Synthesis of 6-DOF 3-chain isotropic parallel manipulators

Isotropic manipulators are generally considered as manipulators with optimum dexterity. Currently, many serial, redundant, or parallel isotropic manipulators can be easily developed from the so-called isotropic generators that consist of six straight lines and a reference point. Most existing isotropic generators, however, cannot be employed to develop 6-DOF isotropic parallel manipulators with less kinematic chains. This paper presents special isotropic generators for developing 6-DOF parallel manipulators with three kinematic chains. Link parameters of each limb can be obtained by solving 4^th degree polynomials. Several desired link parameters can be specified because the number of design variables is larger than the number of equations. The proposed methods can also be utilized to develop 6-chain parallel manipulators.