Matching Items (10)

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Assessment of Upper Limb Function and the Underlying Movement Strategies with Potential Application to Rotator Cuff Tears

Description

Introduction: Individuals with rotator cuff tears (RCT) have been found to compensate in their movement patterns by using lower thoracohumeral elevation angles during certain tasks, as well as increased internal

Introduction: Individuals with rotator cuff tears (RCT) have been found to compensate in their movement patterns by using lower thoracohumeral elevation angles during certain tasks, as well as increased internal rotation of the shoulder (Vidt et al., 2016). The leading joint hypothesis (LJH) suggests there is one leading joint that creates the foundation for the entire limb motion, and there are other subordinate joints that monitor the passive interaction torque (IT) and create a net torque (NT) aiding to limb motions required for the task. This experiment hopes to establish a better understanding of joint control strategies during a wide range of arm movements. Based off of the LJH, we hypothesize that when a subject has a rotator cuff tear, their performance of planar and three- dimensional motions should be altered not only at the shoulder, which is often the leading joint, but also at other joints on the arm such as the elbow and wrist.

Methods: There were 3 groups of participants: healthy younger adults (age 21.74 ± 1.97), healthy older adult controls (age 69.53 ± 6.85), and older adults with a RCT (age 64.33 ± 4.04). All three groups completed strength testing, horizontal drawing and pointing tasks, and three-dimensional (3D) activities of daily living (ADLs). Kinematic and kinetic variables of the arm were obtained during horizontal and 3D tasks using data from 13 reflective markers placed on the arm and trunk, 8 motion capture cameras, and Cortex motion capture software (Motion Analysis Corp., Santa Rosa, CA). During these tasks, electromyography (EMG) electrodes were placed on 12 muscles along the arm that affect shoulder, elbow, and wrist rotation. Strength testing tasks were measured using a dynamometer. All strength testing and 3D tasks were completed for three trials and horizontal tasks were completed for two trials.

Results: Results of the younger adult participants showed that during the forward portion of seven 3D tasks, there were four phases of different joint control mechanics seen in a majority of the movements. These phases included active rotation of both the shoulder and the elbow joint, active rotation of the shoulder with passive rotation of the elbow, passive rotation of the shoulder with active rotation of the elbow, and passive rotation of both the shoulder and the elbow. Passive rotation during movements was a result of gravitational torque (GT) on the different segments of the arm and IT caused as a result the multi-joint structure of human limbs. The number of tested participants for the healthy older adults and RCT older adults groups is not yet high enough to produce significant results and because of this their results are not reported in this article.

Discussion: Through the available results, multiple phases were found where one or both of the joints of the arm moved passively which further supports the LJH and extends it to include 3D movements. This article is a part of a bigger project which hopes to get a better understanding of how older adults adjust to large passive torques acting on the arm during 3D movements and how older adults with RCTs compensate for the decreased strength, the decreased range of motion (ROM), and the pain that accompany these types of tears. Hopefully the results of this experiment lead to more research toward better understanding how to treat patients with RCTs.

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Date Created
  • 2018-05

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A Mechanical Analysis of Trained Violinist Kinematics

Description

Central to current conceptions concerning the function of the nervous system is the consideration of how it manages to maintain precise control for repetitive tasks such as reaching, given the

Central to current conceptions concerning the function of the nervous system is the consideration of how it manages to maintain precise control for repetitive tasks such as reaching, given the extensive observable mechanical degrees of freedom. Especially in the upper extremities, there are an infinite number of orientations (degrees of freedom) that can produce the same ultimate outcome. Consider, for example, a man in a seated position pointing to an object on a table with his index finger: even if we vastly simplify the mechanics involved in that action by considering three principle joints - the shoulder, elbow, and wrist - there are an infinite number of upper arm orientations that would result in the same position of the man's index finger in three-dimensional space. It has been hypothesized that the central nervous system is capable of simplifying reaching tasks by organizing the DOFs; this suggests that repetitive, simple tasks such as reaching can be planned, that the variability in repetitive tasks is minimized, and that the central nervous system is capable of increasing stability by instantaneously resisting perturbations. Previous literature indicates that variability is decreased and stability increased in trained upper extremity movement. In this study, mechanical discrepancies between violinists of varying levels of experience were identified. It was hypothesized that variability in the positional error (deviation from an expected line of motion) and velocity of the bow, as well as the produced variability in resultant elbow angles, would decrease with increasing proficiency, and that training would have no observable effect on average peak bow velocity. Data acquisition was accomplished by constructing LED triads and implementing a PhaseSpace 3D Motion Capture system. While the positional variance and peak velocity magnitude of the bow appeared unaffected by training (p >> 0.05), more advanced players demonstrated significantly higher variability in bow velocity (p << 0.001). As such, it can be concluded that repetitive training does manifest in changes in variability; however, further investigation is required to reveal the nature of these changes.

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Created

Date Created
  • 2018-05

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Kinematics of Soccer Players During a 5-10-5 Agility Drill

Description

Purpose: The purpose of this study was to observe similarities and differences within soccer players during a 5-10-5 agility drill between the first and second change of direction. Overall body

Purpose: The purpose of this study was to observe similarities and differences within soccer players during a 5-10-5 agility drill between the first and second change of direction. Overall body mechanics and center of mass position relative to the feet were assessed within players. Methods: A total of 6 soccer players participated in the study. Each player ran through the 5-10-5 agility drill 10 times. All trials were video recorded and oriented to include the whole drill. Data was assessed using the program Kinovea (open-source) for 5 out of the 6 players. One player was excluded due to not meeting the inclusion criteria. The metrics assessed were total time to complete the task, the change of direction time, the time it took for the lag leg to stop moving laterally to the planting of the lead leg, and the leg angle. All tasks, except for total task time, were assessed for both the first and second change of direction. An individual analysis was performed for each player in order to obtain observational differences between the first and second change of direction for players. Results: The total task time determined the order of the players, thus the fastest player became player 1 and the slowest player 5. Players 1, 2, 4, and 5 were all found to have a statistical significance in change of direction time. When statistically significant the change of direction time was faster for the second change of direction. The slower players, player 4 and 5, had a statistically significant difference in leg angle, with the leg angle being larger for the first change of direction. Player 3 had no significant differences between any of the metrics. When looking closer at the faster players an observable difference in center of mass position relative to the feet was observed. The second change of direction showed the center of mass being positioned further anterior to the feet, and better mechanics were used to slow down and prepare to change direction. Discussion: The center of mass position relative to the feet could likely explain why the second change of direction was faster for 4 out of the 5 players. With the current information from the present study it could be adapted to help coaches instruct players to incorporate better mechanics into their change of direction tasks, and possibly improve their agility. This study could be improved by using multiple camera angles, high definition cameras, body markers, and force plates. By using these tools information could be obtained about variables that impact change of direction tasks but were not measured in the current study.

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Date Created
  • 2020-12

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Applications of Machine Learning to Animation and Computer Graphics for Optimized Real-Time Performance

Description

This thesis surveys and analyzes applications of machine learning techniques to the fields of animation and computer graphics. Data-driven techniques utilizing machine learning have in recent years been successfully applied

This thesis surveys and analyzes applications of machine learning techniques to the fields of animation and computer graphics. Data-driven techniques utilizing machine learning have in recent years been successfully applied to many subfields of animation and computer graphics. These include, but are not limited to, fluid dynamics, kinematics, and character modeling. I argue that such applications offer significant advantages which will be pivotal in advancing the fields of animation and computer graphics. Further, I argue these advantages are especially relevant in real-time implementations when working with finite computational resources.

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Created

Date Created
  • 2019-05

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Force Measurement of Basilisk Lizard Running on Water

Description

Basilisk lizards are often studied for their unique ability to run across the surface of

water. Due to the complicated fluid dynamics of this process, the forces applied on the

water’s surface

Basilisk lizards are often studied for their unique ability to run across the surface of

water. Due to the complicated fluid dynamics of this process, the forces applied on the

water’s surface cannot be measured using traditional methods. This thesis presents a

novel technique of measuring the forces using a fluid dynamic force platform (FDFP),

a light, rigid box immersed in water. This platform, along with a motion capture

system, can be used to characterize the kinematics and dynamics of a basilisk lizard

running on water. This could ultimately lead to robots that can run on water in a

similar manner.

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Agent

Created

Date Created
  • 2019

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Impact of Total Knee Arthroplasty on Dynamic Fall Response

Description

Falls are the leading cause of fatal and non-fatal injuries in the older adult population with more than 27,000 fall related deaths reported every year[1]. Adults suffering from lower extremity

Falls are the leading cause of fatal and non-fatal injuries in the older adult population with more than 27,000 fall related deaths reported every year[1]. Adults suffering from lower extremity arthritis have more than twice the likelihood of experiencing multiple falls resulting in increased fall-related injuries compared to healthy adults. People with lower extremity end-stage osteoarthritis(KOA), experience a number of fall risk factors such as knee instability, poor mobility, and knee pain/stiffness. At end-stage knee OA, the space between the bones in the joint of the knee is significantly reduced, resulting in bone to bone frictional wearing causing bone deformation. In addition, an impaired stepping response during a postural perturbation is seen in people with OA related knee instability. The most common treatment for end-stage knee osteoarthritis is a surgical procedure called, total knee replacement (TKR). It is known that TKR significantly reduces pain, knee stiffness, and restores musculoskeletal functions such as range of motion. Despite studies concluding that knee OA increases fall-risk, it remains unknown if standard treatments, such as TKR, can effectively decrease fall-risk. Analyzing the compensatory step response during a fall is a significant indicator of whether a fall or a recovery will occur in the event of a postural disturbance and is key to determining fall risk among people. Studies have shown reduced trunk stability and step length, as well as increased trunk velocities, correspond to an impaired compensatory step. This study looks at these populations to determine whether TKR significantly enhances compensatory stepping response by analyzing trunk velocities and flexions among other kinematic/kinetic variable analysis during treadmill induced perturbations and clinical assessments.

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Agent

Created

Date Created
  • 2019

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Adaptive mixed reality rehabilitation for stroke

Description

Millions of Americans live with motor impairments resulting from a stroke and the best way to administer rehabilitative therapy to achieve recovery is not well understood. Adaptive mixed reality rehabilitation

Millions of Americans live with motor impairments resulting from a stroke and the best way to administer rehabilitative therapy to achieve recovery is not well understood. Adaptive mixed reality rehabilitation (AMRR) is a novel integration of motion capture technology and high-level media computing that provides precise kinematic measurements and engaging multimodal feedback for self-assessment during a therapeutic task. The AMRR system was evaluated in a small (N=3) cohort of stroke survivors to determine best practices for administering adaptive, media-based therapy. A proof of concept study followed, examining changes in clinical scale and kinematic performances among a group of stroke survivors who received either a month of AMRR therapy (N = 11) or matched dosing of traditional repetitive task therapy (N = 10). Both groups demonstrated statistically significant improvements in Wolf Motor Function Test and upper-extremity Fugl-Meyer Assessment scores, indicating increased function after the therapy. However, only participants who received AMRR therapy showed a consistent improvement in their kinematic measurements, including those measured in the trained reaching task (reaching to grasp a cone) and in an untrained reaching task (reaching to push a lighted button). These results suggest that that the AMRR system can be used as a therapy tool to enhance both functionality and reaching kinematics that quantify movement quality. Additionally, the AMRR concepts are currently being transitioned to a home-based training application. An inexpensive, easy-to-use, toolkit of tangible objects has been developed to sense, assess and provide feedback on hand function during different functional activities. These objects have been shown to accurately and consistently track hand function in people with unimpaired movements and will be tested with stroke survivors in the future.

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Agent

Created

Date Created
  • 2012

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Movement kinematics and fractal properties in Fitts' law task

Description

Fractal analyses examine variability in a time series to look for temporal structure

or pattern that reveals the underlying processes of a complex system. Although fractal

property has been found in many

Fractal analyses examine variability in a time series to look for temporal structure

or pattern that reveals the underlying processes of a complex system. Although fractal

property has been found in many signals in biological systems, how it relates to

behavioral performance and what it implies about the complex system under scrutiny are

still open questions. In this series of experiments, fractal property, movement kinematics,

and behavioral performance were measured on participants performing a reciprocal

tapping task. In Experiment 1, the results indicated that the alpha value from detrended

fluctuation analysis (DFA) reflected deteriorating performance when visual feedback

delay was introduced into the reciprocal tapping task. This finding suggests that this

fractal index is sensitive to performance level in a movement task. In Experiment 2, the

sensitivity of DFA alpha to the coupling strength between sub-processes within a system

was examined by manipulation of task space visibility. The results showed that DFA

alpha was not influenced by disruption of subsystems coupling strength. In Experiment 3,

the sensitivity of DFA alpha to the level of adaptivity in a system under constraints was

examined. Manipulation of the level of adaptivity was not successful, leading to

inconclusive results to this question.

Contributors

Agent

Created

Date Created
  • 2019

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Effects of pressure and free throw routine on basketball kinematics and sport performance

Description

In sports, athletes reach new levels every day and are truly masters of their own bodies. Yet, when placed under pressure, the pin-point accuracy and elite level of performance can

In sports, athletes reach new levels every day and are truly masters of their own bodies. Yet, when placed under pressure, the pin-point accuracy and elite level of performance can begin to wane.  Despite plentiful literature investigating the effects of pressure on performance, the underlying mechanisms behind decreased performance in sport are not yet clear.  The current research discusses possible theories for “choking under pressure”, the specific mechanisms through which pressure has its effects, and methods to prevent “choking.”  Fourteen current and former basketball players shot free throws with two primary predictor variables: the presence/absence of performance pressure and the restriction
on-restriction of movement during the pre-shot routine. Results were analyzed using 2x2 Within-Subjects Analysis of Variance. For shooting performance, there was an interaction (approaching significance) such that participants were more affected by pressure when allowed to execute their pre-shot routine. For kinematic variables, significant interactions between pressure and movement restriction were found for elbow-knee cross correlations and there were significant main effects of variability of the acceleration of both the elbow and knee angles. In all kinematic measures, participants exhibited more “novice-like” patterns of movement under pressure when movement was not restricted during the pre-shot routine. Primary results indicate promising evidence that motor control may be a mediating variable between pressure and performance and bring into question the value of a pre-shot routine in basketball.

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Agent

Created

Date Created
  • 2017

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The theory behind setup maps: a computational tool to position parts for machining

Description

When manufacturing large or complex parts, often a rough operation such as casting is used to create the majority of the part geometry. Due to the highly variable nature of

When manufacturing large or complex parts, often a rough operation such as casting is used to create the majority of the part geometry. Due to the highly variable nature of the casting process, for mechanical components that require precision surfaces for functionality or assembly with others, some of the important features are machined to specification. Depending on the relative locations of as-cast to-be-machined features and the amount of material at each, the part may be positioned or ‘set up’ on a fixture in a configuration that will ensure that the pre-specified machining operations will successfully clean up the rough surfaces and produce a part that conforms to any assigned tolerances. For a particular part whose features incur excessive deviation in the casting process, it may be that no setup would yield an acceptable final part. The proposed Setup-Map (S-Map) describes the positions and orientations of a part that will allow for it to be successfully machined, and will be able to determine if a particular part cannot be made to specification.

The Setup Map is a point space in six dimensions where each of the six orthogonal coordinates corresponds to one of the rigid-body displacements in three dimensional space: three rotations and three translations. Any point within the boundaries of the Setup-Map (S-Map) corresponds to a small displacement of the part that satisfies the condition that each feature will lie within its associated tolerance zone after machining. The process for creating the S-Map involves the representation of constraints imposed by the tolerances in simple coordinate systems for each to-be-machined feature. Constraints are then transformed to a single coordinate system where the intersection reveals the common allowable ‘setup’ points. Should an intersection of the six-dimensional constraints exist, an optimization scheme is used to choose a single setup that gives the best chance for machining to be completed successfully. Should no intersection exist, the particular part cannot be machined to specification or must be re-worked with weld metal added to specific locations.

Contributors

Agent

Created

Date Created
  • 2016