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

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.

Three-dimensional printing in prosthetics: Method for managing rapid limb volume change

2020 ◽  
Vol 44 (5) ◽  
pp. 355-358 ◽  
Author(s):  
Eric Nickel ◽  
Kyle Barrons ◽  
Barry Hand ◽  
Alana Cataldo ◽  
Andrew Hansen
Keyword(s):  
Service Life ◽  
Three Dimensional ◽  
Residual Limb ◽  
Volume Loss ◽  
Limb Volume ◽  
Three Dimensional Printing ◽  
Body Mass Change ◽  
Prosthetic Socket ◽  
Test Distance ◽  
Gain Loss

Background and Aim: During post-amputation recovery or rapid body mass change, residual limb volume can change quickly, requiring frequent adjustments or replacement of the socket to maintain fit. The aim of this pilot test was to evaluate the feasibility of using a three-dimensional-printed insert to extend the service life of a prosthetic socket after substantial residual limb volume loss. Technique: One research subject with a well-fitting transtibial prosthetic socket had an oversized socket fabricated to simulate substantial limb volume loss. The digital shapes of the oversized and well-fitting sockets were used to create a three-dimensional-printed insert to restore fit. Discussion: Two-minute walk test distance decreased when using the oversized socket without the insert, but not when using the socket with the insert. Socket comfort score was 8+ under all conditions. These results suggest that three-dimensional-printed inserts may be an effective method of extending the service life of prosthetic sockets when rapid limb volume loss occurs. Clinical relevance Three-dimensional (3D) printing gives prosthetists a new tool to manage large volume changes without refabricating entire sockets. Sockets can be fabricated in anticipation of volume gain/loss, using replaceable 3D-printed inserts to maintain fit and comfort.

scholarly journals A comparison of three-dimensional rotation formalisms for least-squares and Bayesian inverse kinematics

2021 ◽  
Author(s):  
Ben Serrien ◽  
Klevis Aliaj ◽  
Todd Pataky
Keyword(s):  
Least Squares ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Estimation Error ◽  
Computational Cost ◽  
Three Dimensional ◽  
Linear Least Squares ◽  
Computationally Efficient ◽  
Rotational Degrees Of Freedom ◽  
Value Decomposition

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.

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

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.

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

2016 ◽  
Vol 8 (6) ◽  
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.

scholarly journals Improved crystal orientation and physical properties from single-shot XFEL stills

2014 ◽  
Vol 70 (12) ◽  
pp. 3299-3309 ◽  
Author(s):  
Nicholas K. Sauter ◽  
Johan Hattne ◽  
Aaron S. Brewster ◽  
Nathaniel Echols ◽  
Petrus H. Zwart ◽  
...  
Keyword(s):  
Crystal Orientation ◽  
Degrees Of Freedom ◽  
Reciprocal Lattice ◽  
Single Shot ◽  
X Ray Diffraction ◽  
Reciprocal Lattice Point ◽  
X Ray ◽  
Structure Factors ◽  
Rotational Degrees Of Freedom ◽  
Diffraction Patterns

X-ray diffraction patterns from still crystals are inherently difficult to process because the crystal orientation is not uniquely determined by measuring the Bragg spot positions. Only one of the three rotational degrees of freedom is directly coupled to spot positions; the other two rotations move Bragg spots in and out of the reflecting condition but do not change the direction of the diffracted rays. This hinders the ability to recover accurate structure factors from experiments that are dependent on single-shot exposures, such as femtosecond diffract-and-destroy protocols at X-ray free-electron lasers (XFELs). Here, additional methods are introduced to optimally model the diffraction. The best orientation is obtained by requiring, for the brightest observed spots, that each reciprocal-lattice point be placed into the exact reflecting condition implied by Bragg's law with a minimal rotation. This approach reduces the experimental uncertainties in noisy XFEL data, improving the crystallographicRfactors and sharpening anomalous differences that are near the level of the noise.

Technique modifications for a suction suspension version of the Northwestern University Flexible Sub-Ischial Vacuum socket: The Northwestern University Flexible Sub-Ischial Suction socket

2018 ◽  
Vol 43 (2) ◽  
pp. 233-239 ◽  
Author(s):  
Ryan Caldwell ◽  
Stefania Fatone
Keyword(s):  
Relative Motion ◽  
Clinical Relevance ◽  
Technical Note ◽  
Residual Limb ◽  
Transfemoral Amputation ◽  
Prosthetic Socket ◽  
Northwestern University

Background and Aim: Development of a passive suction version of the Northwestern University Flexible Sub-Ischial Vacuum socket would expand application of sub-ischial sockets to a larger proportion of persons with transfemoral amputation. While active vacuum suspension provides more positive coupling of the residual limb to the prosthetic socket, there are circumstances when use of active vacuum is not appropriate or feasible. Therefore, this technical note describes the technique modifications required to cast, fabricate, and fit a passive suction version of the Northwestern University Flexible Sub-Ischial Vacuum socket (i.e. the Northwestern University Flexible Sub-Ischial Suction socket). Technique: Most technique modifications stem from the use of an internal seal with the Northwestern University Flexible Sub-Ischial Suction socket and the need to account for the greater relative motion occurring between the residual limb and socket with passive suction compared to active vacuum suspension. Discussion: Between January 2015 and March 2018, 266 Northwestern University Flexible Sub-Ischial Suction sockets were fit successfully using the described technique modifications. Clinical relevance A passive suction version of the Northwestern University Flexible Sub-Ischial Vacuum socket—the Northwestern University Flexible Sub-Ischial Suction socket—broadens the application of sub-ischial sockets to a larger proportion of the population with transfemoral amputation.

Overview of Digital Breast Tomosynthesis

2018 ◽  
Author(s):  
Emily F. Conant
Keyword(s):  
Cancer Detection ◽  
Three Dimensional ◽  
Digital Breast Tomosynthesis ◽  
Early Screening ◽  
Breast Tomosynthesis ◽  
X Ray ◽  
Effectiveness Studies ◽  
Work Up ◽  
Diagnostic Setting ◽  
Efficient Work

Digital breast tomosynthesis (DBT) is a relatively new X-ray technique that allows quasi–three-dimensional imaging of the breast to overcome limitations of conventional 2-D digital mammography (DM). Several early screening studies have shown that DBT reduces the number of false-positive recalls while simultaneously improving the cancer detection rate. Cost-effectiveness studies have shown that incorporating DBT in screening has the potential to save health care dollars due to lower recall rates as well as reduced treatment costs resulting from the earlier detection of breast cancer. In the diagnostic setting, DBT imaging may allow a more efficient work-up of breast lesions due to improved lesion conspicuity and the ability to better localize lesions within the breast.

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

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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