The Kinematic Synthesis of a Robust RCCC Mechanism for Pick-and-Place Operations

2012 ◽  
Author(s):  
Khalid M. Al-Widyan ◽  
Jorge Angeles
Keyword(s):  
Rigid Body ◽  
Robust Design ◽  
Theoretical Framework ◽  
Synthesis Problem ◽  
Kinematic Synthesis ◽  
General Methodology ◽  
Pick And Place ◽  
Four Bar Linkage ◽  
Pick And Place Operation ◽  
Selection Of

Proposed in this paper is a methodology to synthesize a RCCC four-bar linkage intended for pick-and-place operations. The synthesis problem is set in the context of rigid-body guidance, which can be solved exactly for up to four prescribed poses of the coupler link. As a consequence, for a pick-and-place operation, the selection of the unspecified two intermediate poses is thus left up to the mechanism designer’s judgment. In this paper, we propose a method to determine the two intermediate poses resorting to the concept of robustness. In fact, robustness is needed in this context to overcome the presence of uncertainty due to the selection of the two unspecified poses. To this end, a theoretical framework for model-based robust design is invoked and a general methodology for robust kinematic synthesis is laid down. A numerical example is included to validate the concepts and illustrate the application of the methodology proposed here.

The Robust Linkage Synthesis for Planar Rigid-Body Guidance

2010 ◽  
Author(s):  
Khalid Al-Widyan ◽  
Jorge Angeles
Keyword(s):  
Rigid Body ◽  
Robust Design ◽  
Theoretical Framework ◽  
Planar Motion ◽  
Kinematic Synthesis ◽  
The Subject ◽  
Four Bar Linkage ◽  
Guidance Problem ◽  
Selection Of ◽  
Linkage Synthesis

The kinematic synthesis of planar motion generators in the presence of an incomplete set of finitely separated poses is the subject of this paper. Given that the planar rigid-body guidance problem in the realm of four-bar linkage synthesis can be solved exactly for up to five prescribed poses of the coupler link, any number of poses smaller than five is considered incomplete in this paper. The poses completing the set are determined so as to produce a robust linkage against variations in the unspecified poses. To this end, a theoretical framework for model-based robust design is invoked and a general methodology for robust kinematic synthesis is laid down. Robustness is needed in this context to overcome the presence of uncertainty due to the selection of the unprescribed poses, which many a time are left up to the mechanism designer’s judgment. To validate the concepts and illustrate the application of the methodology proposed here, an example is included.

The Synthesis of Spherical Motion Generators in the Presence of an Incomplete Set of Attitudes

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Khalid Al-Widyan ◽  
Jorge Angeles
Keyword(s):  
Rigid Body ◽  
Engineering Design ◽  
Theoretical Framework ◽  
General Methodology ◽  
Four Bar Linkage ◽  
Robust Engineering Design ◽  
Guidance Problem ◽  
Spherical Motion ◽  
Spherical Rigid Body ◽  
Selection Of

Proposed in this paper is a general methodology applicable to the synthesis of spherical motion generators in the presence of an incomplete set of finitely separated attitudes. The spherical rigid-body guidance problem in the realm of four-bar linkage synthesis can be solved exactly for up to five prescribed attitudes of the coupler link, and hence, any number of attitudes smaller than five is considered incomplete in this paper. The attitudes completing the set are determined to produce a linkage whose performance is robust against variations in the unprescribed attitudes. Robustness is needed in this context to overcome the presence of uncertainty due to the selection of the unspecified attitudes, that many a time are specified implicitly by the designer upon choosing, for example, the location of the fixed joints of the dyads. A theoretical framework for model-based robust engineering design is thus, recalled, and a methodology for the robust synthesis of spherical four-bar linkages is laid down. An example is included here to concretize the concepts and illustrate the application of the proposed methodology.

The Synthesis of Robust Spherical Motion Generators

2004 ◽  
Author(s):  
Khalid Al-Widyan ◽  
Jorge Angeles
Keyword(s):  
Theoretical Framework ◽  
Numerical Example ◽  
General Methodology ◽  
Spherical Motion ◽  
Selection Of ◽  
Robust Synthesis

The synthesis of spherical motion generators in the presence of an incomplete set of finitely-separated attitudes is discussed in this paper. Given that five attitudes of the coupler link define a discrete set of dyads, any number of attitudes smaller than five is considered incomplete in this paper. The attitudes completing the set are determined so as to produce a robust linkage against variations in these attitudes. To this end, a theoretical framework as well as a general methodology for robust synthesis are laid down. Robustness is needed in this context to overcome the presence of uncertainty due to the selection of the intermediate attitudes, which many a time are left up to the mechanism designer’s judgment. To validate the concepts and illustrate the application of the methodology proposed here, we include a numerical example.

Software for the Kinematic Synthesis of Coupler-Driven Spherical Four-Bar Mechanisms

2007 ◽  
Author(s):  
Eric M. Grimm ◽  
Andrew P. Murray ◽  
Michael L. Turner
Keyword(s):  
Rigid Body ◽  
Kinematic Synthesis ◽  
Prismatic Joint ◽  
Second Stage ◽  
Typical Scheme ◽  
Four Bar Linkage

A spatial analogue of the Stephenson III six-bar mechanism can be formed by the connection of an SPS chain to the coupler of a spherical four-bar linkage. With the prismatic joint actuated, the spherical four-bar is driven via a force applied directly to the coupler. This linkage is termed the coupler-driven spherical four-bar mechanism, and defines an alternative to the typical scheme of actuating the four-bar via a torque applied at the input link. This paper presents software developed to assist in the kinematic synthesis of these mechanisms. In the first stage of the design, a circuit-defect free spherical four-bar is dimensioned with the capacity to guide a rigid body through two orientations. The second stage of the design is to locate the SPS leg such that the four-bar is smoothly drivable between the orientations.

scholarly journals Moving from tradition-based to competence-based psychotherapy

2021 ◽  
pp. ebmental-2020-300219
Author(s):  
Winfried Rief
Keyword(s):  
Basic Science ◽  
Theoretical Framework ◽  
Psychological Interventions ◽  
Skills Acquisition ◽  
Relationship Patterns ◽  
Cognitive Behavioural ◽  
Training Programmes ◽  
New Research ◽  
And Training ◽  
Selection Of

Current education and training in psychological interventions is mostly based on different ‘schools’ (traditions such as cognitive–behavioural or psychodynamic therapy), and strong identification with these specific traditions continuously hinders a scientifically based development of psychotherapy. This review is selective rather than systematic and comprehensive. In addition to the consideration of other influential publications, we relied on a literature search in Web of Science using the following terms (update: 24 December 2020): (psychotherapy AND meta-analy* AND competence*). After summarising current problems, a pathway for solving these problems is presented. First, we have to recategorise psychological interventions according to the mechanisms and subgoals that are addressed. The interventions can be classified according to the foci: (1) skills acquisition (eg, communication, emotion regulation, mentalisation); (2) working with relationship patterns and using the therapeutic relationship to modify them; and (3) clarification of motives and goals. Afterwards, the training of psychotherapists can switch from focusing on one theoretical framework to learning the different competences for modification according to these new categories. The selection of topics to be addressed should follow best evidence-based mechanisms and processes of mental disorders and interventions. Psychology offers knowledge about these mechanisms that can be understood as a basic science for psychological treatments in general. This requires better connection with basic science, new research efforts that focus on treatment subgoals, theory-overarching optimisation of the selection and personalisation of treatments, and new types of training for psychotherapists that are designed to optimise therapists’ competences accordingly, instead of limiting training programmes to one single theoretical framework.

scholarly journals Optimal synthesis of a four-bar linkage by method of controlled deviation

2004 ◽  
Vol 31 (3-4) ◽  
pp. 265-280 ◽  
Author(s):  
Radovan Bulatovic ◽  
Stevan Djordjevic
Keyword(s):  
Objective Function ◽  
Optimal Synthesis ◽  
Straight Line ◽  
Individual Comparison ◽  
Four Bar Linkage ◽  
The Given ◽  
Initial Selection ◽  
Selection Of ◽  
Process Calculation ◽  
Made In

This paper considers optimal synthesis of a four-bar linkage by method of controlled deviations. The advantage of this approximate method is that it allows control of motion of the coupler in the four-bar linkage so that the path of the coupler is in the prescribed environment around the given path on the segment observed. The Hooke-Jeeves?s optimization algorithm has been used in the optimization process. Calculation expressions are not used as the method of direct searching, i.e. individual comparison of the calculated value of the objective function is made in each iteration and the moving is done in the direction of decreasing the value of the objective function. This algorithm does not depend on the initial selection of the projected variables. All this is illustrated on an example of synthesis of a four-bar linkage whose coupler point traces a straight line, i.e. passes through sixteen prescribed points lying on one straight line. .

scholarly journals Kinematic synthesis of planar, shape-changing, rigid body mechanisms for design profiles with significant differences in arc length

2013 ◽  
Vol 70 ◽  
pp. 425-440 ◽  
Author(s):  
Shamsul A. Shamsudin ◽  
Andrew P. Murray ◽  
David H. Myszka ◽  
James P. Schmiedeler
Keyword(s):  
Rigid Body ◽  
Arc Length ◽  
Kinematic Synthesis ◽  
Planar Shape

Kinematic Synthesis of a D-Drive MEMS Device With Rigid-Body Replacement Method

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Paolo Sanò ◽  
Matteo Verotti ◽  
Paolo Bosetti ◽  
Nicola P. Belfiore
Keyword(s):  
Rigid Body ◽  
Experimental Testing ◽  
Micro Electro Mechanical System ◽  
Element Analysis ◽  
Kinematic Synthesis ◽  
Replacement Method ◽  
Rigid Body Model ◽  
Mems Device ◽  
Conjugate Surfaces ◽  
Line Path

In this paper, a microsystem with prescribed functional capabilities is designed and simulated. In particular, the development of a straight line path generator micro electro mechanical system (MEMS) device is presented. A new procedure is suggested for avoiding branch or circuit problems in the kinematic synthesis problem. Then, Ball's point detection is used to validate the obtained pseudo-rigid body model (PRBM). A compliant MEMS device is obtained from the PRBM through the rigid-body replacement method by making use of conjugate surfaces flexure hinges (CSFHs). Finally, the functional capability of the device is investigated by means of finite element analysis (FEA) simulations and experimental testing at the macroscale.

Optimal Synthesis of Four-Bar Linkages for Four-Position Rigid-Body Guidance With Selective Tolerance Specifications

1992 ◽  
Author(s):  
Shankar C. Venkataraman ◽  
Gary L. Kinzel ◽  
Kenneth J. Waldron
Keyword(s):  
Rigid Body ◽  
Solution Space ◽  
Optimal Synthesis ◽  
Synthesis Problem ◽  
Manufacturing Processes ◽  
Synthesis Techniques

Abstract In practical rigid-body guidance problems, very often one or more of the design positions need not be generated exactly. Further, extreme accuracy at the design positions is somewhat pointless considering the inherent limitations in linkage manufacturing processes. This emphasizes the requirement of synthesis techniques to be able to handle tolerance specifications on the nominal design positions. A favorable offshoot of the tolerance incorporation would be the accompanying increase in the solution space of the synthesis problem thereby yielding better linkage solutions.

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