The Instantaneous Screw Axis of Motions in the Kinematic Image Space

Abstract

In the velocity analysis of mechanisms the instantaneous screw axes and the corresponding axodes play an important role. The instantaneous screw axis is computed via the velocity operator, this is the skew-symmetric matrix \(\mathbf {\dot{A} A^T }\), where \(\mathbf {A}\) is the transformation matrix. From this operator the Plucker coordinates of the instantaneous screw axis are known. When the Study parameters of a one parametric motion are given a direct computation of the instantaneous screw axis would be more convenient. Without computing \(\mathbf {A}\) and its derivative first, this paper shows a way of computing the instantaneous screw axis directly from the Study parameterization of the one parametric motion.