Influence of head orientation on visually and memory-guided arm movements

2011 ◽  
Vol 136 (3) ◽  
pp. 390-398 ◽  
Author(s):  
Michel Guerraz ◽  
Sébastien Caudron ◽  
Noémylle Thomassin ◽  
Jean Blouin
Keyword(s):  
Arm Movements ◽  
Head Orientation

scholarly journals Role of Eye, Head, and Shoulder Geometry in the Planning of Accurate Arm Movements

2002 ◽  
Vol 87 (4) ◽  
pp. 1677-1685 ◽  
Author(s):  
D.Y.P. Henriques ◽  
J. D. Crawford
Keyword(s):  
Visual Information ◽  
Arm Movements ◽  
Head Rotation ◽  
Head Position ◽  
Open Loop ◽  
Target Line ◽  
Head Orientation ◽  
Complex Process ◽  
Hand Coordination ◽  
Shoulder Geometry

Eye-hand coordination requires the brain to integrate visual information with the continuous changes in eye, head, and arm positions. This is a geometrically complex process because the eyes, head, and shoulder have different centers of rotation. As a result, head rotation causes the eye to translate with respect to the shoulder. The present study examines the consequences of this geometry for planning accurate arm movements in a pointing task with the head at different orientations. When asked to point at an object, subjects oriented their arm to position the fingertip on the line running from the target to the viewing eye. But this eye-target line shifts when the eyes translate with each new head orientation, thereby requiring a new arm pointing direction. We confirmed that subjects do realign their fingertip with the eye-target line during closed-loop pointing across various horizontal head orientations when gaze is on target. More importantly, subjects also showed this head-position–dependent pattern of pointing responses for the same paradigm performed in complete darkness. However, when gaze was not on target, compensation for these translations in the rotational centers partially broke down. As a result, subjects tended to overshoot the target direction relative to current gaze; perhaps explaining previously reported errors in aiming the arm to retinally peripheral targets. These results suggest that knowledge of head position signals and the resulting relative displacements in the centers of rotation of the eye and shoulder are incorporated using open-loop mechanisms for eye-hand coordination, but these translations are best calibrated for foveated, gaze-on-target movements.

scholarly journals Orientation of the Head and Trunk During Functional Upper Limb Movement

2020 ◽  
Vol 10 (6) ◽  
pp. 2115
Author(s):  
Agnès Roby-Brami ◽  
Marie-Martine Lefèvre Colau ◽  
Ross Parry ◽  
Sessi Acapo ◽  
Francois Rannou ◽  
...  
Keyword(s):  
Upper Limb ◽  
Visual Target ◽  
Tracking System ◽  
Arm Movements ◽  
Axial Rotation ◽  
Head Orientation ◽  
Trunk Rotation ◽  
Future Studies ◽  
Trunk Posture ◽  
Trunk Orientation

Upper limb activities imply positioning of the head with respect to the visual target and may impact trunk posture. However, the postural constraints imposed on the neck remains unclear. We used kinematic analysis to compare head and trunk orientation during arm movements (pointing) with isolated movements of the head (heading). Ten right-handed healthy adults completed both experimental tasks. In the heading task, subjects directed their face toward eight visual targets placed over a wide frontal workspace. In the pointing task, subjects pointed to the same targets (each with their right arm). Movements were recorded using an electromagnetic spatial tracking system. Both orientation of the head and trunk in space (Euler angles) and orientation of the head relative to the trunk were extracted. The orientation of the head in space was closely related to target direction during both tasks. The trunk was relatively stable during heading but contributed to pointing, with leftward axial rotation. These findings illustrate that the neck compensates for trunk rotation during pointing, engaging in specific target-dependent 3D movement in order to preserve head orientation in space. Future studies may investigate neck kinematics of people experiencing neck pain in order to identify and correct inefficient movement patterns, particularly in athletes.

Perceiving Affect From Point-Light Displays of Arm Movements

2000 ◽  
Author(s):  
Frank E. Pollick ◽  
Helena Paterson ◽  
Andrew J. Calder ◽  
Armin Bruderlin ◽  
Anthony J. Sanford
Keyword(s):  
Arm Movements ◽  
Point Light

Improvement Of Free Convection From Three horizontal Finned Cylinders Fixed Between Two Walls

2018 ◽  
Vol 6 (2) ◽  
pp. 98-114 ◽  
Author(s):  
Hassan K. Abdullah ◽  
Haneen H. Rahman
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Prandtl Number ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Heat Fluxes ◽  
Head Orientation ◽  
Outer Diameter ◽  
Gravitational Acceleration ◽  
Convection Heat

Improvement of  free convection heat transfer from three finned cylinders arranged at a triangle shape fixed between two walls has been investigated in this study. Three mild steel finned cylinders fixed between two walls from Pyrex glass have been used as a test rig. It has been changed the spacing between the cylinders (X/D=1,2,3 & S/D=2,4,6) and the head orientation of a triangle to the top under constant heat flux values (38, 254, 660, 1268) W/m2 and compare with case of three finned cylinders arranged in vertical array in line fixed between two wall. The experiments are carried for Rayleigh number (Ra) from (15x103 to 14 x104 ) and Prandtl  number from (0.706-0.714 ). The results indicated an increase in Nu with increasing Ra for all cylinders. Furthermore,hx and Nu increased proportionally with the increasing of cylinder spacings for all heat fluxes. Also the experimental results show the case of triangle arrangement is improvement the heat transfer more than case of vertical arrangement. Heat transfer dimensionless correlating equation is also proposed.              Nomeclature: Ax: surface area(m2), T∞: surrounding temperature(k), D: the outer diameter of fin (m), Kf: the thermal conductivity for air at film temperature(W/m.k), hx: Local convection heat transfer(W/m2.k),  Gravitational acceleration(m/s2), I: Electric current (Amp), Nu: Nusselt number, Pr: Prandtl number

Features of prototyping the kinematic movements of human extremities during the implementation of demonstration robots

2020 ◽  
Keyword(s):  
Arm Movements ◽  
Robot Arm ◽  
Movement Coordination ◽  
Movement Kinematic

The features of prototyping the movement kinematic of human extremities during in the implementation of demonstration robots based on a hinged three-link are considered. Keywords demonstration robot; three-link manipulator; trajectory of movement; coordination of robot arm movements

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