Workspace atlas and stroke analysis of seven-bar mechanisms with the translation-output

A two-degree of freedom seven-bar mechanism, which is composed of a hinged five-bar mechanism and a RPP grade-II Assur group, can realize translation-output if two driving links are appropriately programmed. This type of translation-output mechanisms can generate functions typically obtained in a cam mechanism with a translation follower and is closely related to the characteristics of the coupler reference point. Based on the segment-resolving method, the procedure of obtaining the workspace boundary curves of the coupler reference point of the double-crank seven-bar mechanism and the triple-crank seven-bar mechanism are presented. When the coupler-point angular offset parameter varies from 0° to 360°, the workspace atlases of the double-crank seven-bar mechanism and triple-crank seven-bar mechanism are obtained for every variation of the seven-bar mechanisms. The characteristics of the workspace and the translation-output stroke as a function of the coupler point angular offset β are further analyzed. The analysis results in a theoretical basis with adjustable controlled structural parameters to realize the required translation-output motion rules.