Bi-objective pareto optimization of centric crank-rocker mechanisms

Abstract

AbstractThis paper revisits a classical problem in linkage mechanism design, specifically the design of centric crank-rocker mechanisms for a specified rocker stroke with unit time ratio. Beyond the traditional objective of minimizing the transmission angle’s deviation from 90 degrees, this paper uses another objective: maximizing the shortest-to-longest link-length ratio in the linkage. The former objective ensures motion transmission quality in the mechanism, while the latter aims to make the mechanism less sensitive to variations in link lengths. It is shown that these two objectives are inherently conflicting, necessitating a trade-off solution. To address this, a Pareto front is developed by analyzing the governing design equations. The front is further normalized by relating each objective to its limit value. A design example using the normalized front is provided that showcases different optimization options. The TOPSIS method is used to illustrate the selection of a preferred design alternative.

Keywords

• Optimum design
• crank-rocker
• transmission angle
• Pareto analysis
• normalized front
• Pham D. T., University of Birmingham, United Kingdom