Mobility analysis of RSSR linkage and type maps of special cases

An RSSR mechanism is analyzed by treating the linkage as two manipulators. The intersection region of the working volumes generated by both manipulators represents the mobility region of the input link or the output link. Finding the mobility region is to solve equations of an ellipse and a unit circle mathematically. For planar four-bar, one of the special RSSR linkage, Grashof’s rule is derived. The method of efficiently determining the type of a simply skewed four-bar is also proposed. For the purpose of synthesis, the type maps for planar and simply skewed four-bar are performed. The abscissa and ordinate of the map are the lengths of input link and output link, respectively. With developed type maps, the lengths of both input and output links can be selected easily when synthesizing a linkage with specified type.