Planar Four-bar Path Generation Considering Worst Case Joint Tolerances

Four-bar path generation is used to calculate the mechanism parameters required to achieve or approximate a set of prescribed rigid-body path points. This work will discuss the path generation of four-bar mechanism with position tolerance variations due to joint running clearance. The tolerance variations study will be based on the standards of American National Standard Institute (ANSI). The new design constraint introduced in this paper will consider the joint tolerances and incorporate it into the displacement position matrix of the mechanism described in the conventional planar four-bar path generation models. The synthesized planar four-bar mechanism will produce tolerance limits for moving pivots and link length from which any mechanism can be synthesized to satisfy the prescribed path for the coupler point with its prescribed tolerance. The included example demonstrates the synthesis of a four-bar mechanism with joint tolerances.