Circuit rectification for four precision position synthesis of stephenson six-bar linkages

Circuit rectification ensures that a linkage may reach all precision positions without disassembly. The circuit characteristics of Stephenson six-bar linkages can be established by examining the interaction of the four-bar and five-bar chains within the linkage. Preliminary synthesis of the four-bar chain introduces specific conditions that must be met by the five-bar chain for all of the precision positions to lie on a single circuit. These conditions are based on the relationship between the four-bar coupler curve and the dyads/triads that are generated from the centerpoint curve of the final synthesis step. The travel of the coupler curve between the precision positions is compared with the reach of the final dyad/triad to establish circuit conditions. The circuit conditions are applied to points along the centerpoint curve of the final synthesis step to identify those curve segments which will produce a mechanism with all precision positions on the same circuit.