Determinate Design and Analytical Analysis of a Class of Symmetrical Flexure Guiding Mechanisms for Linear Actuators

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Guangbo Hao
Keyword(s):  
Mechanism Design ◽  
Performance Characteristics ◽  
Dimensional Synthesis ◽  
Analytical Analysis ◽  
Primary Motion ◽  
Flexure Mechanism ◽  
Parasitic Motion ◽  
Different Types ◽  
Low Stiffness ◽  
Linear Actuators

This paper designs and analyses a class of single-axis translational flexure guiding mechanisms for linear actuators. The proposed flexure mechanisms have symmetrical configurations to eliminate parasitic motion for better precision and can provide large stiffness in the constraint directions and low stiffness in the actuation direction. Each flexure linear mechanism is composed of identical wire beams uniformly distributed in two planes (perpendicular to the actuation direction) with the minimal number of over-constraints. Analytical (symbolic) models are derived to quickly reflect effects of different parameters on performance characteristics of the flexure mechanism, enabling dimensional synthesis of different types of mechanisms. An optimal, compact, and symmetrical, flexure linear mechanism design is finally presented and prototyped with focused discussions on its primary motion.

Elastic Averaging in Flexure Mechanisms: A Muliti-Beam Parallelogram Flexure Case-Study

2006 ◽  
Author(s):  
Shorya Awtar ◽  
Edip Sevincer
Keyword(s):  
Mechanism Design ◽  
Parametric Model ◽  
Nonlinear Load ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Flexure Mechanism ◽  
Important Concern ◽  
Proposed Model ◽  
Geometric Arrangements

Over-constraint is an important concern in mechanism design because it can lead to a loss in desired mobility. In distributed-compliance flexure mechanisms, this problem is alleviated due to the phenomenon of elastic averaging, thus enabling performance-enhancing geometric arrangements that are otherwise unrealizable. The principle of elastic averaging is illustrated in this paper by means of a multi-beam parallelogram flexure mechanism. In a lumped-compliance configuration, this mechanism is prone to over-constraint in the presence of nominal manufacturing and assembly errors. However, with an increasing degree of distributed-compliance, the mechanism is shown to become more tolerant to such geometric imperfections. The nonlinear load-stiffening and elasto-kinematic effects in the constituent beams have an important role to play in the over-constraint and elastic averaging characteristics of this mechanism. Therefore, a parametric model that incorporates these nonlinearities is utilized in predicting the influence of a representative geometric imperfection on the primary motion stiffness of the mechanism. The proposed model utilizes a beam generalization so that varying degrees of distributed compliance are captured using a single geometric parameter.

A Compliance-Based Compensation Approach for Designing High-Precision Flexure Mechanism

2012 ◽  
Author(s):  
S. Z. Li ◽  
J. J. Yu ◽  
G. H. Zong ◽  
Hai-jun Su
Keyword(s):  
High Precision ◽  
Motion Compensation ◽  
Design Method ◽  
Flexure Mechanism ◽  
Parasitic Motion ◽  
Translation Error ◽  
Fea Simulation ◽  
Compensation Approach ◽  
Robust Design Method

This paper presents an approach of utilizing parasitic motion compensation for designing high-precision flexure mechanism. This approach is expected to improve the accuracy of flexure mechanism without changing its degree of freedom (DOF) characteristic. Different from the method which mainly concentrates on how to compensate the parasitic translation error of a parallelogram-type flexure mechanism existing in most of the literatures, the proposed approach can compensate the parasitic motion produced by rotation in company with translation. Besides, the parasitic motion of a flexure mechanism is formulated and evaluated by utilizing its compliance. To specify it, the compliance of a general flexure mechanism is calculated firstly. Then the parasitic motions introduced by both rotation and translation are analyzed by utilizing the resultant compliance. Subsequently, a compliance-based compensation approach is addressed as the most important part of this paper. The design principles and procedure are further proposed in detail to help with improving the accuracy of the flexure mechanism. Finally, a case study of a 2R1T flexure mechanism is provided to illustrate this approach, and FEA simulation is implemented to demonstrate its validity. The result shows that it is a robust design method for the design of high-precision flexure mechanism.

On a New Approach to Mechanism Topology Identification

1999 ◽  
Vol 121 (1) ◽  
pp. 57-64 ◽  
Author(s):  
W. J. Zhang ◽  
Q. Li
Keyword(s):  
Mechanism Design ◽  
Design Process ◽  
New Approach ◽  
Topology Identification ◽  
Different Types ◽  
Extended Code ◽  
Abstraction Levels ◽  
Different Levels

This paper argues that different levels of mechanism topology should be considered in order to make the activity or tool of the computer comparison of mechanism topology more useful to support a whole design process of mechanisms. In this connection, four abstraction levels are identified to relate the different types of mechanism topology with reference to mechanism design tasks, processes or objectives. A new approach is developed to compare mechanism topology for all these levels. One of the ideas of this approach is to extend the existing incident degree code approach by identifying more features of mechanism topology and to define them into an extended code. This is further enhanced by an algorithm to perform permutation (without a need of exhaustive enumeration) within a group of vertices that have the same features. Examples are given to show how the approach works. Compared with some existing methods for mechanism topology identification, this approach is shown to be more effective and efficient.

Robust Design of Flexure Based Nano Precision Compliant Mechanisms With Application to Nano Imprint Lithography

2008 ◽  
Author(s):  
Chinmaya B. Patil ◽  
S. V. Sreenivasan ◽  
Raul G. Longoria
Keyword(s):  
Analytical Model ◽  
Robust Design ◽  
Compliant Mechanisms ◽  
Design Approach ◽  
Iteration Step ◽  
Geometric Errors ◽  
Imprint Lithography ◽  
Flexure Mechanism ◽  
Parasitic Motion ◽  
Nano Imprint

Flexure-based compliant mechanisms are the preferred motion guiding systems for small range, nano-precision positioning applications because of excellent characteristics like friction-free continuous motion. These mechanisms are commonly used in nano fabrication equipment and ultra precision instruments. However, machining imperfections induced geometric errors in the mechanisms are known to cause undesirable parasitic motion and significant loss of precision. A systematic design approach to minimize the sensitivity of the flexure mechanisms to geometric errors induced by machining tolerances is presented here. Central to the design approach is the screw systems based analytical model to study the spatial motion characteristics of flexure mechanisms. Using this model, the parasitic motion is classified into those errors which can be corrected by calibration (extrinsic) and those which are coupled with the mechanism motion and cannot be corrected by apriori calibration (intrinsic). Metric to quantify the intrinsic parasitic motion results naturally from the screw systems analysis, and is used to represent the precision capability of the flexure mechanism. The analytical model enables the selection of geometric parameters of flexure joints of the mechanism via an optimization scheme with the aim of minimizing the parasitic motion metric. The statistical nature of the machining tolerances is accounted for by sampling the random variables at every iteration step of the optimization, leading to a stochastic formulation. The robust design approach is illustrated using a one DOF rotational flexure mechanism that is used in nano-imprint lithography equipment. Numerical results of the optimization indicate up to 40% improvement in the precision capability of the mechanism without any change in the manufacturing tolerance limits. Further, it is shown via eigenscrew analysis of mechanism compliance that the robustness resulting from the optimal flexure joint design can be attributed to the improved compliance distribution.

Dimensional Synthesis of Planar Eight-Bar Linkages Based on a Parallel Robot With a Prismatic Base Joint

2013 ◽  
Author(s):  
Gim Song Soh ◽  
Fangtian Ying
Keyword(s):  
Rigid Body ◽  
Design Process ◽  
Parallel Robot ◽  
Degree Of Freedom ◽  
Dimensional Synthesis ◽  
End Effector ◽  
Prismatic Joint ◽  
Serial Chain ◽  
Different Types

This paper details the dimensional synthesis for the rigid body guidance of planar eight-bar linkages that could be driven by a prismatic joint at its base. We show how two RR cranks can be added to a planar parallel robot formed by a PRR and 3R serial chain to guide its end-effector through a set of five task poses. This procedure is useful for designers who require the choice of ground pivot locations. The results are eight different types of one-degree of freedom planar eight-bar linkages. We demonstrate the design process with the design of a multifunctional wheelchair that could transform its structure between a self-propelled wheelchair and a walking guide.

Automatic Page Turner

2010 ◽  
Vol 166-167 ◽  
pp. 27-32
Author(s):  
Alexandra Maria Aluţei ◽  
Beniamin Vasile Chetran ◽  
Ion Lungu ◽  
Dan Mândru
Keyword(s):  
Multiple Sclerosis ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Assistive Technology ◽  
Mechanism Design ◽  
Upper Limbs ◽  
Motor Functions ◽  
Functional Aspects ◽  
Different Types ◽  
Points Of View

This paper presents the development of an Assistive Technology representative product: an automatic page turner system, designed for persons with issues like multiple sclerosis, Parkinson’s disease and other various disabilities that involve the motor functions of the upper limbs. Firstly, the authors emphasize specific features of Assistive Technology and analyse the most important functional aspects concerning different types of page turner devices. The proposed page turner system is based on a four-bar mechanism. Design aspects from the constructive and functional points of view are exposed and the developed prototype is described.

Topological Synthesis for Linkage Mechanism Design Using the Minimum Potential Energy Principle

2005 ◽  
Author(s):  
Hae Chang Gea ◽  
Jaehyun Kwon
Keyword(s):  
Potential Energy ◽  
Mechanism Design ◽  
Compliant Mechanism ◽  
Analysis Method ◽  
Dimensional Synthesis ◽  
Linkage Mechanism ◽  
Minimum Potential Energy ◽  
Minimum Potential ◽  
Number Synthesis ◽  
Topological Synthesis

A mechanism is a device transmits motion in a predetermined manner in order to accomplish specific objectives. Mechanism design can be divided into three steps: type synthesis, number synthesis and dimensional synthesis, where the number synthesis is also called topological synthesis. In this paper, a new approach for topological synthesis and dimensional synthesis of linkage mechanism design with pin joints is presented. This approach is based on the discrete element approach which always provides clear definitions of number of linkages and joints. In order to extend its applications beyond the compliant mechanism, a novel analysis method based on the principle of minimum potential energy for linkage topology optimization is employed. Unlike the traditional FEM based approaches, this novel analysis method can be applied to multiple joint linkage designs directly. Genetic Algorithm is chosen as the optimizer. Finally, a few design examples from the proposed method are presented.

Performance of Calorimeter Systems

2018 ◽  
Author(s):  
Richard Wigmans
Keyword(s):  
Energy Resolution ◽  
Line Shape ◽  
Scientific Literature ◽  
Performance Characteristics ◽  
Generation Mechanism ◽  
Particle Identification ◽  
Signal Generation ◽  
Pile Up ◽  
Different Types

The most important practical aspects of the performance of calorimeter systems are reviewed. Each aspect is illustrated with examples published in the scientific literature. One of the most important performance characteristics is the energy resolution, which is shown separately for electrons, hadrons and jets. The same distinction is also made for the position and angular resolutions that are achieved in practice. The time characteristics of the calorimeter signals, which are important for a variety of purposes (e.g. pile-up), depend on the signal generation mechanism (Cherenkov, scintillation). The e/h values of different types of calorimeters, as well as the effects of non-compensation in these devices (non-linearity, line shape, resolution), are reviewed. It is shown how calorimeter data can be used for particle identification purposes, and how the granularity affects the capability to recognize close doublets as such. The chapter ends with a brief review of the different tasks typically carried out by calorimeters in modern experiments.

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