A Sardashti

Bio: A Sardashti is an academic researcher. The author has contributed to research in topics: Error function & Adaptive algorithm. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

Geometrical Similarity Error Function-Innovative Adaptive Algorithm methodology in path generation synthesis of the four-bar mechanism using metaheuristic algorithms

Abstract: This paper presents a novel methodology for path generation synthesis of the four-bar mechanism. A new objective function for the path generation synthesis problem, namely, the Geometrical Similari...

A new approach to shape optimization for closed path synthesis of planar mechanisms

Abstract: A method for the synthesis of four-bar mechanisms to generate closed paths through shape optimization is herein introduced. The objective function is not based on Fourier descriptors, rather on the cyclic angular deviation (CAD) vector associated with a set of desired points on the curve. A simple method is introduced to account for the starting point shift between the desired CAD and the generated one. Following shape optimization, a simple mathematical approach is devised to properly scale, rotate, and translate the mechanism to the desired configuration. A case study is presented to demonstrate the effectiveness and robustness of the proposed method.Copyright © 2005 by ASME

Comparative Study on the Synthesis of Path-Generating Four-Bar Linkages Using Metaheuristic Optimization Algorithms

Abstract: Four-bar linkages are one of the most widely used mechanisms in industries. This paper presents a comparative study on the accuracy and efficiency of the optimum synthesis of path-generating four-bar linkages using five metaheuristic optimization algorithms. The utilized metaheuristic methods included two swarm intelligence-based algorithms, i.e., particle swarm optimization and hybrid particle swarm optimization, and three evolutionary-based algorithms, i.e., differential evolution, ensemble of parameters and mutation strategies in differential evolution, and linearly ensemble of parameters and mutation strategies in differential evolution. The objective function to be minimized is the sum of squares of the distance between the generated points and the precision points of a coupler point. The optimal design of four-bar linkages must meet the Grashof’s criteria and exhibit sequential constraints that can prevent the occurrence of order defect. This study investigated five representative cases of the dimensional synthesis of four-bar path generators with and without prescribed timing and compared the optimal solutions of the utilized five metaheuristic methods to those of previously reported algorithms in literature. The improved metaheuristic methods exhibited superior optimal solution and enhanced reliability compared to the original methods. Moreover, three improved metaheuristic methods were not only easy implemented, but also more efficient for solving the optimal synthesis problems, particularly for high dimensional problems.

Modified Shadow Robot Control method for optimal path synthesis of mechanisms: Application to five-link mechanism

Abstract: For optimal path synthesis of a mechanism with a single degree of freedom (DOF), a powerful method called Shadow Robot Control (SRC) has been recently proposed in the literature. However, this method is restricted to synthesis problems with prescribed timing (i.e. problems in which a particular input crank angle is associated with each point of the desired trajectory). In this paper, the SRC method was elaborated and modified to be capable of synthesizing both prescribed and nonprescribed timing problems. For this purpose, a new structure of contour error and objective function estimation was presented. As a result, there is no need to consider the input angles (crank angles) corresponding to desired path points as optimization parameters, even for non-prescribed timing problems. This prevents unnecessarily enlarging the search space, providing a more effective and robust optimization method (with respect to initial guess). The synthesis of a geared five-link mechanism was used to detail the proposed algorithm as a case study. Despite the five-link mechanism capability and simplicity of generating a complicated trajectory, this single DOF path generator seems less investigated in the literature. Few existing numerical problems of the five-link mechanism in the literature were solved. The comparison of the results shows the effective performance of the proposed algorithm in synthesizing the mechanism.