임의의 크기를 갖는 스프링 연결 블록 모델을 이용한 4절 기구의 통합 기구합성

Abstract

Most machines are composed of several simple or complex linkage mechanisms that usually convert an input motion to a desired output motion. To produce a desired output motion, a linkage mechanism has to be designed properly. Design of a linkage mechanism includes a process often called kinematic synthesis. The kinematic topology and the geometry of a mechanism are determined through kinematic synthesis. The kinematic topology of a linkage mechanism needs to be determined before its geometry is determined in most conventional kinematic synthesis methods. The dimensional synthesis can usually be accomplished using a numerical method. However, it can begin only after the kinematic topology is determined with the type synthesis. Conventionally, the type synthesis has been carried out using the experience and intuition of a good mechanism design engineer. Since it is difficult to implement this experience and intuition in a computer program, most linkage design programs rarely employ an efficient type synthesis capability. Unified mechanism synthesis methods have been proposed recently. Unified mechanism synthesis is a systematic process to find the type and dimensions of a linkage mechanism simultaneously which satisfies desired kinematic requirements. Actually, this synthesis integrates the type and dimensional syntheses into a single process. In the present study, a unified synthesis method for simultaneously determining the type and dimensions of a planar four-bar mechanism is proposed for the path generation, function generation and body guidance problems. A spring-connected arbitrarily sized block model is introduced and optimization problems using the model are formulated for the three types of problems. The sizes of the rectangular blocks, the stiffness and orientation of the springs, the location of input motion, and the location of the coupler point are chosen as design variables and a global optimization algorithm called the pattern search algorithm is employed to solve the optimization problem. To identify the limitation of the proposed method, two dimensionless indices to measure the level of difficulty of kinematic synthesis problems are proposed. It is shown that the present method can be successfully employed to synthesize a four-bar mechanism within certain limits of the indices.