Assur principle introduction in the lever mechanisms of the second type

The paper considers introduction of the Assur principle in lever mechanisms of the second type. It proposes in the structural analysis to divide the mechanism into initial kinematic chains and structural groups with zero mobility. Structural groups could contain a fixed link, i.e. a rack. The paper suggests to call the initial kinematic chain as the the two moving links connected by an input kinematic pair. The considered modified Assur principle makes it possible to apply the kinematic analysis methods of the first type to the lever mechanisms in computation of the second type mechanisms. The method is based on computing kinematic characteristics in a moving coordinate system rigidly connected with one of the links in the input kinematic chain. In the selected moving coordinate system, the mechanism belongs to the first type of mechanisms, since the input kinematic chain includes a fixed link. Absolute values of velocities and accelerations are computed through the calculated relative values using the rotation matrix and theorems on the velocities and accelerations addition during the point complex motion.
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