Control of round-off propagation in articulating the human figure

Abstract When articulation of a multilink mechanism is specified by rotation of one link relative to another, the similarity transformation can build up severe errors in the rotation matrices. Four algorithms for reorthogonalization of erroneous rotation matrices are described: (a) using the orthonormal relations; (b) reducing to Eulerian angles; (c) reducing to a single rotation about an inclined axis; (d) Newton's method. The relative merits of these are briefly discussed.