Upper-body Motion Research Articles

Upper body motion recognition based on key frame and random forest regression

There are limited approaches using Kinect for upper body motion recognition. Most of the available approaches are conducted when there is no joint occlusion, though some performed with joint occlusion only demonstrated recognition of a few motions at low recognition rates. This paper utilizes OptiTrack and its supporting software to obtain and transfer data into a human skeleton coordinates using Kinect v2, and selects the vector among key joint points and angles as the feature values; the AP clustering algorithm was adopted for the key frames of motions which are marked; then we conduct relative normalization of the feature values, and use the method of random forest regression to realize two functions: (1) conduct derivation based on joint offset of frames detected with Kinect v2 from those detected with OptiTrack, learn the joint offset regression function, and correct the skeleton based on the predictions on joint offset; (2) determine the motions based on predicted posture. This paper performs recognition of 8 types of upper body motions at an average accuracy of 90.86%.

Improving Trunk-Pelvis Stability Using Active Force Control at the Trunk and Passive Resistance at the Pelvis

Standing postural control requires a complex interaction between the sensory and motor systems. Among sensory inputs, proprioception plays a fundamental role in the fine control of postural movements. In some neuromotor disorders, defects in the proprioceptive system may be associated with unsteady, uncoordinated, and exacerbated upper body movements during activities of daily living that may secondarily result in imbalance, falls, and severe injuries. Passive or active proprioceptive interventions are implemented routinely as a critical part of rehabilitation programs that target postural balance disorders. In this study, we have created a novel multimodal robotic platform merging both passive and active modalities to enhance upper body control. We hypothesize that the combination of passive resistance at pelvis in combination with active control of the lower thorax via assist-as-needed haptic feedback can enhance standing postural control. To test this hypothesis, we recruited ten healthy adults and had them perform dexterous reaching tasks either with or without a robotic system, while they stood unstably on a balance ball. The results of our pilot study show that individuals can improve postural stability of the upper body by selectively reducing upper trunk motion relative to caudal segments in the direction of the reaching arm, after training with the robotic platform.

Upper body accelerations as a biomarker of gait impairment in the early stages of Parkinson’s disease

BackgroundChanges in upper body (UB) motion during gait may be a marker of incipient pathology, intervention response and disease progression in Parkinson’s disease (PD), which if independent from the lower body motion, might provide an improved assessment of gait. Research questionThis study aimed to test this hypothesis and establish whether variables calculated from accelerations measured on the UB are unique from spatiotemporal characteristics and can contribute to an improved classification of PD gait. MethodsData was obtained from 70 people with PD (69.2 ± 9.9 y.o., UPDRS III: 36.9 ± 12.3) and 64 age-matched controls (71.6 ± 6.8 y.o.). Spatiotemporal characteristics were measured using a pressure sensitive mat (GAITRite). Head and pelvis accelerations were synchronously measured with wearable inertial sensors (Opal, APDM). Pearson’s product-moment correlations were calculated between 49 selected variables from UB accelerations (representing magnitude, smoothness, regularity, symmetry and attenuation) and 16 traditional spatiotemporal characteristics (representing pace, variability, rhythm, asymmetry and postural control). Univariate and multivariate regression analysis was used to test the variables ability to classify PD gait. ResultsThe variables were mostly unique from each other (67% of variables recorded an r < 0.3). Univariate and multivariate analysis showed that UB variables were moderately better at classifying PD gait than the spatiotemporal characteristics (Univariate: 0.70 to 0.81, Multivariate: 0.88 to 0.91 AUC). SignificanceThis study showed for the first time that, if aiming at objective and optimal sensitive biomarkers for PD, UB variables should be measured in conjunction with spatiotemporal characteristics to obtain a more holistic assessment of PD gait for use in a clinical or free-living environment.

Effect of a unilateral hind limb orthotic lift on upper body movement symmetry in the trotting horse

In trotting horses, movement asymmetry is associated with ground reaction force asymmetry. In humans, limb length differences influence contralateral force production. Here we investigate whether horses, in immediate reaction to limb length changes, show movement asymmetry adaptations consistent with reported force differences. Aim of this study was to quantify pelvic and compensatory head and withers movement asymmetry as a function of limb length changes after application of orthotic lifts. In this experimental study movement asymmetry of eleven trotting horses was calculated from vertical displacement of poll, withers, sacrum and left and right tuber coxae with inertial sensors. Horses were assessed in-hand under 5 conditions (all with hind limb boots): without orthotic lifts, and with a 15mm or 30mm orthotic lift applied to the left hind or right hind. A linear mixed model investigated the influence of orthotic lift condition (P<0.05, pairwise posthoc Bonferroni correction). Pelvic movement asymmetry showed increased pelvic downward movement during stance of the shorter limb and increased pelvic upward movement during and after stance of the longer limb (P<0.001) with asymmetry changes of 3-7mm (4-10mm) for 15mm (30mm) lifts. Hip hike (tuber coxae movement asymmetry) was unaffected (P = 0.348). Head and withers movement asymmetry were affected less consistently (2 of 3 respectively 1 of 3 head or withers parameters). The small sample size of the study reduced generalizability, no direct force measurements were conducted and only immediate effects of orthotic lifts were assessed with no re-assessments days or weeks after. Conclusions about mechanical consequences (weight bearing, pushoff) are based on published movement-force associations. Pelvic movement asymmetry with an artificial change in limb length through application of an orthotic lift indicates increased weight support with the shorter limb and increased pushoff with the longer limb. This may be of relevance for the management of horses with different hoof shapes between contralateral limbs, for example some chronically lame horse.

Determination of a sagittal plane axis of rotation for a dynamic office chair

ObjectiveThis study investigated the location of the axis of rotation in sagittal plane movement of the spine in a free sitting condition to adjust the kinematics of a mobile seat for a dynamic chair. BackgroundDynamic office chairs are designed to avoid continuous isometric muscle activity, and to facilitate increased mobility of the back during sitting. However, these chairs incorporate increased upper body movement which could distract office workers from the performance of their tasks. A chair with an axis of rotation above the seat would facilitate a stable upper back during movements of the lower back. The selection of a natural kinematic pattern is of high importance in order to match the properties of the spine. MethodTwenty-one participants performed four cycles of flexion and extension of the spine during an upper arm hang on parallel bars. The location of the axis of rotation relative to the seat was estimated using infrared cameras and reflective skin markers. ResultsThe median axis of rotation across all participants was located 36 cm above the seat for the complete movement and 39 cm for both the flexion and extension phases, each with an interquartile range of 20 cm. ConclusionThere was no significant effect of the movement direction on the location of the axis of rotation and only a weak, non-significant correlation between body height and the location of the axis of rotation. Individual movement patterns explained the majority of the variance. ApplicationThe axis of rotation for a spinal flexion/extension movement is located above the seat. The recommended radius for a guide rail of a mobile seat is between 36 cm and 39 cm.

The Contribution of Upper Body Movements to Dynamic Balance Regulation during Challenged Locomotion.

Recent studies suggest that in addition to movements between ankle and hip joints, movements of the upper body, in particular of the arms, also significantly contribute to postural control. In line with these suggestions, we analyzed regulatory movements of upper and lower body joints supporting dynamic balance regulation during challenged locomotion. The participants walked over three beams of varying width and under three different verbally conveyed restrictions of arm posture, to control the potential influence of arm movements on the performance: The participants walked (1) with their arms stretched out perpendicularly in the frontal plane, (2) spontaneously, i.e., without restrictions to the arm movements, and (3) with their hands on their thighs. After applying an inverse-dynamics analysis to the measured joint kinematics, we investigated the contribution of upper and lower body joints to balance regulation in terms of torque amplitude and variation. On the condition with the hands on the thighs, the contribution of the upper body remains significantly lower than the contribution of the lower body irrespective of beam widths. For spontaneous arm movements and for outstretched arms we find that the upper body (including the arms) contributes to the balancing to a similar extent as the lower body. Moreover, when the task becomes more difficult, i.e., for narrower beam widths, the contribution of the upper body increases, while the contribution of the lower body remains nearly constant. These findings lend further support to the hypothetical existence of an “upper body strategy” complementing the ankle and hip strategies especially during challenging dynamic balance tasks.

Relations between Automatically Extracted Motion Features and the Quality of Mother-Infant Interactions at 4 and 13 Months.

Bodily movements are an essential component of social interactions. However, the role of movement in early mother-infant interaction has received little attention in the research literature. The aim of the present study was to investigate the relationship between automatically extracted motion features and interaction quality in mother-infant interactions at 4 and 13 months. The sample consisted of 19 mother-infant dyads at 4 months and 33 mother-infant dyads at 13 months. The coding system Coding Interactive Behavior (CIB) was used for rating the quality of the interactions. Kinetic energy of upper-body, arms and head motion was calculated and used as segmentation in order to extract coarse- and fine-grained motion features. Spearman correlations were conducted between the composites derived from the CIB and the coarse- and fine-grained motion features. At both 4 and 13 months, longer durations of maternal arm motion and infant upper-body motion were associated with more aversive interactions, i.e., more parent-led interactions and more infant negativity. Further, at 4 months, the amount of motion silence was related to more adaptive interactions, i.e., more sensitive and child-led interactions. Analyses of the fine-grained motion features showed that if the mother coordinates her head movements with her infant's head movements, the interaction is rated as more adaptive in terms of less infant negativity and less dyadic negative states. We found more and stronger correlations between the motion features and the interaction qualities at 4 compared to 13 months. These results highlight that motion features are related to the quality of mother-infant interactions. Factors such as infant age and interaction set-up are likely to modify the meaning and importance of different motion features.

Asymmetrical trunk movement during walking improved to normal range at 3months after corrective posterior spinal fusion in adolescent idiopathic scoliosis.

To investigate the effects of posterior spinal fusion (PSF) and curve type on upper body movements in Adolescent Idiopathic Scoliosis (AIS) patients during gait. Twenty-four girls (12-18years) with AIS underwent PSF. 3D-Gait-analyses were performed preoperatively, at 3months and 1year postoperatively. Mean position (0° represents symmetry) and range of motion (ROM) of the trunk (thorax-relative-to-pelvis) in all planes were assessed. Lower body kinematics and spatiotemporal parameters were also evaluated. Mean trunk position improved from 7.0° to 2.9° in transversal plane and from 5.0° to - 0.8° in frontal plane at 3months postoperative (p<0.001), and was maintained at 1year. Trunk ROM in transverse plane decreased from 9.6° to 7.5° (p<0.001) after surgery. No effects of PSF were observed on the lower body kinematics during the gait cycle. Patients with a double curve had a more axial rotated trunk before and after surgery (p=0.013). In AIS patients, during gait an evident asymmetrical position of the trunk improved to an almost symmetric situation already 3months after PSF and was maintained at 1year. Despite a reduction of trunk ROM, patients were able to maintain the same walking pattern in the lower extremities after surgery. This improvement of symmetry and maintenance of normal gait can explain the rapid recovery and well functioning in daily life of AIS patients, despite undergoing a fusion of large parts of their spine.

Force direction patterns promote whole body stability even in hip-flexed walking, but not upper body stability in human upright walking.

Directing the ground reaction forces to a focal point above the centre of mass of the whole body promotes whole body stability in human and animal gaits similar to a physical pendulum. Here we show that this is the case in human hip-flexed walking as well. For all upper body orientations (upright, 25°, 50°, maximum), the focal point was well above the centre of mass of the whole body, suggesting its general relevance for walking. Deviations of the forces' lines of action from the focal point increased with upper body inclination from 25 to 43 mm root mean square deviation (RMSD). With respect to the upper body in upright gait, the resulting force also passed near a focal point (17 mm RMSD between the net forces' lines of action and focal point), but this point was 18 cm below its centre of mass. While this behaviour mimics an unstable inverted pendulum, it leads to resulting torques of alternating sign in accordance with periodic upper body motion and probably provides for low metabolic cost of upright gait by keeping hip torques small. Stabilization of the upper body is a consequence of other mechanisms, e.g. hip reflexes or muscle preflexes.

Effects of Central and Peripheral Vision Occlusion on Motor Performance during Hand Coordination Tasks

OCCUPATIONAL APPLICATIONS Our study examined the influences of visual occlusion on healthy adults during the performance of hand coordination tasks. We found that central vision occlusion, similar to that seen in age-related macular degeneration, reduced all aspects of prehension (grasp, reach, place, and return). In contrast, peripheral vision occlusion, similar to that seen in glaucoma, only affected grasp. Furthermore, the effects of vision occlusion were more pronounced during more complex prehension tasks. Age-related macular degeneration and glaucoma, which both cause vision occlusion, are common in older workers, and our results suggest that these disorders may adversely affect task efficiency and safety during complex hand coordination tasks. Further study of the effects of age-related vision issues are needed, though, to understand any effects on work disability among individuals with age-related visual disorders.TECHNICAL ABSTRACT Background: Vision loss is associated with changes in work performance that may result in work disability. Purpose: The current study was conducted to examine the effect of simulated central and peripheral vision loss on motor performance during hand coordination tasks in a sample of healthy adults. We hypothesized that central vision occlusion would have a greater effect on (1) hand coordination (increased time) and (2) upper body movement (increased path length) than either peripheral vision occlusion or normal vision (unoccluded). Methods: Nine healthy young adults with normal ocular histories completed two coordination tasks of varying visual complexity (insertion of cylindrical pegs and key-shaped pegs) under three visual conditions: central and peripheral vision occluded with special contact lenses and unoccluded vision. Outcome variables of time and path length (motion capture kinematic analyses) were calculated for four components of prehension (grasp, reach, place, return). Results: Central vision occlusion resulted in statistically significant but small reductions in grasp, reach, and place times compared to peripheral vision occlusion (p < 0.001, d = −0.24 to −0.58), and significant but small increases in path lengths for grasp, reach, place, and return (p < 0.05, d = −0.21 to −0.56). Differences in outcomes among the coordination tasks were dependent on task complexity.Conclusions: Simulated visual field loss resulted in slower hand coordination and increased upper body movement for central vision occlusion compared to peripheral vision occlusion. Using healthy adults allowed us to control for age-related impairments that could confound our ability to detect the effects of vision. With the increasing number of older adults with visual impairment who will remain in the workforce, we must further study the effects of vision loss on work performance in people with age-related visual diseases to determine what interventions may be necessary to mitigate their effects.

Children show limited movement repertoire when learning a novel motor skill.

Examining age differences in motor learning using real-world tasks is often problematic due to task novelty and biomechanical confounds. Here, we investigated how children and adults acquire a novel motor skill in a virtual environment. Participants of three different age groups (9-year-olds, 12-year-olds, and adults) learned to use their upper body movements to control a cursor on a computer screen. Results showed that 9-year-old and 12-year-old children showed poorer ability to control the cursor at the end of practice. Critically, when we investigated the movement coordination, we found that the lower task performance of children was associated with limited exploration of their movement repertoire. These results reveal the critical role of motor exploration in understanding developmental differences in motor learning.

Walking with wider steps changes foot placement control, increases kinematic variability and does not improve linear stability.

Walking humans respond to pulls or pushes on their upper body by changing where they place their foot on the next step. Usually, they place their foot further along the direction of the upper body perturbation. Here, we examine how this foot placement response is affected by the average step width during walking. We performed experiments with humans walking on a treadmill, both normally and at five different prescribed step widths. We prescribed step widths by requiring subjects to step on lines drawn on the treadmill belt. We inferred a linear model between the torso marker state at mid-stance and the next foot position. The coefficients in this linear model (which are analogous to feedback gains for foot placement) changed with increasing step width as follows. The sideways foot placement response to a given sideways torso deviation decreased. The fore–aft foot placement response to a given fore–aft torso deviation also decreased. Coupling between fore–aft foot placement and sideways torso deviations increased. These changes in foot placement feedback gains did not significantly affect walking stability as quantified by Floquet multipliers (which estimate how quickly the system corrects a small perturbation), despite increasing foot placement variance and upper body motion variance (kinematic variability).

운전자 상체 경사운동이 안정성에 미치는 영향에 관한 연구

The purpose of this study is to analyze the effect of upper body motion on bicycle self-stability. The bicycle equation of motion considering the driver"s upper body lean motion was developed and the influence of the upper body lean motion on stability was investigated. The linearized equations of motion of the bicycle, which is a constrained multibody dynamics system, was obtained by applying a systematic method. It is confirmed that the prediction results of the linear model show the same results in the nonlinear bicycle model through the multibody dynamics model simulation.

Veterinary student competence in equine lameness recognition and assessment: a mixed methods study

The development of perceptual skills is an important aspect of veterinary education. The authors investigated veterinary student competency in lameness evaluation at two stages, before (third year) and during (fourth/fifth...

Measuring upper body motion provides unique information about gait impairment in the early stages of Parkinson’s disease

Measuring upper body motion provides unique information about gait impairment in the early stages of Parkinson’s disease

Learning new movements after paralysis: Results from a home-based study

Body-machine interfaces (BMIs) decode upper-body motion for operating devices, such as computers and wheelchairs. We developed a low-cost portable BMI for survivors of cervical spinal cord injury and investigated it as a means to support personalized assistance and therapy within the home environment. Depending on the specific impairment of each participant, we modified the interface gains to restore a higher level of upper body mobility. The use of the BMI over one month led to increased range of motion and force at the shoulders in chronic survivors. Concurrently, subjects learned to reorganize their body motions as they practiced the control of a computer cursor to perform different tasks and games. The BMI allowed subjects to generate any movement of the cursor with different motions of their body. Through practice subjects demonstrated a tendency to increase the similarity between the body motions used to control the cursor in distinct tasks. Nevertheless, by the end of learning, some significant and persistent differences appeared to persist. This suggests the ability of the central nervous system to concurrently learn operating the BMI while exploiting the possibility to adapt the available mobility to the specific spatio-temporal requirements of each task.

Analysis of the posture pattern during robotic simulator tasks using an optical motion capture system

Surgeons are sometimes forced to maintain uncomfortable joint positions during robotic surgery despite the high degree of instrument maneuverability. This study aimed to use an optical motion capture system to analyze the differences in posture patterns during robotic simulator tasks between surgeons at two skill levels. Ten experienced and ten novice surgeons performed two tasks in a da Vinci Skills Simulator: Suture Sponge 1 (SP) and Tubes (TU). The participants' upper body motion during each task was captured, including the joint angles (axilla, elbow, and wrist), the percentage of time when the wrist height was lower than the elbow height (PTW), and the height of the elbow and wrist relative to the armrest. The novice group showed significantly more excess extension in both elbow angles and extension (>50°) in both wrist angles than did the experienced group. The novice group had significantly lower PTW than the experienced group on the right side in both tasks (both p<0.001), and on the left side in SP (p<0.001). Compared with the experienced group, the novice group had a significantly higher elbow relative to the armrest on the right side (SP, TU: p<0.05), and a significantly lower wrist relative to the armrest on the right side (SP, TU: p<0.05). An optical motion capture system can detect the differences in posture patterns in the positional relationship between the elbow and wrist and the joint angles of the upper limb between two groups of surgeons at different skill levels during robotic simulator tasks.

Use of dynamic movement orthoses to improve gait stability and trunk control in ataxic patients.

Patients with cerebellar ataxia show increased upper body movements, which have an impact on balance and walking. In this study, we investigated the effect of using dynamic movement orthoses (DMO), designed as elastic suits, on trunk motion and gait parameters. Longitudinal uncontrolled study. Outpatient rehabilitation unit. Eleven patients (7 men, 4 women; mean age: 49.9±9.5 years) with degenerative cerebellar ataxia were enrolled in this study. Linear overground gait of patients was recorded by means of an optoelectronic gait analysis system before DMO use (DMO-) and during DMO use (DMO+). Time-distance parameters, lower limb joint kinematics, body sway, trunk oscillations, and gait variability (coefficient of variation [CV]) were recorded. Patient satisfaction with DMO device was measured using Quebec user evaluation of satisfaction with assistive technology. When using the DMO, patients showed a significant decrease in stance phase duration, double support phase duration, swing phase CV, pelvic range of motion (ROM), body sway, and trunk ROMs. A significant increase was observed in the swing phase duration and knee joint ROM. Out of 11 patients, 10 were either quite satisfied (8 points) or very satisfied (2 points) with the assistive device. The DMO reduce the upper body motion and in improve balance-related gait parameters. We propose use of DMO as an assistive/rehabilitative device in the neurorehabilitation of cerebellar ataxia to improve the trunk control and gait stability. DMO may be considered a prototype that can be modified in terms of material characteristics, textile layers, elastic components, and diagonal and lateral seams.

Do subjective assessments of running patterns reflect objective parameters?

Running patterns are often categorized into subgroups according to common features before data analysis and interpretation. The Volodalen® method is a simple field-based tool used to classify runners into aerial or terrestrial using a 5-item subjective rating scale. We aimed to validate the Volodalen® method by quantifying the relationship between its subjective scores and 3D biomechanical measures. Fifty-four runners ran 30 s on a treadmill at 10, 12, 14, 16, and 18 km h−1 while their kinematics were assessed subjectively using the Volodalen® method and objectively using 3D motion capture. For each runner and speed, two researchers scored the five Volodalen® items on a 1-to-5 scale, which addressed vertical oscillation, upper-body motion, pelvis and foot position at ground contact, and footstrike pattern. Seven 3D biomechanical parameters reflecting the subjective items were also collected and correlated to the subjective scores. Twenty-eight runners were classified as aerial and 26 as terrestrial. Runner classification did not change with speed, but the relative contribution of the biomechanical parameters to the subjective classification was speed dependent. The magnitude of correlations between subjective and objective measures ranged from trivial to very large. Five of the seven objective parameters significantly differed between aerial and terrestrial runners, and these parameters demonstrated the strongest correlations to the subjective scores. Our results support the validity of the Volodalen® method, whereby the visual appreciation of running gait reflected quantifiable objective parameters. Two minor modifications to the method are proposed to simplify its use and improve agreement between subjective and objective measures.

A musculoskeletal model driven by dual Microsoft Kinect Sensor data

Musculoskeletal modeling is becoming a standard method to estimate muscle, ligament and joint forces non-invasively. As input, these models often use kinematic data obtained using marker-based motion capture, which, however, is associated with several limitations, such as soft tissue artefacts and the time-consuming task of attaching markers. These issues can potentially be addressed by applying marker-less motion capture. Therefore, we developed a musculoskeletal model driven by marker-less motion capture data, based on two Microsoft Kinect Sensors and iPi Motion Capture software, which incorporated a method for predicting ground reaction forces and moments. For validation, selected model outputs (e.g. ground reaction forces, joint reaction forces, joint angles and joint range-of-motion) were compared to musculoskeletal models driven by simultaneously recorded marker-based motion capture data from 10 males performing gait and shoulder abduction with and without external load. The primary findings were that the vertical ground reaction force during gait and the shoulder abduction/adduction angles, glenohumeral joint reaction forces and deltoideus forces during both shoulder abduction tasks showed comparable results. In addition, shoulder abduction/adduction range-of-motions were not significantly different between the two systems. However, the lower extremity joint angles, moments and reaction forces showed discrepancies during gait with correlations ranging from weak to strong, and for the majority of the variables, the marker-less system showed larger standard deviations. Although discrepancies between the systems were identified, the marker-less system shows potential, especially for tracking simple upper-body movements.