Patent ID: 8864794

Claim:
A robotically controlled medical instrument, comprising: an end effector having a base and a manipulatable element; a wrist mechanism having first and second linkages coupled to the base of the end effector; an elongate tube dimensionally insertable through a minimally invasive incision into a patient; and first, second, third, and fourth pins extending through the elongate tube, wherein the fourth pin is always stationary relative to at least the first and second pins and coupled by a ball joint to the base of the end effector at a pivot point, wherein the first and second pins are respectively coupled to the first and second linkages of the wrist mechanism to cause movement of the end effector in first and second degrees of freedom about the pivot point according to push/pull movement of the first and second pins, wherein movement of the first and second pins in a same push/pull direction results in the first degree of freedom movement of the end effector and movement of the first and second pins in different push/pull directions results in the second degree of freedom movement of the end effector, and wherein the third pin is coupled to the manipulatable element of the end effector to cause manipulation of the manipulatable element according to push/pull movement of the third pin.