Abstract: An analytical approach for the dimensional synthesis of the spherical parallel mechanism having equal apex angles is presented. Both the dexterity and the behavior of the direct Jacobian matrix in the initial configuration are optimized, resulting in a set of closed-form dimensional parameters that enable a global conditioning index to be achieved in the overall workspace. The outcomes conform the optimality of the orthogonal spherical parallel mechanism are achieved by the numerical results in the previous work.

Key words: Force transmission, Isotropy, Optimal design, Spherical parallel mechanism