ON THE STIFFNESS OF A NOVEL 6-DEGREE-OF-FREEDOM PARALLEL MINIMANIPULATOR

The dimensionally uniform Jacobian matrix of a novel three-limbed, six degree-of-freedom (DOF) minimanipulator is used to derive its dimensionally uniform stiffness matrix. The minimanipulator limbs are inextensible and its actuators are base-mounted. The lower ends of the limbs are connected to bidirectional linear stepper motors that are constrained to move on a base plane. The minimanipulator is capable of providing high positional resolution and high stiffness. It is shown that, at a central configuration, the stiffness matrix of the minimanipulator can be decoupled (diagonalized), if proper design parameters are chosen. It is also shown that the stiffness of the minimanipulator is higher than that of the Stewart platform. Guidelines for obtaining large minimanipulator stiffness values are established. (C) 1995 John Wiley & Sons, Inc.