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- All Subjects: Kinematics
- Creators: Davidson, Joseph K.
- Creators: Garnica, Nicholas
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 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.
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.
ContributorsGarnica, Nicholas (Co-author) / Perrine, Austin (Co-author) / Schalk, Courtney (Co-author) / Dounskaia, Natalia (Thesis director) / Vidt, Meghan (Committee member) / School of Nutrition and Health Promotion (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
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 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.
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.
ContributorsKalish, Nathan (Author) / Davidson, Joseph K. (Thesis advisor) / Shah, Jami J. (Thesis advisor) / Ren, Yi (Committee member) / Arizona State University (Publisher)
Created2016