Geometric formulation approach for determining the actual solution of the forward kinematics of 6-DOF parallel manipulators

This paper presents a new formulation approach for determining the actual solution of the forward kinematics of 6-DOF parallel manipulators. We show that a geometric structure of the 3-6 platform with a 3-2-1 type that has a unique closed form solution provides a useful guideline for formulating the forward kinematics of 6-DOF parallel manipulators and for determining their actual solution. We use the tetrahedron geometry to find the actual solution. The formulation approach is simple and effective for determining the actual solution of many 6-DOF parallel manipulators.