Synthesis of Planar Four-Link Path Generator Planar Four-Link Path Generator : On the Singular Points

Four-link coupler curve is discontinuous at the change point, and is separable into two or four curves by reversing the driven link about the fixed link. Nevertheless, in former algebraic analysis of singular points, it was not able to distinguish between the singular points on one curve and those on two curves. For practical uses of mechanisms it is required to analyze the singular points on one curve and to synthesize a mechanism having such singular points. In the present paper, the authors first obtain the number of singular points on one coupler curve of planar four-link crank-and-rocker mechanism, and derive the conditions for syntheses. Second, calculating the inclinations of tangents at the singular points, they synthesize the mechanisms satisfying the number and the positions of singular points and the inclinations of tangents at the singular points. As a result, it became possible to apply the coupler curve to automatic assembling and conveying machines.