Motion Measurement Method Research Articles

Assessing validity of thoracic spine rotation range of motion measurement methods: comparison of magnetic resonance imaging and clinical measurements.

[Purpose] This work was designed to establish criteria for assessing common clinical measurement methods for thoracic spinal rotation angles by comparing their results with magnetic resonance imaging measurements. [Participants and Methods] Twenty-six healthy participants underwent thoracic rotation angle assessments using an electronic goniometer in three positions: lumbar-locked, seated, and half-kneeling. We compared these results with measurements obtained by magnetic resonance imaging. [Results] A moderate but significant positive correlation was observed between the thoracic rotation angle measured by magnetic resonance imaging and the lumbar-locked rotation test. The respective 95% confidence intervals of these correlation coefficients were 0.09 and 0.72. Bland-Altman analysis revealed a fixed error in the lumbar-locked rotation test, suggesting that the test tended to overestimate thoracic rotation compared with magnetic resonance imaging, but proportional errors could not be definitively identified. [Conclusions] Thoracic spine rotation angles measured using magnetic resonance imaging aligned closely with previously reported results. Notably, although measurements obtained by the lumbar-locked rotation test correlated with magnetic resonance imaging results, they exhibited fixation errors. Functional tests (seated and half-kneeling) showed limited correlations with magnetic resonance imaging results. The influence of adjacent joints on clinical measurements should be considered.

Robot motion visual measurement based on RANSAC and weighted constraints method

Precision of the coordinate transformation model parameters is crucial for the accuracy of the vision-based robot spatial motion measurement method. In this work, an optimization algorithm integrating RANSAC and iterative weighted singular value decomposition (IR-SVD) is proposed for improving the coordinate transformation model solution precision, aiming at enhancing the spatial motion measurement accuracy of the binocular vision system. Considering noises existing in reference transformation point pairs, the RANSAC algorithm is introduced to filter the raw measurement point pairs and extract inliers, thereby eliminating potential gross errors and realizing the cluster of advantageous points. An enhanced SVD method based on iterative weighted constraints is proposed to substitute traditional SVD. After calculating the coordinate transformation model parameters, the measurement errors of inliers are solved synchronously, and the weights are reallocated in light of the measurement errors value, subsequently recalculating the coordinate transformation model parameters repeatedly until the errors converge. The validation experiments are conducted on the self-built three-degree-of-freedom rectangular coordinate robot platform. The experimental results of discrete point-to-point motion and continuous trajectory motion measurement show that the proposed method can improve the coordinate transformation model parameters solution accuracy effectively, comparing with the traditional SVD method. Comparative experiment with existing commonly used coordinate transformation methods including Quaternion and iterative closest point indicates that the proposed method exhibits the best applicability and minimal errors in robot motion visual measurement. Both accuracy of the coordinate transformation model solution and the visual system’s motion measurement are enhanced with this newly-proposed, optimized method.

Human motion analysis and measurement techniques: current application and developing trend

Human motion analysis and measurement technology have been widely used in the fields of medical treatment, sports science, and rehabilitation. In clinical practice, motion analysis has been applied in the diagnosis and individualized treatment planning of various musculoskeletal diseases, and it is also an important objective scientific method to evaluate the therapeutic effect and the effectiveness of medical equipment. This study aimed to introduce the common modern motion capture measurement technology and equipment, the clinical application and limitations of motion analysis, and the possible development trend of motion analysis measuring techniques in the future. Motion analysis and measurement systems and medical image measurement and analysis technology have made landmark improvements over the past few decades in terms of orthopaedical biomechanics. Nevertheless, limitations still exist, both subjective and objective. All these drawbacks have promoted the exploration of the integrated methods that have now been widely used in motion analysis. The results of the case study about the subject-specific finite element modeling of the foot and sports shoe complex have also shown great consistency. Nevertheless, several possible future directions for motion analysis measuring techniques still exist. In the future, the progress of motion analysis and measurement methods will simultaneously drive the progress of orthopedics, rehabilitation, precision personalized medicine, and medical engineering.

Five-degrees-of-freedom error motion measurement method of precision rotary table based on BMPES

It is essential to obtain the five-degrees-of-freedom (5-DOF) error motion of a rotary table to reconstructthe real trajectory of the rotating shaft, but there are many error coupling problems when measuring the error motion of a rotary table. In order to improve the measurement accuracy of the 5-DOF error motion of the rotary table, a method of measuring the error motions based on bidirectional multi-point error separation (BMPES) is proposed. First, by analyzing the motion characteristics of the rotary table with multiple degrees of freedom error during the rotation, a detection system with a double-layer structure probe arrangement is designed. Then, the three-point method is used in the radial direction to separate the roundness error of the measuring disk, which improves the measurement accuracy of radial error. Finally, the coupling relationship between the mixing errors collected by the axial probes is researched, and a face-four-point error separation method is proposed, which can separate the flatness error of the lower surface of the measuring disk and complete the decoupling of the tilt error and the axial runout error. Simulation results show that for the measurement of radial, tilt and axial errors, the measurement errors of the BMPES method proposed in this paper are reduced by 97.89%, 68.40% and 99.99%, respectively, compared with the five-point method, and when eccentricity errors exist, the measurement errors of the radial and tilt errors are reduced by 99.06% and 85.67%, which verifies that the method can accurately obtain the 5-DOF motion of the rotary table errors.

Research on vision-based robot planar motion measurement method

Research on vision-based robot planar motion measurement method

Robot 3D spatial motion measurement via vision-based method

Measuring the motion of a robot accurately is an important and integral part of evaluating the dynamic and static performance of the robot. The performance index of a robot, such as kinematic accuracy, bearing capacity, deformation, vibration, stability, and structural mode can all be calculated according to the motion displacement of the robot. Therefore, improving the robot motion measurement method, promoting the measurement accuracy, and enriching the measurement content have received considerable scholarly attention worldwide. In this paper, an approach based on binocular vision was proposed to measure the 3D spatial motion of a robot. In the process of reconstructing robot movement, a mathematical model that can facilitate the solving process and improve the accuracy of results was derived to build 3D coordinates information. A novel coordinate transformation method that is based on the singular value decomposition was drawn up to realize the transformation from camera coordinates to robot coordinates. Several experiments were carried out on the self-built three-degree-of-freedom rectangular coordinate robot platform. The marker was designed specially and glued to the end of robot, and a new train of thought was adopted to extract the marker’s feature point. The vision-based measurement results were compared with the actual coordinate value. Results of experiments demonstrated that the proposed method can successfully reconstruct the 3D spatial motion of a robot more exactly, which can meet the requirements of high-precision motion control, motion performance evaluation, and operation state evaluation.

Contactless multiscale measurement of cardiac motion using biomedical radar sensor.

A contactless multiscale cardiac motion measurement method is proposed using impulse radio ultra-wideband (IR-UWB) radar at a center frequency of 7.29 GHz. Electrocardiograph (ECG), heart sound, and ultrasound are traditional state-of-the-art heartbeat signal measurement methods. These methods suffer from defects in contact and the existence of a blind information segment during the cardiogram measurement. Experiments and analyses were conducted using coarse-to-fine scale. Anteroposterior and along-the-arc measurements were taken from five healthy male subjects (aged 25-43) when lying down or prone. In every measurement, 10 seconds of breath-holding data were recorded with a radar 55 cm away from the body surface, while the ECG was monitored simultaneously as a reference. Cardiac motion detection from the front was superior to that from the back in amplitude. In terms of radar detection angles, the best cardiac motion information was observed at a detection angle of 120°. Finally, in terms of cardiac motion cycles, all the ECG information, as well as short segments of cardiac motion details named blind ECGs segments, were detected. A contactless and multiscale cardiac motion detection method is proposed with no blind detection of segments during the entire cardiac cycle. This paves the way for a potentially significant method of fast and accurate cardiac disease assessment and diagnosis that exhibits promising application prospects in contactless online cardiac monitoring and in-home healthcare.

A novel relative motion measurement method based on distributed POS relative parameters matching transfer alignment

The relative motion measurement has become the key technology for high precision imaging of array Synthetic Aperture Radar (SAR), which can be obtained by distributed Position and Orientation System (POS). The traditional method based on absolute parameters matching transfer alignment can measure the relative motion, but it will be affected by the main-system motion error and reduce precision. To solve this problem, a novel relative motion measurement method based on distributed POS relative parameters matching transfer alignment is proposed. Firstly, the relative inertial navigation algorithm is used to preliminarily measure the relative motion. Then, the transfer alignment model based on relative parameters matching is established to rectify the inertial measured error and obtain the high-precision relative motion. Finally, experimental results show the proposed method is effective to isolate the main-system motion error and improve relative motion measurement accuracy compared to the traditional method.

A Novel Relative Motion Measurement Method Based on Distributed Pos Relative Parameters Matching Transfer Alignment

A Novel Relative Motion Measurement Method Based on Distributed Pos Relative Parameters Matching Transfer Alignment

Feature-extraction and motion-measurement method for noncooperative space targets

<p indent="0mm">Space targets served on the orbit have a noncooperative characteristic. Thus, it is difficult to extract their features and measure their motions. To resolve this problem, a feature-extraction and motion-measurement method for noncooperative space targets is proposed in this paper. First, threshold segmentation is performed with the images captured using the binocular camera to separate the satellite-rocket docking ring section from the surrounding background. Additionally, the Canny operator method is used to detect the edge of the satellite-rocket docking ring. Based on the analysis of the characteristic of the edge’s shape, Hough transformation is employed to extract the line feature of the cross. The contour of the satellite-rocket docking ring is fitted using the least square method. Furthermore, the parallel equivalent projection and the epipolar line alignment methods are used to match the images of the left and right cameras in the convergence binocular vision. Finally, the relative position of the satellite-rocket docking ring is obtained through a three-dimensional reconstruction of the feature points on the satellite-rocket docking ring and cross. Additionally, the dual-vector pose-determination method is employed to obtain the relative pose of the satellite-rocket docking ring. The ground simulation test shows that this algorithm can measure the relative position and pose of the satellite-rocket docking ring effectively. At a distance of <sc>1.5 m</sc> from the target, the precision of the relative position is <sc>15 mm,</sc> and that of the relative pose is 1.12°. This research can achieve an accurate measurement of the relative position and pose of the noncooperative target’s docking ring, providing the measurement basis and important support for on-orbit service missions, such as the grasping, repairing, refueling, and module replacement of noncooperative space targets; thus, it has important practical application value.

Validation of Relative Motion Measurement Method of Lateral Compression Pelvic Fractures During Examination Under Anesthesia.

To determine if the relative distance between the acetabular teardrops on unstressed and lateral compressive stress examination under anesthesia (EUA) pelvic fluoroscopic images is reproducible between independent reviewers. Retrospective database review. Level 1 trauma center. Fifty-eight patients with a lateral compression type 1 pelvic ring injury who underwent EUA. Validation of EUA objective measurements between blinded, independent reviewers using interclass and intraclass correlation coefficients. There was excellent interobserver and intraobserver reliability between all reviewers. Values for each intraclass correlation coefficients (including 95% confidence intervals) were between 0.96 (0.95-0.098) and 0.99 (0.99-0.99) for all measurements. P values were <0.0001 for all measured parameters. The relative change in distance between the acetabular tear drops during lateral compressive EUA of lateral compression type 1 pelvic injuries is reliable between independent reviewers. This allows for accurate, objective measurement of pelvic motion independent of patient size or body habitus. Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Proposal of walking motion measurement method when walking with a walker using an RGB-D camera

Proposal of walking motion measurement method when walking with a walker using an RGB-D camera

A Novel Relative Motion Measurement Method Based on Distributed Pos Relative Parameters Matching Transfer Alignment

A Novel Relative Motion Measurement Method Based on Distributed Pos Relative Parameters Matching Transfer Alignment

Using Body Sensor Network to Measure the Effect of Rehabilitation Therapy on Improvement of Lower Limb Motor Function in Children With Spastic Diplegia

Evaluation of the motor ability of children with cerebral palsy (CP) based on International Classification of Functioning, Disability and Health for Children and Youth (ICF-CY) framework is an effective way to evaluate exercise rehabilitation therapy at present. Spastic diplegia (SD) is a common symptom in children with CP, which can cause movement disorders and physical disability of lower limbs. To rehabilitate these children, it is important to assess their exercise level in different treatment stages. In this study, an effective method of motion measurement based on inertial sensor network is proposed to evaluate the children’s motor ability in the purpose of the therapy effectiveness validation for the CP children. The extended Kalman filter (EKF) is used to fuse the sensor signals to measure the motion of body segments whose accuracy is verified by the OptiTrack optical system. A novel kinetic model based on a skeletal vector is proposed to reconstruct the posture of children in sports training to evaluate the effect of exercise rehabilitation. Statistical analysis is deployed to analyze the rehabilitation of motor function corresponding to SD children. The results are encouraging; some children’s motor functions of lower limbs have been improved postrehabilitation training.

Analysis of the Position Recognition of the Bucket Tip According to the Motion Measurement Method of Excavator Boom, Stick and Bucket.

On modern construction sites, guidance and automation systems are increasingly applied to excavators. Recently, studies have been actively conducted to compare the estimation results of the bucket tip with the motion measurement method of the boom, stick, and bucket and the sensor selection. This study selected the method of measuring the cylinder length of boom, stick, and bucket, and the method of directly measuring the boom, arm, and bucket, which are commonly used in guidance and automation systems. A low-cost sensor that can be attached and detached to the excavator in modular form was selected to apply the above methods to commercial excavator. After the sensor selection, hardware and excavator simulation models for sensor measurements were constructed. Finally, the trajectory of the bucket tip was compared and analyzed through graphs and simulation results when the boom, stick, and bucket were independently rotated one by one, or together. The results gives a guideline on what kinds of sensors would be better in machine guidance or controlling an excavator according to given external environments.

어깨 동작 분석을 위한 해부학적 기준자세 기반 3차원 관절가동범위 측정 방법

최근, 스포츠 트레이닝 및 운동 재활 연구에서는 어깨 동작에 따른 3차원 관절가동범위를 분석하기 위해 모션 캡처 장치 및 의료 영상이 이용되고 있다. 그러나 이러한 방법들은 체형 및 초기 자세 불일치에 따른 3차원 관절가동범위의 측정 오차가 발생하는 문제가 있다. 본 논문에서는 기존 방법들의 문제점을 개선하기 위해 해부학적 기준자세 기반 관절가동범위 측정 방법을 제안한다. 제안된 방법은 어깨의 해부학적 특징들에 기초하여 기준 자세를 생성하고, 이러한 해부학적 기준자세를 이용하여 3차원 관절가동범위를 측정한다. 제안된 방법의 성능은 기존 방법과의 비교를 통해 검토된다.

Consistency of Outputs of the Selected Motion Acquisition Methods for Human Activity Recognition.

The aim of this paper is to choose the optimal motion sensor for the selected human activity recognition. In the described studies, different human motion measurement methods are used simultaneously such as optoelectronics, video, electromyographic, accelerometric, and pressure sensors. Several analyses of activity recognition were performed: recognition correctness for all activities together, matrices of the recognition errors of the individual activities for all volunteers for the individual sensors, and recognition correctness of all activities for each volunteer and each sensor. The experiments enabled to find a range of interchangeability and to choose the most appropriate sensor for recognition of the selected motion.

Application of IMU-based Motion Measurement Methods to Table Tennis Coaching

Application of IMU-based Motion Measurement Methods to Table Tennis Coaching

Non-cooperative maritime target position and velocity measuring method based on monocular trajectory intersection for video satellite

This paper presents a passive measuring method based on monocular trajectory intersection, aimed at realizing the position and velocity measurement of a non-cooperative maritime target for video satellite. Due to the fact that the target’s moving range is relatively small in comparison to that of the satellite during the observation time, a large measuring error results when directly using the monocular trajectory intersection method for 3D motion measurement. Therefore, the dynamic sea surface elevation model is employed to increase the maritime target movement constraints, which simplifies the 3D spatial motion of the target to 2D surface motion. By combining the surface constraint and monocular trajectory intersection method, measurement robustness for a non-cooperative maritime target can be greatly improved. Furthermore, a line-surface intersection method is proposed to obtain the initial solution for motion parameters, which increases the nonlinear optimization efficiency. Simulation experiments are conducted to analyze the effect of different error factors on position and velocity accuracy. The results indicate that the proposed method achieves high measurement accuracy and is feasible in practical applications for video satellite.

Estimating the lower leg muscle activity from distal biosignals around the ankles.

Electromyogram signals (EMG) can be used not only to measure motions, but also to control devices such as exoskeleton robots. Sensor electrodes need to be placed on each muscle based on kinematics and anatomical characteristics. Wearable EMG measurement approach is also investigated in recent years. Electrodes are fixed to the clothes. In this paper, we propose a motion measurement method based on propagation characteristics of biopotential signal. An experiment with walking and plantar flexion motion as tasks. The results showed that the signals calculated from proposed method were comparable with that of conventional method. We confirmed that there were few individual differences for calculating the signals of tibialis anterior, gastrocnemius and peroneal muscles.