Formulating Assur kinematic chains as projective extensions of Baranov trusses

The real roots of the characteristic polynomial of a planar linkage determine its assembly modes. In this work it is shown how the characteristic polynomial of a Baranov truss derived using a distance-base formulation contains all the necessary and sufficient information for solving the position analysis of the Assur kinematic chains resulting from replacing some of its revolute joints by slider joints. This is a relevant result because it avoids the case-by-case treatment that requires new sets of variable eliminations to obtain the characteristic polynomial of each Assur kinematic chain.