A method of displacement analysis of the four-link spatial mechanism is developed. The results through this analysis will be exact solutions that can be obtained without Introduction A recent survey of space mechanism research [1], which covers analytical methods developed mainly since the 1950s with numerous pertinent references, serves as an extensive and informative source of background material. However, several selective references of well-known methods for the displacement analysis of spatial linkage may be mentioned. Among them are the 4x4 matrix iterative method [2, A method of displacement analysis using direction cosine matrices as transformation matrices for the four-link spatial mechanisms is developed and applied to various four-bar spatial linkages in this paper. The mathematics involved are elementary; the operations are simple without loss of geometric interpretation, and the solutions are exact. Th
