DETERMINATION OF THE UNIQUE ORIENTATION OF 2 BODIES CONNECTED BY A BALL-AND-SOCKET JOINT FROM 4 MEASURED DISPLACEMENTS

In previous analyses, it has been shown that a maximum of eight relati ve orientations exist for two bodies connected by a ball-and-socket jo int when the distances between three pairs of points are measured. In this paper it is shown how a unique orientation can be determined if t he distances between four pairs of points are known. At the outset, th e introduction of redundant information is an attractive method for ob taining the unique orientation result. However, this paper demonstrate s that high accuracy in the measurement of the linear displacements mu st be maintained to obtain an accurate result for the orientation. (C) 1998 John Wiley & Sons, Inc.