Multi-Objective Optimization of Kinematic Characteristics of Geneva Mechanism

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Mechanics, Materials Science & Engineering, March 2017

ISSN 2412-5954

Multi-Objective Optimization of Kinematic Characteristics of Geneva Mechanism Using High-Tech Optimization Methods8 Arash Mohammadzadeh Gonabadi 1,a, Mohammad Nouri Damghani 1,b 1

Department of mechanical engineering, Semnan University, Semnan, Iran

a

arash_mg@semnan.ac.ir

b

mnoori@semnan.ac.ir DOI 10.2412/mmse.26.65.331 provided by Seo4U.link

Keywords: Geneva wheel mechanism; dynamic modeling; kinematic characteristics; multi-objective optimization; GA; ICA

ABSTRACT. This research is aimed toward using variable input speed for triple-objective optimization of kinematic characteristics of a Geneva wheel mechanism. High-tech optimization methods including genetic algorithm (GA) and imperialist competitive algorithm (ICA) are used in this study. The objective functions in both methods are magnitude of the maximum output angular velocity, magnitude of the maximum output angular acceleration as well as magnitude of the maximum output angular jerk of driven wheel. The motion equations of Geneva mechanism are first extracted with their boundary conditions determined. Then, above objective functions are minimized using the considered algorithms. Utilization of the input velocity may contribute to improve output kinematic characteristics of the mechanism.

Introduction. Developments achieved in the industries and widespread application of mechanisms throughout various industries have motivated researchers to rise their efforts in the course of ell as performance of automatic machines. Today, correspondingly, many undergoing researches are dedicated to analysis of mechanisms as well as their synthesis. In conventional methods, a constant input speed is assumed for any mechanism; so as an improvement in mechanism performance is impossible in many cases where researchers are forced to design a new mechanism with higher kinematic performance [5]. For instance, the researchers designed a new mechanism to enhance kinematic characteristics of a cam mechanism [10]. The idea to use variable input speed into mechanisms was first implemented in a cam mechanism whose input mechanism was, in fact, the output of a Whitworth quick-return mechanism [13]. These researches utilized variable input speeds to reduce the cam dimensions and consequently, its pressure angle. Other researchers showed, in both experimental and theoretical way, that considering a variable input speed, one can control and improve output characteristics of a mechanism [2, 4, 14]. Optimization of kinematic characteristics of a Geneva mechanism is addressed in this research. Geneva mechanism is one of the most applied and simple mechanisms for generating periodic motions. Such mechanisms are widely used in many devices such as clocks, machine tools, printing and pressing machineries, packaging machineries as well as automotive machines. Although numerous kinds of tools are designed for the sake of periodic motion generation, but Geneva mechanisms are among the first choices for this purpose due to their simplicity, lower price, higher safety factor, long life and also smooth motion curves they produce [1, 7-8]. While simple Geneva mechanisms (with constant input speed) are popular, they suffer from a set of associated deficiencies. In Geneva mechanisms, output plots are not under control by the designer with angular acceleration of driven wheel having non-zero values at the beginning and the end of 8

-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

MMSE Journal. Open Access www.mmse.xyz

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