Simultaneous Type and Dimensional Synthesis of Planar 1DOF Mechanisms Using Evolutionary Search and Convertible Agents

2009 ◽  
Author(s):  
John C. Oliva ◽  
Erik D. Goodman
Keyword(s):  
Case Studies ◽  
Evolutionary Search ◽  
Dimensional Synthesis ◽  
Mechanism Synthesis ◽  
Computing Technique ◽  
Single Degree Of Freedom ◽  
Solution Strategies ◽  
Single Degree ◽  
Novel Approach ◽  
Design Challenges

This paper introduces a novel approach to automated mechanism synthesis called “convertible agents”. The evolutionary computing technique has been developed specifically for the unique design challenges encountered when synthesizing a mechanism for both type and dimensionality. Several case studies are presented which demonstrate the approach’s effectiveness over earlier solution strategies. In these studies, six different planar single-degree-of-freedom mechanism types are considered: a four-bar mechanism, Stephenson’s six-bar-mechanisms (types I, II, and III), and Watt’s six-bar-mechanisms (types I and II). The method is readily scalable to account for any number of different mechanism types and complexities.

Simultaneous Type and Dimensional Synthesis of Planar 1DOF Mechanisms Using Evolutionary Search and Convertible Agents (DETC2009-86722)

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
John C. Oliva ◽  
Erik D. Goodman
Keyword(s):  
Case Studies ◽  
Evolutionary Search ◽  
Dimensional Synthesis ◽  
Mechanism Synthesis ◽  
Computing Technique ◽  
Single Degree Of Freedom ◽  
Solution Strategies ◽  
Single Degree ◽  
Novel Approach ◽  
Design Challenges

This paper introduces a novel approach to automated mechanism synthesis called “convertible agents.” The evolutionary computing technique has been developed specifically for the unique design challenges encountered when synthesizing a mechanism for both type and dimensionality. Several case studies are presented, which demonstrate the approach’s effectiveness over earlier solution strategies. In these studies, six different planar single-degree-of-freedom mechanism types are considered: a four-bar mechanism, Stephenson’s six-bar-mechanisms (types I, II, and III), and Watt’s six-bar-mechanisms (types I and II). The synthesis technique selects the best suited mechanism type from this set and optimizes its dimensions to meet the design objective at hand. The method is readily scalable to account for any number of different mechanism types and complexities.

Fourier Methods for Kinematic Synthesis of Coupled Serial Chain Mechanisms

2005 ◽  
Vol 127 (2) ◽  
pp. 232-241 ◽  
Author(s):  
Xichun Nie ◽  
Venkat Krovi
Keyword(s):  
Low Cost ◽  
Synthesis Method ◽  
Path Following ◽  
Degree Of Freedom ◽  
Dimensional Synthesis ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Serial Chain ◽  
End Effectors ◽  
Serial Chains

Single degree-of-freedom coupled serial chain (SDCSC) mechanisms are a class of mechanisms that can be realized by coupling successive joint rotations of a serial chain linkage, by way of gears or cable-pulley drives. Such mechanisms combine the benefits of single degree-of-freedom design and control with the anthropomorphic workspace of serial chains. Our interest is in creating articulated manipulation-assistive aids based on the SDCSC configuration to work passively in cooperation with the human operator or to serve as a low-cost automation solution. However, as single-degree-of-freedom systems, such SDCSC-configuration manipulators need to be designed specific to a given task. In this paper, we investigate the development of a synthesis scheme, leveraging tools from Fourier analysis and optimization, to permit the end-effectors of such manipulators to closely approximate desired closed planar paths. In particular, we note that the forward kinematics equations take the form of a finite trigonometric series in terms of the input crank rotations. The proposed Fourier-based synthesis method exploits this special structure to achieve the combined number and dimensional synthesis of SDCSC-configuration manipulators for closed-loop planar path-following tasks. Representative examples illustrate the application of this method for tracing candidate square and rectangular paths. Emphasis is also placed on conversion of computational results into physically realizable mechanism designs.

Singularity-Free RPR and SPS Chains for Actuating Single Degree of Freedom Planar and Spherical Mechanisms

2010 ◽  
Author(s):  
David A. Perkins ◽  
Andrew P. Murray
Keyword(s):  
Reference Frame ◽  
Unique Fixed Point ◽  
Degree Of Freedom ◽  
Moving Frame ◽  
Dimensional Synthesis ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Fixed Frame ◽  
Spherical Mechanisms ◽  
Spherical Mechanism

This paper presents a method of selecting joints relative to a fixed and moving (coupler) frame that can be used to actuate a single degree of freedom planar mechanism using a revolute-prismatic-revolute (RPR) chain or a spherical mechanism via a spherical-prismatic-spherical (SPS) chain. Given a single degree of freedom mechanism, a moving reference frame attached to any link has a motion that can be described with a single parameter. A point relative to this moving frame is sought such that it either continually increases or decreases in distance from a point in the fixed frame over the entire motion. The mechanism can then be moved by placing an actuated prismatic joint between the two points. Moreover, the singularities relative to the joints in the original mechanism are not a concern and the dimensional synthesis can focus on creating the set of circuit-defect free solutions. From this analysis, a unique fixed point is determined relative to two positions and their velocities with the following characteristic. All points in the moving reference frame that are moving away from it in the first position are approaching it in the second position, and vice versa.

Expedient Estimation of the Maximum Amplification Factor in Damped Mistuned Bladed Disks

2007 ◽  
Author(s):  
Yun Han ◽  
Bing Xiao ◽  
Marc P. Mignolet
Keyword(s):  
Upper Bound ◽  
Amplification Factor ◽  
Degree Of Freedom ◽  
Mode Shapes ◽  
Computational Technique ◽  
Bladed Disks ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Novel Approach ◽  
Maximum Amplification

This paper focuses on the formulation and validation of a novel approach for the expedient estimation of the maximum amplification factor induced by mistuning in damped bladed disks. This computational approach is based on earlier analytical results yielding an upper bound of the maximum amplification factor in the limit of zero damping. Extensions of these results are derived first to broaden the applicability of the methodology. Next, the computational technique is described: it involves the components of one of the mode shapes of the mistuned disk and the associated frequency as the variables over which the optimization is carried out. Further, the initial guess for these variables is obtained from the analytical estimates of the upper bound. This approach removes the limitations of earlier analytical efforts, i.e. damping is considered, and the actual value of the maximum amplification factor and the corresponding mistuning of the blade properties are obtained. Limitations on the magnitude of the mistuning could also be considered in the algorithm if desired. This novel approach was applied for the parametric study of the maximum amplification factor as a function of damping in two single-degree-of-freedom per blade disk models as well as in a reduced order model of a blisk. The results obtained in connection with the two single-degree-of-freedom systems very closely match the global maxima predicted by an existing, more tedious algorithm introduced earlier to avoid convergence to one of the many local maxima known to often exist.

Singularity Free Revolute–Prismatic–Revolute and Spherical–Prismatic–Spherical Chains for Actuating Planar and Spherical Single Degree of Freedom Mechanisms

2012 ◽  
Vol 4 (1) ◽  
Author(s):  
David A. Perkins ◽  
Andrew P. Murray
Keyword(s):  
Reference Frame ◽  
Unique Fixed Point ◽  
Degree Of Freedom ◽  
Moving Frame ◽  
Dimensional Synthesis ◽  
Planar Case ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Fixed Frame ◽  
Spherical Mechanism

Given a single degree of freedom mechanism, a moving reference frame attached to any link has a motion that can be described with a single parameter. A point relative to this moving frame is sought such that it either continually increases or decreases in distance from a point in the fixed frame over the entire motion. These points can be used to define a revolute–prismatic–revolute (RPR) chain for a planar mechanism or a spherical–prismatic–spherical (SPS) chain for a spherical mechanism capable of actuating the device over its entire range of motion. Moreover, the singularities relative to the joints in the original mechanism are not a concern and the dimensional synthesis can focus on creating the set of circuit-defect free solutions. From this analysis, a unique fixed point is determined in the planar case relative to two positions and their velocities with the following characteristic. All points in the moving reference frame that are moving away from it in the first position are approaching it in the second position, and vice versa. This point is as critical to the identification of singularity-free driving chains as the centrodes or the poles.

scholarly journals Optimization of Multiple Tuned Mass Damper (MTMD) Parameters for a Primary System Reduced to a Single Degree of Freedom (SDOF) through the Modal Approach

2021 ◽  
Vol 11 (4) ◽  
pp. 1389
Author(s):  
Piotr Wielgos ◽  
Robert Geryło
Keyword(s):  
Degrees Of Freedom ◽  
Research Work ◽  
System Optimization ◽  
Degree Of Freedom ◽  
Primary System ◽  
Single Degree Of Freedom ◽  
Modal Approach ◽  
Single Degree ◽  
Novel Approach ◽  
The Impact

The research paper presents a novel approach toward constructing motion equations for structures with attached MTMDs (multiple tuned mass dampers). A primary system with MDOF (multiple dynamic degrees of freedom) was reduced to an equivalent system with a SDOF (single degree of freedom) through the modal approach, and equations from additional MTMDs were added to a thus-created system. Optimization based on ℌ2 and ℌ∞ for the transfer function associated with the generalized displacement of an SDOF system was applied. The research work utilized GA (genetic algorithms) and SA (simulated annealing method) optimization algorithms to determine the stiffness and damping parameters for individual TMDs. The effect of damping and stiffness (MTMD tuning) distribution depending on the number of TMDs was also analyzed. The paper also reviews the impact of primary system mass change on the efficiency of optimized MTMDs, as well as confirms the results of other authors involving greater MTMD effectiveness relative to a single TMD.

Kinematic and Kinetostatic Synthesis of Planar Coupled Serial Chain Mechanisms

2002 ◽  
Vol 124 (2) ◽  
pp. 301-312 ◽  
Author(s):  
Venkat Krovi ◽  
G. K. Ananthasuresh ◽  
Vijay Kumar
Keyword(s):  
Degree Of Freedom ◽  
Dimensional Synthesis ◽  
Single Degree Of Freedom ◽  
End Effector ◽  
Solution Approach ◽  
Single Degree ◽  
Design Specifications ◽  
Serial Chain ◽  
Gear Trains ◽  
External Loads

Single Degree-of-freedom Coupled Serial Chain (SDCSC) mechanisms form a novel class of modular and compact mechanisms with a single degree-of-freedom, suitable for a number of manipulation tasks. Such SDCSC mechanisms take advantage of the hardware constraints between the articulations of a serial-chain linkage, created using gear-trains or belt/pulley drives, to guide the end-effector motions and forces. In this paper, we examine the dimensional synthesis of such SDCSC mechanisms to perform desired planar manipulation tasks, taking into account task specifications on both end-effector motions and forces. Our solution approach combines precision point synthesis with optimization to realize optimal mechanisms, which satisfy the design specifications exactly at the selected precision points and approximate them in the least-squares sense elsewhere along a specified trajectory. The designed mechanisms can guide a rigid body through several positions while supporting arbitrarily specified external loads. Furthermore, torsional springs are added at the joints to reduce the overall actuation requirements and to enhance the task performance. Examples from the kinematic and the kinetostatic synthesis of planar SDCSC mechanisms are presented to highlight the benefits.

Design of Graphical User Interfaces for the Synthesis of Planar RR Dyads

2014 ◽  
Author(s):  
Jugesh Sundram ◽  
Venkatesh Venkataramanujam ◽  
Pierre Larochelle
Keyword(s):  
Case Studies ◽  
User Interfaces ◽  
Graphical User Interfaces ◽  
Dimensional Synthesis ◽  
Motion Generation ◽  
Mechanism Synthesis ◽  
Generation Task ◽  
Design And Implementation ◽  
Design Case ◽  
Hybrid Motion

This article discusses the design and implementation of two Matlab graphical user interfaces (GUIs) for mechanism synthesis. The first GUI addresses the four location Burmester synthesis problem. The designer specifies the 4 locations that are used to generate the Burmester curves for these prescribed locations. The GUI enables the designer to interact with these curves and choose a pair of moving and fixed pivots forming an RR dyad. The second GUI addresses dimensional synthesis of RR dyads for hybrid motion generation tasks. Given a hybrid motion generation task, the designer can either pick the fixed or moving pivots and the corresponding pivots of an RR dyad is determined. In both the interfaces, the designer is provided with tools to specify tasks. The GUIs were designed with an objective to provide the designer with a simple workflow. Design case studies that illustrate the features and capabilities of each GUI are included.

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