The design methodology for fewer input–more output parallel mechanisms

• A novel concept, fewer input-more output mechanism (Fi-Mo Mechanism), is proposed.
• A design methodology for Fi-Mo mechanisms is established
• 1-dof 1T2R output and 1-dof 3R output Fi-Mo mechanisms are designed to illustrate the methodology.
• The novel prototypes of parallel vibrating screen and foot massager device based on Fi-Mo mechanism are invented.

Based on the industrial application background, the concept and methodology for fewer input–more output parallel mechanisms, Fi–Mo mechanisms, are proposed. The most important characteristic of Fi–Mo mechanisms is that parasitic motions of these mechanisms are utilized fully which are generally viewed as harmful motions and eliminated. The research background, definition and characteristics of Fi–Mo mechanisms are introduced. Then, design methodology for Fi–Mo mechanisms is established, which includes 1) a mathematical model which correlates the number of actuated input (W), degrees of freedom (DOF) and numbers of output motion (position and orientation) (Nout) is deduced; 2) the design principles and flow chart for designing Fi–Mo mechanisms are proposed; 3) all (1–5) DOF Fi–Mo parallel mechanisms of sixty-nine types are put forward. Meanwhile, topological structure theory for parallel mechanisms based on position and orientation characteristics (POC) set and ordered single-open-chain (SOC)units used to analyze topological characters of Fi–Mo mechanisms is introduced. Furthermore, two examples of 1-DOF 1T2R, 1-DOF 3R output Fi–Mo mechanisms and their prototypes, novel parallel vibrating screen and parallel foot massager, have been designed to illustrate the design methodology.