A Framework and Design Sythesis Tool Used to Generate, Evaluate and Optimize Compliant Mechanism Concepts for Research and Education Activities

2004 ◽  
Author(s):  
Martin L. Culpepper ◽  
Soohyung Kim
Keyword(s):  
Compliant Mechanisms ◽  
Screw Theory ◽  
Compliant Mechanism ◽  
Mems Accelerometer ◽  
Award Winning ◽  
Mechanism Research ◽  
Big Picture ◽  
Research And Education ◽  
New Research ◽  
Student Projects

In 2002, a Microsoft-MIT iCampus effort was initiated to generate methods and tools which accelerate the process by which students and researchers acquire perspective and skill in compliant mechanism design: (1) Experience and skill: A synthesis tool, CoMeT, was developed as a means for researchers and students to gain experience and skill in working with old (education) and new (research) compliant mechanisms. The simulator is based on compliance theory and screw theory. (2) Perspective: A framework, the 5 Fs, was developed to help designers form a holistic perspective on compliant mechanisms. A “big picture” view helps them systematically identify and link the important elements of a compliant mechanism problem. This opens to door for them to properly conceptualize, model and fabricate these mechanisms. In this paper we discuss the work of early compliant mechanism/instrument designers to gain insight into how they thought about, designed and taught others about compliant mechanisms. We explain how their work has influenced the development of our framework and simulator. We then show results obtained by using the framework and simulator at MIT in: (1) Compliant mechanism research: Generation of a compliant mechanism for an R&D 100 award winning, six-axis Nanomanipulator. (2) Compliant mechanism education: Use within student projects to design two devices: A compliant x-y Nanomanipulator with 30×30 μm range and a MEMS accelerometer. Both devices are designed, fabricated and tested in a semester-long class. The paper closes with an appendix which highlights the main steps of a CoMeT study on the screw axis characteristics of a four bar compliant mechanism. The CoMeT simulator and a CoMeT User’s Guide have been made publicly available for academic use at psdam.mit.edu.

Analysis of Parasitic Motion in Compliant Mechanisms Using Eigenwrenches and Eigentwists

2018 ◽  
Author(s):  
Werner W. P. J. van de Sande ◽  
Just L. Herder
Keyword(s):  
Compliant Mechanisms ◽  
Screw Theory ◽  
Compliant Mechanism ◽  
Degree Of Freedom ◽  
Compliance Matrix ◽  
Parasitic Motion ◽  
Actual Degree ◽  
Motion Metrics ◽  
Mechanism Kinematic ◽  
Kinematic Information

Parasitic motion is undesired in precision mechanisms, it causes unwanted kinematics. These erroneous motions are especially apparent in compliant mechanisms. Usually an analysis of parasitic motion is only valid for one type of mechanism. Kinematic information is imbedded in the compliance matrix of any mechanism; an eigenscrew decomposition expresses this kinematic information as screws. It uses screw theory to identify the lines along which a force yields a parallel translation and a rotation yields a parallel moment. These lines are called eigenwrenches and eigentwists. Any other load on the compliant mechanism will lead to parasitic motion. This article introduces two parasitic motion metrics using eigenscrew decomposition: the parasitic resultant from an applied screw and the deviation of an actual degree of freedom from a desired degree of freedom. These metrics are applicable to all compliant mechanism and allow comparison between two compliant mechanisms. These metrics are applied to some common compliant mechanisms as an example.

scholarly journals A Screw Theory Approach for the Type Synthesis of Compliant Mechanisms With Flexures

2009 ◽  
Author(s):  
Hai-Jun Su ◽  
Denis V. Dorozhkin ◽  
Judy M. Vance
Keyword(s):  
Compliant Mechanisms ◽  
Screw Theory ◽  
Compliant Mechanism ◽  
Computational Techniques ◽  
Theory Approach ◽  
Type Synthesis ◽  
Precision Engineering ◽  
Pattern Design ◽  
Design Constraint ◽  
Systematic Formulation

This paper presents a screw theory based approach for the type synthesis of compliant mechanisms with flexures. We provide a systematic formulation of the constraint-based approach which has been mainly developed by precision engineering experts in designing precision machines. The two fundamental concepts in the constraint-based approach, constraint and freedom, can be represented mathematically by a wrench and a twist in screw theory. For example, an ideal wire flexure applies a translational constraint which can be described a wrench of pure force. As a result, the design rules of the constraint-based approach can be systematically formulated in the format of screws and screw systems. Two major problems in compliant mechanism design, constraint pattern analysis and constraint pattern design are discussed with examples in details. This innovative method paves the way for introducing computational techniques into the constraint-based approach for the synthesis and analysis of compliant mechanisms.

scholarly journals DAS-2D: a concept design tool for compliant mechanisms

2016 ◽  
Vol 7 (2) ◽  
pp. 135-148 ◽  
Author(s):  
Omer Anil Turkkan ◽  
Hai-Jun Su
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Design Tool ◽  
Concept Design ◽  
Simulation Tools ◽  
Element Simulation ◽  
Mechanism Research ◽  
Analysis And Synthesis ◽  
Engineering Practices

Abstract. Compliant mechanisms utilize the deformation of the elastic members to achieve the desired motion. Currently, design and analysis of compliant mechanisms rely on several commercial dynamics and finite element simulation tools. However, these tools do not implement the most recently developed theories in compliant mechanism research. In this article, we present DAS-2D (Design, Analysis and Synthesis), a conceptual design tool which integrates the recently developed pseudo-rigid-body models and kinetostatic analysis/synthesis theories for compliant mechanisms. Coded in Matlab, the software features a kinematic solver for general rigid-body mechanisms, a kinetostatic solver for compliant mechanisms and a fully interactive graphical user interface. The implementation details of all modules of the program are presented and demonstrated with four different case studies. This tool can be beneficial to classroom teaching as well as engineering practices in design of compliant mechanisms.

Origami Kaleidocycle-Inspired Symmetric Multistable Compliant Mechanisms

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Hongchuan Zhang ◽  
Benliang Zhu ◽  
Xianmin Zhang
Keyword(s):  
Arbitrary Number ◽  
Compliant Mechanisms ◽  
Rotation Angle ◽  
Screw Theory ◽  
Compliant Mechanism ◽  
Mobility Analysis ◽  
Stable States ◽  
Deployable Structures ◽  
Basic Dimension ◽  
Metamorphic Robots

Compliant kaleidocycles can be widely used in a variety of applications, including deployable structures, origami structures, and metamorphic robots, due to their unique features of continuous rotatability and multistability. Inspired by origami kaleidocycles, a type of symmetric multistable compliant mechanism with an arbitrary number of units is presented and analyzed in this paper. First, the basic dimension constraints are developed based on mobility analysis using screw theory. Second, the kinematic relationships of the actual rotation angle are obtained. Third, a method to determine the number of stabilities and the position of stable states, including the solution for the parameterized boundaries of stable regions, is developed. Finally, experimental platforms are established, and the validity of the proposed multistable mechanisms is verified.

scholarly journals A Screw Theory Approach for the Conceptual Design of Flexible Joints for Compliant Mechanisms

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
Hai-Jun Su ◽  
Denis V. Dorozhkin ◽  
Judy M. Vance
Keyword(s):  
Compliant Mechanisms ◽  
Screw Theory ◽  
Compliant Mechanism ◽  
Computational Techniques ◽  
Theory Approach ◽  
Flexible Joints ◽  
Precision Engineering ◽  
Design Constraint ◽  
Analysis And Synthesis ◽  
Prismatic Joints

This paper presents a screw theory based approach for the analysis and synthesis of flexible joints using wire and sheet flexures. The focus is on designing flexure systems that have a simple geometry, i.e., a parallel constraint pattern. We provide a systematic formulation of the constraint-based approach, which has been mainly developed by precision engineering experts in designing precision machines. The two fundamental concepts in the constraint-based approach, constraint and freedom, can be represented mathematically by a wrench and a twist in screw theory. For example, an ideal wire flexure applies a translational constraint, which can be described by a wrench of pure force. As a result, the design rules of the constraint-based approach can be systematically formulated in the format of screws and screw systems. Two major problems in compliant mechanism design, constraint pattern analysis, and constraint pattern design are discussed with examples in details. Lastly, a case study is provided to demonstrate the application of this approach to the design of compliant prismatic joints. This innovative method paves the way for introducing computational techniques into the constraint-based approach for the synthesis and analysis of compliant mechanisms.

The Three Rs in Research and Education: A Long Road Ahead in the United States

1996 ◽  
Vol 24 (2) ◽  
pp. 151-158 ◽  
Author(s):  
F. Barbara Orlans
Keyword(s):  
United States ◽  
Animal Experiments ◽  
The United States ◽  
Education Student ◽  
Funding Sources ◽  
Research And Education ◽  
The Right ◽  
Student Projects ◽  
Institutional Oversight ◽  
The Three Rs

Attitudes toward the Three Rs concept of refinement, reduction and replacement in the United States in research and education are widely divergent. Positive responses have come from several sources, notably from four centres established to disseminate information about alternatives. Funding sources to support work in the Three Rs have proliferated. The activities of institutional oversight committees have resulted in the nationwide implementation of important refinements. In the field of education, student projects involving pain or death for sentient animals have declined, and the right of students to object to participation in animal experiments on ethical grounds has been widely established. However, there is still a long way to go. Resistance to alternatives is deep-seated within several of the scientific disciplines most closely associated with animal research. The response of the National Institutes of Health to potentially important Congressional directives on the Three Rs has been unsatisfactory. The prestigious National Association of Biology Teachers, which at first endorsed the use of alternatives in education, later rescinded this policy, because of opposition to it. An impediment to progress is the extreme polarisation of viewpoints between the biomedical community and the animal protectionists.

Structure Synthesis of 3-RRS Type Spatial Compliant Parallel Manipulator

2010 ◽  
Vol 44-47 ◽  
pp. 1375-1379
Author(s):  
Da Chang Zhu ◽  
Li Meng ◽  
Tao Jiang
Keyword(s):  
Parallel Manipulator ◽  
Compliant Mechanisms ◽  
Screw Theory ◽  
Weight Ratio ◽  
Parallel Manipulators ◽  
Robot System ◽  
New Approach ◽  
Structure Synthesis ◽  
Rigid Joints ◽  
Type 3

Parallel manipulators has been extensively studied by virtues or its high force-to-weight ratio and widely spread applications such as vehicle or flight simulator, a machine tool and the end effector of robot system. However, as each limb includes several rigid joints, assembling error is demanded strictly, especially in precision measurement and micro-electronics. On the other hand, compliant mechanisms take advantage of recoverable deformation to transfer or transform motion, force, or energy and the benefits of compliant mechanisms mainly come from the elimination of traditional rigid joints, but the traditional displacement method reduce the stiffness of spatial compliant parallel manipulators. In this paper, a new approach of structure synthesis of 3-DoF rotational compliant parallel manipulators is proposed. Based on screw theory, the structures of RRS type 3-DoF rotational spatial compliant parallel manipulator are developed. Experiments via ANSYS are conducted to give some validation of the theoretical analysis.

Bistable Compliant Four-Bar Mechanisms With a Single Torsional Spring

2006 ◽  
Author(s):  
Adarsh Mavanthoor ◽  
Ashok Midha
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanism Design ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Stored Energy ◽  
Element Analysis ◽  
Bistable Behavior ◽  
Torsional Spring ◽  
Bistable Mechanism

Significant reduction in cost and time of bistable mechanism design can be achieved by understanding their bistable behavior. This paper presents bistable compliant mechanisms whose pseudo-rigid-body models (PRBM) are four-bar mechanisms with a torsional spring. Stable and unstable equilibrium positions are calculated for such four-bar mechanisms, defining their bistable behavior for all possible permutations of torsional spring locations. Finite Element Analysis (FEA) and simulation is used to illustrate the bistable behavior of a compliant mechanism with a straight compliant member, using stored energy plots. These results, along with the four-bar and the compliant mechanism information, can then be used to design a bistable compliant mechanism to meet specified requirements.

Design of a Generic Zero Stiffness Compliant Joint

2010 ◽  
Author(s):  
Femke M. Morsch ◽  
Just L. Herder
Keyword(s):  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Great Promise ◽  
Optimized Design ◽  
Analytic Model ◽  
Total Potential ◽  
Fea Model ◽  
Compliant Joint ◽  
Joint Element ◽  
Cross Axis

The objective of this paper is to design a generic zero stiffness compliant joint. This compliant joint could be used as a generic construction element in a compliant mechanism. To avoid the spring-back behavior of conventional compliant joints, the principle of static balancing is applied, implying that for each position of the joint the total potential energy should be constant. To this end, a conventional balanced mechanism, consisting of two pivoted bodies which are balanced with two zero-free-length springs, is taken as an initial concept. The joint is replaced by a compliant cross-axis flexural pivot and each spring is replaced by a pair of compliant leaf springs. For both parts an analytic model was implemented and a configuration with the lowest energy fluctuation was found through optimization. A FEA model was used to verify the analytic model of the optimized design. A prototype was manufactured and tested. Both the FEA model and the experiment confirm the reduction of the needed moment to rotate the compliant joint. The experiment shows the balanced compliant joint is not completely balanced but the moment required to rotate the joint is reduced by 70%. Thus, a statically balanced compliant generic joint element was designed which bears great promise in designing statically balanced compliant mechanisms and making this accessible to any designer.

A Simple and Accurate Method for Determining Large Deflections in Compliant Mechanisms Subjected to End Forces and Moments

1998 ◽  
Vol 120 (3) ◽  
pp. 392-400 ◽  
Author(s):  
A. Saxena ◽  
S. N. Kramer
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Elliptic Integral ◽  
Beam Equation ◽  
Large Deflections ◽  
Euler Beam ◽  
Body Model ◽  
Rigid Body Model ◽  
Analysis And Synthesis

Compliant members in flexible link mechanisms undergo large deflections when subjected to external loads. Because of this fact, traditional methods of deflection analysis do not apply. Since the nonlinearities introduced by these large deflections make the system comprising such members difficult to solve, parametric deflection approximations are deemed helpful in the analysis and synthesis of compliant mechanisms. This is accomplished by representing the compliant mechanism as a pseudo-rigid-body model. A wealth of analysis and synthesis techniques available for rigid-body mechanisms thus become amenable to the design of compliant mechanisms. In this paper, a pseudo-rigid-body model is developed and solved for the tip deflection of flexible beams for combined end loads. A numerical integration technique using quadrature formulae has been employed to solve the large deflection Bernoulli-Euler beam equation for the tip deflection. Implementation of this scheme is simpler than the elliptic integral formulation and provides very accurate results. An example for the synthesis of a compliant mechanism using the proposed model is also presented.

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