scholarly journals A Specific Problem of Mechanism Synthesis

2014 ◽  
Vol 19 (3) ◽  
pp. 513-522 ◽  
Author(s):  
J. Buśkiewicz
Keyword(s):  
Specific Problem ◽  
Degree Of Freedom ◽  
Mechanism Synthesis ◽  
Mathematical Basis ◽  
Revolute Joints ◽  
Path Synthesis

Abstract A technique for path synthesis is employed to design a feeder for carrying products between two points. The feeder is assumed to be a one degree of freedom system of six links connected by means of revolute joints. The mathematical basis of the concept is presented. An exemplary solution is presented and discussed

Design and Virtual Prototyping of Rehabilitation Aids

1997 ◽  
Author(s):  
Venkat Krovi ◽  
Vijay Kumar ◽  
G. K. Ananthasuresh ◽  
Jean-Marc Vezien
Keyword(s):  
Virtual Prototyping ◽  
Assistive Devices ◽  
Cad Model ◽  
Mechanism Synthesis ◽  
Design And Optimization ◽  
Revolute Joints ◽  
Synthesis Design ◽  
Serial Chain

Abstract This paper presents a paradigm for virtual prototyping of a class of one-of-a-kind assistive devices that can be customized to the human user. This class consists of passive, articulated mechanical aids for manipulation that are physically coupled to the user. We address the mechanism synthesis, design and optimization and its evaluation in a virtual prototyping environment that consists of a CAD model of the product and a customized model of the human user. In addition, we develop the theory and methodology for designing planar serial chain mechanisms with revolute joints coupled by cable-pulley transmissions. As an illustrative example, we consider the design and prototyping of a customized feeding aid for quadriplegics.

A New Family of Bricard-Derived Deployable Mechanisms

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Hailin Huang ◽  
Bing Li ◽  
Jianyang Zhu ◽  
Xiaozhi Qi
Keyword(s):  
Large Volume ◽  
Computer Aided Design ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
New Family ◽  
Revolute Joints ◽  
Computer Aided ◽  
Cad Models ◽  
Aided Design

This paper proposes a new family of single degree of freedom (DOF) deployable mechanisms derived from the threefold-symmetric deployable Bricard mechanism. The mobility and geometry of original threefold-symmetric deployable Bricard mechanism is first described, from the mobility characterstic of this mechanism, we show that three alternate revolute joints can be replaced by a class of single DOF deployable mechanisms without changing the single mobility characteristic of the resultant mechanisms, therefore leading to a new family of Bricard-derived deployable mechanisms. The computer-aided design (CAD) models are used to demonstrate these derived novel mechanisms. All these mechanisms can be used as the basic modules for constructing large volume deployable mechanisms.

scholarly journals Automated Generation of Linkage Loop Equations for Planar One Degree-of-Freedom Linkages, Demonstrated up to 8-Bar

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Brian E. Parrish ◽  
J. Michael McCarthy ◽  
David Eppstein
Keyword(s):  
Kinematic Analysis ◽  
Degree Of Freedom ◽  
Common Edge ◽  
Adjacency Graph ◽  
Automated Generation ◽  
Cycle Basis ◽  
Revolute Joints

In this paper, we present an algorithm that automatically creates the linkage loop equations for planar one degree of freedom, 1DOF, linkages of any topology with revolute joints, demonstrated up to 8 bar. The algorithm derives the linkage loop equations from the linkage adjacency graph by establishing a rooted cycle basis through a single common edge. Divergent and convergent loops are identified and used to establish the fixed angles of the ternary and higher links. Results demonstrate the automated generation of the linkage loop equations for the nine unique 6-bar linkages with ground-connected inputs that can be constructed from the five distinct 6-bar mechanisms, Watt I–II and Stephenson I–III. Results also automatically produced the loop equations for all 153 unique linkages with a ground-connected input that can be constructed from the 71 distinct 8-bar mechanisms. The resulting loop equations enable the automatic derivation of the Dixon determinant for linkage kinematic analysis of the position of every possible assembly configuration. The loop equations also enable the automatic derivation of the Jacobian for singularity evaluation and tracking of a particular assembly configuration over the desired range of input angles. The methodology provides the foundation for the automated configuration analysis of every topology and every assembly configuration of 1DOF linkages with revolute joints up to 8 bar. The methodology also provides a foundation for automated configuration analysis of 10-bar and higher linkages.

Geometric Design of a Bio-Inspired Flapping Wing Mechanism Based on Bennett-Derived 6R Deployable Mechanisms

2014 ◽  
Author(s):  
Huang Hailin ◽  
Li Bing
Keyword(s):  
Flapping Wing ◽  
Geometric Design ◽  
Geometric Parameters ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Flapping Motion ◽  
Single Degree ◽  
Revolute Joints ◽  
Air Vehicle ◽  
Deployable Mechanism

In this paper, we present the concept of designing flapping wing air vehicle by using the deployable mechanisms. A novel deployable 6R mechanism, with the deploying/folding motion of which similar to the flapping motion of the vehicle, is first designed by adding two revolute joints in the adjacent two links of the deployable Bennett linkage. The mobility of this mechanism is analyzed based on a coplanar 2-twist screw system. An intuitive projective approach for the geometric design of the 6R deployable mechanism is proposed by projecting the joint axes on the deployed plane. Then the geometric parameters of the deployable mechanism can be determined. By using another 4R deployable Bennett connector, the two 6R deployable wing mechanisms can be connected together such that the whole flapping wing mechanism has a single degree of freedom (DOF).

A Compliant Mechanism Design Methodology for Coupled and Uncoupled Systems, and Governing Free Choice Selection Considerations

2004 ◽  
Author(s):  
Ashok Midha ◽  
Yuvaraj Annamalai ◽  
Sharath K. Kolachalam
Keyword(s):  
Rigid Body ◽  
Design Methodology ◽  
Free Choice ◽  
Compliant Mechanisms ◽  
State Of The Art ◽  
Compliant Mechanism ◽  
Mechanism Synthesis ◽  
Strongly Coupled ◽  
Revolute Joints ◽  
Compliant Mechanism Design

Compliant mechanisms are defined as mechanisms that gain some, or all of their mobility from the flexibility of their members. Suitable use of pseudo-rigid-body models for compliant segments, and relying on the state-of-the-art knowledge of rigid-body mechanism synthesis types, greatly simplifies the design of compliant mechanisms. Assuming a pseudo-rigid-body four-bar mechanism, with one to four torsional springs located at the revolute joints to represent mechanism compliance, a simple, heuristic approach is provided to develop various compliant mechanism types. The synthesis with compliance method is used for three, four and five precision positions, with consideration of one to four torsional springs, to systematically develop design tables for standard mechanism synthesis types. These tables appropriately reflect the mechanism compliance by specification of either energy or torque. Examples are presented to demonstrate the use of weakly or strongly coupled sets of kinematic and energy/torque equations, as well as different compliant mechanism types in obtaining solutions.

An Image-Based Approach to Variational Path Synthesis of Linkages

2020 ◽  
Author(s):  
Shrinath Deshpande ◽  
Anurag Purwar
Keyword(s):  
Concept Generation ◽  
Spatial Correlations ◽  
Mechanism Synthesis ◽  
Small Set ◽  
Image Pixels ◽  
Path Synthesis ◽  
Synthesis Approach ◽  
Generation Problem ◽  
Input Curve ◽  
Probabilistic Generative Model

Abstract This paper brings together computer vision, mechanism synthesis, and machine learning to create an image-based variational path synthesis approach for linkage mechanisms. An image-based approach is particularly amenable to mechanism synthesis when the input from mechanism designers is deliberately imprecise or inherently uncertain due to the nature of the problem. In addition, it also lends itself naturally to the creation of a unified approach to mechanism synthesis since pixels do not care if they were generated from a four-bar or six-bar. Path synthesis problem has generally been solved for a set of precision points on the intended path such that the designed mechanism passes through those points. This approach usually leads to a small set of over-fitting solutions to the particular precision points. However, most kinematic synthesis problems are concept generation problem where a designer cares more about generating a large number of plausible solutions. This paper models the input curve as a probability distribution of image pixels and employs a probabilistic generative model to capture the inherent uncertainty in the input. In addition, it gives feedback on the input quality and provides corrections for a more conducive input. The image representation allows for capturing local spatial correlations, which plays an important role in finding a variety of solutions with similar semantics as the input curve.

Workspace of Four-Degree-of-Freedom Manipulators

1996 ◽  
Author(s):  
Karim Abdel-Malek ◽  
Harn-Jou Yeh
Keyword(s):  
Perturbation Technique ◽  
Underlying Mechanism ◽  
Degree Of Freedom ◽  
Parametric Surfaces ◽  
Singular Surfaces ◽  
End Effector ◽  
Serial Manipulators ◽  
Constraint Equations ◽  
First Order ◽  
Revolute Joints

Abstract An analytical method is presented to obtain all boundary surfaces to the accessible output set of four degree-of-freedom serial manipulators. The method is applicable to all manipulators that comprise combinations of prismatic and revolute joints. Position constraints of the end-effector of such mechanisms are formulated using the Denavit-Hartenberg representation. Examining the Jacobian of the underlying mechanism using a row-rank deficiency method yields sets of first-order singularities. These sets of singularities are substituted into the position constraint equations yielding parametric surfaces upon which the manipulator looses at least one degree of mobility. Singular curves are determined by intersecting singular surfaces. Due to the complexity of intersecting parametric singular surfaces, the resultant singular curves are numerically computed. Bifurcation points are identified and tangents are computed. Singular surfaces are partitioned into sub-surfaces that are studied for existence inside the accessible output set using a proposed perturbation technique. The result is a number of sub-surfaces that envelop the accessible output set. The theory presented is validated using a four-degree-of-freedom example.

Single-Degree-of-Freedom Rigidly Foldable Origami Flashers

2015 ◽  
Author(s):  
Robert J. Lang ◽  
Spencer Magleby ◽  
Larry Howell
Keyword(s):  
Degree Of Freedom ◽  
Deployable Structures ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Revolute Joints

We present the design for a family of deployable structures based on the origami flasher that are rigidly foldable, i.e., foldable with revolute joints at the hinges and planar rigid faces, and that exhibit a single degree of freedom in their motion. These structures may be used to realize highly compact deployable mechanisms.

Graphical Methods to Locate the Secondary Instant Centers of Single-Degree-of-Freedom Indeterminate Linkages

2005 ◽  
Vol 127 (2) ◽  
pp. 249-256 ◽  
Author(s):  
David E. Foster ◽  
Gordon R. Pennock
Keyword(s):  
Degree Of Freedom ◽  
Graphical Methods ◽  
Single Degree Of Freedom ◽  
Revolute Joint ◽  
Single Degree ◽  
Revolute Joints ◽  
Straight Line ◽  
Single Link ◽  
Prismatic Joints ◽  
Two Degree Of Freedom

This paper presents graphical techniques to locate the unknown instantaneous centers of zero velocity of planar, single-degree-of-freedom, linkages with kinematic indeterminacy. The approach is to convert a single-degree-of-freedom indeterminate linkage into a two-degree-of-freedom linkage. Two methods are presented to perform this conversion. The first method is to remove a binary link and the second method is to replace a single link with a pair of links connected by a revolute joint. First, the paper shows that a secondary instant center of a two-degree-of-freedom linkage must lie on a unique straight line. Then this property is used to locate a secondary instant center of the single-degree-of-freedom indeterminate linkage at the intersection of two lines. The two lines are obtained from a purely graphical procedure. The graphical techniques presented in this paper are illustrated by three examples of single-degree-of-freedom linkages with kinematic indeterminacy. The examples are a ten-bar linkage with only revolute joints, the single flier eight-bar linkage, and a ten-bar linkage with revolute and prismatic joints.

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