FOUR-CABLE WRIST WITH SOLID SURFACE CABLE CHANNELS
First Claim
1. A medical instrument comprising:
- a first clevis having a first body and a first pin, the first clevis being attached to a base so that the first clevis can rotate about a first axis, wherein the first body includes a plurality of guide channels;
a first jaw attached to the first clevis so that the first jaw can rotate about the first pin; and
a first cable and a second cable attached to the first jaw and routed through the guide channels in the first clevis, wherein pulling the first cable and relaxing the second cable causes a first torque that tends to rotate the first jaw about the first pin, pulling the first and second cables causes a second torque that tends to rotate the first clevis about the first axis, and contact of the first and second cables on surfaces of the guide channels determines a moment arm of the second torque.
2 Assignments
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Accused Products
Abstract
A wrist mechanism for an instrument used in minimally invasive medical procedures employs only four drive cables for control of the pitch, yaw, and grip of an effector. To reduce part count, no pulleys are used. Instead, solid surfaces of devises in the wrist mechanism cradle the drive cables and are curved in multiple directions to maintain a fixed moment arm for cable torques and eliminate the need for large cable wrap angles. Further, the stiffness of each of the four drive cables can be controlled for improved clinical performance. In particular, the stiffness of the two drive cables that cause grips to close can be greater than the stiffness of the remaining two drive cables that cause the grips to open. The arrangement can minimize cable slack, improving fidelity of motion.
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Citations
18 Claims
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1. A medical instrument comprising:
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a first clevis having a first body and a first pin, the first clevis being attached to a base so that the first clevis can rotate about a first axis, wherein the first body includes a plurality of guide channels; a first jaw attached to the first clevis so that the first jaw can rotate about the first pin; and a first cable and a second cable attached to the first jaw and routed through the guide channels in the first clevis, wherein pulling the first cable and relaxing the second cable causes a first torque that tends to rotate the first jaw about the first pin, pulling the first and second cables causes a second torque that tends to rotate the first clevis about the first axis, and contact of the first and second cables on surfaces of the guide channels determines a moment arm of the second torque. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A medical instrument comprising:
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a first clevis having a first pin; a second clevis rotatably mounted on the first pin, the second clevis includes a second pin, a first guide channel, a second guide channel, a third guide channel and a fourth guide channel; a first jaw rotatably mounted on the second pin; a first cable that extends through the first clevis, rides on a first solid surface that is part of the first guide channel, and attaches to the first jaw; a second cable that extends through the first clevis, rides on a second solid surface that is part of the second guide channel, and attaches to the first jaw; a second jaw rotatably mounted on the second pin; a third cable that extends through the first clevis, rides on a third solid surface that is part of the third guide channel, and attaches to the second jaw; and a fourth cable that extends through the first clevis, rides on a fourth solid surface that is part of the fourth guide channel, and attaches to the second jaw. - View Dependent Claims (11, 12, 13, 14)
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15. A method for operating a wrist mechanism, comprising:
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pulling on a first cable and a second cable that are attached to a first jaw that is rotatably mounted on a first pin in a clevis, the first and second cables respectively resting on first and second guide channels that pass through the clevis, wherein pulling on the first and second cables causes a first torque on the clevis, the first torque causing the clevis to rotate about a second pin and having a moment arm that depends on a distance from the first and second guide channels to the second pin; and pulling on the first cable while releasing the second cable, wherein pulling on the first cable and releasing the second cables causes a second torque on the first jaw, the second torque causing the first jaw to rotate about a first pin. - View Dependent Claims (16, 17, 18)
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Specification