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.

Type Synthesis of Compliant Mechanisms Employing a Simplified Approach to Segment Type

1994 ◽  
Author(s):  
Morgan D. Murphy ◽  
Ashok Midha ◽  
Larry L. Howell
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Type Synthesis ◽  
Simplified Approach ◽  
Design Procedures ◽  
Synthesis Techniques ◽  
Design Solutions ◽  
Synthesis Methodology

Abstract The formulation of design procedures for rigid-body mechanisms has benefited from the application of type-synthesis techniques. Therefore, with modifications to allow for inclusions of compliance, type synthesis is seen as a useful tool in the design of compliant mechanisms. Previous efforts have developed methods that result in a large number of possible design solutions to a given problem. This paper deals primarily with the development of a simplified compliant-mechanism type-synthesis methodology that limits the number of design solutions considered. The techniques are derived by modifying existing compliant mechanism type-synthesis techniques to yield a simpler model with greater pragmatic value.

Geometric Design of Spherical Serial Chains With Curvature Constraints in the Environment

2011 ◽  
Author(s):  
Nina Robson ◽  
Anurag Tolety
Keyword(s):  
Rigid Body ◽  
Robot Manipulator ◽  
Normal Direction ◽  
Geometric Design ◽  
Failure Recovery ◽  
Kinematic Synthesis ◽  
Synthesis Techniques ◽  
Moving Body ◽  
Trajectory Interpolation ◽  
Serial Chains

This paper builds up on recent results on planar kinematic synthesis with contact direction and curvature constraints on the workpiece. We consider the synthesis of spherical serial chains to guide a rigid body, such that it does not violate normal direction and curvature constraints imposed by contact with objects in the environment. We show how to derive these constraints from the geometry of the task and transform them into conditions on velocity and acceleration of points in the moving body to obtain synthesis equations which can be solved by algebraic elimination. Trajectory interpolation formulas yield the movement of the chain with the desired contact properties in each of the task positions. An example shows the application of the developed theory to the failure recovery of a robot manipulator, using kinematic synthesis techniques.

On the Classification of Compliant Mechanisms and Synthesis of Compliant Single-Strip Mechanisms

2011 ◽  
Author(s):  
Ashok Midha ◽  
Sharath K. Kolachalam ◽  
Yuvaraj Annamalai
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Basic Mechanism ◽  
Governing Equations ◽  
Mechanism Synthesis ◽  
Synthesis Techniques ◽  
Single Strip

Compliant mechanisms, unlike rigid-body mechanisms, are devices that derive some or all of their mobility due to the deformation of their flexible members. The knowledge of existing rigid-body mechanism synthesis techniques is very useful in designing compliant mechanisms. In rigid-body mechanisms, a four-bar is treated as the basic mechanism that can transfer motion, force or energy. In this paper, a compliant single-strip continuum is introduced as the basic compliant mechanism that can transfer motion, force or energy. A classification of compliant mechanisms is presented herein. A methodology for compliant single-strip mechanism synthesis for energy, force or torque specifications is developed in this research as our second objective. The synthesis types, the governing equations, and the variables involved are enumerated.

Kinetostatic Synthesis of Coupled Serial Chains

1998 ◽  
Author(s):  
Venkat Krovi ◽  
G. K. Ananthasuresh ◽  
Vijay Kumar
Keyword(s):  
Virtual Work ◽  
Degree Of Freedom ◽  
Optimal Synthesis ◽  
Synthesis Problem ◽  
Equilibrium Equations ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Angular Velocities ◽  
Kinematic Loop ◽  
Serial Chains

Abstract Single Degree-of-freedom Coupled Serial Chain (SDCSC) mechanisms are a novel class of modular and compact mechanisms with single degree-of-freedom actuation and control. In this paper, the kinetostatic synthesis of SDCSC mechanisms is addressed. Using the principle of virtual work, the static force equilibrium equations are developed for two-link SDCSCs. These are combined with the previously developed kinematic loop-closure equations to solve the kinetostatic precision point synthesis problem. Since the ratios of the angular velocities at the joints are constants by virtue of cable-pulley coupling in SDCSCs, it possible to render the kinetostatic equations linear in terms of the mechanism parameters. As a result, the solution of the precision point synthesis problem of SDCSCs becomes simpler compared to that of the four-bar mechanism. In order to meet additional criteria such as minimizing the maximum torque required over the entire range of motion of the mechanism, an optimization problem is formulated. The free choices in the precision point synthesis are used as variables in the optimal synthesis problem. The paper also addresses how torsional springs at the joints can be utilized to reduce the required input torque in supporting a specified load at the end-effector. Numerical examples are presented to illustrate the precision point and the optimal synthesis of two-link SDCSC mechanism with and without torsional springs at the joints.

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.

Comparative study of genetic algorithm and simulated annealing for optimal tolerance design formulated with discrete and continuous variables

2005 ◽  
Vol 219 (10) ◽  
pp. 735-758 ◽  
Author(s):  
P K Sing ◽  
S C Jain ◽  
P K Jain
Keyword(s):  
Genetic Algorithm ◽  
Simulated Annealing ◽  
Design Problem ◽  
Optimal Solution ◽  
Solution Space ◽  
Optimization Techniques ◽  
Manufacturing Processes ◽  
Tolerance Design ◽  
Solution Algorithms ◽  
Selection Of

Optimal tolerance design has been the focus of extensive research for a few decades. This has resulted in several formulations and solution algorithms for systematic tolerance design considering various aspects. Availability of different alternative manufacturing processes or machines for realization of a dimension is frequently encountered. In such cases optimal tolerance design must also consider optimal selection of a set of manufacturing processes or machines as appropriate. Such a non-linear multivariate optimal tolerance design problem results in a combinatorial and multi-modal solution space. Optimal solution of this advanced tolerance design problem is difficult using traditional optimization techniques. The problem formulation becomes more complex with simultaneous selection of design and manufacturing tolerances. The focus of the current research is on the optimal solution of this advanced and complex tolerance design problem. Genetic algorithm and simulated annealing as non-traditional global optimization techniques have been used to obtain the solution. Application of the solution techniques has been demonstrated with the help of appropriate examples. Comparison of the results establishes that the genetic algorithm is the superior of the two approaches.

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