Gravity-Balanced Arm Support With Energy-Free Adjustment

2007 ◽  
Vol 1 (2) ◽  
pp. 151-158 ◽  
Author(s):  
Wouter D. van Dorsser ◽  
Rogier Barents ◽  
Boudewijn M. Wisse ◽  
Just L. Herder
Keyword(s):  
Muscle Force ◽  
Neuromuscular Diseases ◽  
Total Potential Energy ◽  
External Energy ◽  
Support Mechanism ◽  
Total Potential ◽  
Arm Support ◽  
Support Mechanisms ◽  
Clinical Trial Results ◽  
Novel Design

People with neuromuscular diseases have very limited muscle force. Many of them rely on mobile arm supports to move their arms. Most of these supports incorporate gravity balancers, i.e., spring-loaded mechanisms that achieve a constant total potential energy, thus eliminating any preferred position. The springs and the mechanism topology and dimensions are designed to exactly or approximately balance the weight of the user’s arm. Quasistatically, the mechanism, once statically balanced, can thus be moved virtually without operating energy. In case of change of effective arm weight, e.g., due to picking up an object or putting on a coat, the support mechanism should ideally be readjusted. In all available support mechanisms, this adjustment is associated with considerable mechanical effort, while clearly this application would benefit greatly from an energy-free adjustment. This paper will present an arm support that includes a novel design concept to adjust spring-based static balancers with no need for external energy. This concept will be explained, and several variants will be shown. Subsequently, the application of this concept in a mobile arm support will be described in detail, including preliminary clinical trial results.

Energy-Free Adjustment of Gravity Equilibrators With Application in a Mobile Arm Support

2006 ◽  
Author(s):  
Wouter D. van Dorsser ◽  
Rogier Barents ◽  
Boudewijn M. Wisse ◽  
Just L. Herder
Keyword(s):  
Potential Energy ◽  
Muscle Force ◽  
Neuromuscular Diseases ◽  
Total Potential Energy ◽  
External Energy ◽  
Static Balancing ◽  
Support Mechanism ◽  
Total Potential ◽  
Arm Support

Static balancing is a useful concept to reduce operating effort of mechanisms. Very often, spring mechanisms are used to achieve a constant total potential energy, thus eliminating any preferred position. The springs and the mechanism dimensions are designed to exactly or approximately balance other forces present in the mechanism, such as gravity. Quasistatically, the mechanism, once statically balanced, can be moved virtually without operating energy. In some cases it is desirable to adjust the balancer characteristic, for instance due to a change of payload in a gravity balanced mechanism. The adjustment of present static balancers requires significant operating energy. This paper will present a novel principle to adjust spring and linkage-based static balancers with no need for external energy. This principle will be explained and several variants will be shown. A mobile arm support for people with neuromuscular diseases is used as a design example. These people have very limited force and rely on their arm support to move their arms. When picking up objects their support mechanism should ideally be adjusted. Due to the limited available muscle force, this application greatly benefits from an energy-free adjustment.

Energy-free adjustment of gravity equilibrators by adjusting the spring stiffness

2008 ◽  
Vol 222 (9) ◽  
pp. 1839-1846 ◽  
Author(s):  
W D van Dorsser ◽  
R Barents ◽  
B M Wisse ◽  
M Schenk ◽  
J L Herder
Keyword(s):  
Potential Energy ◽  
Total Potential Energy ◽  
Spring Stiffness ◽  
External Energy ◽  
Static Balancing ◽  
Concept Model ◽  
Total Potential ◽  
Novel Variant ◽  
Energy Conserving

Static balancing is a useful concept to reduce the operating effort of mechanisms. Spring mechanisms are used to achieve a constant total potential energy, thus eliminating any preferred position. Quasi-statically, the mechanism, once statically balanced, can be moved virtually without the operating energy. In some cases, it is desirable to adjust the characteristic of the balancer, for instance, due to a change in the payload in a gravity balanced mechanism. The adjustment of current static balancers requires significant operating energy. This paper will present a novel variant to adjust the spring- and linkage-based static balancers without the need for external energy. The variant makes use of the possibility to adjust the spring stiffness in an energy-conserving way by adjusting the number of active coils. The conditions under which it functions properly will be given, and a proof of the concept model will be shown.

A simplified formulation of adhesion problems with elastic plates

2009 ◽  
Vol 465 (2107) ◽  
pp. 2217-2230 ◽  
Author(s):  
Carmel Majidi ◽  
George G. Adams
Keyword(s):  
Potential Energy ◽  
Contact Area ◽  
Contact Region ◽  
Bending Moment ◽  
Total Potential Energy ◽  
Work Of Adhesion ◽  
Contact Radius ◽  
Algebraic Complexity ◽  
Elastic Plates ◽  
Total Potential

The solution of adhesion problems with elastic plates generally involves solving a boundary-value problem with an assumed contact area. The contact region is then found by minimizing the total potential energy with respect to the contact area (i.e. the contact radius for the axisymmetric case). Such a procedure can be extremely long and tedious. Here, we show that the inclusion of adhesion is equivalent to specifying a discontinuous internal bending moment at the contact region boundary. The magnitude of this moment discontinuity is related to the work of adhesion and flexural rigidity of the plate. Such a formulation can greatly reduce the algebraic complexity of solving these problems. It is noted that the related plate contact problems without adhesion can also be solved by minimizing the total potential energy. However, it has long been recognized that it is mathematically more efficient to find the contact area by specifying a continuous internal bending moment at the boundary of the contact region. Thus, our moment discontinuity method can be considered to be a generalization of that procedure which is applicable for problems with adhesion.

Vibration Analysis of the Continuous Truss Girder Bridge by the Finite Truss Elements

2011 ◽  
Vol 268-270 ◽  
pp. 557-560
Author(s):  
Shi Ruo Yang
Keyword(s):  
Composite System ◽  
Elastic System ◽  
Total Potential Energy ◽  
Time Varying ◽  
Girder Bridges ◽  
Total Potential ◽  
Vibration Responses ◽  
Pass Through ◽  
Girder Bridge ◽  
Set Up

The train and the continuous truss girder bridge are coupled together as one composite system. Truss girder bridge is idealized as an assemblage of finite truss element. The equations of the train and truss girder bridges time varying system are set up by using the principle of total potential energy with stationary value in elastic system dynamics and the“set-in-right-position”rule for forming structural matrices. This method is more convenient than the finite elements. The vibration responses of the train and bridge are calculated when the the passenger trains pass through a continuous truss girder bridge at speeds of 90km/h and 120km/h The results show that the passenger train can pass it safely and comfortably

An Optimization Method for the Static Balancing of Manipulators Using Springs

2020 ◽  
Author(s):  
Jieyu Wang ◽  
Xianwen Kong
Keyword(s):  
Potential Energy ◽  
Objective Function ◽  
Multiple Solutions ◽  
Optimization Method ◽  
Total Potential Energy ◽  
Static Balancing ◽  
Attachment Point ◽  
Total Potential

Abstract This paper discusses a novel optimization method to design statically balanced manipulators. Only springs are used to balance the manipulators composed of revolute (R) joints. Since the total potential energy of the system is constant when statically balanced, the sum of squared differences between the two potential energy when giving different random values of joint variables is set as the objective function. Then the optimization tool of MATLAB is used to obtain the spring attachment points. The results show that for a 1-link manipulator mounted on an R joint, in addition to attaching the spring right above the R joint, the attachment point can have offset. It also indicates that an arbitrary spatial manipulator with n link, whose weight cannot be neglected, can be balanced using n springs. Using this method, the static balancing can be readily achieved, with multiple solutions.

Automatic Refinement of FE Shell Models Based on a Local Energy Function

2013 ◽  
Author(s):  
Antonio Carminelli ◽  
Giuseppe Catania
Keyword(s):  
Potential Energy ◽  
Local Density ◽  
Free Vibration Analysis ◽  
Element Model ◽  
Companion Paper ◽  
Total Potential Energy ◽  
Shape Functions ◽  
Total Potential ◽  
Error Functional ◽  
Local Patch

This paper deals with an adaptive refinement technique of a B-spline degenerate shell finite element model, for the free vibration analysis of curved thin and moderately thick-walled structures. The automatic refinement of the solution is based on an error functional related to the density of the total potential energy. The model refinement is generated by locally increasing, in a sub-domain R of a local patch domain, the number of shape functions while maintaining constant the functions polynomial order. The local refinement strategy is described in a companion paper, written by the same authors of this paper and presented in this Conference. A two-step iterative procedure is proposed. In the first step, one or more sub domains to be refined are identified by means of a point-wise error functional based on the system total potential energy local density. In the second step, the number of shape functions to be added is iteratively increased until the difference of the total potential energy, calculated on the sub domain between two iteration, is below a user defined tolerance. A numerical example is presented in order to test the proposed approach. Strengths and limits of the approach are critically discussed.

First-Principles Study on Crystal Configuration and Many-Body Cohesive Energy of Solid Argon

2019 ◽  
Vol 807 ◽  
pp. 135-140
Author(s):  
Xi Jin Fu
Keyword(s):  
Potential Energy ◽  
Interaction Energy ◽  
First Principles ◽  
Total Potential Energy ◽  
Basis Set ◽  
Many Body ◽  
Body Interaction ◽  
Total Potential ◽  
Geometric Configurations ◽  
Solid Argon

Based on the first-principles, using CCSD(T) ab initio calculation method, many-body potential energy of solid argon are accurately calculated with the atomic distance R from 2.0Å to 3.6Å at T=300K, and firstly establish and discuss the face-centered cubic (fcc) atomic crystal configurations of two-, three-, and four-body terms by geometry optimization. The results shows that the total number of (Ar)2 clusters is 903, which belongs to 12 different geometric configurations, the total number of (Ar)3 clusters is 861, which belongs to 25 different geometric configurations, and the total number of (Ar)4 clusters of is 816 which belongs to 27 different geometric configurations. We find that the CCSD(T) with the aug-cc-pVQZ basis set is most accurate and practical by comprehensive consideration. The total potential energy Un reachs saturation at R>2.0Å when the only two-and three-body interaction energy are considered. When R≤2.0Å, the total potential energy Un must consider four-and higher-body interaction energy to achieve saturation. Many-body expansion potential of fcc solid argon is an exchange convergent series.

scholarly journals Base functions effect in stability finite element analysis of compressed plate

2020 ◽  
Vol 310 ◽  
pp. 00018 ◽  
Author(s):  
Ivana Veghova ◽  
Martin Psotny
Keyword(s):  
Finite Element Analysis ◽  
Stiffness Matrix ◽  
Nonlinear Problems ◽  
Total Potential Energy ◽  
Element Analysis ◽  
Basic Assumptions ◽  
Total Potential ◽  
Geometric Nonlinear ◽  
Base Functions ◽  
Newton Raphson

Geometric nonlinear solution of a compressed plate is presented in this paper. Basic assumptions are specified and incremental conditional equations are derived from the variational principle of minimum of total potential energy. Full Newton-Raphson procedure, in which the stiffness matrix is updated at every equilibrium iteration, has been applied for solution. The importance of modifications of base functions for solving geometric nonlinear problems is analysed. The solved example is presented, the differences are compared and explained.

Structure électronique de dérivés sulfures. XI. Thiétanne et dérivés

1975 ◽  
Vol 53 (8) ◽  
pp. 1224-1236 ◽  
Author(s):  
Claude Guimon ◽  
Daniel Liotard ◽  
Geneviève Pfister-Guillouzo
Keyword(s):  
Experimental Data ◽  
Potential Energy ◽  
Total Potential Energy ◽  
Geometric Parameters ◽  
The Third ◽  
Total Potential ◽  
Partial Energy ◽  
Chloro Derivatives ◽  
Semi Empirical ◽  
Structure Electronique

The conformations of thietane, thietane sulfoxide, and their 3-chloro derivatives were obtained theoretically by minimization of the energy with respect to geometric parameters using the semi-empirical CNDO/2 method extended to the third period. The results agree well with known experimental data. The respective stabilities of the different conformers are explained by partial energy results obtained by a bicentric partition of the total potential energy of the molecules. [Journal translation]

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