Motion Profiles Research Articles

The Impact of Mean-State Moisture Biases on MJO Skill in the Navy ESPC

Abstract The Madden–Julian oscillation (MJO) is a key source of predictability in the subseasonal time scale (weeks to months) and influences a wide range of weather and climate phenomena. Although there have been enormous gains in simulating the MJO, many climate and forecast models still have biases in MJO behavior and structure. In this study, we examine the MJO in the Navy Earth System Prediction Capability (Navy ESPC) forecasts performed for the Subseasonal Experiment (SubX) using process-based diagnostics and a moisture budget analysis that uses wavenumber–frequency filtering to isolate the MJO. The MJO in the Navy ESPC is too strong in both boreal winter and summer. This amplitude bias is driven by biases in the vertical moisture advection in the Navy ESPC, which is too strong and deep, driven by a more bottom-heavy vertical motion profile and too steep lower-tropospheric vertical moisture gradient. Additionally, the convective moisture adjustment time scale in the Navy ESPC is faster than observed, such that for a given moisture anomaly the precipitation response is greater than observed. In the Navy ESPC, the MJO propagation shows strong agreement with observations in the Indian Ocean, followed by too rapid propagation east of the Maritime Continent in both seasons. This MJO acceleration east of the Maritime Continent is linked to an acceleration of moisture anomalies driven by biases in anomalous moisture tendency. The mechanisms that drive this bias have seasonal differences, with excess evaporation in the western Pacific dominating in boreal winter and horizontal moisture advection dominating in boreal summer.

Analysis of Gait Sub-Movements to Estimate Ataxia Severity Using Ankle Inertial Data.

Assessment of motor severity in cerebellar ataxia is critical for monitoring disease progression and evaluating the effectiveness of therapeutic interventions. Though wearable sensors have been used to monitor gait tasks in order to enable frequent assessment, existing solutions only estimate gait performance severity rather than comprehensive motor severity. In this study, we propose a new approach that analyzes sub-second movement profiles of the lower-limbs during gait to estimate overall motor severity in cerebellar ataxia. A total of 37 ataxia subjects and 12 healthy subjects performed a 5 m walk-and-turn task with two ankle-worn inertial sensors. Lower-limb movements were decomposed into one-dimensional sub-movements, namely movement elements. Supervised regression models trained on data features of movement elements estimated the Brief Ataxia Rating Scale (BARS) and its sub-scores evaluated by clinicians. The proposed models were also compared to models trained on widely-accepted spatiotemporal gait features. Estimated total BARS showed strong agreement with clinician-evaluated scores with r2 = 0.72 and a root mean square error of 2.6 BARS points. Movement element-based models significantly outperformed conventional, spatiotemporal gait feature-based models. The proposed algorithm accurately assessed overall motor severity in cerebellar ataxia using inertial data collected from bilaterally-placed ankle sensors during a simple walk-and-turn task. Our work could support fine-grained monitoring of disease progression and patients' responses to medical/clinical interventions.

Integrating Privacy into the Electric Vehicle Charging Architecture

The Electric Vehicle (EV) charging architecture consists of several actors which communicate with different protocols. A serious issue is the lack of adequate privacy-preserving measures that enables the generation of movement profiles or inferring consumer habits by all of the involved actors. In this paper, we propose an extension of a Trusted Platform Module (TPM)-based Direct Anonymous Attestation (DAA) scheme to enable privacy-preserving charging authorization and billing. Our implementation shows that our solution can be easily integrated into existing protocols of the Plug-and-Charge (PnC) EV charging architecture and introduces only minor overhead. The formal analysis using the Tamarin prover shows the security and privacy of our protocol extension.

Construction and benchmark of an autonomous tracked mobile robot system

Robots require a certain set of skills to perceive and analyse the environment and act accordingly. For tracked mobile robots getting good odometry data from sensory information is a challenging key prerequisite to perform in an unstructured dynamic environment, thus an essential issue in the tracked mobile robotics domain. In this article, we construct a ROS-based tracked mobile robot system taking the Jaguar V4 mobile robot as the base platform. On which several visual odometry solutions based on different cameras and methods (Intel RealSense T265, Zed camera, RTAB-Map RGBD) are integrated and benchmark comparison is performed. Analysis of new challenges faced by different methods while applied on a tracked vehicle as well as recommendations and conclusions are presented. Intel RealSense T265 solution proved to perform well in uncertain conditions which involves bounded vibrations and low lighting conditions with low latency, which result in good map generation. Further evaluations with a path planning algorithm and Intel RealSense T265 were conducted to test the effect of the robot’s motion profiles on odometry data accuracy.

Identification of Secondary Biomechanical Abnormalities in the Lower Limb Joints after Chronic Transtibial Amputation: A Proof-of-Concept Study Using SPM1D Analysis.

SPM is a statistical method of analysis of time-varying human movement gait signal, depending on the random field theory (RFT). MovementRx is our inhouse-developed decision-support system that depends on SPM1D Python implementation of the SPM (spm1d.org). We present the potential application of MovementRx in the prediction of increased joint forces with the possibility to predispose to osteoarthritis in a sample of post-surgical Transtibial Amputation (TTA) patients who were ambulant in the community. We captured the three-dimensional movement profile of 12 males with TTA and studied them using MovementRx, employing the SPM1D Python library to quantify the deviation(s) they have from our corresponding reference data, using “Hotelling 2” and “T test 2” statistics for the 3D movement vectors of the 3 main lower limb joints (hip, knee, and ankle) and their nine respective components (3 joints × 3 dimensions), respectively. MovementRx results visually demonstrated a clear distinction in the biomechanical recordings between TTA patients and a reference set of normal people (ABILITY data project), and variability within the TTA patients’ group enabled identification of those with an increased risk of developing osteoarthritis in the future. We conclude that MovementRx is a potential tool to detect increased specific joint forces with the ability to identify TTA survivors who may be at risk for osteoarthritis.

Speech Kinematics and Coordination Measured With an MEG-Compatible Speech Tracking System.

Articulography and functional neuroimaging are two major tools for studying the neurobiology of speech production. Until recently, however, it has generally not been possible to use both in the same experimental setup because of technical incompatibilities between the two methodologies. Here we describe results from a novel articulography system dubbed Magneto-articulography for the Assessment of Speech Kinematics (MASK), which we used to derive kinematic profiles of oro-facial movements during speech. MASK was used to characterize speech kinematics in two healthy adults, and the results were compared to measurements from a separate participant with a conventional Electromagnetic Articulography (EMA) system. Analyses targeted the gestural landmarks of reiterated utterances /ipa/, /api/ and /pataka/. The results demonstrate that MASK reliably characterizes key kinematic and movement coordination parameters of speech motor control. Since these parameters are intrinsically registered in time with concurrent magnetoencephalographic (MEG) measurements of neuromotor brain activity, this methodology paves the way for innovative cross-disciplinary studies of the neuromotor control of human speech production, speech development, and speech motor disorders.

A pilot study of a single intermittent arm cycling exercise programme on people affected by Facioscapulohumeral dystrophy (FSHD).

For patients affected by Facioscapulohumeral dystrophy (FSHD), alternate methods for increasing physical activity engagement that may benefit shoulder function and wider health are needed. Arm cycling has been proposed as a potential method for achieving this although dosage parameters and evidence is limited. The aim of this study was to conduct a pilot study evaluating the effect of a single intermittent arm cycling exercise programme on people affected by FSHD. People with confirmed genetic diagnosis of FSHD between the ages 18-60 years were recruited to attend a single session for the exercise intervention (5 exercise efforts lasting 2 minutes each with 30 seconds of rest between each effort). Prior to exercise, measures of shoulder function (Oxford shoulder score), strength and range of movement were recorded. During the exercise participants were video recorded to quantify range of movement and extract movement profile features. Participants comments were recorded and followed up four days later to check for adverse events. Fifteen participants, (6F:9M) were recruited with median (IQR) Oxford Shoulder Scores of 25 (18 to 39). All participants successfully completed the exercise intervention with only transient symptoms consistent with exercise being reported and achieving a median (IQR) rate of perceived exertion scores of 13 (12 to 13). Movement profile data was available for 12 out of 15 participants and suggests that exercise intensity did not compromise movement. An association between strength and shoulder function (R2 = 0.5147), Rate of perceived exertion (RPE) of the final effort against shoulder function and strength (R2 = 0.2344 and 0.1743 respectively) was identified. Participant comments were positive regarding the exercise intervention. Our study demonstrates that an intermittent arm cycling programme is feasible for people affected by FSHD. Further work is needed to evaluate physiological responses to exercise across variations in programme variables and equipment set up in a larger sample of people affected by FSHD.

The Validity of the 2-Point Method for Assessing the Force-Velocity Relationship of the Knee Flexors and Knee Extensors: The Relevance of Distant Force-Velocity Testing.

Over the past decade, force-velocity (F-v) profiling has emerged as a promising tool for assessing neuromuscular capacity to design individually tailored interventions in diverse populations. To date, a limited number of studies have addressed the optimization of the linear method for measuring F-v profiles of single-joint isokinetic movements. We aimed to simplify the measurement of knee extension (KE) and knee flexion (KF) isokinetic tasks by evaluating the most appropriate combination of two velocities (i.e., the 2-point method). Twenty-two healthy participants (11 males and 11 females) were included in the study. Isokinetic peak torque was measured at nine angular velocities (30-60-90-120-150-180-210-240-300°/s) and under isometric conditions (at 150° and 120° of KF for KE, and KF, respectively). Maximal theoretical force (F0), maximal theoretical velocity (v0), slope of the relationship (Sfv) and maximal theoretical power (Pmax) were derived from the linear F-v profiles of KE and KF and compared between the 9-point method and all possible combinations (36 in total) of the 2-point methods. The F-v profiles obtained from nine points were linear for KE (R2 = 0.95; 95% CI = 0.94–0.96) and KF (R2 = 0.93; 95% CI = 0.90–0.95), with F0 underestimating isometric force. Further analyses revealed great to excellent validity (range: ICCs = 0.89–0.99; CV = 2.54%–4.34%) and trivial systematic error (range: ES = −0.11–0.24) of the KE 2-point method when force from distant velocities (30°/s, 60°/s or 90°/s combined with 210°/s, 240°/s or 300°/s) was used. Similarly, great to excellent validity and trivial systematic error of the KF 2-point method for F0 and Pmax (range: ICC = 0.90–0.96; CV = 2.94%–6.38%; ES = −0.07–0.14) were observed when using the previously described combinations of velocities. These results suggest that practitioners should consider using more distant velocities when performing simplified isokinetic 2-point single-joint F-v profiling. Furthermore, the F-v profile has the potential to differentiate between the mechanical properties of knee extensors and flexors and could therefore serve as a potential descriptor of performance.

Evaluating denoising strategies in resting-state functional magnetic resonance in traumatic brain injury (EpiBioS4Rx).

Resting‐state functional MRI is increasingly used in the clinical setting and is now included in some diagnostic guidelines for severe brain injury patients. However, to ensure high‐quality data, one should mitigate fMRI‐related noise typical of this population. Therefore, we aimed to evaluate the ability of different preprocessing strategies to mitigate noise‐related signal (i.e., in‐scanner movement and physiological noise) in functional connectivity (FC) of traumatic brain injury (TBI) patients. We applied nine commonly used denoising strategies, combined into 17 pipelines, to 88 TBI patients from the Epilepsy Bioinformatics Study for Anti‐epileptogenic Therapy clinical trial. Pipelines were evaluated by three quality control (QC) metrics across three exclusion regimes based on the participant's head movement profile. While no pipeline eliminated noise effects on FC, some pipelines exhibited relatively high effectiveness depending on the exclusion regime. Once high‐motion participants were excluded, the choice of denoising pipeline becomes secondary ‐ although this strategy leads to substantial data loss. Pipelines combining spike regression with physiological regressors were the best performers, whereas pipelines that used automated data‐driven methods performed comparatively worse. In this study, we report the first large‐scale evaluation of denoising pipelines aimed at reducing noise‐related FC in a clinical population known to be highly susceptible to in‐scanner motion and significant anatomical abnormalities. If resting‐state functional magnetic resonance is to be a successful clinical technique, it is crucial that procedures mitigating the effect of noise be systematically evaluated in the most challenging populations, such as TBI datasets.

Robustness evaluation of control algorithms for a long-stroke fast tool servo

Fast tool servo (FTS) is an effective freeform surface machining technology in precision machining. The robustness of the FTS control algorithm is an important factor influencing the quality of machining. In this paper, an advanced PID control algorithm and a hybrid control algorithm are tested on a Lorentz force FTS. A mathematical simulation model is built according to the system characteristics. The model is verified by the system identification model and used for the simulation of the system's motion under disturbance. Simulation results show that the advanced PID control results in more significant differences in tracking error, amplitude error, and phase errors than the hybrid control. Four machining experiments are designed and conducted. The motion profile results from simulations and experiments show that the hybrid control (<0.5% tracking error) has better robustness than advanced PID control (>1.5% tracking error). In addition, the hybrid control exhibits rapid response speed. From the 3D profile of the machined microstructured surface, the hybrid control helps to achieve better form accuracy in the workpiece than the advanced PID control.

A Morphometric Fixed-Bearing Unicompartmental Knee Arthroplasty Can Reproduce Normal Knee Kinematics. An In Vitro Robotic Evaluation

BackgroundA new morphometric fixed-bearing unicompartmental knee arthroplasty (UKA) system has been introduced to address the anatomical patient-specific challenges. It was our hypothesis that accurate restoration of the patient-specific anatomy would restore normal knee kinematics after UKA. Therefore, we aimed in this cadaveric study to analyze the impact of a medial morphometric UKA on (1) the varus-valgus and anterior-posterior stability of the knee, (2) the knee kinematics during standardized activities of the daily living, and (3) the patellar tracking, measured using a dedicated robotic testing protocol. MethodsEight human knee specimens underwent full-leg computed tomography CT scanning and comprehensive robotic assessments of tibiofemoral and patellofemoral kinematics. Specimens were tested in the intact state and after implantation of a fixed-bearing medial UKA. Assessments included passive flexion, laxity testing and simulations of level walking, lunge, and stair descent. ResultsMedial and lateral joint laxity after UKA closely resembled intact laxity across the full arc of flexion. Anterior-posterior envelope of motion showed a close match between the intact and UKA groups. Net rollback and average laxity were both not statistically different. Simulation of activities of daily living showed a close match in the anterior-posterior motion profile between the medial condyle and lateral condyle. Patellar tilt and medial-lateral shift during knee flexion matched closely between groups. ConclusionFunctional assessment of this UKA system shows nearly identical behavior to the intact knee. Fixed-bearing UKA with morphometric, compartment-specific geometry and precise mechanical instrumentation replicates complex knee balance and kinematics.

Accuracy vs. Practicality of Inertial Measurement Unit Sensors to Evaluate Motor Competence in Children.

The TGMD (i.e., Test of Gross Motor Development) has been considered as one of the gold standards of assessment tools for analysis of motor competence in children. However, it is rarely used by teachers in schools because the time, resources, and expertise required for one teacher to assess a class of students is prohibitive in most cases. A potential solution may be to automate the testing protocol using objective measures and inertial measurement unit sensors. An accurate method using 17 sensors to capture full body motion profiles and machine learning methods to objectively assess proficiency has been developed; however, feasibility of this method was low. Subsequently, a simplified method using four sensors (i.e., attached to wrists and ankles) was found to be effective, efficient, and potentially highly feasible for use in school settings. For some skills, however, not all skill criteria could be assessed. Additionally, misclassification on occasion, marred results. In the present paper we consider a previous experiment that used wireless motion capture to assess criteria from the TGMD-3. We discuss the advantages alongside the disadvantages of testing motor competence in children using sensors and consider the question—Can a compromise be struck between accuracy and feasibility?

Damping oscillations in a wire bending process

This paper presents an approach to modify CAD/CAM generated motion profiles for wire bending machines, in order to damp wire oscillations without decreasing machine throughput. Two different methodologies are presented, both leveraging on a simple and easily identifiable model of wire oscillations, the first one based on a filtering approach, the second one on an optimisation approach. The two methodologies are both characterised by a low computational complexity, allowing them to be integrated directly in the bending machine user interface, and can rely on a standard camera to identify wire oscillation parameters. A thorough experimental validation of the approaches is also presented, showing promising results in damping oscillations with wires of different materials.

Assessing corticospinal excitability and reaching hand choice during whole body motion.

Behavioral studies have shown that humans account for inertial acceleration in their decisions of hand choice when reaching during body motion. Physiologically, it is unclear at what stage of movement preparation information about body motion is integrated with the process of hand selection. Here, we addressed this question by applying transcranial magnetic stimulation over left motor cortex (M1) of human participants who performed a preferential reach task while they were sinusoidally translated on a linear motion platform. If M1 only represents a read-out of the final hand choice, we expect the body motion not to affect the motor-evoked potential (MEP) amplitude. If body motion biases the hand selection process before target onset, we expect corticospinal excitability to be influenced by the phase of the motion, with larger MEP amplitudes for phases that show a bias to using the right hand. Behavioral results replicate our earlier findings of a sinusoidal modulation of hand choice bias with motion phase. MEP amplitudes also show a sinusoidal modulation with motion phase, suggesting that body motion influences corticospinal excitability, which may ultimately reflect changes of hand preference. The modulation being present before target onset suggests that competition between hands is represented throughout the corticospinal tract. Its phase relationship with the motion profile indicates that other processes after target onset take up time until the hand selection process has been completely resolved, and the reach is initiated.NEW & NOTEWORTHY Full body-motion biases decisions of hand choice. We examined the signatures of this bias in hand preference in corticospinal excitability before a reach target was presented. Our results show that behavior and corticospinal excitability modulate depending on the state of the body in motion. This suggests that information about body motion penetrates deeply within the motor system.

Electro‐magneto‐hydrodynamic Eyring‐Powell fluid flow through micro‐parallel plates with heat transfer and non‐Darcian effects

The Eyring‐Powell fluid flow between two micro‐parallel plates in the context of electro‐magneto‐hydrodynamic is the focus of the article. The Lorentz force, which is generated by the interactions of a vertical magnetic field and an externally imposed horizontal electrical field, is presumed to be unilateral and one‐dimensional. Using the Darcy‐Brinkman‐Forchheimer model, the medium of the micro‐parallel plates is assumed to be porous. The energy equation evaluates the effect of viscous dissipation and joule heating as well. To solve the nonlinear coupled differential equations, analytical solutions are derived using the multi‐step differential transform method. For the velocity and temperature profiles, the impact of all evolving variables is explored and illustrated in graphs and tables. It can be seen from the graphical results that the Darcy parameter, and also the magnetic field, are oppositional to both fluid motion and temperature profile. Additionally, the thermal Grashof number improves the velocity and temperature profiles of the system. On the velocity and temperature profiles, the outcomes for both fluid parameters are nearly identical.

A Differential-Flatness-Based Approach for Autonomous Helicopter Shipboard Landing

This paper presents a differential flatness-based approach to trajectory planning and tracking for helicopters and demonstrates this strategy for time-optimal autonomous helicopter shipboard landing. For planning and outer-loop tracking control, helicopter dynamics are captured by a simplified nonlinear model that is shown to be differentially flat, which enables the transformation of the original nonlinear system dynamics into an equivalent linear form with endogenous nonlinear constraints. For time-optimal trajectory planning, this equivalent model is used to construct a computationally-efficient optimization problem for free end-time end-state problems, where the decision-space is that of the trajectories of the flat outputs and their derivatives. While the attitude dynamics are stabilized by an inner loop controller, for tracking the planned trajectory a flatness-based outer loop control law is designed to stabilize the unstable zero dynamics. Further, analytical guarantees that relate inner loop tracking error to outer loop robust stability and tracking performance are derived. Simulations are performed on a high-fidelity numerical UH-60 helicopter model under ground effect and ship airwake disturbances, together with ship motion profiles collected from a naval environment to validate the proposed approach for realistic landing scenarios.

Analysis of Circular Saw Tooth Marks Profile on Material Machined Surface After Filtering with Fast Fourier Transform (FFT)

The article presents theoretical analysis of machined surface roughness after sawing on circular saw and implementation of fast Fourier transform (FFT) as a possible simple filtering method for filtering out just the saw blade and saw tooth influence on the surface roughness. Surface roughness profile is represented as a signal that can be obtained as a sum of complex periodic signals that represent theoretical profile of tooth marks and lateral movement of tooth due to saw lateral movement and signals that represent structural roughness of wood combined with machining roughness, represented as a Gaussian noise. The application of FFT based filtering on such a signal can be effectively used to extract the main frequency components due to tool influence on total surface signal and the time domain of filtered signals display can then be obtained by use of the inverse Fourier transform. In order to test the theoretical assumptions, the machining tests in sawing of solid oak wood (Quercus robur L.) and medium density fiberboard (MDF) was conducted. Machined surface roughness was measured and analyzed in accordance with theoretical assumptions. It was concluded that a combination of discrete Fourier transform of surface roughness profile and standard roughness parameters can give a more complete representation of machined surface roughness after sawing with circular saws and that filtering of surface roughness profile signal with FFT filter can be used as a simple and effective method in quantifying tool influence on machined surface roughness after sawing on circular saw in varying machining conditions and on different workpiece material.

Video-oculographic measures of eye movement control in the smooth pursuit neck torsion test can classify idiopathic neck pain patients from healthy individuals: A datamining based diagnostic accuracy study

BackgroundIdiopathic neck pain patients frequently experience oculomotor disfunctions with deficits in eye movement control between neutral and neck torsion position (SPNT test) being commonly investigated in clinical and research settings. ObjectivesThe aim of the study was to determine accuracy of SPNT test in classifying idiopathic neck pain patients. Designa datamining based diagnostic accuracy study. MethodsThe study was conducted on a referred sample of 38 chronic neck pain patients from orthopaedic outpatient clinic and 40 healthy controls. Video-oculography was used to study gain and SPNTdiff during SPNT test under three target movement velocities and amplitudes and two different angles of neck torsion. A Naïve Bayesian predictive model was used to classify neck pain patients based on gain or SPNTdiff. ResultsGain during two target movement profiles at velocities of 30°s−1 and amplitudes of 30° and 40° under 45° of neck torsion presented with highest area under the curve (0.837), specificity (92%), sensitivity (94%), highest true positive and lowest false negative predicted value. Highest area under the curve (0.760), specificity (50%), sensitivity (71%), highest true positive and lowest false negative values were observed for SPNTdiff at velocities of 30°s−1 and amplitude of 30° applying 45° of neck torsion. ConclusionSPNT test provides useful diagnostic tool for classifying neck pain patients when using single or combination of two target movement profiles. Neck torsion of 45° as opposed to 30° should be used during SPNT test when investigating patients with neck pain disorders.

Capture, analyse, visualise: An exemplar of performance analysis in practice in field hockey.

The goal of performance analysis is to capture the multitude of factors that affect sports strategy, and present them in an informative, interpretable, and accessible format. The aim of this study was to outline a performance analysis process in field hockey that captures, analyses and visualises strategy in layers of detail culminating in the creation of an RStudio Shiny application. Computerised notational analysis systems were developed to capture in-game events and ball tracking data of 74 matches from the Women’s Pro League 2019. Game styles were developed using k-means cluster analysis to reduce detailed in-game events into practical profiles to identify the attack types, game actions and tempo of a team’s strategy. Ball movement profiles were developed to identify the predictability (entropy) and direction (progression rates) of ball movements, and consequent distribution of possession in different attacking zones. The Shiny application, an interactive web-platform, links the information from simple game profiles with detailed game variables to understand each teams’ holistic game plan, how they are different, and how to exploit these differences. The process outlined can be applied to any team invasion sport to understand, develop and communicate successful strategies under different match situations.

An optimized cosine jerk motion profile with higher efficiency and flexibility

PurposeThe purpose of this paper is to propose a new acceleration/deceleration (acc/dec) algorithm for motion profiles. The motion efficiency, flexibility of the motion profiles and the residual vibration of the movement are discussed in this paper.Design/methodology/approachA dynamics model is developed to assess the residual vibration of these two kinds of motion profile. And a Simulink model is created to assess the motion efficiency and flexibility of the motion profiles with the proposed acc/dec algorithm.FindingsConsidering the flexibility of trigonometric motion profiles and the higher motion efficiency of S-curve motion profiles, the authors add the polynomial parts into the jerk profile of the cosine function acc/dec algorithm to hold the jerk when it reaches the maximum so that the motion efficiency can increase and decrease residual vibration at the same time. And the cyclical parameter k shows the decisive factor for the flexibility of trigonometric motion profiles.Originality/valueComparing with the traditional motion profiles, the proposed motion profiles have higher motion efficiency and excite less residual vibration. The acc/dec algorithm proposed in this paper is useful for the present motion control and servo system.