Synthesis of Two Four-bar in Series for Body Guidance

Department of Mechanical Engineering, Chinese Culture University, Taipei, Taiwan

Abstract

Using planar two-degree-of-freedom mechanism for the task of body guidance is evaluated and presented. This mechanism consists of two four-bar in series. For some applications of simple planar movement, planar robot with three actuators can be replaced by this mechanism to save cost and reduce complexity. This work reveals that at most seventeen precision positions can be prescribed theoretically. Based on synthetic consideration, each four-bar is proposed to be in charge of some prescribed positions and thus can be designed separately. Decomposing the prescribed precision positions into the assignment of body guidance for each constituent four-bar is developed. Both four-bar are then assembled to successfully execute the task of at most nine precision positions. Numerical example is given to illustrate the synthesis process. Problems of order defect, branch defect and ratio of link lengths are all considered to ensure the performance and applicability of the mechanism.