scholarly journals Type Synthesis Principle and Practice of Flexure Systems in the Framework of Screw Theory: Part III—Numerations and Synthesis of Flexure Mechanisms

2010 ◽  
Author(s):  
S. Z. Li ◽  
J. J. Yu ◽  
X. Pei ◽  
Hai-jun Su ◽  
J. B. Hopkins ◽  
...  
Keyword(s):  
High Precision ◽  
Screw Theory ◽  
Degree Of Freedom ◽  
Type Synthesis ◽  
General Design ◽  
Flexure Mechanism ◽  
Design Philosophy ◽  
Large Motion ◽  
Application Requirements ◽  
Made In

In recent years, the increasing of application requirements call for development of a variety of flexure mechanisms with high precision or large motion and both. Therefore, in Part III of this series of papers we demonstrate how to use the methodology addressed in Part I to synthesize concepts for two kinds of flexure mechanisms, i.e. kinematics-type flexure mechanisms (KFMs) and constraint-type flexure mechanisms (CFMs) with the specified-DOF (Degree of Freedom) characteristics. Although most of them utilize parallel configurations and flexure elements, there is a clear difference in the behavior of flexures between KFMs and CFMs, The resultant type synthesis approaches fall into two distinct categories i.e. freedom-based and constraint-based one, both of which have presented in Part I. In order to derive useful flexure mechanism concepts available for different applications, a general design philosophy and rules are summarized firstly. As the main content of this part, the classifications, numerations, and synthesis for KFMs and CFMs are made in a systematic way. As a result, a majority of new precision flexure mechanisms are developed. In addition, qualitative comparisons are provided to demonstrate the performance and application differences between kinematic-type and constraint-type flexure mechanisms with the same DOF.

scholarly journals A New Method for Type Synthesis of 2R1T and 2T1R 3-DOF Redundant Actuated Parallel Mechanisms with Closed Loop Units

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Yongquan Li ◽  
Yang Zhang ◽  
Lijie Zhang
Keyword(s):  
Closed Loop ◽  
Screw Theory ◽  
Line Graph ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Allocation Criteria ◽  
Grassmann Line Geometry ◽  
Moving Platform ◽  
Atlas Method

Abstract The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms, or using screw theory to perform multiple getting intersection and union to complete type synthesis. The number of redundant parallel mechanisms obtained by these two methods is limited. In this paper, based on Grassmann line geometry and Atlas method, a novel and effective method for type synthesis of redundant actuated parallel mechanisms (PMs) with closed-loop units is proposed. Firstly, the degree of freedom (DOF) and constraint line graph of the moving platform are determined successively, and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph, and a branch constraint allocation scheme is formulated based on the allocation criteria. Secondly, a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop units. Finally, the branch chains that meet the requirements of branch chains configuration criteria and F&C (degree of freedom & constraint) line graph are assembled. In this paper, two types of 2 rotational and 1 translational (2R1T) redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational (2T1R) redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples, and 238, 92 and 15 new configurations were synthesized. All the mechanisms contain closed-loop units, and the mechanisms and the actuators both have good symmetry. Therefore, all the mechanisms have excellent comprehensive performance, in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently controlled. The instantaneous analysis shows that all mechanisms are not instantaneous, which proves the feasibility and practicability of the method.

scholarly journals Type Synthesis Principle and Practice of Flexure Systems in the Framework of Screw Theory: Part II—Numerations and Synthesis of Complex Flexible Joints

2010 ◽  
Author(s):  
J. J. Yu ◽  
X. Pei ◽  
S. Z. Li ◽  
Hai-jun Su ◽  
J. B. Hopkins ◽  
...  
Keyword(s):  
High Performance ◽  
Screw Theory ◽  
Companion Paper ◽  
Synthesis Process ◽  
Type Synthesis ◽  
Flexible Joints ◽  
Flexible Joint ◽  
Modeling And Analysis ◽  
Revolute Joints ◽  
Application Requirements

In recent years, the increasing of application requirements call for development of a variety of high-performance (e.g. large-displacement, high-precision) flexible joints. In this paper we demonstrate how to use the proposed methodology for the type synthesis of flexure systems given in the companion paper to synthesize concepts for complex flexible joints. According to the joint characteristics other than other flexure systems, a basic design philosophy and a general type synthesis process for flexible joints are presented firstly. The numerations and type synthesis for four commonly used flexible joint types, i.e. flexible revolute joints (FRJs), flexible translational joints (FTJs), flexible universal joints (FUJs), and flexible spherical joints (FSJs) are investigated in detail. As a result, not only a variety of known flexible joints are systematically surveyed and classified, but also are some new flexible joints developed. The output of this process is the derivation of a multiple of flexible joint concepts that would then be modeled and optimized by existing modeling and analysis methods.

scholarly journals Type Synthesis of Two DOF Hybrid Translational Parallel Manipulators

2016 ◽  
Vol 836 ◽  
pp. 48-53 ◽  
Author(s):  
Latifah Nurahmi ◽  
Stéphane Caro
Keyword(s):  
Screw Theory ◽  
Synthesis Method ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Type Synthesis ◽  
In Series ◽  
Actuation Scheme ◽  
Two Degree Of Freedom

This paper introduces a methodology for the type synthesis of two degree-of-freedom hybrid translational manipulators with identical legs. The type synthesis method is based upon the screw theory. Three types of two degree-of-freedom hybrid translational manipulators with identical legs are identified based upon their wrench decomposition. Each leg of the manipulators is composed of a proximal module and a distal module mounted in series. The assembly conditions and the validity of the actuation scheme are also defined. Eventually, some novel two degree-of-freedom hybrid translational manipulators are synthesized with the proposed procedure.

Type Synthesis of Three-Degree-of-Freedom Translational Compliant Parallel Mechanisms

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Cong Yue ◽  
Ying Zhang ◽  
Hai-Jun Su ◽  
Xianwen Kong
Keyword(s):  
Screw Theory ◽  
Rigid Bodies ◽  
Degree Of Freedom ◽  
Design Stage ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Geometric Conditions ◽  
Synthesis Procedure ◽  
Flexure Joints ◽  
Three Degree Of Freedom

In this paper, we apply screw theory to type synthesis of compliant parallel mechanisms (PMs) with translational degree-of-freedom (DOF). Compliant PMs are formed by a moving platform supported by three or more limbs each of which is a serial chain of flexure joints and rigid bodies. They achieve movement through the deformation of flexure joints and have been widely used in precision machinery. As an important task in the conceptual design stage, the goal of type synthesis is to determine the chain of each limb as well as their relationship when they are assembled in parallel for a prescribed motion pattern. In our approach, we study a category of commonly used flexure primitives and flexure elements whose freedom and constraint spaces are characterized by twists and wrenches in screw theory. Following the well-studied synthesis procedure for rigid body PMs, we propose a synthesis procedure for compliant PMs via screw theory. As an example, we demonstrate the procedure for synthesizing compliant PMs with three translational DOF. Tables of limbs, types, and geometric conditions for the assemblies of these limbs are presented. The paper provides a catalog of 3DOF translational compliant PM designs. At last, we developed finite element simulation to validate one of the synthesized designs.

Type Synthesis of 3-DOF Rotational Parallel Mechanisms With No Intersecting Axes

2012 ◽  
Author(s):  
Ziming Chen ◽  
Wen-ao Cao ◽  
Zhen Huang
Keyword(s):  
Parallel Mechanism ◽  
Screw Theory ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Constraint Force ◽  
New Approach ◽  
Spherical Parallel Mechanism ◽  
Rotational Motions

Parallel mechanisms which can realize three rotational motions are very important in the parallel mechanism family. Not the same with the traditional spherical parallel mechanism, a new kind of 3-DOF (degree of freedom) rotational parallel mechanism with no intersecting axes (RPMNIA) are proposed in this paper. This kind of rotational parallel mechanisms have the advantages of easy manufacturing. A new approach using the screw theory and the subchain theory is proposed to design the branches with only one constraint force and some new one-force-branches are found. Using these new branches, a group of 3-DOF rotational parallel mechanisms without intersecting axes are synthesized.

Screw Theory Based Methodology for the Deterministic Type Synthesis of Flexure Mechanisms

2011 ◽  
Vol 3 (3) ◽  
Author(s):  
Jingjun Yu ◽  
Shouzhong Li ◽  
Hai-jun Su ◽  
M. L. Culpepper
Keyword(s):  
System Theory ◽  
Screw Theory ◽  
Building Blocks ◽  
Mathematical Tool ◽  
Geometric Form ◽  
Type Synthesis ◽  
Mechanism Synthesis ◽  
Flexure Mechanism ◽  
Synthesis Methodology ◽  
Set Operation

Flexure mechanism synthesis, however, is still a comparably difficult task. This paper aims at exploring a simple but systematic type synthesis methodology for general flexure mechanisms. The applied mathematical tool is reciprocal screw system theory in geometric form, and the proposed approach is an improvement of freedom and constraint topology (FACT), which is based on the FACT approach, combining with other methods including equivalent compliance mapping, set operation on building blocks, etc. As a result, it enables the type synthesis of flexure mechanisms simple, complete, and effective. What is more significant is that the proposed approach makes the unified type synthesis of both constraint-based and kinematics-based flexure mechanisms available. That is also the new contribution to the flexure de-sign.

Realizing Orthogonal Motions With Wire Flexures Connected in Parallel

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Hai-Jun Su ◽  
Hafez Tari
Keyword(s):  
Screw Theory ◽  
Degree Of Freedom ◽  
Design Approach ◽  
Theory Approach ◽  
Mobility Pattern ◽  
Type Synthesis ◽  
Simply Connected ◽  
Typical Design

In this paper, we study the type synthesis of wire flexures to achieve orthogonal motions by using a recently developed screw theory based design approach. For a given desired mobility pattern, our goal is to find a system of wire flexures that are simply connected in parallel between the functional stage and the ground. It has been shown that a wire flexure is essentially a pure force or a line screw. An n degree-of-freedom (DOF) motion space (allowable motion) is realizable if its reciprocal constraint space can be spanned by 6-n line screws or forces. We first enumerate 34 possible 1–5DOF spaces that are formed by motions along the coordinate axes attached on the functional stage. For each of these 34 motion spaces, we apply the screw theory approach to find its reciprocal force space as well as its rank. At last, a typical design is provided for each of these motion spaces.

Type Synthesis of Three-DOF Translational Parallel Mechanisms

2003 ◽  
Author(s):  
Jingjun Yu ◽  
Shusheng Bi ◽  
Guanghua Zong ◽  
Tieshi Zhao ◽  
Zhen Huang
Keyword(s):  
Degrees Of Freedom ◽  
Screw Theory ◽  
Synthesis Method ◽  
Reciprocal Relationship ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Constraint Forces ◽  
Novel Synthesis ◽  
Spatial Translation ◽  
Made In

This paper presents a simple but effective type synthesis method for spatial parallel mechanisms with three translational degrees of freedom based on the screw theory. Firstly all possible connecting-chain structures of three-DOF parallel mechanisms are enumerated. According to the reciprocal relationship between screw constraint forces and the motion screw, a novel synthesis method is presented. By using this method, type synthesis for three-DOF translational parallel mechanisms has been made in a systematic and detailed way. As a result, some novel parallel mechanisms generating spatial translation have been obtained. To verify the significance of type synthesis for this kind of mechanism, the paper also gives a concrete application instance, which is used for a micromanipulator for manipulating the bio-cells.

FIB Micromachining and Nano-Structure Fabrication

1999 ◽  
Author(s):  
Raymond A. Lee ◽  
Patrick J. Wolpert
Keyword(s):  
High Precision ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Biological Applications ◽  
Optical Lens ◽  
Nano Structure ◽  
Beam System ◽  
Afm Tips ◽  
Established Technique ◽  
Made In

Abstract FIB Micromachining has long been an established technique, but until recently it has been overshadowed by the more mainstream semiconductor application of the Focused Ion Beam system. Nano- Structure fabrication using the FIB system has become more popular recently due to several factors. The need for sub-micron structures have grown significantly due to a need for enhanced optical and biological applications. Another reason for the growth in micromachining is the improvement made in the ability of FIB systems to produce geometric shapes with high precision. With the latest high-end FIB systems, it is possible to produce microstructures with tens of nano-meters of precision. Optical lens, AFM tips, and nano-apertures are all part of the growing application for FIB Micromachining. This paper will discuss the ability and limitations of the FIB system and some possible application for FIB Micromachining.

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