A positioning data calculating procedure calculates analytically relative rotation
angles for the links arranged in series to form an articulated manipulator to locate
an object in a desired orientation at a desired position. Coordinate expressions
including an x-coordinate expression representing the x-coordinate of a triaxial
intersection point, a yz addition coordinate expression representing the sum of
the y- and the z-coordinate of the triaxial intersection point, and a yz subtraction
coordinate expression representing the remainder of subtraction of the z-coordinate
from the y-coordinate of the triaxial intersection point, and including first to
third rotation angles corresponding to rotation angles through which the second
link is turned relative to the first link, through which the third link is turned
relative to the second link, and through which the fourth link is turned relative
to the third link as variables are solved. The first to the third rotation angles
can easily and analytically be determined by using the yz addition coordinate expression
and the yz subtraction coordinate expression. Fourth to sixth angles can analytically
be determined on the basis of the first to the third rotation angle. The determination
of the first to the sixth rotation angle by an analytical operation needs a time
shorter than that needed by the determination of the same by a convergence operation.