 2D and 3D data, with higher percentages of false U-turn counts and missing U-turn counts compared to correct counts in the 2D view. These findings suggest that reducing the monitoring dimension may impact the accurate estimation of swimming motion, potentially resulting in inaccurate outcomes. Finally, the statistical analyses of the non-linear properties of fractal dimension revealed significant differences among the various monitoring methods. This conclusion has practical implications for biologists and physicists, enabling them to improve the accuracy of behavioral phenotyping for organisms exhibiting 3D motion.

A Motion-Based Conceptual Space Model to Support 3D Evacuation Simulation in Indoor Environments

Three-dimensional (3D) indoor models are a crucial component to simulate pedestrian evacuations realistically in indoor environments. However, existing 3D indoor models cannot fully represent realistic indoor environments to enable the simulation of 3D pedestrian motions in evacuations because spaces above/below some physical components (e.g., desks, chairs) have been largely overlooked. Thus, this paper introduces a conceptual space model to advance a space identification and classification scheme that can fully capture 3D pedestrian motions. This paper first proposes the definition and parameterisation of different 3D pedestrian motions. Then, the definition and specifications of three categories of space components are elaborated on based on the motions. Finally, a voxel-based approach is introduced to identify and classify the space components, which are demonstrated by an illustrative example. This work contributes to advancing 3D indoor modelling to enable a more realistic simulation of 3D pedestrian motions.

Numerical studies of complex fluid-solid interactions with a six degrees of freedom quaternion-based solver in the SPH framework

Six-degree-of-freedom (6-DOF) motions of structures widely exist in aeronautics and ocean engineering. It is significant to study the 6-DOF motion for simulating the trajectory and impact load of structures. This paper uses the smoothed particle hydrodynamics (SPH) method combined with some modified numerical techniques to simulate the fluid-solid interactions (FSI), then a quaternion-based method is adopted to simulate the free motion of rigid bodies, where the calculation process of 6-DOF motions based on quaternion is elaborated in detail. The accuracy of this method is verified through two benchmark tests, including water entry of a cuboid and skipping stone, which can prove the pressure calculation and motion prediction of rigid bodies are consistent with the experimental results. At last, the 6-DOF ditching process of a seaplane is simulated by the quaternion method embedded in the SPH model, and the simulation results are consistent with those simulated by the finite volume method (FVM). The above three tests demonstrate that the SPH model combined with a 6-DOF quaternion-based solver can accurately solve FSI problems from basic to complex at different scales. Besides, the SPH model shows significant advantages in capturing large-deformed free surfaces and splashing droplets compared with Eulerian-grid-based methods.

Measuring gaze angle changes to maintain fixation upon a small target during motion: 3D motion tracking versus wearable eye-tracker

Recently we demonstrated how changes in gaze angle can be determined without an eye-tracker. The approach uses 3D motion-capture, to track the viewed target in the head’s reference frame and assumes head or target movement causes a gaze-angle change. This study determined the validity of this “assumed-gaze” method. Participants read information presented on a smartphone whilst walking. Changes in gaze angles were simultaneously assessed with an eye-tracker and our assumed-gaze method. The spatial and temporal agreement of the assumed-gaze approach with the eye-tracker were ∼1 deg and ∼0.02 s, respectively, and spatial congruence indicated the direction of changes in the assumed-gaze angle were in accordance with those determined with the eye tracker for ∼81 % of the time. Findings indicate that when the head is moving and gaze is continually directed to a small target, our assumed-gaze approach can determine changes in gaze angle with comparable precision to a wearable eye-tracker.

Movement Component Analysis of Reaching Strategies in Individuals With Stroke: Preliminary Study.

Upper limb motor paresis is a major symptom of stroke, which limits activities of daily living and compromises the quality of life. Kinematic analysis offers an in-depth and objective means to evaluate poststroke upper limb paresis, with anticipation for its effective application in clinical settings. This study aims to compare the movement strategies of patients with hemiparesis due to stroke and healthy individuals in forward reach and hand-to-mouth reach, using a simple methodology designed to quantify the contribution of various movement components to the reaching action. A 3D motion analysis was conducted, using a simplified marker set (placed at the mandible, the seventh cervical vertebra, acromion, lateral epicondyle of the humerus, metacarpophalangeal [MP] joint of the index finger, and greater trochanter of the femur). For the forward reach task, we measured the distance the index finger's MP joint traveled from its starting position to the forward target location on the anterior-posterior axis. For the hand-to-mouth reach task, the shortening of the vertical distance between the index finger MP joint and the position of the chin at the start of the measurement was measured. For both measurements, the contributions of relevant upper limb and trunk movements were calculated. A total of 20 healthy individuals and 10 patients with stroke participated in this study. In the forward reach task, the contribution of shoulder or elbow flexion was significantly smaller in participants with stroke than in healthy participants (mean 52.5%, SD 24.5% vs mean 85.2%, SD 4.5%; P<.001), whereas the contribution of trunk flexion was significantly larger in stroke participants than in healthy participants (mean 34.0%, SD 28.5% vs mean 3.0%, SD 2.8%; P<.001). In the hand-to-mouth reach task, the contribution of shoulder or elbow flexion was significantly smaller in participants with stroke than in healthy participants (mean 71.8%, SD 23.7% vs mean 90.7%, SD 11.8%; P=.009), whereas shoulder girdle elevation and shoulder abduction were significantly larger in participants with stroke than in healthy participants (mean 10.5%, SD 5.7% vs mean 6.5%, SD 3.0%; P=.02 and mean 16.5%, SD 18.7% vs mean 3.0%, SD 10.4%; P=.02, respectively). Compared with healthy participants, participants with stroke achieved a significantly greater distance via trunk flexion in the forward reach task and shoulder abduction and shoulder girdle elevation in the hand-to-mouth reach task, both of these differences are regarded as compensatory movements. Understanding the characteristics of individual motor strategies, such as dependence on compensatory movements, may contribute to tailored goal setting in stroke rehabilitation.

Chemical Homogeneity of Wide Binary Systems: An Approach from Near-Infrared Spectroscopy

Wide binaries, with separations between the two stars from a few au to more than several thousand au, are valuable objects for various research topics in Galactic astronomy. As the number of newly reported wide binaries continues to increase, studying the chemical abundances of their component stars becomes more important. We conducted high-resolution near-infrared (NIR) spectroscopy for six pairs of wide binary candidates using the Immersion Grating Infrared Spectrometer at the Gemini-South telescope. One pair was excluded from the sample due to a significant difference in radial velocity between its component stars, while the remaining five pairs exhibited homogeneous properties in 3D motion and chemical composition among the pair stars. The differences in [Fe/H] ranged from 0.00 to 0.07 dex for these wide binary pairs. The abundance differences between components are comparable to the previous results from optical spectroscopy for other samples. In addition, when combining our data with literature data, it appears that the variation of abundance differences increases in wide binaries with larger separations. However, SVO 2324 and SVO 3206 showed minimal differences in most elements despite their large separation, supporting the concept of multiple formation mechanisms depending on each wide binary. This study is the first approach to the chemical properties of wide binaries based on NIR spectroscopy. Our results further highlight that NIR spectroscopy is an effective tool for stellar chemical studies based on equivalent measurements of chemical abundances from the two stars in each wide binary system.

Sex differences in pelvis, thigh, and shank coordination during walking

Differences in lower limb kinematics between males and females during functional activities may be attributed to sex differences in the incidence of patellofemoral pain, which is more common in females. To better comprehend the knee joint motion, it is necessary to understand both inter-segmental coordination patterns and angular amplitude. This exploratory study aimed to assess sex differences in pelvis–thigh and thigh–shank coordination patterns in the frontal and horizontal planes during walking. Data regarding the kinematic characteristics of the pelvis, thigh, and shank segments were collected from 26 males and 26 females performing walking at self-selected speeds using a 3D motion capture system. Furthermore, we compared the kinematics of the pelvis, thigh, and shank during walking as well as the pelvis–thigh and thigh–shank coordination patterns in the frontal and horizontal planes during the stance phase between males and females. Compared to males, females had greater thigh adduction (p < 0.001) and internal rotation (p < 0.001) throughout the stance phase; significantly greater frequency of the pelvis–thigh anti-phase pattern in the frontal plane in the early (p = 0.002) and mid-stance (p = 0.003); and significantly greater thigh–shank anti-phase pattern in the frontal plane in the early (p = 0.001) and mid-stance (p = 0.015). These results suggest the presence of sex differences in the inter-segmental coordination of the pelvis and lower limb during walking. However, as this study could not determine a causal relationship between female sex and knee joint injury, further longitudinal studies are needed to determine the effects of differences in coordination patterns on the pathophysiology of the injury and pain generation.

3D stellar motion in the axisymmetric Galactic potential and the e–z resonances

Context. The full phase-space information on the kinematics of a huge number of stars provided by Gaia Data Release 3 increases the demand for a better understanding of the 3D stellar dynamics. Aims. In this paper, we investigate the possible regimes of motion of stars in the axisymmetric approximation of the Galactic potential, applying a 3D observation-based model developed elsewhere. The model consists of three components: the axisymmetric disc, the central spheroidal bulge, and the spherical halo of dark matter. The axisymmetric disc model is divided into thin and thick stellar discs and H I and H2 gaseous disc subcomponents, by combining three Miyamoto-Nagai disc profiles of any model order (1, 2, or 3) for each disc subcomponent, to reproduce a radially exponential mass distribution. The physical and structural parameters of the Galaxy components are adjusted by observational kinematic constraints. Methods. The phase space of the two-degrees-of-freedom model was studied by means of the Poincaré and dynamical mapping, the dynamical spectrum method, and the direct numerical integrations of the Hamiltonian equations of motion. Results. For the chosen physical parameters, the nearly circular (close to the rotation curve) and low-altitude stellar behaviour is composed of two weakly coupled simple oscillations, radial and vertical motions. The amplitudes of the vertical oscillations of these orbits gradually increase with the growing Galactocentric distances, in concordance with the exponential mass decay assumed. However, for increasing planar eccentricities, e, and the altitudes over the equatorial disc, z, new regimes of stellar motion emerge as a result of the beating between the radial and vertical oscillation frequencies, which we refer to as e–z resonances. The corresponding resonant motion produces the characteristic sudden increase or decrease in the amplitude of the vertical oscillation, bifurcations in the dynamical spectra, and the chains of islands of stable motion in the phase space. Conclusions. The results obtained can be useful in understanding and interpreting the features observed in the stellar 3D distribution around the Sun.

For higher accuracy: 3D eye movement gaze depth estimation method based on Mix-TCN

Currently, the biggest obstacle in applying eye tracking technology in Virtual Reality (VR) and Augmented Reality (AR) scenes is the particular difficulty in choosing distance and object distance in 3D scenes. In previous research, geometric calculation methods using vestibular ocular reflex (VOR) and research on binocular visual angle have been studied to some extent, but unfortunately, their effects have not reached a practical level. The paper proposes a new research idea to estimate the depth of binocular gaze using a method of time series eye movement data analysis based on depth learning, and proposes a Mix-Temporal Convolutional Network (TCN) optical time series network. By combining VOR and deep learning theory, the paper has realized the current state-of-the-art technology for estimating the depth of gaze from the movement of the gaze.

3-D Integrated Sub-Domain Model for On-Load Magnetic Field and Force Analysis of 6-DOF Screw-Motion Permanent Magnet Synchronous Motor

This paper presents the 3-dimensional integrated sub-domain model (3-D ISM) for the 6-degree-of-freedom (DOF) screw-motion permanent-magnet synchronous motors (Sm-PMSMs). For the actively controlled and decoupled 6-DOF motion, the novel pattern of PM-array is introduced, consisting of the checker-board PMs to drive the 2-DOF screw motion and the additional tilting PMs for the other 4-DOF magnetic bearings. The armature of the proposed Sm-PMSM design contains both the linear coil sets and the rotational coil sets, where the D-Q current excitation scheme with the peak current modulation method is utilized to generate the 6-DOF forces and torques in a decoupled manner. The 3-D ISM presented in this paper accurately estimates the magnetic fields in the 3-D cylindrical space with an on-load condition, integrating the PM-induced fields from the magnetic scalar potential model and the current-induced fields from the hybrid vector potential model. The proposed 3-D ISM is validated by the equivalent 3-D finite element analysis (FEA) model, comparing the on-load magnetic fields, and the decoupled 6-DOF forces and torques. The fidelity of the proposed model is observed with an accuracy greater than 96%, while simultaneously improving the computational speed by two orders-of-magnitude as compared to the 3-D FEA.

Analysis of Stator-Slot and Pole-Pair Combinations in a Two-Degree-of-Freedom Split-Stator Induction Machine Based on Motion Coupling Model

2-degree-of-freedom split-stator induction machine (2DoFSSIM) exhibits high integration and material utilization for 2DoF motions, but the attractive topologies are difficult to determine due to exciting two different magnetic fields and two-directional motions. This paper investigates the helical motion coupling effect of rotary and linear motion parts, then the influence of stator-slot and pole-pair combinations on three motion characteristics is analyzed. Based on the proposed motion coupling model, the resistant torque and force production mechanism is revealed. It can be concluded that the output torque, force, and helical motion coupling effect are dominantly determined by the magnetic loading and pole-pair number of two motion parts. However, there is a tradeoff in choosing the pole-pair number to get the 2DoFSSIMs with high output performances and low helical motion coupling effect. Then, the stator-slot and pole-pair combinations selection method is proposed, and the topologies with attractive performances are chosen at different geometric diameters. Finally, the finite element analysis and experimental results are given to validate the proposed technique. <list list-type="simple" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <list-item> 2-degree-of-freedom split-stator induction machine, motion coupling model, helical motion. </list-item> </list>

Hierarchical computation of 3D motion across macaque areas MT and FST

Computing behaviorally relevant representations of three-dimensional (3D) motion from two-dimensional (2D) retinal signals is critical for survival. To ascertain where and how the primate visual system performs this computation, we recorded from the macaque middle temporal (MT) area and its downstream target, the fundus of the superior temporal sulcus (area FST). Area MT is a key site of 2D motion processing, but its role in 3D motion processing is controversial. The functions of FST remain highly underexplored. To distinguish representations of 3D motion from those of 2D retinal motion, we contrast responses to multiple motion cues during a motion discrimination task. The results reveal a hierarchical transformation whereby many FST but not MT neurons are selective for 3D motion. Modeling results further show how generalized, cue-invariant representations of 3D motion in FST may be created by selectively integrating the output of 2D motion selective MT neurons.

Contribution of finger gnosia and fine motor skills to early numerical and arithmetic abilities: New insights from 3D motion analyses.

Finger gnosia and fine motor skills (FMS) are assumed to play a key role in the development of arithmetic abilities, but their contribution to early numerical skills (i.e., enumeration skills and cardinality) has received little attention so far. The purpose of this study was to investigate the predictive value of finger gnosia and FMS to enumeration, cardinal, and arithmetical abilities and how these different dimensions contribute to arithmetic development. Overall, 3- to 5-year-old preschoolers were asked to perform tasks assessing enumeration, cardinality, and early arithmetic, as well as finger gnosia and FMS. FMS, involving either static or dynamic fine finger movement, were examined using 3D motion analyses. Using hierarchical regression, FMS were found to be the best predictor of both cardinality and early arithmetic skills, while finger gnosia did not predict the additional variance of arithmetic performance when FMS and age were considered in the regression model. Moreover, neither finger gnosia nor FMS were significant predictors of enumeration. Mediation analyses indicated that knowledge of the cardinal principle fully mediates the relationship between FMS and arithmetic skills, suggesting that FMS contribute to cardinal principle knowledge development, which would be a gateway to more complex arithmetical processing. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Markerless motion capture technology to quantify functional performance in dementias: a systematic review

AbstractBackgroundQuantifying functional performance objectively and unobtrusively could offer vital insights for clinical decision making on the level of support required by people living with dementia and other neurodegenerative conditions. Markerless motion capture (MMC) is more suitable for deployment in clinical and real‐world settings because single sensor MMC systems are less expensive and less complex compared to marker‐based systems. The aim of this study was to complete a systematic review of published literature on the use of MMC with full‐body tracking in people with dementias.MethodWe systematically searched for relevant articles using the search terms motion capture, motion analysis and movement analysis combined with dementia, mild cognitive impairment (MCI) and Parkinson’s disease (PD) which yielded a total of 1103 results. Inclusion criteria were MMC and full‐body tracking. Studies evaluating marker‐based motion capture, body‐worn sensors or Inertial Measurement Units, virtual reality, kinetics and interventions like DBS or exercises were excluded. 134 studies were included for full article screening out of which 17 eligible studies that met the selection criteria were included in the review.ResultMMC devices used in the reviewed studies included Microsoft Kinect (n = 15) and unspecified 2D motion camera (n = 2). Patient groups included in the studies were PD (n = 12), dementia (n = 4) and MCI (n = 1). Functional performance components evaluated were gait (n = 16), sit to stand (n = 2), turning (n = 1) and stepping in place (n = 1). About half the studies used advanced machine learning methods whereas the other half used descriptive statistical methods. The lack of standardisation in the measures used prevented us from comparing and synthesizing study results.ConclusionAlthough MMC has the potential to be used for quantifying functional performance in people with dementia, MCI and PD, there appears to be significant variation in the methods used in its evaluation. Although features of mobility were measured, none of the reviewed studies analysed activities of daily living tasks, a key component of functional performance. Standardising the process for extracting features and assessing accuracy would enable more effective validation of real‐world impact. Further research is required in people with neurodegenerative conditions for MMC to be routinely used in clinical and real‐world applications.

MFOGCN: multi-feature-based orthogonal graph convolutional network for 3D human motion prediction

MFOGCN: multi-feature-based orthogonal graph convolutional network for 3D human motion prediction

Modelling and analysis for the dynamic behavior of 6-DOF motion platform used for simulating aerospace mechanical environment

As high carrying capacity, high frequency response and high precision control performance are presented, the 6 degree of freedom (DOF) motion platform is chosen as the aerospace device to implement mechanical environment simulation experiment on the ground. In this paper, a dynamic model of the 6 DOF motion platform is firstly developed based on the Newton-Euler method. Then the attitude determination and the driving force are analyzed by solving the dynamic equations. Furthermore, a parametric modelling method for the 6 DOF motion platform is proposed and applied to obtain the expansion amounts and the driving forces of the 6 hydraulic rods in the motion platform by adopting the Adams software. Results show a good agreement with the computation results of the theory dynamic model, which demonstratesthe validity of the proposed modelling method for analysis of the dynamic behavior of the 6-DOF motion platform.

The relationship between low back pain, pelvic tilt, and lumbar lordosis with urinary incontinence using the DIERS formetric 4D motion imaging system.

Urinary incontinence (UI) is a common public health problem and postural changes may be crucial in women presenting with UI. This study was aimed at evaluating the relationship between low back pain (LBP), pelvic tilt (PT), and lumbar lordosis (LL) in women with and without UI using the DIERS formetric 4D motion imaging system. To date no study has to our knowledge compared postural changes and LBP in women with UI using the DIERS 4D formetric system. This was a case-control study. We included 33 women with UI and 33 without incontinence. The severity of urogenital symptoms was assessed by the IIQ-7 (Incontinence Impact Score) and UDI-6 (Urogenital Distress Inventory), and disability owing to LBP was evaluated using the Oswestry Disability Index (ODI). Posture and movement assessment, LL angle, thoracic kyphosis, and PT assessment were performed with the DIERS Formetric 4D motion imaging system. The LL angle and pelvic torsion degree were higher in the incontinence group than in the control group (53.9 ± 9.5° vs 48.18 ± 8.3°; p= 0.012, 3.9 ± 4.1 vs 2.03 ± 1.8 mm; p= 0.018 respectively). The LBP visual analog scale value was also significantly higher in the incontinence group (5.09 ± 2.3 vs 1.7 ± 1.8 respectively, p< 0.0001). The LL angle showed a positive correlation with pelvic obliquity, (r = 0.321, p< 0.01) and fleche lombaire (r = 0.472, p< 0.01) and a negative correlation with lumbar range of motion measurements. Pelvic obliquity correlated positively with pelvic torsion (r = 0.649, p< 0.01), LBP (r = 0.369, p< 0.01), and fleche lombaire (r = 0.269, p< 0.01). Women with UI were more likely to have lumbopelvic sagittal alignment changes and a higher visual analog scale for LBP. These findings show the need for assessment of lumbopelvic posture in women with UI.

Kinematic alteration in three-dimensional reaching movement in C3-4 level cervical myelopathy.

This study aimed to compare the reaching movement between two different spinal cord compression level groups in cervical myelopathy (CM) patients. Nine CM patients with maximal cord compression at the C3-4 level (C3-4 group) and 15 CM patients with maximal cord compression at the C4-7 level (C4-7 group) participated in the study. We monitored three-dimensional (3D) reaching movement using an electronic-mechanical whack-a-mole-type task pre-and post-operatively. Movement time (MT) and 3D movement distance (MD) during the task were recorded. An analysis of variance for split-plot factorial design was performed to investigate the effects of compression level or surgery on MT and MD. Moreover, we investigated the relationship between these kinematic reaching parameters and conventional clinical tests. The 3D reaching trajectories of the C3-4 group was unstable with higher variability. The C3-4 group showed longer MT (p < 0.05) and MD (p < 0.01) compared with the C4-7 group both before and after surgery. Moreover, MT was negatively correlated with the Japanese Orthopedic Association score only in the C3-4 group (r = - 0.48). We found that spinal cord compression at the C3-4 level had a negative effect on 3D reaching movement and the kinematic alteration influenced the upper extremity performance. This new knowledge may increase our understanding of kinematic alteration in patients with CM.

Knee Flexion While Walking Exceeds Knee Flexion Contracture in Children with Spastic Cerebral Palsy.

Flexed knee gait is commonly related to contractures in children with cerebral palsy (CP). Therefore, knee position while walking was compared with passive knee extension and explored with respect to functional mobility. Gait was assessed with 3D motion analysis in 30 children with bilateral spastic CP, Gross Motor Function Classification System (GMFCS) levels I-III, and in 22 typically developing (TD) children. Knee angle at initial contact (KneeAngleIC) was greater than knee flexion in stance (MinKneeFlexSt) in all groups. MinKneeFlexSt exceeded knee contractures at GMFCS levels II and III. Both KneeAngleIC and MinKneeFlexSt were greater at GMFCS II and III than at GMFCS I and the TD group. The excessive knee flexion while walking at GMFCS II and III could not be explained by knee joint contractures. Functional mobility measured with the timed-up-and-go test took longer in children at GMFCS level III compared to the other groups, assumed to be explained by the energy-requiring flexed knee gait and spatial insecurity. Discriminating between passive knee extension at the physical assessment and maximum knee extension while weight bearing may contribute to further understanding of flexed knee gait and its causes in ambulating children with spastic bilateral CP.

Validation of machine vision and action sport cameras for 3D motion analysis model reconstruction

The study investigated the feasibility of using action sport cameras for motion analysis research. Data acquired from two different marker-based motion capture systems and six different camera combinations were analyzed for motion reconstruction accuracy. Two different calibration procedures were used to determine the influence on marker position reconstruction. Static and dynamic calibration mean merit score differences between the reference and experimental camera systems were 0.4 mm and 1.3 mm, respectively. Angular displacement difference between the reference and experimental camera systems range between 0.1 and 2.0 degrees. A systematic bias (− 0.54 to 0.19 degrees) was determined between the reference and the experimental camera systems for range of motion. The mean of the multi-trial findings suggests the machine vision camera system calibrated with a dynamic procedure generated highly accurate three-dimensional reconstructed ROM data (0.5 degree) followed closely by the four action sport cameras implementing a static calibration procedure (0.5 degree). The overall findings suggest the selected machine vision and action sport camera systems produced comparable results to the reference motion analysis system. However, the combination of camera type, processing software, and calibration procedure can influence motion reconstruction accuracy.