Motion Measurement System Research Articles

Accuracy improvement in motion‐measurement using frequency‐weighted Kalman filter

Accurate antenna motion-measurement is an essential pre-condition for synthetic aperture radar (SAR) to produce well-focused images. The measurement accuracy at high and low frequencies affects the quality of images and the geolocation error. Hence, motion compensation and focusing techniques require a minimum degree of accuracy in the radar motion measurements. The Inertial Measurement Unit (IMU) sensor selection process is done based on the SAR parametric requirements. The IMU instruments have inherent limited precision and accuracy, which are significantly related to the technology and the cost. The navigation algorithm may improve the precision and accuracy to overcome the limitations of the IMU sensor. This study intends to improve motion measurement accuracy using frequency-weighted state estimation. The proposed algorithm shows an error reduction in state estimation and an improvement in some parameter indices which are in relation to SAR image quality and geolocation. Two innovative algorithms are proposed in this study. The first one is the frequency-weighted Kalman filter which is an improved form of the Kalman filter. Another one is multi-resolution decomposition which is an approach to evaluate the SAR motion measurement system.

Reliability and validity analyzes of Kinect V2 based measurement system for shoulder motions

Telerehabilitation systems provide some advantages against the classic rehabilitation methods. The ability of the shoulders depends on active motion range of them to do activities in daily life and to do sports. To evaluate the shoulder motions, range of motion (ROM) measurement is a basic method. Clinical goniometer and digital goniometer are the most commonly used measurement tools. However, these measurement tools have some deficiencies and difficulties. In this paper, we consider a Kinect One Sensor (Kinect V2) based measurement system for shoulder motions as an alternative method. The aim of this study is to examine the reliability and validity analyzes of the proposed shoulder measurement system. Three systems were used to evaluate validity of the Kinect V2 to measure shoulder motions: Kinect V2 based system, clinical goniometer and digital goniometer. One expert physical therapist measured shoulder abduction, flexion, external rotation, internal rotation and extension ROM values using a clinical goniometer and a digital goniometer in 40 healthy volunteers (22 males, 18 females, and 19–33 years old). All poses for each shoulder motion were captured with the Kinect V2 based system again and the ROM values were calculated. These procedures were carried out with all of the volunteer participants in three repetitions. In reliability for Kinect V2 based shoulder motion measurement system, we used the intraclass correlation coefficients (ICC), standard error of the measure (SEM), minimal detectable change (MDC). The validity test includes the 95% limits of agreement (LOA) and mean difference between the Kinect V2 based system and the both of the goniometer systems for measuring shoulder motions. The high ICC values show that the Kinect V2 based shoulder motion measurement system has very good intra-rater reliability for abduction, flexion, external rotation, internal rotation shoulder poses. For extension pose, it has good reliability result according to the ICC value. The validity analysis gives good results for all shoulder poses except internal rotation between Kinect V2 and clinical/digital goniometer. As a result, Kinect V2 based measurement system is a reliable and valid alternative telerehabilitation tool for shoulder motions.

Corrections to “High-Accuracy Calibration of a Visual Motion Measurement System for Planar 3-DOF Robots Using Gaussian Process”

In the above paper, in the first paragraph of the last section VI. Conclusion, the citation [?] should show as [3].

Design of Calibration System for Motion Attitude Measurement of Large-caliber Projectile

To meet the large-caliber projectile motion measurement system calibration requirement, developed a large-caliber projectile motion measurement system calibration system, gives the calibration principle and working process, design a visibility good green light source as the collimating light source, the design targets based on the filtering and PSD field grid position detection module; Aiming at the calibration requirement that the six faces of cavity cross grids frame cannot be shielded, the cavity cross grids adjustment module is designed. Error analysis shows that the calibration error of the system is 0.062mm.

High-Accuracy Calibration of a Visual Motion Measurement System for Planar 3-DOF Robots Using Gaussian Process

Visual motion measurement systems (VMMSs) are widely used in robotics for pose estimation. A common characteristic of VMMSs is that the measurement repeatability is high, but the absolute measurement accuracy is relatively low, once a commercial lens with a large field of view is used. To improve the measurement accuracy of the VMMS for pose tracking of planar 3-degree-of-freedom (3-DOF) robots, a coarse-to-fine calibration method is presented in this paper. In this paper, after the VMMS is constructed, a degenerated perspective-n-point (DPnP) algorithm for pose estimation of 3-DOF robots is introduced. Then, an analytical calibration technique is implemented to obtain the camera intrinsic parameters required by the DPnP algorithm. Subsequently, a fine calibration step based on Gaussian process is developed to compensate the estimated pose of the DPnP algorithm. To investigate the effectiveness and performance of the proposed method, a series of the simulations and experiments are carried out on a planar 3-DOF robot. The results demonstrate that the proposed calibration method is quite robust and can improve the measurement accuracy up to 90.47%. Specifically, in a measurement field of view of 200 mm $\times200$ mm, the absolute errors of the 3-DOF pose obtained from the VMMS are reduced to below 0.03 mm and 0.016°.

294. Coupled rotation patterns in cervical axial rotation can change when the head is kept level

BACKGROUND CONTEXT Axial rotation of the cervical spine with the cranium held level occurs during certain daily activities such as looking over one's shoulder when walking or driving. These activities require rotation from the suboccipital and subaxial cervical spine. The literature on cervical spine axial rotation and coupled rotations has been obtained from experiments where the segmental axis of rotation is aligned with the global axis of rotation. In looking over one's shoulder, the segmental rotation axes may not be aligned with the global and primarily vertical rotation axis due to curvature of the spine. Furthermore, fusion may limit the amount of rotation that can be obtained from the subaxial spine and reduce the facility with which the daily activities are performed. PURPOSE (1) To define the rotation of the intact subaxial spine during horizontal axial rotation of the cranium, and (2) To measure the effect of C5-C7 fusion on the rotation of the subaxial spine during horizontal axial rotation of the cranium. STUDY DESIGN/SETTING Biomechanical experiment. PATIENT SAMPLE Five C0-T1 cadaveric spine specimens (38-54 years old, 3 female and 2 male). OUTCOME MEASURES Rotation of the subaxial cervical spine in response to applied axial rotation moment. METHODS A left and right axial rotation moment of 1Nm was applied to specimens mounted in an apparatus that held the cranium in an orientation consistent with horizontal gaze (horizontal Frankfort line). The axial rotation axis passed through the midpoint between the two external auditory meatuses. Rotations of the individual vertebrae before and after C5-C7 fusion using lateral mass screws and posterior rods were measured using an optoelectronic motion measurement system. RESULTS C5-C7 fusion reduced the C3-T1 axial rotation range of motion from a mean of 31±5° to 22±5°. In the nonfused levels, the axial rotation range of motion changed less than half a degree. Holding the cranium level (horizontal gaze) changes the segmental and overall coupled rotation behavior of the cervical spine during axial rotation. In 3 specimens, left axial rotation induced both right lateral bending in the lower segments and left lateral bending in upper segments, and vice versa with right axial rotation. In the three specimens in which both left and right lateral bending was induced by axial rotation, there was a 0.1° to 3.7° reduction in the coupled C3-C4 lateral bending range of motion. In the other two specimen, C3-C4 lateral bending range of motion increased by 0.8° to 1.8°. C5-C7 fusion changed the amount but not the direction of coupled lateral bending of unfused segments. CONCLUSIONS Without the horizontal gaze constraint, right axial rotation has been shown to induce right lateral bending in the cervical spine. There are various activities of daily living, such as looking over one's shoulder, that involve holding the gaze horizontal while axially rotating the cervical spine. In this biomechanical experiment, a constrained horizontal axial rotation resulted in specimen-specific coupled rotation of the subaxial cervical spine. In three of the specimen, axial rotation induced left and right segmental lateral bending regardless of the axial rotation direction.This specimen-specific difference in the coupled lateral bending and in the ability to perform constrained axial rotation after C5-C7 fusion leads us to wonder whether there may also be a patient-specific difference. This difference would have clinical implications for patients who are candidates for C5-C7 fusion. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

DEVELOPMENT AND VALIDATION OF THREE-DIMENSIONAL HUMAN RANGE OF MOTION MEASUREMENT SYSTEM

Three-dimensional human range motion measurement system is developed by inertial sensor technology and wireless bluetooth acquisition technology. This paper describes the internal structure and the data processing method of the measurement system in detail. This measurement system is capable of testing the range of each joint motion, and can be easily carried to the rehabilitation hall, wards and other occasions for test and evaluation. It plays an extremely important role in its application in monitoring rehabilitation process, assessing disability, doing scientific research, and in many other fields. Three experienced teachers tested the range of motion of cervical spine, lumbar spine, right side of the shoulder, elbow, wrist, hip, knee, ankle, and other joints of ten college students. Through comparing the test results and the obtained results of this measurement system by using the method of paired samples T-test, they got the results that the bilateral significance level (Sig) was greater than 0.05, which can be considered that there were no significant differences between these two sets of results. Then it verifies the validity of the data in this system.

Seated versus supine: consideration of the optimum measurement posture for brain-dedicated PET

Some recently developed brain-dedicated positron emission tomography (PET) scanners measure subjects in a sitting position. Sitting enables PET scanning under more natural conditions for the subjects and also helps with making the scanners smaller. It is unclear, however, how much the degree of head motion when sitting differs from the supine posture commonly employed in clinical PET. In this report, we describe development of a markerless and contactless head motion tracking system and a study of healthy volunteers in several different postures to determine the optimum posture for brain PET. We used Kinect® (Microsoft) and developed software that can measure head motion with about 1 mm (translation) and less than 1° (rotation) accuracy. In the volunteer study, we measured the amount of head motion, with and without head fixation, in supine, normal sitting, and reclining postures. The results indicated that the normal sitting posture without head fixation had the largest head movement, and that the reclining and supine postures were similarly effective for minimizing head movement (average head movement of about 0.5 mm during 1 min). We also visualized the influence that head motion had on images for each pose by simulating the actual motions obtained from the volunteer study using a digital Hoffman phantom. Comparisons with the original image showed that the extent to which motion was reduced in the reclining and supine postures were quantitatively equivalent. The head motions of the volunteer studies were also reproduced using a mannequin head on a motorized stage to assess how well the proposed motion measurement system worked when used for motion correction. The results indicated that even though the system improved image quality for all postures, the reclining and supine postures could provide better image quality than the normal sitting posture.

A Review of Soil Dynamics in Traction Studies

As the world population increases more than ever before and increasing demand on food, feed and fiber, and security, the number of off-the-road vehicles is rapidly increasing for agriculture, forestry, military, mining and construction industries. Many researchers have studied and still investigating traction as it relates off-road vehicles and publications abound especially from developed countries of Europe, America and others. In our generation scientists are trying to put robotic vehicles on the lunar and Martian terrains. This trend makes the study of soil dynamics in traction a sine qua non in our tertiary and research institutions. In Nigeria there is a dearth of publications in this specialized area of study. This is a review paper and the purpose is to highlight some of the studies that have been conducted over the years, with a view to enlightening, encouraging, stimulating and challenging would be researchers. Trends in the development of soil bin with single wheel testers were reviewed including tractive and transport devices used in them. Traction parameters including motion resistance, measurement and data acquisition systems, traction predictive equations including wheel numeric and mobility numbers were also reviewed. Efforts made in the development of soil bin for soil dynamics research and further research interest at the Federal University of Technology, Akure (FUTA) were highlighted.

Human scratching motion analysis method by using three-dimensional motion measurement system

Human scratching motion analysis method by using three-dimensional motion measurement system

SAR Processing Without a Motion Measurement System

This paper leads a discussion on how to form a Synthetic Aperture Radar (SAR) image without knowing the relative track. That is, within the scope of factorized geometrical autofocus (FGA). The FGA algorithm is a base-2 fast factorized back-projection (FFBP) formulation with six free geometry parameters (per subaperture pair). These are tuned step by step until a sharp image is obtained. This innovative autofocus concept can compensate completely for an erroneous geometry. The FGA algorithm has been applied successfully on two ultrawideband (UWB) data sets, acquired by the CARABAS II system at very high frequency (VHF)-band. The relative tracks are known (measured accurately). We, however, adopt and modify a basic geometry model. A linear equidistant track at fixed altitude is initially assumed. Apart from deviations due to linearization, a ~2.5-m/s along-track velocity error is also introduced. Resulting FGA images are compared to reference images and verified to be focused. This indicates that it is feasible to form a wavelength-resolution SAR image at VHF-band without support from a motion measurement system. The execution time for the examples in this paper is about five times longer with autofocus than without. Hence, the FGA algorithm is now fit for use on a regular basis.

Towards Wearable Comprehensive Capture and Analysis of Skeletal Muscle Activity during Human Locomotion.

Background: Motion capture and analyzing systems are essential for understanding locomotion. However, the existing devices are too cumbersome and can be used indoors only. A newly-developed wearable motion capture and measurement system with multiple sensors and ultrasound imaging was introduced in this study. Methods: In ten healthy participants, the changes in muscle area and activity of gastrocnemius, plantarflexion and dorsiflexion of right leg during walking were evaluated by the developed system and the Vicon system. The existence of significant changes in a gait cycle, comparison of the ankle kinetic data captured by the developed system and the Vicon system, and test-retest reliability (evaluated by the intraclass correlation coefficient, ICC) in each channel’s data captured by the developed system were examined. Results: Moderate to good test-retest reliability of various channels of the developed system (0.512 ≤ ICC ≤ 0.988, p < 0.05), significantly high correlation between the developed system and Vicon system in ankle joint angles (0.638R ≤ 0.707, p < 0.05), and significant changes in muscle activity of gastrocnemius during a gait cycle (p < 0.05) were found. Conclusion: A newly developed wearable motion capture and measurement system with ultrasound imaging that can accurately capture the motion of one leg was evaluated in this study, which paves the way towards real-time comprehensive evaluation of muscles and joint motions during different activities in both indoor and outdoor environments.

Development of 3D motion measurement system for sport climbing

Development of 3D motion measurement system for sport climbing

A 3-D finger motion measurement system via soft strain sensors for hand rehabilitation

Finger mobility plays a crucial role in everyday lives and is especially a leading indicator during hand rehabilitation and assistance tasks. In this study, a soft sensor-based three-dimensional (3-D) finger motion measurement system is proposed. Specifically, we report the use of a soft rope-embedded microfluidic sensor with high sensitivity and responsivity for strain sensing in the proposed system. These microfluidic strain sensors are proved to have the advantages of being easy to fabricate, chemically inert, with low hysteresis and good flexibility in their output signals. Besides, kinematic modeling of different finger joints are also provided to investigate the reasonable sensor locations for obtaining accurate measurements. Algorithms to identify the varied non-coplanar motions (abduction/adduction and flexion/extension joint angles) are presented by means of tracking the locations of the first metacarpal bone in multiple thumb postures. As a demonstration of their potential, the rope-embedded strain sensing units were used as curvature sensors mounted on the dorsum of target joints. The soft sensor-based 3-D finger motion measurement system and algorithms are experimentally verified by comparison with a camera-based motion capture device. Placing sensors at the optimal locations, joint angle measurement can reach up <3.5-deg accuracy. The proposed algorithms for improving the accuracy of the sensing system can be extended to other complicated finger joints.

Twin neighboring tunnel construction under an operating airport runway

Beijing Capital International Airport, as one of the busiest airports in the world, has three terminals and three runways. The middle runway lies between Terminal 2 and Terminal 3, and underground transportation is necessary to alleviate the congested surface traffic and reduce the impact of the surface traffic on the middle runway operations. As a result, twin neighboring tunnels, one each for passenger transportation and automobiles, passing underneath the operating middle runway were constructed. The section of the twin tunnels that was approximately 6 m under the operating runway was excavated using the sequential excavation method under the protection of a pipe-screen system. The elaborate installation of the pipe-screen system was performed using slurry pipe-jacking machines with an excavation diameter of 1020 mm. The annular gap between the excavation diameter and the outer diameter of the pipe was filled in time to reduce surface settlements. To conduct an information-oriented construction project, the real-time monitoring of the runway pavement surface with high-precision automatic total stations was employed during and after construction. With the monitored results, in-pipe grouting was performed when necessary to decrease the runway settlements. The undercrossing construction was completed as scheduled, and the final settlements of the runway were controlled within the predefined allowable settlement. The airport continued all operations without any interruptions. The success of crossing under the operational runway of the twin tunnels lies in the use of the large-diameter pipe screen, the well-controlled excavation of the twin tunnels, the installation of the high-precision and automatic runway movement measurement system and, most importantly, the employment of the in-pipe grouting system.

A new lumbar fixation device alternative to pedicle-based stabilization for lumbar spine: In vitro cadaver investigation

Context: To evaluate the stability provided by a new bilateral fixation technique using an in vitro investigation for posterior lumbar segmental instrumentation.Design: Experimental cadaver study. In this study, we propose an alternative technique for a posterior lumbar fixation technique called “inferior-oblique transdiscal fixation” (IOTF).Setting: Study performed at Engineering Center for Orthopedic Research Exellence (ECORE) in Toledo University-Ohio.Participants: Six human lumbar cadaveric specimen used in this study.Interventions: In this study, we propose an alternative technique for a posterior lumbar fixation technique called “inferior-oblique transdiscal fixation” (IOTF). As a novel contribution to the classical technique, the entry point of the screw is the supero-lateral point of the intersecting line drawn between the corpus and the pedicle of the upper vertebra. This approach enables the fixation of two adjacent vertebrae using a single screw on each side without utilizing connecting rods.Outcome Measures: Flexion (Flex), extension (Ext), right and left lateral bending (LB & RB), and right and left axial rotation (LR & RR), and the position data were captured at each load step using the Optotrak motion measurement system and compared for IOTF and posterior transpedicular stabilization.Results: The Posterior stabilization system (PSS) and IOTF significantly reduced the ROM of L4-L5 segment compared to intact segment’s ROM. During axial rotation (AR) IOTF fused index segment more than PSS. Besides this, addition of transforaminal lumbar interbody fusion (TLIF) cage improved the stabilization of IOTF system during flexion, extension and lateral bending. Whereas, PSS yielded better fusion results during extension compared to IOTF with and without interbody fusion cages.Conclusions: We hypothesized that the new posterior bilateral system would significantly decrease motion compared to the intact spine. This cadaver study showed that the proposed new posterior fusion technique IOTF fused the index segment in a similar fashion to the classical pedicle screw fusion technique.

A Biomechanical Analysis of Ankle Instability in Supination External Rotation Ankle Fractures

Category: Trauma Introduction/Purpose: Supination external rotation (SER) 2 and SER3 ankle injuries are thought to be stable whereas SER4 injuries are thought to be unstable. In other words, deltoid rupture is thought to be a necessary component of instability in SER injuries. However, biomechanical evidence has shown that as little as 1 mm talar shift results in 40% loss in contact area leading to increased contact forces. Additionally, the external rotation stress exam which is the typical test used to detect instability is poorly standardized in the literature limiting its ability to detect subtle instability. Therefore the purpose of this study is to analyze talar rotation and translation with external rotation stress specifically in SER2 and SER3 patterns in an effort to better define which injury patterns are unstable. Methods: 19 legs disarticulated below the knee were obtained. Optotrak optoelectronic 3D motion measurement system was used to determine positioning of the talus compared to the tibia. Specimens were first tested intact using a jig capable of exerting known axial and rotational forces through the hindfoot in line with the weightbearing axis of the tibia. Specimens were loaded with 150N to simulate physiologic load and sequentially stressed with 0, 1, 2, 3, and 4Nm of external rotation. SER2 injury was then created by creating a Weber B distal fibula fracture and AITFL rupture. The above testing was then repeated. Next the injury was converted to SER3 by rupturing the PITFL, and the above testing was repeated. In all conditions coronal and sagittal translation as well as axial and coronal angulation from the uninjured/unstressed state were recorded. The SER2 and SER3 conditions were compared to the intact condition using a paired t-test. Results: When compared to the uninjured state, the SER2 injury pattern demonstrated statistically significant differences in the following parameters: - axial rotation at 1Nm (11.0±4.2°, p&lt;0.0005), 2Nm (12.8±4.4°, p&lt;0.0005), 3Nm (14.4±4.9°, p&lt;0.0005), and 4Nm (15.8±5.2°, p&lt;0.0005) - sagittal translation at 1Nm (5.2±3.6 mm, p=0.007), and 2Nm (6.4±3.9 mm, p=0.02) - coronal translation at 3Nm(0.6±3.2 mm, p=0.004), and 4Nm (0.7±3.5 mm, p=0.003) When compared to the uninjured state, the SER3 injury pattern demonstrated statistically significant differences in the following parameters: - coronal rotation at 4Nm (-0.9±6.8°, p=0.03) - axial rotation at 1Nm (12.3±4.4°, p&lt;0.0005), 2Nm (16.0±4.7°, p&lt;0.0005), 3Nm (18.2±5.1°, p&lt;0.0005), and 4Nm (20.4±5.7°, p&lt;0.0005) - sagittal translation at 1Nm (5.0±3.9 mm, p=0.03), and 2Nm (6.4±3.9 mm, p=0.01) - coronal translation at 1Nm (0.7±1.9 mm, p=0.05), 2Nm (0.8±2.5 mm, p=0.01), 3Nm (1.1±3.0 mm, p&lt;0.0005), and 4Nm (1.5±3.6 mm, p&lt;0.0005) Conclusion: Current literature describes ankle instability in SER injury patterns in terms of coronal translation, and suggests that SER2 and SER3 injury patterns are stable. However, our data demonstrates that even SER2 and SER3 injury patterns with an intact deltoid ligament show signs of instability in sagittal translation and axial rotation as well as subtle signs of instability in coronal translation, especially at higher torques. As previously stated, subtle instability has been shown to significantly decrease contact forces, and therefore this data supports further study of long term clinical outcomes and reconsideration of our treatment algorithms for SER2 and SER3 fractures.

A high bandwidth three-axis out-of-plane motion measurement system based on optical beam deflection.

Multi-axis measurement of motion is indispensable for characterization of dynamic systems and control of motion stages. This paper presents an optical beam deflection-based measurement system to simultaneously measure three-axis out-of-plane motion of both micro- and macro-scale targets. Novel strategies are proposed to calibrate the sensitivities of the measurement system. Subsequently the measurement system is experimentally realized and calibrated. The system is employed to characterize coupled linear and angular motion of a piezo-actuated stage. The measured motion is shown to be in agreement with theoretical expectation. Next, the high bandwidth of the measurement system has been showcased by utilizing it to measure coupled two-axis transient motion of a Radio Frequency Micro-Electro-Mechanical System switch with a rise time of about 60 μs. Finally, the ability of the system to measure out-of-plane angular motion about the second axis has been demonstrated by measuring the deformation of a micro-cantilever beam.

Construction of Real-time Motion Measurement System using Inertial Sensors and its Application to Robot Teaching System

Construction of Real-time Motion Measurement System using Inertial Sensors and its Application to Robot Teaching System

Variable compensation during the sit-to-stand task among individuals with severe knee osteoarthritis

BackgroundIndividuals with knee osteoarthritis (OA) show variability during the sit-to-stand (STS) task, so they may not perform the STS in the same way. This study aimed to determine whether individuals with knee OA have different strategies in performing the STS. MethodsParticipants with knee OA and able-bodied individuals underwent STS evaluation at a self-selected pace with use of a motion measurement system consisting of 12 cameras and 2 force plates. ResultsIn total, 101 participants (57 women) with knee OA showed 3 main STS strategies. As compared with the 27 controls (14 women), 24 OA participants, compensated STS, showed greater trunk flexion (47.1° vs. 38.3°; P<0.01) and trunk obliquity (4.6° vs. –0.8°; P<0.001) when completing the STS task in the same amount of time as controls (2.4 vs. 2.7s; P=0.999). The second group (n=59), inadequately compensated STS, also compensated with trunk flexion (47.7° vs. 38.3°; P<0.01) and trunk obliquity (1.6° vs. –0.8°; P<0.001) but took longer than controls (3.4 vs. 2.7s; P=0.001). The third group (n=18), severe impaired STS, took an extended amount of time to execute the STS (6s), with marked trunk flexion (59.2°) and obliquity (4.1°), so participants in this group were perhaps severely impaired in completing the STS. ConclusionThis study identified 3 groups STS trunk strategies among participants with STS. Moreover, the data reveal a concise representation of the relations among strategy variables. The findings could be used to simplify the characterization of the STS among patients with knee OA and aid with follow-up.