Medical instrument electrically energized using drive cables
An electrically energized medical instrument uses one or more drive cables to both actuate mechanical components of a wrist mechanism or an effector and to electrically energize the effector. Electrical isolation can be achieved using an insulating main tube through which drive cables extend from a backend mechanism to the effector, an insulating end cover that leaves only the desired portions of the effector exposed, and one or more seals to prevent electrically conductive liquid from entering the main tube. Component count and cost may be further reduced using a pair of pulleys that are shared by four drive cables.
1. An apparatus, comprising:
a shaft comprising a distal end portion and a proximal end portion;
a wrist mechanism comprising a distal portion movably coupled to a proximal portion, the wrist mechanism coupled to the distal end portion of the shaft, and the wrist mechanism defining a wrist portion of a cable path;
an end effector coupled to the distal portion of the wrist mechanism, actuation of the end effector producing movement of the end effector relative to the distal portion of the wrist mechanism;
a cable pair routed through the wrist portion of the cable path, a first portion of the cable pair being coupled to the end effector; and
a transmission coupled to a portion of the shaft, the transmission comprising a drive shaft and a rocker arm,
the transmission defining a transmission portion of the cable path between the drive shaft and the shaft, the cable pair being routed through the transmission portion of the cable path,
the drive shaft being configured to move a portion of the cable pair to actuate the end effector,
the rocker arm coupled to a pulley in contact with the cable pair, the rocker arm configured to move the pulley to change a length of the transmission portion of the cable path.
2. The apparatus of claim 1 , wherein the rocker arm comprises a first arm portion with the pulley mounted thereon, the pulley defining a portion of the transmission portion of the cable path.
3. The apparatus of claim 2 , wherein rotation of the first arm portion causes the pulley to move relative to the drive shaft.
4. The apparatus of claim 2 , wherein the pulley is a first pulley, the cable pair is a first cable pair, the cable path is a first cable path,
the rocker arm further comprises a second arm portion, the transmission comprises a second pulley mounted on the second arm portion of the rocker arm,
the transmission defining a transmission portion of a second cable path between a second drive shaft and the shaft, and
a second cable pair is in contact with the second pulley, the second cable pair being routed along the transmission portion of the second cable path.
5. The apparatus of claim 4 , wherein the rocker arm is configured to move the first pulley and the second pulley to lengthen the transmission portion of the first cable path while shortening the transmission portion of the second cable path.
6. The apparatus of claim 5 , wherein the first arm portion and the second arm portion are operatively connected such that the first arm portion and the second arm portion rotate together.
7. The apparatus of claim 4 , wherein the first arm portion and the second arm portion are between the drive shaft and the proximal end portion of the shaft.
8. The apparatus of claim 1 , wherein:
the drive shaft is operatively coupled to a second portion of the cable pair and configured to move the second portion of the cable pair, and
the pulley rotates between a first position relative to the drive shaft and a second position relative to the drive shaft to change the length of the transmission portion of the cable path, wherein the pulley is closer to the drive shaft in the first position than in the second position.
9. The apparatus of claim 8 , wherein the cable path is a first cable path, the cable pair is a first cable pair, and the transmission further comprises a transmission portion of a second cable path, and
a second cable pair is routed through the transmission portion of the second cable path, and in contact with a second pulley,
the rocker arm is configured to move the second pulley to lengthen the transmission portion of the first cable path while shortening the transmission portion of the second cable path.
10. The apparatus of claim 1 , wherein the pulley is a first pulley, and the transmission further comprises a second pulley in contact with a second cable pair, the first pulley is mounted on a first arm portion of the rocker arm, and the second pulley that is mounted on a second arm portion of the rocker arm.
11. The apparatus of claim 10 , wherein the first arm portion and the second arm portion are operatively connected such that the first arm portion and the second arm portion rotate together.
12. The apparatus of claim 1 , wherein the cable path is a first cable path, the cable pair is a first cable pair, the pulley is a first pulley, the drive shaft is a first drive shaft, and the transmission further comprises a second pulley, a second drive shaft, and defines a transmission portion of a second cable path between the second drive shaft and the shaft, the apparatus further comprising:
a second cable pair routed through the transmission portion of the second cable path, and in contact with the second pulley, and
the rocker arm is configured to move the first pulley closer to the first drive shaft to lengthen the transmission portion of the first cable path while shortening the length of the transmission portion of the second cable path.
13. The apparatus of claim 1 , wherein the cable path is a first cable path, the cable pair is a first cable pair, the pulley is a first pulley, the drive shaft is a first drive shaft, and the transmission further comprises a second pulley, a second drive shaft, and defines a transmission portion of a second cable path between the second drive shaft and the shaft, the apparatus further comprising:
a second cable pair routed through the transmission portion of the second cable path, and in contact with the second pulley, and
the rocker arm is configured to move the second pulley closer to the second drive shaft to lengthen the transmission portion of the second cable path while shortening the length of the transmission portion of the first cable path.