Video-based Motion Tracking Research Articles

Agreement in Knee Flexion and Hip Extension Range of Motion Assessment between Digital Goniometer and Video-based Motion Tracking Technology

Precise range of motion (ROM) measurements are critical for diagnosing musculoskeletal impairments, planning treatment strategies and monitoring rehabilitation progress. This study compares the reliability and accuracy of ROM measurements using the EasyAngle electronic goniometer device and the Kemtai pose estimation video-based motion tracking software. Participants performed hip extension and knee flexion movements, with measurements taken by two examiners using both tools. The results show that both EasyAngle and Kemtai provide high inter-repetition reliability for knee flexion (ICC 0.93 and. 0.91) and hip extension (ICC 0.96 and 0.93). Kemtai generally overestimated ROM compared to EasyAngle, with relative agreement ranging from poor to good (ICC = 0.71 for knee flexion, ICC = 0.66 for hip extension). Future development and research should focus on refining digital tools like Kemtai to enhance their accuracy and reliability. Given its low cost and ease of use, Kemtai could be a useful tool for clinical practice.

Self-Aligning Finger Exoskeleton for the Mobilization of the Metacarpophalangeal Joint.

In the context of hand and finger rehabilitation, kinematic compatibility is key for the acceptability and clinical exploitation of robotic devices. Different kinematic chain solutions have been proposed in the state of the art, with different trade-offs between characteristics of kinematic compatibility, adaptability to different anthropometries, and the ability to compute relevant clinical information. This study presents the design of a novel kinematic chain for the mobilization of the metacarpophalangeal (MCP) joint of the long fingers and a mathematical model for the real-time computation of the joint angle and transferred torque. The proposed mechanism can self-align with the human joint without hindering force transfer or inducing parasitic torque. The chain has been designed for integration into an exoskeletal device aimed at rehabilitating traumatic-hand patients. The exoskeleton actuation unit has a series-elastic architecture for compliant human-robot interaction and has been assembled and preliminarily tested in experiments with eight human subjects. Performance has been investigated in terms of (i) accuracy of the MCP joint angle estimation through comparison with a video-based motion tracking system, (ii) residual MCP torque when the exoskeleton is controlled to provide null output impedance and (iii) torque-tracking performance. Results showed a root-mean-square error (RMSE) below 5 degrees in the estimated MCP angle. The estimated residual MCP torque resulted below 7 mNm. Torque tracking performance shows an RMSE lower than 8 mNm in following sinusoidal reference profiles. The results encourage further investigations of the device in a clinical scenario.

Visual Perturbation Suggests Increased Effort to Maintain Balance in Early Stages of Parkinson's to be an Effect of Age Rather Than Disease.

Postural instability marks a prevalent symptom of Parkinson’s disease (PD). It often manifests in increased body sway, which is commonly assessed by tracking the Center of Pressure (CoP). Yet, in terms of postural control, the body’s Center of Mass (CoM), and not CoP is what is regulated in a gravitational field. The aim of this study was to explore the effect of early- to mid-stage PD on these measures of postural control in response to unpredictable visual perturbations. We investigated three cohorts: (i) 18 patients with early to mid-stage PD [Hoehn & Yahr stage (1–3); 1.94 ± 0.70]; (ii) a group of 15 age-matched controls (ECT); and (iii) a group of 12 young healthy adults (YCT). Participants stood on a force plate to track their CoP, while the movement of their entire body was recorded with a video-based motion tracking system to monitor their CoM. A moving room paradigm was applied through a head-mounted virtual reality headset. The stimulus consisted of a virtual tunnel that stretched in the anterior-posterior direction which either remained static or moved back and forth in an unpredictable fashion.We found differences in mean sway amplitude (MSA) and mean velocities of CoP and CoM between the groups under both conditions, with higher MSA of CoP and CoM for PD and higher mean velocities of both variables for PD and ECT when compared with YCT. Visual perturbation increased mean CoP velocity in all groups but did not have effects on mean CoM velocity or MSA. While being significantly lower for the young adults, the net effect of visual perturbation on mean CoP velocity was similar between patients with PD and age-matched controls. There was no effect of the visual perturbation on mean CoM velocity for any of the groups.Our simultaneous assessment of CoP and CoM revealed that postural control is reflected differently in CoM and CoP. As the motion of CoM remained mostly unaffected, all groups successfully counteracted the perturbation and maintained their balance. Higher CoP velocity for PD and ECT revealed increased corrective motion needed to achieve this, which however was similar in both groups. Thus, our results suggest increased effort, expressed in CoP velocity, to be an effect of age rather than disease in earlier stages of PD.

The quantification of gesture\u2013speech synchrony: A tutorial and validation of multimodal data acquisition using device-based and video-based motion tracking

There is increasing evidence that hand gestures and speech synchronize their activity on multiple dimensions and timescales. For example, gesture’s kinematic peaks (e.g., maximum speed) are coupled with prosodic markers in speech. Such coupling operates on very short timescales at the level of syllables (200 ms), and therefore requires high-resolution measurement of gesture kinematics and speech acoustics. High-resolution speech analysis is common for gesture studies, given that field’s classic ties with (psycho)linguistics. However, the field has lagged behind in the objective study of gesture kinematics (e.g., as compared to research on instrumental action). Often kinematic peaks in gesture are measured by eye, where a “moment of maximum effort” is determined by several raters. In the present article, we provide a tutorial on more efficient methods to quantify the temporal properties of gesture kinematics, in which we focus on common challenges and possible solutions that come with the complexities of studying multimodal language. We further introduce and compare, using an actual gesture dataset (392 gesture events), the performance of two video-based motion-tracking methods (deep learning vs. pixel change) against a high-performance wired motion-tracking system (Polhemus Liberty). We show that the videography methods perform well in the temporal estimation of kinematic peaks, and thus provide a cheap alternative to expensive motion-tracking systems. We hope that the present article incites gesture researchers to embark on the widespread objective study of gesture kinematics and their relation to speech.

Characterization and real-time removal of motion artifacts from EEG signals

Objective. Accurate implementation of real-time non-invasive brain-machine/computer interfaces (BMI/BCI) requires handling physiological and nonphysiological artifacts associated with the measurement modalities. For example, scalp electroencephalographic (EEG) measurements are often considered prone to excessive motion artifacts and other types of artifacts that contaminate the EEG recordings. Although the magnitude of such artifacts heavily depends on the task and the setup, complete minimization or isolation of such artifacts is generally not possible. Approach. We present an adaptive de-noising framework with robustness properties, using a Volterra based non-linear mapping to characterize and handle the motion artifact contamination in EEG measurements. We asked healthy able-bodied subjects to walk on a treadmill at gait speeds of 1-to-4 mph, while we tracked the motion of select EEG electrodes with an infrared video-based motion tracking system. We also placed inertial measurement unit (IMU) sensors on the forehead and feet of the subjects for assessing the overall head movement and segmenting the gait. Main results. We discuss in detail the characteristics of the motion artifacts and propose a real-time compatible solution to filter them. We report the effective handling of both the fundamental frequency of contamination (synchronized to the walking speed) and its harmonics. Event-related spectral perturbation (ERSP) analysis for walking shows that the gait dependency of artifact contamination is also eliminated on all target frequencies. Significance. The real-time compatibility and generalizability of our adaptive filtering framework allows for the effective use of non-invasive BMI/BCI systems and greatly expands the implementation type and application domains to other types of problems where signal denoising is desirable. Combined with our previous efforts of filtering ocular artifacts, the presented technique allows for a comprehensive adaptive filtering framework to increase the EEG signal to noise ratio (SNR). We believe the implementation will benefit all non-invasive neural measurement modalities, including studies discussing neural correlates of movement and other internal states, not necessarily of BMI focus.

Verification of a Portable Motion Tracking System for Remote Management of Physical Rehabilitation of the Knee.

Rehabilitation following knee injury or surgery is critical for recovery of function and independence. However, patient non-adherence remains a significant barrier to success. Remote rehabilitation using mobile health (mHealth) technologies have potential for improving adherence to and execution of home exercise. We developed a remote rehabilitation management system combining two wireless inertial measurement units (IMUs) with an interactive mobile application and a web-based clinician portal (interACTION). However, in order to translate interACTION into the clinical setting, it was first necessary to verify the efficacy of measuring knee motion during rehabilitation exercises for physical therapy and determine if visual feedback significantly improves the participant’s ability to perform the exercises correctly. Therefore, the aim of this study was to verify the accuracy of the IMU-based knee angle measurement system during three common physical therapy exercises, quantify the effect of visual feedback on exercise performance, and understand the qualitative experience of the user interface through survey data. A convenience sample of ten healthy control participants were recruited for an IRB-approved protocol. Using the interACTION application in a controlled laboratory environment, participants performed ten repetitions of three knee rehabilitation exercises: heel slides, short arc quadriceps contractions, and sit-to-stand. The heel slide exercise was completed without feedback from the mobile application, then all exercises were performed with visual feedback. Exercises were recorded simultaneously by the IMU motion tracking sensors and a video-based motion tracking system. Validation showed moderate to good agreement between the two systems for all exercises and accuracy was within three degrees. Based on custom usability survey results, interACTION was well received. Overall, this study demonstrated the potential of interACTION to measure range of motion during rehabilitation exercises for physical therapy and visual feedback significantly improved the participant’s ability to perform the exercises correctly.

Behavioral tracking gets real.

A deep-learning-based software package called DeepLabCut rapidly and easily enables video-based motion tracking in any animal species. Such tracking technology is bound to revolutionize movement science and behavioral tracking in the laboratory and is also poised to find many applications in the real world.

MotionComposer: un dispositivo que convierte el movimiento en música

Using video-based motion tracking technology, it is possible to make music without touching a musical instrument, but instead by gesturing in space. With a focus on therapeutic, healthcare and pedagogic contexts, the MotionComposer (MC) is one of a small but growing number of tools being developed today which let all kinds of users participate, including those with different abilities. The aim of the MotionComposer is not just to make a fun trick, but rather to delve into the deeper muscle-music relationships that lie at the heart of healthy music and dance expression. After briefly describing the device, this paper describes some of the therapeutic and pedagogical aspects of its use.

Data-Driven Approach to Synthesizing Facial Animation Using Motion Capture.

Producing cartoon animations is a laborious task, and there is a distinct lack of automatic tools to help animators, particularly with creating facial animation. The proposed method uses real-time video-based motion tracking to generate facial motion as input and then matches it to existing hand-created animation curves. The synthesized animations can then be refined and polished by an animator, saving considerable time in overall production.

モーショントラッキング機能を備えたラット二重課題実験系の構築

Dual-task paradigm is a behavioral procedure in which subjects are required to perform two independent tasks in parallel, each of which involves a distinct stimulus-response association that leads to a unique goal. Although dual tasks are widely used in human studies, they are seldom used in animals. One such rare case was a rat simultaneous temporal processing (STP) task, in which rats were asked to time two different intervals simultaneously(1). However, there are a few limitations in this paradigm, such that, for example, each of the two component tasks was not clearly associated with a unique stimulus-response association. In this report, in order to better characterize temporal dual-task performance in rats, we developed a modified version of the STP task that was comprised of two clearly-divided component tasks, and equipped our experimental system with a novel video-based motion tracking system. We show that even under this more rigidly controlled dual-task setting, rats are able to time two different intervals virtually without interference, and that our tracking system can simultaneously detect head-direction and body-location of a rat with high accuracy. These results suggest that the present experimental paradigm should be useful for investigating cognitive processes that underlie dual-task performance at both the behavioral and neuronal levels.

An Evaluation of the Feasibility, Validity, and Reliability of Laparoscopic Skills Assessment in the Operating Room

To assess the use of a synchronized video-based motion tracking device for objective, instant, and automated assessment of laparoscopic skill in the operating room. The assessment of technical skills is fundamental to recognition of proficient surgical practice. It is necessary to demonstrate the validity, reliability, and feasibility of any tool to be applied for objective measurement of performance. Nineteen subjects, divided into 13 experienced (performed >100 laparoscopic cholecystectomies) and 6 inexperienced (performed <10 LCs) surgeons completed LCs on 53 patients who all had a diagnosis of biliary colic. Each procedure was recorded with the ROVIMAS video-based motion tracking device to provide an objective measure of the surgeon's dexterity. Each video was also rated by 2 experienced observers on a previously validated operative assessment scale. There were significant differences for motion tracking parameters between the 2 groups of surgeons for the Calot triangle dissection part of procedure for time taken (P = 0.002), total path length (P = 0.026), and number of movements (P = 0.005). Both motion tracking and video-based assessment displayed intertest reliability, and there were good correlations between the 2 modes of assessment (r = 0.4 to 0.7, P < 0.01). An instant, objective, valid, and reliable mode of assessment of laparoscopic performance in the operating room has been defined. This may serve to reduce the time taken for technical skills assessment, and subsequently lead to accurate and efficient audit and credentialing of surgeons for independent practice.