A Visualization Approach for Analyzing and Synthesizing Serial Flexure Elements

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Jonathan B. Hopkins
Keyword(s):  
Case Studies ◽  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Negative Effects ◽  
Constraint Topologies ◽  
Synthesis Approach

In this paper, we extend the principles of the freedom and constraint topologies (FACT) synthesis approach such that designers can analyze and synthesize serial flexure elements—not to be confused with serial flexure systems. Unlike serial systems, serial elements do not possess intermediate rigid bodies within their geometry and thus avoid the negative effects of unnecessary mass and underconstrained bodies that generate uncontrolled vibrations. Furthermore, in comparison with other common parallel flexure elements such as wire, blade, and living hinge flexures, serial elements can be used within flexure systems to achieve (i) a larger variety of kinematics, (ii) more dynamic and elastomechanic versatility, and (iii) greater ranges of motion. Here, we utilize the principles of FACT to intuitively guide designers in visualizing a multiplicity of serial flexure element geometries that can achieve any desired set of degrees of freedom (DOFs). Using this approach, designers can rapidly generate a host of new serial flexure elements for synthesizing advanced flexure systems. Thirty seven serial flexure elements are provided as examples, and three flexure systems that consist of some of these elements are synthesized as case studies.

Analyzing and Designing Serial Flexure Elements

2013 ◽  
Author(s):  
Jonathan B. Hopkins
Keyword(s):  
Case Studies ◽  
Degrees Of Freedom ◽  
Compliant Mechanisms ◽  
Rigid Bodies ◽  
The Other ◽  
Geometric Shapes ◽  
Other Hand ◽  
Constraint Topologies ◽  
Synthesis Approach

In this paper we introduce the principles necessary to analyze and design serial flexure elements, which may be used to synthesize advanced compliant mechanisms (CMs). The most commonly used flexure elements (e.g., wire, blade, or living hinge flexures) are often parallel and thus impose constraining forces directly through all parts of their geometry to the rigid bodies that they join within the CM. Serial flexure elements, on the other hand, constrain rigid bodies with a larger variety of forces and moments and thus enable CMs to achieve (i) more degrees of freedom (DOFs), (ii) larger dynamic and elastomechanic versatility, and (iii) greater ranges of motion than parallel elements. In this paper, we extend the principles of the Freedom and Constraint Topologies (FACT) synthesis approach such that it enables the synthesis of CMs that are not only constrained by parallel flexure elements, but also by serial elements. FACT utilizes geometric shapes to intuitively guide designers in visualizing compliant element geometries that achieve any desired set of DOFs. In this way, designers can rapidly generate a host of new serial flexure elements for various CM applications. Such elements are provided here as case studies.

scholarly journals Designing hybrid flexure systems and elements using Freedom and Constraint Topologies

2013 ◽  
Vol 4 (2) ◽  
pp. 319-331 ◽  
Author(s):  
J. B. Hopkins
Keyword(s):  
Hybrid Systems ◽  
Case Studies ◽  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Geometric Shapes ◽  
Design Requirements ◽  
Constraint Topologies ◽  
Exact Constraint ◽  
Synthesis Approach

Abstract. In this paper we introduce the principles necessary to synthesize hybrid flexure systems and elements. Flexure systems consist of rigid bodies that are joined together by flexure elements that elastically deform to guide the system's rigid bodies with desired degrees of freedom (DOFs). The principles introduced here for synthesizing hybrid flexure systems and elements are extensions of the Freedom and Constraint Topologies (FACT) synthesis approach. FACT utilizes a comprehensive library of geometric shapes from which designers can rapidly consider and compare a multiplicity of flexure concepts that achieve any desired set of DOFs. Prior to this paper, designers primarily used these shapes to synthesize parallel and serial flexure systems and elements. With this paper, designers may now use these same shapes to synthesize more general flexures that consist of various combinations of parallel and serial systems and elements (i.e., hybrid configurations). As such, designers can access a larger body of flexure solutions that satisfy demanding design requirements. Instructions for helping designers utilize or avoid the advantages and challenges of over-, under-, and exact-constraint are also provided. Hybrid systems and elements are analysed and designed as case studies.

Synthesizing Parallel Flexures That Mimic the Kinematics of Serial Flexures Using Freedom and Constraint Topologies

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Jonathan B. Hopkins
Keyword(s):  
Case Studies ◽  
Degrees Of Freedom ◽  
General Purpose ◽  
Complete List ◽  
Geometric Shapes ◽  
Point Of Interest ◽  
Precision Motion ◽  
Constraint Topologies ◽  
Synthesis Approach

The principles of the freedom and constraint topologies (FACT) synthesis approach are adapted and applied to the design of parallel flexure systems that mimic degrees of freedom (DOFs) primarily achievable by serial flexure systems. FACT provides designers with a comprehensive library of geometric shapes. These shapes enable designers to visualize the regions wherein compliant flexure elements may be placed for achieving desired DOFs. By displacing these shapes far from the point of interest of the stage of a flexure system, designers can compare a multiplicity of concepts that utilizes the advantages of both parallel and serial systems. A complete list of which FACT shapes mimic which DOFs when displaced far from the point of interest of the flexure system's stage is provided as well as an intuitive approach for verifying the completeness of this list. The proposed work intends to cater to the design of precision motion stages, optical mounts, microscopy stages, and general purpose flexure bearings. Two case studies are provided to demonstrate the application of the developed procedure.

Synthesizing Soft Parallel Robots Comprised of Active Constraints

2014 ◽  
Author(s):  
Jordan Rivera ◽  
Jonathan B. Hopkins ◽  
Charles Kim
Keyword(s):  
Case Studies ◽  
Degrees Of Freedom ◽  
Parallel Systems ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Soft Robot ◽  
Active Constraints ◽  
New Type ◽  
Constraint Topologies ◽  
Synthesis Approach

In this paper, we introduce a new type of spatial parallel robot that is comprised of soft inflatable constraints called Tri-Chamber Actuators (TCAs). We extend the principles of the Freedom and Constraint Topologies (FACT) synthesis approach to enable the synthesis and analysis of this new type of soft robot. The concepts of passive and active freedom spaces are introduced and applied to the design of general parallel systems that consist of active constraints (i.e., constraint that can be actuated to impart various loads onto the system’s stage) that both drive desired motions and guide the system’s desired degrees of freedom (DOFs). We provide the fabrication details of the TCA constraints introduced in this paper and experimentally validate their FACT-predicted kinematics. Examples are provided as case studies.

Synthesis and Analysis of Soft Parallel Robots Comprised of Active Constraints

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Jonathan B. Hopkins ◽  
Jordan Rivera ◽  
Charles Kim ◽  
Girish Krishnan
Keyword(s):  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Soft Robot ◽  
Element Analysis ◽  
Active Constraints ◽  
New Type ◽  
Constraint Model ◽  
Constraint Topologies ◽  
Synthesis Approach

In this paper, we introduce a new type of spatial parallel robot that is comprised of soft inflatable constraints called trichamber actuators (TCAs). We extend the principles of the freedom and constraint topologies (FACT) synthesis approach to enable the synthesis and analysis of this new type of soft robot. The concepts of passive and active freedom spaces are introduced and applied to the design of general parallel systems that consist of active constraints (i.e., constraint that can be actuated to impart various loads onto the system's stage) that both drive desired motions and guide the system's desired degrees of freedom (DOFs). We provide the fabrication details of the TCA constraints introduced in this paper and experimentally determine their appropriate FACT-based constraint model. We fabricate a soft parallel robot that consists of three TCA constraints and verify and validate its FACT-predicted performance using finite element analysis (FEA) and experimental data. Other such soft robots are synthesized using FACT as case studies.

scholarly journals An Efficient Contact Model for the Simulation of Cargo Airdrop Extraction Phase

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Leiming Ning ◽  
Jichang Chen ◽  
Mingbo Tong
Keyword(s):  
Degrees Of Freedom ◽  
Friction Model ◽  
Rigid Bodies ◽  
Contact Dynamics ◽  
Moving Frame ◽  
Contact Friction ◽  
Practical Implementation ◽  
Contact Formulation ◽  
Efficient Code ◽  
Extraction Phase

A high-fidelity cargo airdrop simulation requires the accurate modeling of the contact dynamics between an aircraft and its cargo. This paper presents a general and efficient contact-friction model for the simulation of aircraft-cargo coupling dynamics during an airdrop extraction phase. The proposed approach has the same essence as the finite element node-to-segment contact formulation, which leads to a flexible, straightforward, and efficient code implementation. The formulation is developed under an arbitrary moving frame with both aircraft and cargo treated as general six degrees-of-freedom rigid bodies, thus eliminating the restrictions of lateral symmetric assumptions in most existing methods. Moreover, the aircraft-cargo coupling algorithm is discussed in detail, and some practical implementation details are presented. The accuracy and capability of the present method are demonstrated through four numerical examples with increasing complexity and fidelity.

scholarly journals An Asymptotically Optimal NMPC Core for Multi Degrees of Freedom Rigid Bodies

2012 ◽  
Vol 45 (17) ◽  
pp. 207-212
Author(s):  
Chyon Hae Kim ◽  
Shimon Sugawara ◽  
Shigeki Sugano
Keyword(s):  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Asymptotically Optimal

Generalized Abbe Principle: Position Error Propagation in Machine Elements

1996 ◽  
Author(s):  
Joseph Pegna
Keyword(s):  
Error Propagation ◽  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Statistical Characterization ◽  
Physical Limit ◽  
Potential Applications ◽  
Machine Elements ◽  
Tolerance Verification ◽  
Precision Machines

Abstract In the quest for ever finer levels of technology integration, mechanical linkages reach their precision limits at about 5micrometers per meter of workspace. Beyond this physical limit, all six dimensional degrees of freedom need to be precisely ascertained to account for mechanical imperfections. This paper substantiates Wu’s vision of “precision machines without precision machinery.” A formulation and statistical characterization of position and orientation error propagation in rigid bodies are presented for two extreme models of measurement. It is shown that error distribution is uniquely dependent upon the design of the measurement plan. The theoretical foundations presented were evolved in the course of designing precision machinery. Other potential applications include: fixture design, metrology, and geometric tolerance verification.

Embracing Organizational Trauma

2017 ◽  
pp. 1526-1542
Author(s):  
Mike Szymanski ◽  
Erik Schindler
Keyword(s):  
Organizational Culture ◽  
Organizational Behavior ◽  
Case Studies ◽  
Traumatic Experiences ◽  
Negative Effects ◽  
Organizational Behaviour ◽  
And Performance ◽  
Organizational Trauma ◽  
Near Death Experiences

Organizational trauma is traditionally associated with negative effects on organizational behavior and performance. In this chapter the authors seek to answer the question how organizational trauma, and in particular near-death experiences, can positively influence organizational culture in the long term. In doing so, the authors briefly review the recent literature on organizational trauma and near death experiences, and discuss how these negative traumatic experiences can turn into prosocial organizational behaviour. The authors then present three case studies to illustrate how an organization can manage to incorporate near death experiences into its organizational culture in a positive way.

Health and well-being in the digital society

2017 ◽  
Author(s):  
Nathan Critchlow
Keyword(s):  
Sedentary Behaviour ◽  
Case Studies ◽  
Internet Use ◽  
Well Being ◽  
Risk Behaviours ◽  
Negative Effects ◽  
Digital Society ◽  
Use Of Technology ◽  
Internet Users ◽  
Health And Well Being

This chapter examines the negative effects of increased use of technology on health and well-being using two case studies that illustrate the influence of alcohol use on young people. It first provides an overview of the digital society and Internet use before discussing the ways in which growing engagement with technology has affected sedentary behaviour and how it can also influence mental health. It then considers how the content created by other Internet users may encourage or reinforce health risk behaviours and how digital marketing can affect behaviour. The two case studies show that extensive Internet use, particularly among the youth, emphasises the importance of identifying and addressing determinants of health and well-being in a digital society, and that it is increasing sedentary behaviour that leads to a range of adverse physical and mental outcomes.

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