An application, AutoDesk ForceEffect Motion, was used to create a 4-bar mechanism based on the desired path of Sisyphus' feet. When actuated at point A, the links drawn in black produced a near elliptical path shown in blue, which indicated the path of the feet. The red lines represent velocity vectors at select points along the path. We then implemented this design in SolidWorks to create our mechanism.
The prototype was made primarily out of wood. The large circle, representing the world, spins opposite the smaller circle. The figure walks along the incline, continuously pushing the boulder.
Behind the the larger circle is a center pulley that delivers power via belts to the large and small circles and to the drive shaft connected to the four bar mechanism associated with each leg of the figure. Also tucked behind the boulder are the out of phase 4-bar mechanism which create the foot motion of the walking figure.
The figure was made out of 1/4" sheets of wood, cut out on a band saw. The figure is fastened to the frame at the upper body and on the ground link of the mechanism. Two out of phase four bar mechanism drive the foot motion, and then the lower and upper legs pivot freely to follow the foot motion. The axles are 1/16" steel rod that was force fit into smaller holes drilled into the wooden links. For the protoype, this force fit allowed for rotational motion at each pin but was tight enough so that the pins did not fall out.
