On the closure modes of a generalised Altmann linkage

Among the analytical challenges posed by six-revolute kinematic loops is that of determining distinct input–output relationships for all of their closure modes, and hence access to points of intersection. Such a matter has practical relevance to potential places of bifurcation in the operation of a mechanism. The required study can be confused by incorrect treatment of expected symmetries in the linkage's movement. This article is intended to furnish an example of a suitable approach for a particular sub-family of six-bar chains.

► The “generalised Altmann linkage” is defined and its known input–output equations given.
► A second pair of closure modes is determined and the equations developed.
► The two solution sets are examined for points of intersection.