Quantum dynamics for vibrational and rotational degrees of freedom using Gaussian wave packets: Application to the three‐dimensional photodissociation dynamics of ICN

Marker-based inverse kinematics (IK) is prone to errors arising from measurementnoise and soft-tissue artefacts. Various least-squares and Bayesian methods canbe applied to limit the estimation error to a minimum. Recently proposed meth-ods like Bayesian IK come at an increased computational cost however. In thistechnical paper, we present an overview of eight different least squares or BayesianIK methods, including their accuracy and computational load for IK problemsinvolving a single rigid body and three rotational degrees-of-freedom, whose at-titude is estimated from four noisy marker positions. The results indicate thatNon-Linear Least Squares, Variational Bayesian and full Bayesian IK are supe-rior to Singular Value Decomposition in terms of accuracy, with approximatelya two-fold error reduction. However, only Non-Linear Least Squares and Varia-tional Bayesian IK are computationally efficient enough to scale towards practicaluse in biomechanical applications, with computational durations of 1-10 ms; fullyBayesian procedures required approximately 30 s for single rotation calculations.All Python code and supplementary material can be found in this paper’s GitHubrepository: https://github.com/benserrien/pybik.

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A Four-Node Tetrahedral Finite Element Based on Space Fiber Rotation Concept

Acta Universitatis Sapientiae Electrical and Mechanical Engineering ◽

10.2478/auseme-2019-0006 ◽

2019 ◽

Vol 11 (1) ◽

pp. 67-78

Author(s):

Kamel Meftah ◽

Lakhdar Sedira

Keyword(s):

Finite Element ◽

Strain Field ◽

Stiffness Matrix ◽

Degrees Of Freedom ◽

Three Dimensional ◽

Field Tensor ◽

Tetrahedral Element ◽

Numerical Studies ◽

Rotational Degrees Of Freedom ◽

Tensor Approximation

Abstract The paper presents a four-node tetrahedral solid finite element SFR4 with rotational degrees of freedom (DOFs) based on the Space Fiber Rotation (SFR) concept for modeling three-dimensional solid structures. This SFR concept is based on the idea that a 3D virtual fiber, after a spatial rotation, introduces an enhancement of the strain field tensor approximation. Full numerical integration is used to evaluate the element stiffness matrix. To demonstrate the efficiency and accuracy of the developed four-node tetrahedron solid element and to compare its performance with the classical four-node tetrahedral element, extensive numerical studies are presented.

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Novel Design and Three-Dimensional Printing of Variable Stiffness Robotic Grippers

Journal of Mechanisms and Robotics ◽

10.1115/1.4033728 ◽

2016 ◽

Vol 8 (6) ◽

Cited By ~ 20

Author(s):

Yang Yang ◽

Yonghua Chen ◽

Ying Wei ◽

Yingtian Li

Keyword(s):

3D Printing ◽

Degrees Of Freedom ◽

Shape Memory Polymer ◽

Three Dimensional ◽

Acrylonitrile Butadiene Styrene ◽

Variable Stiffness ◽

Analytical Models ◽

Printing Process ◽

Finger Joints ◽

Rotational Degrees Of Freedom

In this paper, a novel robotic gripper design with variable stiffness is proposed and fabricated using a modified additive manufacturing (hereafter called 3D printing) process. The gripper is composed of two identical robotic fingers and each finger has three rotational degrees-of-freedom as inspired by human fingers. The finger design is composed of two materials: acrylonitrile butadiene styrene (ABS) for the bone segments and shape-memory polymer (SMP) for the finger joints. When the SMP joints are exposed to thermal energy and heated to above their glass transition temperature (Tg), the finger joints exhibit very small stiffness, thus allow easy bending by an external force. When there is no bending force, the finger will restore to its original shape thanks to SMP's shape recovering stress. The finger design is actuated by a pneumatics soft actuator. Fabrication of the proposed robotic finger is made possible by a modified 3D printing process. An analytical model is developed to represent the relationship between the soft actuator's air pressure and the finger's deflection angle. Furthermore, analytical modeling of the finger stiffness modulation is presented. Several experiments are conducted to validate the analytical models.

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Observation of wave packets with simultaneous electronic, vibrational, and rotational degrees of freedom in Li2

Chemical Physics Letters ◽

10.1016/j.cplett.2004.11.128 ◽

2005 ◽

Vol 402 (1-3) ◽

pp. 27-31 ◽

Cited By ~ 7

Author(s):

Joshua B. Ballard ◽

Xingcan Dai ◽

Alan N. Arrowsmith ◽

Lutz Hüwel ◽

Hans U. Stauffer ◽

...

Keyword(s):

Degrees Of Freedom ◽

Wave Packets ◽

Rotational Degrees Of Freedom

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A new meta-module design for efficient reconfiguration of modular robots

Autonomous Robots ◽

10.1007/s10514-021-09977-6 ◽

2021 ◽

Author(s):

Irene Parada ◽

Vera Sacristán ◽

Rodrigo I. Silveira

Keyword(s):

Degrees Of Freedom ◽

Three Dimensional ◽

Central Point ◽

The Other ◽

Three Dimensions ◽

Modular Robots ◽

The Novel ◽

Modular Robot ◽

Module Design ◽

Rotational Degrees Of Freedom

AbstractWe propose a new meta-module design for two important classes of modular robots. The new meta-modules are three-dimensional, robust and compact, improving on the previously proposed ones. One of them applies to so-called edge-hinged modular robot units, such as M-TRAN, SuperBot, SMORES, UBot, PolyBot and CKBot, while the other one applies to so-called central-point-hinged modular robot units, which include Molecubes and Roombots. The new meta-modules use the rotational degrees of freedom of these two types of robot units in order to expand and contract, as to double or halve their length in each of the two directions of its three dimensions, therefore simulating the capabilities of Crystalline and Telecube robots. Furthermore, in the edge-hinged case we prove that the novel meta-module can also perform the scrunch, relax and transfer moves that are necessary in any tunneling-based reconfiguration algorithm for expanding/contracting modular robots such as Crystalline and Telecube. This implies that the use of meta-meta-modules is unnecessary, and that currently existing efficient reconfiguration algorithms can be applied to a much larger set of modular robots than initially intended. We also prove that the size of the new meta-modules is optimal and cannot be further reduced.

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Effects of Prosthetic Socket Design on Residual Femur Motion Using Dynamic Stereo X-Ray - A Preliminary Analysis

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2021.697651 ◽

2021 ◽

Vol 9 ◽

Author(s):

Jason T. Maikos ◽

John M. Chomack ◽

J. Peter Loan ◽

Kathryn M. Bradley ◽

Susan E. D’Andrea

Keyword(s):

Degrees Of Freedom ◽

Three Dimensional ◽

Residual Limb ◽

Transfemoral Amputation ◽

X Ray ◽

Prosthetic Socket ◽

Rotational Degrees Of Freedom ◽

Socket Technology ◽

Effectiveness Studies ◽

Analytical Tools

Individuals with transfemoral amputation experience relative motion between their residual limb and prosthetic socket, which can cause inefficient dynamic load transmission and secondary comorbidities that limit mobility. Accurately measuring the relative position and orientation of the residual limb relative to the prosthetic socket during dynamic activities can provide great insight into the complex mechanics of the socket/limb interface. Five participants with transfemoral amputation were recruited for this study. All participants had a well-fitting, ischial containment socket and were also fit with a compression/release stabilization socket. Participants underwent an 8-wk, randomized crossover trial to compare differences between socket types. Dynamic stereo x-ray was used to quantify three-dimensional residual bone kinematics relative to the prosthetic socket during treadmill walking at self-selected speed. Comfort, satisfaction, and utility were also assessed. There were no significant differences in relative femur kinematics between socket types in the three rotational degrees of freedom, as well as anterior-posterior and medial-lateral translation (p > 0.05). The ischial containment socket demonstrated significantly less proximal-distal translation (pistoning) of the femur compared to the compression/release stabilization socket during the gait cycle (p < 0.05), suggesting that the compression/release stabilization socket provided less control of the residual femur during distal translation. No significant differences in comfort and utility were found between socket types (p > 0.05). The quantitative, dynamic analytical tools used in the study were sensitive to distinguish differences in three-dimensional residual femur motion between two socket types, which can serve as a platform for future comparative effectiveness studies of socket technology.

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