scholarly journals Synergies reciprocally relate end-effector and joint-angles in rhythmic pointing movements

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tim A. Valk ◽  
Leonora J. Mouton ◽  
Egbert Otten ◽  
Raoul M. Bongers
Keyword(s):  
Dynamical System ◽  
Degrees Of Freedom ◽  
Index Finger ◽  
Elbow Flexion ◽  
Human Action ◽  
Joint Angles ◽  
End Effector ◽  
Action System ◽  
Flexion Extension ◽  
Pointing Movements

AbstractDuring rhythmic pointing movements, degrees of freedom (DOF) in the human action system—such as joint-angles in the arm—are assumed to covary to stabilise end-effector movement, e.g. index finger. In this paper, it is suggested that the end-effector movement and the coordination of DOF are reciprocally related in synergies that link DOF so as to produce the end-effector movement. The coordination of DOF in synergies and the relation between end-effector movement and DOF coordination received little attention, though essential to understand the principles of synergy formation. Therefore, the current study assessed how the end-effector movement related to the coordination of joint-angles during rhythmic pointing across target widths and distances. Results demonstrated that joint-angles were linked in different synergies when end-effector movements differed across conditions. Furthermore, in every condition, three joint-angles (shoulder plane of elevation, shoulder inward-outward rotation, elbow flexion-extension) largely drove the end-effector, and all joint-angles contributed to covariation that stabilised the end-effector. Together, results demonstrated synergies that produced the end-effector movement, constrained joint-angles so that they covaried to stabilise the end-effector, and differed when end-effector movement differed. Hence, end-effector and joint-angles were reciprocally related in synergies—indicating that the action system was organised as a complex dynamical system.

scholarly journals Arm Position Constraints During Pointing and Reaching in 3-D Space

1997 ◽  
Vol 78 (2) ◽  
pp. 660-673 ◽  
Author(s):  
C.C.A.M. Gielen ◽  
E. J. Vrijenhoek ◽  
T. Flash ◽  
S.F.W. Neggers
Keyword(s):  
Eye Movements ◽  
Degrees Of Freedom ◽  
Arm Movements ◽  
Saccadic Eye Movements ◽  
Elbow Flexion ◽  
Upper Arm ◽  
Arm Position ◽  
Flexion Extension ◽  
Pointing Movements ◽  
Rotation Vectors

Gielen, C.C.A.M., E. J. Vrijenhoek, T. Flash, and S.F.W. Neggers. Arm position constraints during pointing and reaching in 3-D space. J. Neurophysiol. 78: 660–673, 1997. Arm movements in 3-D space were studied to investigate the reduction in the number of rotational degrees of freedom in the shoulder and elbow during pointing movements with the fully extended arm and during pointing movements to targets in various directions and at various distances relative to the shoulder, requiring flexion/extension in the elbow. The postures of both the upper arm and forearm can be described by rotation vectors, which represent these postures as a rotation from a reference position to the current position. The rotation vectors describing the posture of the upper arm and forearm were found to lie in a 2-D (curved) surface both for pointing with the fully extended arm and for pointing with elbow flexion. This result generalizes on previous results on the reduction of the number of degrees of freedom from three to two in the shoulder for the fully extended arm to a similar reduction in the number of degrees of freedom for the upper arm and forearm for normal arm movements involving also elbow flexion and extension. The orientation of the 2-D surface fitted to the rotation vectors describing the position of the upper arm and forearm was the same for pointing with the extended arm and for movements with flexion/extension of the elbow. The scatter in torsion of the rotation vectors describing the position of the upper arm and forearm relative to the 2-D surface was typically 3–4°, which is small considering the range of ∼180 and 360° for torsional rotations of the upper arm and the forearm, respectively. Donders' law states that arm posture for pointing to a target does not depend on previous positions of the arm. The results of our experiments demonstrate that the upper arm violates Donders' law. However, the variations in torsion of the upper arm are small, typically a few degrees. These deviations from Donders' law have been overlooked in previous studies, presumably because the variations are relatively small. These variations may explain the larger scatter of the rotation vectors for arm movements (3–4°) than reported for the eye (1°). Unlike for saccadic eye movements, joint rotations in the shoulder during aiming movements were not all single-axis rotations. On the contrary, the direction of the angular velocity vector varied during the movement in a consistent and reproducible way, depending on amplitude, direction, and starting position of the movement. These results reveal several differences between arm movements during pointing and saccadic eye movements. The implications for our understanding of the coordination of eye and arm movements and for the planning of 3-D arm movements are discussed.

scholarly journals Design and evaluation of a novel upper limb rehabilitation robot with space training based on an end effector

2021 ◽  
Vol 12 (1) ◽  
pp. 639-648
Author(s):  
Qiaoling Meng ◽  
Zongqi Jiao ◽  
Hongliu Yu ◽  
Weisheng Zhang
Keyword(s):  
Upper Limb ◽  
Degrees Of Freedom ◽  
Elbow Flexion ◽  
Rehabilitation Robot ◽  
End Effector ◽  
Upper Limb Rehabilitation ◽  
Flexion Extension ◽  
Robot Configuration ◽  
Limb Rehabilitation ◽  
Equivalent Mechanism

Abstract. The target of this paper is to design a lightweight upper limb rehabilitation robot with space training based on end-effector configuration and to evaluate the performance of the proposed mechanism. In order to implement this purpose, an equivalent mechanism to the human being upper limb is proposed before the design. Then, a 4 degrees of freedom (DOF) end-effector-based upper limb rehabilitation robot configuration is designed to help stroke patients perform space rehabilitation training of the shoulder flexion/extension and adduction/abduction and elbow flexion/extension. Thereafter, its kinematical model is established together with the proposed equivalent upper limb mechanism. The Monte Carlo method is employed to establish their workspace. The results show that the overlap of the workspace between the proposed mechanism and the equivalent mechanism is 96.61 %. In addition, this paper also constructs a human–machine closed-chain mechanism to analyze the flexibility of the mechanism. According to the relative manipulability and manipulability ellipsoid, the highly flexible area of the mechanism accounts for 67.6 %, and the mechanism is far away from the singularity on the drinking trajectory. In the end, the single-joint training experiments and a drinking water training trajectory planning experiment are developed and the prototype is manufactured to verify it.

scholarly journals Recording of length-tension relationship of elbow flexors and extensors by varying elbow angle in human

2021 ◽  
Vol 64 ◽  
pp. S46-S50
Author(s):  
Hanjabam Barun Sharma ◽  
Arani Das ◽  
Prashant Tayade ◽  
Kishore K. Deepak
Keyword(s):  
Skeletal Muscle ◽  
Muscle Length ◽  
Elbow Flexion ◽  
Isometric Strength ◽  
Undergraduate Teaching ◽  
Joint Angles ◽  
Custom Made ◽  
Flexion Extension ◽  
Relationship Of ◽  
Living Person

Objectives: The concept of length-tension relationship in skeletal muscle can be studied in a living person by demonstrating the relationship between isometric strength and joint angles. There is lack of an effective practical module to demonstrate this concept in living person, hence the study was planned. Materials and Methods: A simple, feasible and novel practical is designed using a custom-made isometric elbow flexion-extension exercising instrument, in which isometric elbow strength is measured using a dynamometer against various elbow joint angles measured using a goniometer. Result: Elbow isometric strength varied across its joint angles and was maximum at the optimum angle, which was 90°. Conclusion: We propose a simple and novel practical to understand the skeletal muscle length-tension relationship in a living person partly, by using the angle-strength relationship for undergraduate teaching in physiology.

scholarly journals Wearable upper limb motion assist robot for eating activity

2020 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Uzair Kashtwari ◽  
Norsinnira Zainul Azlan ◽  
Ifrah Shahdad
Keyword(s):  
Upper Limb ◽  
Daily Living ◽  
Degrees Of Freedom ◽  
Low Cost ◽  
Elbow Flexion ◽  
Disabled People ◽  
Flexion Extension ◽  
Feeding Cycle ◽  
The Disabled ◽  
Upper Limb Movements

Many people all around the world are suffering from various types of disabilities and need to depend on others to perform activities of daily living. One of the essential daily living activities is eating. The disabled people should be able to eat their food independently at any time and place, without relying on the caregivers. This paper presents the development of a new wearable upper limb motion assist robot for helping the disabled to eat by themselves. The motion assists robot consists of two degrees of freedom (DOF) movement, focusing on the two most crucial upper limb movements in eating activity, which is the elbow flexion/extension and forearm pronation/supination. A light-weight material was used for the fabrication of the wearable motion assist robot, and Arduino was utilized as the microcontroller. The originality of the study was in terms of the design, operational sequence setting, and kinematic analysis of the wearable upper limb motion assist robot that was explicitly focusing on eating activity. The resulted prototype was portable, compact, light in weight, simple and low cost. The experimental results have proven that the proposed wearable upper limb motion assist robot for eating activity was successful in helping the users to perform the main upper extremity motions in eating. The success rate of the proposed system was 80%, and it took 6 seconds for the system to complete one feeding cycle.

scholarly journals Kinematic Analysis During Straight Line Free Swimming in Horses: Part 1 - Forelimbs

2021 ◽  
Vol 8 ◽  
Author(s):  
Emma Santosuosso ◽  
Renaud Leguillette ◽  
Tatiana Vinardell ◽  
Silvio Filho ◽  
Shannon Massie ◽  
...  
Keyword(s):  
Sports Medicine ◽  
Elbow Flexion ◽  
Carpal Bone ◽  
Joint Angles ◽  
Straight Line ◽  
Flexion Extension ◽  
Angular Velocities ◽  
Equine Sports ◽  
Swimming Kinematics ◽  
Rehabilitation Exercise

Background: Swimming is used for rehabilitation and conditioning purposes in equine sports medicine despite the lack of understanding of equine swimming kinematics. The aim of this study was to assess forelimb joints kinematics (elbow, carpus, and fetlock) in swimming horses. The specific objectives were 1- to calculate and compare joint angles in swimming vs. passive mobilizations (PM), 2- to determine joint angular velocities during a swimming stride cycle.Methods: Eleven elite endurance horses swam in a 100-m straight pool. Underwater (swimming) and overground (PM) videos were recorded from the horses' left side. Joint markers were applied on the lateral hoof wall, lateral metacarpal epicondyle, ulnar carpal bone, lateral humeral epicondyle, and the greater tubercle of humerus, from which elbow, carpus and fetlock angles, and angular velocities were obtained. As a reference, maximal fetlock, carpus, and elbow flexion/extension angles were determined during PM overground. Differences between angle extrema, angular velocities and range of motion (ROM) were compared.Results: Carpus and fetlock ROM were significantly smaller (p < 0.001) during swimming when compared with PM, while there was no difference in elbow ROM between both situations. The carpus had the greatest ROM of all joints during swimming. Absolute angular velocities values of all joints during swimming were greater during retraction than protraction (p < 0.001). When compared to other joints during protraction, the carpus joint reached the highest angular velocity.Conclusion: Swimming, as a rehabilitation exercise, has the potential to benefit horses where great elbow ROM with a moderate carpus and fetlock extension are wanted.

scholarly journals Control of redundant pointing movements involving the wrist and forearm

2018 ◽  
Vol 120 (4) ◽  
pp. 2138-2154 ◽  
Author(s):  
Garrett R. Dorman ◽  
Kevin C. Davis ◽  
Allan W. Peaden ◽  
Steven K. Charles
Keyword(s):  
Potential Energy ◽  
Path Length ◽  
Degrees Of Freedom ◽  
Control Strategies ◽  
Wrist Flexion ◽  
Forearm Rotation ◽  
Flexion Extension ◽  
Pointing Movements ◽  
Control Research ◽  
Observed Behavior

The musculoskeletal system can move in more ways than are strictly necessary, allowing many tasks to be accomplished with a variety of limb configurations. Why some configurations are preferred has been a focus of motor control research, but most studies have focused on shoulder-elbow or whole arm movements. This study focuses on movements involving forearm pronation-supination (PS), wrist flexion-extension (FE), and wrist radial-ulnar deviation (RUD) and elucidates how these three degrees of freedom (DOF) combine to perform the common task of pointing, which only requires two DOF. Although pointing is more sensitive to FE and RUD than to PS and could be easily accomplished with FE and RUD alone, subjects tend to involve a small amount of PS. However, why we choose this behavior has been unknown and is the focus of this paper. With the use of a second-order model with lumped parameters, we tested a number of plausible control strategies involving minimization of work, potential energy, torque, and path length. None of these control schemes robustly predicted the observed behavior. However, an alternative control scheme, hypothesized to control the DOF that were most important to the task (FE and RUD) and ignore the less important DOF (PS), matched the observed behavior well. In particular, the behavior observed in PS appears to be a mechanical side effect caused by unopposed interaction torques. We conclude that moderately sized pointing movements involving the wrist and forearm are controlled by ignoring forearm rotation even though this strategy does not robustly minimize work, potential energy, torque, or path length. NEW & NOTEWORTHY Many activities require us to point our hands in a given direction using wrist and forearm rotations. Although there are infinitely many ways to do this, we tend to follow a stereotyped pattern. Why we choose this pattern has been unknown and is the focus of this paper. After testing a variety of hypotheses, we conclude that the pattern results from a simplifying strategy in which we focus on wrist rotations and ignore forearm rotation.

scholarly journals Deep Learning-Based Upper Limb Functional Assessment Using a Single Kinect v2 Sensor

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1903 ◽  
Author(s):  
Ye Ma ◽  
Dongwei Liu ◽  
Laisi Cai
Keyword(s):  
Deep Learning ◽  
Upper Limb ◽  
Short Term Memory ◽  
External Rotation ◽  
Kinematic Model ◽  
Elbow Flexion ◽  
Supervised Machine Learning ◽  
Joint Angles ◽  
Kinect V2 ◽  
Flexion Extension

We develop a deep learning refined kinematic model for accurately assessing upper limb joint angles using a single Kinect v2 sensor. We train a long short-term memory recurrent neural network using a supervised machine learning architecture to compensate for the systematic error of the Kinect kinematic model, taking a marker-based three-dimensional motion capture system (3DMC) as the golden standard. A series of upper limb functional task experiments were conducted, namely hand to the contralateral shoulder, hand to mouth or drinking, combing hair, and hand to back pocket. Our deep learning-based model significantly improves the performance of a single Kinect v2 sensor for all investigated upper limb joint angles across all functional tasks. Using a single Kinect v2 sensor, our deep learning-based model could measure shoulder and elbow flexion/extension waveforms with mean CMCs >0.93 for all tasks, shoulder adduction/abduction, and internal/external rotation waveforms with mean CMCs >0.8 for most of the tasks. The mean deviations of angles at the point of target achieved and range of motion are under 5° for all investigated joint angles during all functional tasks. Compared with the 3DMC, our presented system is easier to operate and needs less laboratory space.

scholarly journals Robust Identification of Three-Dimensional Thumb and Index Finger Kinematics With a Minimal Set of Markers

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Raviraj Nataraj ◽  
Zong-Ming Li
Keyword(s):  
Coordinate System ◽  
Degrees Of Freedom ◽  
Index Finger ◽  
Three Dimensional ◽  
Axial Rotation ◽  
Solution Model ◽  
Convergence Criteria ◽  
Minimal Set ◽  
Motion Error ◽  
Flexion Extension

This study presents a methodology to determine thumb and index finger kinematics while utilizing a minimal set of markers. The motion capture of skin-surface markers presents inherent challenges for the accurate and comprehensive measurement of digit kinematics. As such, it is desirable to utilize robust methods for assessing digit kinematics with fewer markers. The approach presented in this study involved coordinate system alignment, locating joint centers of rotation, and a solution model to estimate three-dimensional (3-D) digit kinematics. The solution model for each digit was based on assumptions of rigid-body interactions, specific degrees of freedom (DOFs) at each located joint, and the aligned coordinate system definitions. Techniques of inverse kinematics and optimization were applied to calculate the 3-D position and orientation of digit segments during pinching between the thumb and index finger. The 3-D joint center locations were reliably fitted with mean coefficients of variation below 5%. A parameterized form of the solution model yielded feasible solutions that met specified tolerance and convergence criteria for over 85% of the test points. The solution results were intuitive to the pinching function. The thumb was measured to be rotated about the CMC joint to bring it into opposition to the index finger and larger rotational excursions (>10 deg) were observed in flexion/extension compared to abduction/adduction and axial rotation for all joints. While the solution model produced results similar to those computed from a full marker set, the model facilitated the usage of fewer markers, which inherently lessened the effects of passive motion error and reduced the post-experimental effort required for marker processing.

scholarly journals Measurements of Tendon Movement Within the Bicipital Groove After Suprapectoral Intra-articular Biceps Tenodesis in a Cadaveric Model

2021 ◽  
Vol 9 (1) ◽  
pp. 232596712097753
Author(s):  
Brian J. Kelly ◽  
Alan W. Reynolds ◽  
Patrick J. Schimoler ◽  
Alexander Kharlamov ◽  
Mark Carl Miller ◽  
...  
Keyword(s):  
Biceps Tendon ◽  
Full Range ◽  
Elbow Flexion ◽  
Biceps Tenodesis ◽  
Bicipital Groove ◽  
Biceps Tenotomy ◽  
Flexion Extension ◽  
Before And After ◽  
Long Head ◽  
Scapular Motion

Background: Lesions of the long head of the biceps can be successfully treated with biceps tenotomy or tenodesis when surgical management is elected. The advantage of a tenodesis is that it prevents the potential development of a cosmetic deformity or cramping muscle pain. Proponents of a subpectoral tenodesis believe that “groove pain” may remain a problem after suprapectoral tenodesis as a result of persistent motion of the tendon within the bicipital groove. Purpose/Hypothesis: To evaluate the motion of the biceps tendon within the bicipital groove before and after a suprapectoral intra-articular tenodesis. The hypothesis was that there would be minimal to no motion of the biceps tendon within the bicipital groove after tenodesis. Study Design: Controlled laboratory study. Methods: Six fresh-frozen cadaveric arms were dissected to expose the long head of the biceps tendon as well as the bicipital groove. Inclinometers and fiducials (optical markers) were used to measure the motions of the scapula, forearm, and biceps tendon through a full range of shoulder and elbow motions. A suprapectoral biceps tenodesis was then performed, and the motions were repeated. The motion of the biceps tendon was quantified as a function of scapular or forearm motion in each plane, both before and after the tenodesis. Results: There was minimal motion of the native biceps tendon during elbow flexion and extension but significant motion during all planes of scapular motion before tenodesis, with the most motion occurring during shoulder flexion-extension (20.73 ± 8.21 mm). The motion of the biceps tendon after tenodesis was significantly reduced during every plane of scapular motion compared with the native state ( P < .01 in all planes of motion), with a maximum motion of only 1.57 mm. Conclusion: There was a statistically significant reduction in motion of the biceps tendon in all planes of scapular motion after the intra-articular biceps tenodesis. The motion of the biceps tendon within the bicipital groove was essentially eliminated after the suprapectoral biceps tenodesis. Clinical Relevance: This arthroscopic suprapectoral tenodesis technique can significantly reduce motion of the biceps tendon within the groove in this cadaveric study, possibly reducing the likelihood of groove pain in the clinical setting.

scholarly journals Annular Defects Impair the Mechanical Stability of the Intervertebral Disc

2021 ◽  
pp. 219256822110060
Author(s):  
Jun-Xin Chen ◽  
Yun-He Li ◽  
Jian Wen ◽  
Zhen Li ◽  
Bin-Sheng Yu ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Degrees Of Freedom ◽  
Mechanical Stability ◽  
Biomechanical Testing ◽  
Bending Stiffness ◽  
Biomechanical Study ◽  
Torsional Stiffness ◽  
P Value ◽  
Lateral Bending ◽  
Flexion Extension

Study Design: A biomechanical study. Objectives: The purpose of this study was to investigate the effects of cruciform and square incisions of annulus fibrosus (AF) on the mechanical stability of bovine intervertebral disc (IVD) in multiple degrees of freedom. Methods: Eight bovine caudal IVD motion segments (bone-disc-bone) were obtained from the local abattoir. Cruciform and square incisions were made at the right side of the specimen’s annulus using a surgical scalpel. Biomechanical testing of three-dimensional 6 degrees of freedom was then performed on the bovine caudal motion segments using the mechanical testing and simulation (MTS) machine. Force, displacement, torque and angle were recorded synchronously by the MTS system. P value <.05 was considered statistically significant. Results: Cruciform and square incisions of the AF reduced both axial compressive and torsional stiffness of the IVD and were significantly lower than those of the intact specimens ( P < .01). Left-side axial torsional stiffness of the cruciform incision was significantly higher than a square incision ( P < .01). Neither incision methods impacted flexional-extensional stiffness or lateral-bending stiffness. Conclusions: The cruciform and square incisions of the AF obviously reduced axial compression and axial rotation, but they did not change the flexion-extension and lateral-bending stiffness of the bovine caudal IVD. This mechanical study will be meaningful for the development of new approaches to AF repair and the rehabilitation of the patients after receiving discectomy.

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