Position Of Body Segments Research Articles

Novel calibration method for improved UWB sensor distance measurement in the context of application for 3D analysis of human movement

Integrated UWB and MIMU sensor systems have become popular for pedestrian tracking and indoor localization, since this facilitates data fusion that improves position estimation accuracy by exploiting the complementary nature of their error sources. Integrated UWB/MIMU sensors also have great potential in only on-body use for 3D analysis of human movement, as with MIMU sensors alone accurate direct estimation of (relative) body segment position is not possible. For this, a position estimation accuracy with errors smaller than 1 cm is deemed required. The lowest position estimating error with integrated UWB/MIMU systems, reported so far, is around 5 cm. The main accuracy limiting factors were found to be the systematic errors in the distance estimates from the UWB sensor. Multiple reported attempts to calibrate for these systematic errors failed to achieve the desired accuracy. This article presents a novel distance-bias calibration method that minimizes the residual systematic distance estimate errors using multiple sensors in a swarm configuration. Validation was performed against synthetic reference data and against reference data measured with an optical motion tracking system. Significantly reduced systematic distance estimate errors (≤0.5 cm) were found. These results promise to facilitate significantly better position estimates in future UWB/MIMU data fusion.

Assessment of joint position sense in active and passive modes with various elbow flexion angles and movement speeds using an isokinetic dynamometer

BackgroundJoint position sense is the ability to detect body segment position in space and is commonly used to represent proprioceptive performance. The isokinetic dynamometer is frequently used to evaluate elbow joint position sense during active and passive reproduction tasks with various testing protocols. However, few studies have reported the performance of joint position sense under different testing conditions. ObjectiveTo compare elbow joint position sense between active and passive reproduction tasks under different matching speeds and reference targets. DesignA cross-sectional study. MethodsTwenty participants without a history of upper-extremity surgery or neuromuscular diseases that affect the joint position sense of the elbow. Active and passive ipsilateral matching tasks were performed at four movement speeds (0.5°/s, 1°/s, 2°/s, and 4°/s) and three reference targets (elbow flexion at 0°–15°, 45°–60°, and 75°–90°), using an isokinetic dynamometer. The absolute and variable errors of each condition were calculated for comparison. ResultsIn active matching task with elbow flexion of 0°–15°, the absolute error at 0.5°/s was significantly larger than that at 2°/s and 4°/s, while the variable error at 1°/s was significantly larger than that at 2°/s. However, no differences were found at elbow flexion angles of 45°–60° and 75°–90°. Larger absolute errors were found at 4°/s with three testing angles in passive matching task. ConclusionsThis study compared the joint position sense errors under various testing conditions in the active and passive reproduction tasks. The movement speeds and target position effects should be considered during evaluation.

Arduino-Based Development of Automatic Body Posture Measuring Device for Rapid Entire Body Assessment Method

Workers from various industries can be exposed to musculoskeletal disorders (MSDs) risks in the workplace. Most cases of MSDs happen because of the accumulation of repetitive bad postures. Postural analysis can be done to implement changes that minimize MSDs risks in the workplace. The rapid entire body assessment (REBA) method provides an easy and fast measurement to analyze various postures. The accuracy of REBA assessments from observations is not good enough due to the limitations of human vision. The input of photo-based postural analysis also has a lot of error potential and takes up even more time. Therefore, this study aims to design a tool to do body posture measurements accurately and quickly. The Arduino-based postural analysis tool measures the position of several body segments, which are then used as the input of REBA in real time. The acceleration of each body segment recorded by the MPU6050 will be processed as displacement data and used to analyze the posture. The posture measurements detected by the tool is then used as input for REBA assessment. The device's accuracy was tested by comparing the photo-based postural analysis result to the postural analysis result of the tool. The reliability of the device was tested by Cronbach's Alpha method. The Cronbach's Alpha value of normal standing posture is 0.692, and the extreme posture's Cronbach's alpha value is 0.537. Multiple postures can be recorded at once using the tool. The tool can capture and assess multiple postures in approximately 6 minutes.

Augmenting inertial motion capture with SLAM using EKF and SRUKF data fusion algorithms

This paper proposes quaternion-based extended and square-root unscented Kalman filters to estimate human body segment positions and orientations using low-cost IMUs in conjunction with a SLAM method. The Kalman filters use measurements based on SLAM output, multilink biomechanical constraints, and vertical referencing to correct errors. In addition to the sensor biases, the fusion algorithm is capable of estimating link geometries, allowing the imposition of biomechanical constraints without a priori knowledge of sensor positions. The proposed algorithms achieve up to 5.87 (cm) and 1.1 (deg) accuracy in position and attitude estimation in various scenarios of human arm movements. Compared to the EKF, the SRUKF algorithm presents a smoother and higher convergence rate but is 2.4 times more computationally demanding. After convergence, the SRUKF is up to 17% less and 36% more accurate than the EKF in position and attitude estimation, respectively.

Effect of the soft tissue artifact on marker measurements and on the calculation of the helical axis of the knee during a squat movement: A study on the CAMS-Knee dataset.

Marker-based motion capture recordings of human body segments are often affected by soft tissue artifact (STA). The undesired and uncontrolled motion of the skin may introduce errors in the estimation of motion and position of body segments and, consequently, in the calculation of the relative functional quantities. This study exploited a recently published dataset consisting of six adult subjects that underwent a total knee arthroplasty. The subject performed squat tasks while the motion was concurrently recorded by passive markers attached to the skin of the lower limbs, an optoelectronic system, and a fluoroscope. The STA of shank and thigh was decomposed in local deformation and rigid motion. Additionally, we studied how the instantaneous helical axis (IHA) calculation is affected by STA. The cluster most affected by STA rigid motion was the thigh. The largest estimated effects were about 7deg. and about 20mm. The largest effect of local deformation was about 25mm, and it was observed on the thigh cluster. The STA made the estimation of the IHA unreliable for both position and direction. The choice of the reference configuration influenced the results of the STA analysis.

Whole-body movement analysis using principal component analysis: What is the internal consistency between outcomes originating from the same movement simultaneously recorded with different measurement devices?

A growing number of studies apply Principal Component Analysis (PCA) on whole-body kinematic data to facilitate an analysis of posture changes in human movement. An unanswered question is, how much the PCA outcomes depend on the chosen measurement device. This study aimed to assess the internal consistency of PCA outcomes from treadmill walking motion capture data simultaneously collected through laboratory-grade optical motion capture and field-suitable inertial-based motion tracking. Data was simultaneously collected using VICON (whole-body plug-in gait marker positions) and Xsens (body segment positions) from 20 participants during 2-min treadmill walking. Using PCA, Principal Movements (PMs) were determined using two commonly used practices: on an individual and a grouped basis. For both, correlation matrices were used to determine internal consistency between outcomes from either measurement system for each PM. Both individual and grouped approach showed excellent internal consistency between outcomes from the two systems among the lower order PMs. For the individual analysis, high correlations were only found along the diagonal of the correlation matrix while the grouped analysis also showed high off-diagonal correlations. These results have important implications for future application of PCA in terms of the independence of the resulting PM data, the way group-differences are expressed in higher-order PMs and the interpretation of movement complexity. Concluding, while PCA-outcomes from the two systems start to deviate in the higher order PMs, excellent internal consistency was found in the lower order PMs which already represent about 98% of the variance in the dataset.

Quasi-static methods to evaluate seat strength in rear impacts

Objective Various methods have been used in the past 50 years to apply Quasi-static load to a seat in the rear direction and measure seat performance in rear impacts. This study compared five of the most-common test procedures to evaluate seats. In addition, occupant mass and center of gravity are discussed as important characteristics of rear loading of seats. Method Data was collected and analyzed from five different seat pull tests, including FMVSS 207, modified FMVSS 207, QST, body block and FRED II. Test data included peak force, moment and angle at peak moment. Occupant loading height of was determined using body segment weights and position in the forward (x) and vertical (z) directions based on anthropometry data. Results Some of the inherent differences in the tests are shown by comparing data with the same seat structure. The QST and FRED II use a lower height of loading than FMVSS 207. The QST and FRED II peak moment and force did not coincide with the same seatback angle as in FMVSS 207 and body block testing. Center of gravity height varies depending on whether the whole body or only the upper torso is considered. For the 50th male, it is 171.5 mm (6.8”) with the whole body and 246.7 mm (9.7”) with the upper torso. Conclusion Results from different tests cannot be readily compared because of different loading conditions, including body shape and height of load about the H-point, which can cause the seat structure to respond differently.

Joint Specificity and Lateralization of Upper Limb Proprioceptive Perception.

Proprioception is the sense of position and movement of body segments. The widespread distribution of proprioceptors in human anatomy raises questions about proprioceptive uniformity across different body parts. For the upper limbs, previous research, using mostly active and/or contralateral matching tasks, has suggested better proprioception of the non-preferred arm, and at the elbow rather than the wrist. Here we assessed proprioceptive perception through an ipsilateral passive matching task by comparing the elbow and wrist joints of the preferred and non-preferred arms. We hypothesized that upper limb proprioception would be better at the elbow of the non-preferred arm. We found signed errors to be less variable at the non-preferred elbow than at the preferred elbow and both wrists. Signed errors at the elbow were also more stable than at the wrist. Across individuals, signed errors at the preferred and non-preferred elbows were correlated. Also, variable signed errors at the preferred wrist, non-preferred wrist, and preferred elbow were correlated. These correlations suggest that an individual with relatively consistent matching errors at one joint may have relatively consistent matching errors at another joint. Our findings also support the view that proprioceptive perception varies across upper limb joints, meaning that a single joint assessment is insufficient to provide a general assessment of an individual's proprioception.

Analysis of physical activity as a mediator between non-ergonomic position of upper body segments and musculoskeletal health in bus drivers

The number of injuries and accidents at the workplace are constantly rising, and the most pronounced injuries are related to the musculoskeletal health. Numerous studies have revealed that city bus drivers have a high incidence of musculoskeletal pain. The aim of this study was to determine whether physical activity levels might be a mediator between the non-ergonomic position of the body’s upper segments and musculoskeletal health in professional bus drivers. The study protocol included the assessment of participants’ musculoskeletal health using the Örebro Musculoskeletal Pain Questionnaire, assessment of the non-ergonomic position of the upper body segments when seated by means of the Rapid Upper Limb Assessment, and measuring of the level of physical activity using the Yamax 200 pedometer. The sample consisted of 115 bus drivers, from 40 to 55 years of age, with a minimum work service of 15 years. The relationships among variables were tested using the Spearman correlation coefficient and the Wilcoxon rank sum test to include the selected variables in the multivariate linear regression model. The Box-Cox test indicated the need for logarithmic transformation of the ÖMPQ results used to measure musculoskeletal health, so that a log-linear model was used in the regression analysis. The normality of the distribution of the residual regression models was tested by the Shapiro-Wilk test The main findings of this study indicate that 95.6% of participants reported the presence of musculoskeletal pain and in 24.4% of them a very high risk of the musculoskeletal disorder was observed, which indicated the need for urgent changes. The average number of steps per day was 5,090.8. The physical activity proved (obtained by regression analysis) as a mediator between the non-ergonomic position of the upper body segments and musculoskeletal health (p=.027). The obtained data may serve as an important argument for designing future public health and kinesiology interventions for the improvement of the health of professional bus drivers.

Epidemiology of injuries in female and male senior Slovenian handball leagues.

Handball is associated with a high frequency of injuries due to unexpected situations, external disturbances of movement and extreme positions of body segments. The purpose of this study was to identify and analyze injuries among female and male players from all five senior Slovenian handball leagues in the season 2010/2011. We conducted a retrospective epidemiological study using a questionnaire. Data were collected between February and May 2012. Descriptive analysis is provided. Forty-five percent of all the players were injured, reporting 92 injuries. 0.58 injuries/player occurred, 57 (62%) in females and 35 (38%) in males. Injury incidence in females (27.7 injuries/1000 hours match, 0.97 injuries/1000 hours training) was higher than in men (10.6 injuries/1000 hours match, 0.5 injuries/1000 hours training), respectively. The left- and right-back players were injured most often (41%). Sprain was the most common injury type (55%). Most injuries were severe (29%). The lower limb was injured most frequently (62%). Ankle was injured the most commonly (35%), but ankle injuries were in most cases moderate (38%). More than 70% of knee injuries and 50% of shoulder injuries were severe. In 33%, cause of injury was contact with an opponent/teammate. Thirty-six percent of players reported shoulder and 36% ankle overuse syndromes. Present findings showed a higher incidence of injuries in female than in male senior Slovenian handball players in the 2010/2011 season. Preventive programs should focus not only on the acute ankle and knee injuries, but also on overuse syndromes of the shoulder and ankle.

Estimating Lower Body Kinematics Using a Lie Group Constrained Extended Kalman Filter and Reduced IMU Count

Goal: Gait monitoring is useful for diagnosing movement disorders or assessing surgical outcomes. This paper presents an algorithm for estimating pelvis, thigh, shank, and foot kinematics during walking using only two or three wearable inertial sensors. Methods: The algorithm makes novel use of a Lie-group-based extended Kalman filter. The algorithm iterates through the prediction (kinematic equation), measurement (pelvis position pseudo-measurements, zero-velocity update, and flat-floor assumption), and constraint update (hinged knee and ankle joints, constant leg lengths). Results: The inertial motion capture algorithm was extensively evaluated on two datasets showing its performance against two standard benchmark approaches in optical motion capture (i.e., plug-in gait (commonly used in gait analysis) and a kinematic fit (commonly used in animation, robotics, and musculoskeleton simulation)), giving insight into the similarity and differences between the said approaches used in different application areas. The overall mean body segment position (relative to mid-pelvis origin) and orientation error magnitude of our algorithm ( n=14 participants) for free walking was 5.93 ± 1.33 cm and 13.43 ±1.89 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> when using three IMUs placed on the feet and pelvis, and 6.35 ± 1.20 cm and 12.71 ±1.60 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> when using only two IMUs placed on the feet. Conclusion: The algorithm was able to track the joint angles in the sagittal plane for straight walking well, but requires improvement for unscripted movements (e.g., turning around, side steps), especially for dynamic movements or when considering clinical applications. Significance: This work has brought us closer to comprehensive remote gait monitoring using IMUs on the shoes. The low computational cost also suggests that it can be used in real-time with gait assistive devices.

Relation between frontal plane center of mass position stability and foot elevation during obstacle crossing

High foot elevation during obstacle crossing is viewed as a conservative strategy in older adults, but excessive foot elevation may result in large mediolateral center of mass (CoM) displacement. Since an incorrect transfer of CoM can lead to balance loss during locomotion, both appropriate foot elevation and CoM position must be controlled and coordinated by adjusting body segment positions. However, no studies have revealed time profiles of CoM position by coordinated segment movements and the relation of foot elevation with CoM position during obstacle crossing. Twenty-five healthy older adults crossed an obstacle (depth: 1 cm, width: 60 cm, height: 8 cm) during comfortable-speed walking. Synergy indices were calculated during lead- and trail-limb swing using uncontrolled manifold analysis. High synergy index values indicate a strong multi-joint kinematic synergy, or co-fluctuations in segment movements, to control CoM position. The maximum foot heights of the swing limbs were calculated as the maximum vertical distance between the most distal foot point and the ground. In the mediolateral direction, synergy index values during early lead-limb swing were significantly greater than during early trail-limb swing, and in the vertical direction, large synergy index values were found during early- and mid-swing phases. Moreover, maximum trail-foot height was correlated to vertical synergy index during early phase. CoM position was not well controlled by a kinematic synergy during trail-limb swing and the low control of CoM position was observed with great trail-foot height. The results suggest that a conservative strategy with great trail-foot height would not always be helpful for successful obstacle crossing.

Correlations between malocclusion and anomalies in the posture

Posture is understood as the relative position of various body segments in relation to each other and relative to the environment. Postural control is characterized by the ability to adapt our use of sensory information to changing tasks and environmental conditions. Malocclusion and incorrect body posture are two very common issues in growing subjects and especially in patients with mixed dentition, where it is still possible to intervene to modify and correct both conditions. In order to perform a correct diagnosis and an orthodontic treatment plan, the relationships between occlusion and posture should be evaluated to establish the most appropriate strategy of treatment and an interdisciplinary approach between different healthcare professionals. The aim of this study is to investigate the possible relationship between malocclusion and body posture anomalies.

Machine Learning Improvements to Human Motion Tracking with IMUs.

Inertial Measurement Units (IMUs) have become a popular solution for tracking human motion. The main problem of using IMU data for deriving the position of different body segments throughout time is related to the accumulation of the errors in the inertial data. The solution to this problem is necessary to improve the use of IMUs for position tracking. In this work, we present several Machine Learning (ML) methods to improve the position tracking of various body segments when performing different movements. Firstly, classifiers were used to identify the periods in which the IMUs were stopped (zero-velocity detection). The models Random Forest, Support Vector Machine (SVM) and neural networks based on Long-Short-Term Memory (LSTM) layers were capable of identifying those periods independently of the motion and body segment with a substantially higher performance than the traditional fixed-threshold zero-velocity detectors. Afterwards, these techniques were combined with ML regression models based on LSTMs capable of estimating the displacement of the sensors during periods of movement. These models did not show significant improvements when compared with the more straightforward double integration of the linear acceleration data with drift removal for translational motion estimate. Finally, we present a model based on LSTMs that combined simultaneously zero-velocity detection with the translational motion of sensors estimate. This model revealed a lower average error for position tracking than the combination of the previously referred methodologies.

Validation method for body-mounted sensor attachments

Abstract Small sensor devices like inertial measurement units enable mobile movement and gait analysis, whereby existing systems differ in data acquisition, data processing, and gait parameter calculation. Concerning the validation, recent studies focus on the captured motion and the influence of sensor positioning with respect to the accuracy of the computed biomechanical parameters in comparison to a reference system. Although soft tissue artifact is a major source of error for skin-mounted sensors, there are no investigations regarding the relative movement between the body segment and sensor attachment itself. The aim of this study is to find an evaluation method and to determine parameters that allow the validation of various sensor attachment types and different sensor positionings. The analysis includes the comparison between an adhesive and strap attachment variant as well as the frontal and lateral sensor placement. To validate different attachments, an optical marker-based tracking system was used to measure the body segment and sensor position during movement. The distance between these two positions was calculated and analyzed to determine suitable validation parameters. Despite the exploratory research, the results suggest a feasible validation method to detect differences between the attachments, independent of the sensor type. To have representative and statistically validated results, further studies that involve more participants are necessary.

Kinematic Sequence Classification and the Relationship to Pitching Limb Torques.

The kinematic sequence (KS) during a baseball pitch provides insight into an athlete's ability to efficiently transfer energy and develop segmental velocities, to assess the quality of body segment position and control. Study purposes were 1) to introduce the four-category Kinematic Sequence Classification System and 2) to compare elbow and shoulder torques and shoulder distraction force across the KS categories performed during the fastball pitch. Thirty baseball pitchers (20.0 ± 3.1 yr) underwent 3D biomechanical pitch analyses of 249 fastball pitches. Seventeen distinct KS patterns were identified and assigned into four categories: 1) The proximal-to-distal (PDS) group includes the KS closest to theoretical ideal order of the five body segments (pelvis → trunk → arm → forearm → hand). The other categories were defined based on the segment where the first out-of-sequence peak angular velocity occurred: 2) distal upper extremity (DUE), 3) proximal upper extremity, and 4) pelvis/trunk. Throwing limb shoulder distraction force and shoulder and elbow torques were calculated. Linear mixed model analyses compared variables across KS categories. Average elbow valgus torques differed significantly across all categories, P = 0.023, and were greater for the DUE (73.99 ± 20.84 N·m) than the PDS (61.35 ± 16.79 N·m), P = 0.006. Shoulder external rotation torques were significantly different, P = 0.033, across categories. The PDS group demonstrated less mechanical stresses on the throwing shoulder and elbow but was observed in only 12% of pitches. The DUE group was the most common and generated the greatest elbow valgus and shoulder external rotation torques. The KS can inform coaches and sports medicine clinicians where the greatest torques are incurred by a pitcher. A KS classification system may serve as a screening tool or target pitching instruction for injury avoidance.

Biomechanical Parameterization of Front Handspring Vaults

The motivation of the study is to demonstrate that by evaluating the training process using means to record and analyse the movement of individual body segments it is possible to effectively direct the training process to improve the position of individual body segments that are identified by the analysis as erroneous. By improving the position of individual body segments when performing a front handspring vault (FHV), thanks to targeted training focused on problematic segments, improvement in the posture of the whole body in the process of performing the vault will be achieved. The aim of the work is to contribute to the expansion of knowledge of explicit exercises applied in sports educology of the selected sports discipline. Based on the experimental decomposition of biomechanical parameterization. The study sample consists of ten young gymnasts (five boys (nbi=5) and five girls (ngi=5)). Five boy gymnasts (average age 12.00 &plusmn; 0.71 yrs; avg. body height 142 &plusmn; 9.09 cm; avg. BMI 17.47 &plusmn; 0.78) and five girl gymnasts (avg. age 11.40 &plusmn; 0.89 yrs; avg. body height 141 &plusmn; 10.82 cm; avg. BMI 17.47 &plusmn; 1.01) took part in this study. Their task was to perform input and output FHVs (nIi=10; nOi=10). We used the six-camera optoelectronic system for video-capturing motion analysis (SMART; BTS Bioengineering, Italy) and related technology to make clinical research in gymnastic training of the seven phases of the FHV. Thanks to motion analysis we recorded progress in changes of body symmetry after six weeks of gymnastic training of vaults.

Soft tissue artifact causes underestimation of hip joint kinematics and kinetics in a rigid-body musculoskeletal model

Rigid body musculoskeletal models have been applied to study kinematics, moments, muscle forces, and joint reaction forces in the hip. Most often, models are driven with segment motions calculated through optical tracking of markers adhered to the skin. One limitation of optical tracking is soft tissue artifact (STA), which occurs due to motion of the skin surface relative to the underlying skeleton. The purpose of this study was to quantify differences in musculoskeletal model outputs when tracking body segment positions with skin markers as compared to bony landmarks measured by direct imaging of bone motion with dual fluoroscopy (DF). Eleven asymptomatic participants with normally developed hip anatomy were imaged with DF during level treadmill walking at a self-selected speed. Hip joint kinematics and kinetics were generated using inverse kinematics, inverse dynamics, static optimization and joint reaction force analysis. The effect of STA was assessed by comparing the difference in estimates from simulations based on skin marker positions (SM) versus virtual markers on bony landmarks from DF. While patterns were similar, STA caused underestimation of kinematics, range of motion (ROM), moments, and reaction forces at the hip, including flexion-extension ROM, maximum internal rotation joint moment and peak joint reaction force magnitude. Still, kinetic differences were relatively small, and thus they may not be relevant nor clinically meaningful.

Effects of Visual Feedback Complexity on the Performance of a Movement Task for Rehabilitation

This study investigated the effects of visual feedback (VF) complexity on movement performance to potentially optimize the design of VF-based rehabilitation. We evaluated the effects of VF complexity on performance of the two-legged squat during training with concurrent (real-time) VF and short-term retention with no VF. Four VF cases were employed to train spatial positioning of the thigh segment in unique combinations of complexity (simple, complex) and representation of body-discernibility (abstract, representative). Eighteen able-bodied subjects attempted to minimize the error between individual body segment positions and a target trajectory during concurrent VF and short-term retention tests. Complex-representative VF demonstrated greater potential for training with increased performance consistency in both motion and muscle activity patterns.

Effect of Different Body Postures on the Severity of Stuttering in Young Adults with Developmental Stuttering.

Objective The current study aimed to investigate the effects of body position on the level and severity of stuttering in young adults with developmental stuttering. Methods A total of 24 subjects (male: 17; female: 7; mean age: 24.9 ± 6.2 years) with developmental stuttering participated. The participants were asked to perform oral reading and spontaneous monologue-speaking tasks in different body postures while their speech was recorded. During reading and speaking tasks, the Stuttering Severity Instrument was used to quantify the severity of stuttering. The effects of different body postures on stuttering severity, reading task, and speaking task scores were analyzed. Results Significant differences in stuttering severity, reading task, and speaking task scores were found for different body postures. Post hoc analyses revealed a significant difference in stuttering severity, reading task, and speaking task scores when subjects were sitting on a chair with no arm support compared to lying down (p<0.05). Similarly, there were significant differences for two sitting positions (sitting on a chair with no arm support vs sitting on a chair with arm support (p<0.05)). Conclusions Body postures or body segment positions that relax and facilitate the muscles of the neck and shoulders may potentially improve speech fluency in young adults with developmental stuttering.