The present invention is a wrist mechanism and a method for making robotic devices
in which the transmission of motion, force and/or torque around a revolute joint
can be accomplished without coupling. This construction allows mounting the actuators
on the base or lower elements of a mechanism, so that only linkage elements move
the end-effector. Thus reducing inertia of the moving elements and increasing performance
of the device. The decoupled motion of the end-effector or links is achieved by
routing their transmission cables around idler pulleys placed parallel to the joint
rotation axis on an optimal position such any stretch on the transmission cable
is minimized. In particular, this construction can be use for robotic surgical
tools that have two independently driven jaws, decoupled and orthogonal from its
articulating wrist. This device may be used in grasping, cutting, suturing or alike operations.