Synthesis of a single-loop, overconstrained six revolute joint spatial mechanism for two-position cylindrical rigid body guidance

The synthesis and analysis of a single-loop, overconstrained spatial mechanism with six binary links and six revolute joints for the guidance of a cylindrical rigid body between two positions are presented. The geometric constraints that make the spatial 6R mechanism movable are first introduced. Four features of the geometrical constraints of this mechanism are summarized to demonstrate its mobility and used for dimensional synthesis. Steps for mechanism dimensional synthesis are developed based on the descriptive and analytical geometry. The mechanism analysis based on analytical geometry is also presented. One of the advantages of this spatial mechanism is that the toggle position can be integrated into the synthesis. This is especially attractive in the synthesis of the wheel retract and twist mechanism for aircraft landing gears and the automated grinding wheel or tool changer for machine tools. A detailed example is used to illustrate the mathematical models for mechanism synthesis and analysis.