scholarly journals Passive Rotation Compensation in Parallel Kinematics Using Quaternions

PAMM ◽  
2016 ◽  
Vol 16 (1) ◽  
pp. 51-52 ◽  
Author(s):  
Shucen Du ◽  
Josef Schlattmann ◽  
Stefan Schulz ◽  
Arthur Seibel
Keyword(s):  
Parallel Kinematics ◽  
Passive Rotation ◽  
Rotation Compensation

Does the Motor System Facilitate Spatial Imagery?

2017 ◽  
Vol 49 (3) ◽  
pp. 127-137 ◽  
Author(s):  
Markus Krüger ◽  
Horst Krist
Keyword(s):  
Motor System ◽  
Third Graders ◽  
External Support ◽  
New Paradigm ◽  
Perceptual Condition ◽  
Imagery Condition ◽  
Passive Rotation ◽  
Perception Condition ◽  
Motor Condition ◽  
Dynamic Imagery

Abstract. Recent studies have ascertained a link between the motor system and imagery in children. A motor effect on imagery is demonstrated by the influence of stimuli-related movement constraints (i. e., constraints defined by the musculoskeletal system) on mental rotation, or by interference effects due to participants’ own body movements or body postures. This link is usually seen as qualitatively different or stronger in children as opposed to adults. In the present research, we put this interpretation to further scrutiny using a new paradigm: In a motor condition we asked our participants (kindergartners and third-graders) to manually rotate a circular board with a covered picture on it. This condition was compared with a perceptual condition where the board was rotated by an experimenter. Additionally, in a pure imagery condition, children were instructed to merely imagine the rotation of the board. The children’s task was to mark the presumed end position of a salient detail of the respective picture. The children’s performance was clearly the worst in the pure imagery condition. However, contrary to what embodiment theories would suggest, there was no difference in participants’ performance between the active rotation (i. e., motor) and the passive rotation (i. e., perception) condition. Control experiments revealed that this was also the case when, in the perception condition, gaze shifting was controlled for and when the board was rotated mechanically rather than by the experimenter. Our findings indicate that young children depend heavily on external support when imagining physical events. Furthermore, they indicate that motor-assisted imagery is not generally superior to perceptually driven dynamic imagery.

scholarly journals Biologically Inspired Design and Development of a Variable Stiffness Powered Ankle-Foot Prosthesis

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Alexander Agboola-Dobson ◽  
Guowu Wei ◽  
Lei Ren
Keyword(s):  
Lower Limb ◽  
Degrees Of Freedom ◽  
Sagittal Plane ◽  
Frontal Plane ◽  
Variable Stiffness ◽  
Plane Motion ◽  
Biologically Inspired ◽  
Passive Rotation ◽  
Ground Conditions ◽  
Biologically Inspired Design

Recent advancements in powered lower limb prostheses have appeased several difficulties faced by lower limb amputees by using a series-elastic actuator (SEA) to provide powered sagittal plane flexion. Unfortunately, these devices are currently unable to provide both powered sagittal plane flexion and two degrees of freedom (2-DOF) at the ankle, removing the ankle’s capacity to invert/evert, thus severely limiting terrain adaption capabilities and user comfort. The developed 2-DOF ankle system in this paper allows both powered flexion in the sagittal plane and passive rotation in the frontal plane; an SEA emulates the biomechanics of the gastrocnemius and Achilles tendon for flexion while a novel universal-joint system provides the 2-DOF. Several studies were undertaken to thoroughly characterize the capabilities of the device. Under both level- and sloped-ground conditions, ankle torque and kinematic data were obtained by using force-plates and a motion capture system. The device was found to be fully capable of providing powered sagittal plane motion and torque very close to that of a biological ankle while simultaneously being able to adapt to sloped terrain by undergoing frontal plane motion, thus providing 2-DOF at the ankle. These findings demonstrate that the device presented in this paper poses radical improvements to powered prosthetic ankle-foot device (PAFD) design.

scholarly journals Multiphysics & Parallel Kinematics Modeling of a 3DOF MEMS Mirror

2015 ◽  
Vol 32 ◽  
pp. 01004
Author(s):  
N. Mamat ◽  
K. Rabenorosoa ◽  
C. Clévy ◽  
P. Lutz ◽  
H. Xie
Keyword(s):  
Parallel Kinematics ◽  
Kinematics Modeling

Extended Mobility Carried Out with a Double Hexapod Robot

2010 ◽  
Vol 166-167 ◽  
pp. 271-276 ◽  
Author(s):  
Mihai Margaritescu ◽  
Ana Maria Eulampia Ivan ◽  
Vlad Vaduva ◽  
Cornel Brisan
Keyword(s):  
Fast Response ◽  
High Accuracy ◽  
Positioning System ◽  
Hexapod Robot ◽  
Parallel Kinematics ◽  
High Stiffness ◽  
Serial Robots ◽  
Visual Comparison ◽  
Operating Space

The double hexapod robot consists in two staged hexapod platforms – Stewart Gough platforms - combining in a certain measure the advantages of the robots with parallel kinematics and of the serial robots: high accuracy, high stiffness, fast response and small dimensions, having an extended operating space. Different modelling and construction aspects were described in few previous articles. Some examples of trajectories generated with this positioning system are now presented to illustrate its mobility, as well as the workspaces for one and two hexapods in order to make possible a visual comparison between the two volumes.

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