Knife Drive Mechanism Layout for Stable Robotic Knife Positioning
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Solution Overview
Problem
Unintended movement of surgical knives in robotic systems can frustrate control algorithms and pose hazards during minimally invasive surgery, due to factors such as off-axis loading and tilting of knife drive mechanisms.
Innovation Solution
A knife drive mechanism with a drive rod aligned in a plane with a rotary pinion gear, featuring radial load reactors and a dual pinion mechanism with active or passive secondary input, which reduces off-axis loading and tilting, ensuring precise control of the knife.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cable driven motion system is used to articulate the end effector, then the system allows for more degrees of freedom and natural hand-like articulation, but unintended movement of the knife or knife drive mechanism components may occur
Solution Approach 1:
The knife drive mechanism is segmented into distinct functional components: a drive input for actuation, a capstan assembly with drive gear for motion conversion, a longitudinally driven gear for precise positioning, and a drive rod for force transmission. Each component is independently controllable and monitorable, allowing the system to maintain reliability while providing multiple degrees of freedom through modular architecture.
2Ease of manufacture
If the drive rod is not aligned with the drive gear plane, then the mechanism may be simpler to manufacture, but off-axis loading and tilting occur causing unintended knife movement
Solution Approach 1:
The drive rod is aligned within the drive plane formed by the capstan assembly and drive gear, ensuring that all force transmission occurs in the intended rotational plane. This dimensional alignment prevents off-axis loading and tilting, maintaining manufacturing precision while the overall mechanism design accommodates ease of assembly through standardized interfaces and modular components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The mechanism enhances the precision and safety of surgical knife operations by minimizing unintended movement, thereby improving the reliability and control of robotic surgical instruments.
Implementation Method 1
a capstan assembly arranged within the drive housing and rotatable about a rotational axis, the capstan assembly including a drive gear operatively coupled to the drive input such that rotation of the drive input about the rotational axis correspondingly actuates the drive gear to rotate in a drive plane orthogonal to the rotational axis
Implementation Method 2
a longitudinally driven gear arranged within the drive housing and engageable with the drive gear such that the longitudinally driven gear translates between a proximal home position and a distal extended position in response to actuation of the drive gear
Data Source
AI summary
A surgical tool includes a drive housing, a capstan assembly rotatably mounted within the drive housing and including a drive gear rotatable about a rotational axis, a longitudinally driven gear arranged within the drive housing and engageable with the drive gear such that the longitudinally driven gear translates longitudinally in response to rotation of the drive gear, a drive rod operatively coupled to and extending from the longitudinally driven gear, and a coupling that rotatably couples the drive rod to the longitudinally driven gear such that the drive rod is rotatable about a longitudinal axis of the drive rod and relative to the longitudinally driven gear.