A hybrid computer-aided linkage design system for tracing open and closed planar curves

Abstract

This paper presents a computer-aided linkage design system for tracing prescribed open or closed planar curves. The mechanism design is considered a mixture of science and art. The former is about utilizing computers to rigorously size a mechanism in meeting a set of design requirements and the latter is about taking advantage of designers’ experience to narrow down the design domain and speed up the design process. The ultimate goal of the presented design system is to incorporate both science and art into the linkage design process by (1) developing an automatic design framework that is based on library searching and optimization techniques and (2) developing an interactive design framework that is based on advanced human–computer interfaces. To enable the design automation framework, we first pre-built a library of open and closed planar curves generated by commonly used planar linkages. We then turned the classical linkage path generation problem into a library searching problem together with a local optimization problem. To enable the interactive design framework, we developed a set of design interfaces that facilitate designers to intervene and steer the design process. This hybrid design system was developed based on our existing VRMDS (Virtual Reality Mechanism Design Studio) framework. To demonstrate its functionalities, we provided four representative design cases of 4-bar and crank-slider linkages. The result shows that the system returned a desired solution in seconds. We also demonstrate the extensibility of the system by implementing designs of planar 4-bar and crank-slider linkages.