The figure shows a coupler curve generated by a four-bar linkage (not shown). Link 5 is to be attached to the coupler point, and link 6 is to be a rotating member with O6 as the frame connection. In this problem, we wish to find a coupler curve from the Hrones and Nelson atlas or by precision postures, such that, for an appreciable distance, point C moves through an arc of a circle. Link 5 is then proportioned so that D lies at the center of curvature of this arc.

The result is then called a hesitation motion, since link 6 hesitates in its rotation for the period during which point C transverses the approximate circular arc. Make a drawing of the complete linkage, and plot the first-order kinematic coefficient, φ

6, of link 6 for 360◦ of displacement of the input link.

Coupler curve Figure P9.32