Closed-form solutions for the forward kinematics of a 4-DOFs parallel robot H4

This paper present closed-form solutions for the forward kinematics of a 4-DOFs parallel robot H4. Many researchers have tried to obtain closed-form solutions of 3-and 6-DOFs parallel robots, i.e., planar, Delta, Stewart platform and Hexapod robots, in a single variable polynomial equation. Indeed, there are just few effort have been devoted in the past to 4-DOFs parallel robot. Therefore, we focus on the forward kinematics of a 4-DOFs parallel robot H4. Solutions of the forward kinematic yields a 16^th degree polynomial in a single variable which indicates that there may be up to 16 different configurations for the travelling plate for a given set of motor´s angle. The results are presented via a numerical example.