Abstract: Performance of the serial manipulators has a close relationship with the topologies and the dimensional parameters. It is important to take consider the influence of the dimensional parameters on the kinematic performance of the manipulators. Containing topologies and dimensional parameters, a method for the type synthesis of 6R serial manipulators is presented. On the basis of enumeration of six possible architectures having different joint axis arrangement, a general algorithm for velocity Jacobian matrix in the link frame of middle joint axes is constructed, the Jacobian matrices and their determinants are deduced for these architectures, an index to select the optimal architecture is proposed by minimizing the number of geometrical parameters that may cause the Jacobian determinant to be zero and by maximizing the number of the orthogonally placed joint axes. An optimized architecture which accords with that manipulability index is synthesized out. It shows that the optimized architecture features better dexterity and foldability, and easy motor assembly.

Key words: 6R serial manipulator, Jacobian matrices, Type synthesis