shapes and structures of manipulators. Selfridge [11]
presented an algorithm for finding the boundary of reachable
volume of an arbitrary revolute-joint, serial-link
manipulator. Tsai and Soni [12] developed an algorithm for
the workspace of a general n R robot based on a linear
optimization technique and on small incremental
displacements applied to coordinate transformation equations
relating the kinematic parameters on the n R robot. Yang
and Lee [13] derived the equations representing the
boundaries of the workspace. Existence of holes and voids
in the workspace were also investigated. Lee and Yang [14]
have made a study of outlining the boundary of the
workspace, the quantitative evaluation of the volume, and
introduced a manipulator performance index. Hansen, Gupta
and Kazerounian [15] used a stable iterative algorithm for
inverse kinematic analysis to determine the approach angles
and lengths for reaching points in the workspace.
Freudenstein and Primrose [16] described the workspace of a
three-axis, turning-pair-connected robot arm of general
proportions in terms of the volume swept out by the surface
of a skew torus rotating about an offset axis in space.
Kohli and Spanos [17] studied the workspace analysis of
mechanical manipulators by using polynomial displacement
equations and their discriminants. Spanos and Kohli [18]
performed the study of workspace analysis of a class of
manipulators having the last three revolute joint axes
intersect orthogonally at a point. Cwiakala and Lee [19]