Use of cardan angles to locate rigid bodies in three-dimensional space

A method of locating rigid human body segments in three-dimensional space is presented. This method has the advantages of being applicable to any body segment and in following anatomical movement patterns. The location of each segment is defined by the location of its proximal endpoint and by a set of three cardan angles of the third kind. Cardan angles sequentially rotate a rigid body about each of its three body fixed axes. Examples on how cardan angles can be used to represent segment orientation are given. Exact and best-fit solutions used in solving segment location are described.