Flexible wrist for surgical tool
View Patent ↗The present invention is directed to a tool having a wrist mechanism that provides pitch and yaw rotation in such a way that the tool has no singularity in roll, pitch, and yaw. In one embodiment, a minimally invasive surgical instrument comprises an elongate shaft having a working end, a proximal end, and a shaft axis between the working end and the proximal end; and an end effector. A wrist member has a flexible tube including an axis extending through an interior surrounded by a wall. The wall of the flexible tube includes a plurality of lumens oriented generally parallel to the axis of the flexible tube. The wrist member has a proximal portion connected to the working end of the elongate shaft and a distal portion connected to the end effector. A plurality of actuation cables have distal portions connected to the end effector and extend from the distal portion through the lumens of the wall of the wrist member toward the elongate shaft to proximal portions which are actuatable to bend the wrist member in pitch rotation and yaw rotation.
1. A minimally invasive surgical instrument comprising:
an elongate shaft having a working end, a proximal end, and a shaft axis between the working end and the proximal end;
an end effector;
a wrist member having a flexible tube and an inner spring, the flexible tube including a proximal portion connected to the working end of the elongate shaft and a distal portion connected to the end effector, the inner spring including a proximal portion connected to the workig end of the elongate shaft and a distal portion connected to the end efector, the inner spring being disposed inside an interior cavity of the flexible tube, the inner spring having an axis which is parallel to an axis of the flexible tube; and
a plurality of actuation cables having distal portions connected to the end effector and extending from the distal portion through the wrist member toward the elongate shaft to proximal portions which are actuatable to bend the flexible tube and the inner spring of the wrist member so as to allow pitch rotation and yaw rotation of the end effector;
wherein the inner spring is in the form of a wire wrap that is wrapped around the plurality of actuation cables in a coil spring fashion.
2. The instrument of claim 1 wherein the flexible tube is in the form of a shrink tube covering the wire wrap.
3. The instrument of claim 2 wherein the wire wrap and the shrink tube keep the plurality of actuation cables at approximately fixed distances from each other.
4. The instrument of claim 2 wherein the shrink tube provides electrical isolation.