Robotic Surgical Instrument Cable Drives for Confined-Space Dexterity
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Solution Overview
Problem
Existing robotic surgical instruments face challenges in efficiently maneuvering end effectors within limited access areas due to limitations in actuation mechanisms, particularly in laparoscopic and robotic surgeries.
Innovation Solution
A robotic surgical system with a surgical instrument featuring a dexterous assembly and an instrument cassette assembly that includes a cable drive system with drive dog pinions and rack assemblies, enabling the end effector to move in multiple planes and planes, along with a wrist mechanism for rotation, and a grip mechanism for manipulating jaw members, all controlled by a manual release mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a robotic surgical instrument uses a cable drive assembly with drive dog pinions and rack assemblies to enable multi-planar movement of the end effector, then the dexterity and maneuverability of the end effector is improved, but the device complexity increases
Solution Approach 1:
The actuation system is divided into multiple independent drive dog assemblies, each responsible for specific degrees of freedom. Each drive dog assembly contains a pinion and rack that work independently to control specific movements of the end effector, allowing complex multi-planar manipulation through coordinated action of segmented components.
Solution Approach 2:
The drive dog assemblies are nested within the instrument shaft, with multiple pinion-rack mechanisms housed within the same structural envelope. The racks are positioned to translate relative to one another within the shaft assembly, creating a compact nested arrangement that enables multiple movements without proportionally increasing external dimensions.
2Measurement precision
If the first and second rack assemblies are positioned to translate relative to one another to cause cables to move the end effector, then the precision of end effector positioning is improved, but the manufacturing complexity increases
Solution Approach 1:
The positioning system uses separate first and second rack assemblies that translate independently relative to one another. Each rack assembly can be manufactured and calibrated separately, then assembled into the instrument shaft, allowing for precise positioning through coordinated movement of segmented components rather than requiring a single complex mechanism.
3Adaptability or versatility
If the surgical instrument includes a wrist mechanism with double-sided rack and wrist gear for rotation, then the versatility of surgical tasks is improved, but the device complexity increases
Solution Approach 1:
The wrist mechanism is segmented into a double-sided rack component and a wrist gear component that work together to provide rotation. The double-sided rack can engage with drive dogs from opposite directions, and the wrist gear translates linear rack movement into rotational motion, creating a modular segmented wrist system that adds versatility without requiring a completely integrated complex mechanism.
Data Source
AI summary
A robotic surgical instrument includes an instrument cassette assembly, an elongated shaft assembly extending from the instrument cassette assembly, and an end effector supported on the elongated shaft assembly. The elongated shaft assembly defines a longitudinal axis. The instrument cassette assembly includes a cable drive assembly, a grip mechanism, a manual release mechanism, and a wrist mechanism. The cable drive assembly includes a drive dog assembly having a drive dog pinion, a first rack assembly, and a second rack assembly. The first and second rack assemblies translate relative to one another in response to rotation of the drive dog pinion to cause the end effector to move relative to the longitudinal axis. The grip and wrist mechanisms are coupled to the end effector and the manual release mechanism is coupled to the grip mechanism.