Abstract: The analytical expressions of the local dexterity of Stewart platform described by the singular values of Jacobian matrix are formulated. It is proved that the different kinematic performance indexes to evaluate the dexterity of the platform are inherently identical. The parametric relationship to find a family of isotropy is derived. The design criteria in conjunction with the detailed procedure are proposed according to the specific requirements for the orientation capability and dexterity. It has been concluded via examples that if the dimensional parameters are designed such that the local performance is satisfactory, so is the global performance provided that the reachable orientation of the mobile platform is limited due to the constraints of the passive joints and actuated variables.

Key words: Dexterity Isotropy, Stewart manipulators, Workspace