Knife Drive Mechanism With Radial Load Reactors Against Tilting
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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 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 and radial load reactors to prevent tilting, using a dual pinion mechanism with active or passive secondary inputs and a rotating collar to accommodate tolerance stack-up, reducing off-axis loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a knife drive mechanism is used in robotic surgical systems, then the ability to sever tissue is improved, but unintended movement and tilting of the mechanism occurs due to off-axis loading
Solution Approach 1:
A dedicated knife drive mechanism acts as an intermediary component between the robotic system's control system and the knife. This mechanism includes a drive rod, longitudinally driven gear, and radial load reactors that work together to ensure precise, controlled movement of the knife along the guide track while preventing off-axis loading and tilting, thus maintaining reliability during tissue severing operations
Solution Approach 2:
The knife drive mechanism extracts and isolates the knife actuation function from the main robotic manipulator. By separating the knife drive function into a dedicated mechanism with its own drive rod and gear system, the patent prevents unintended movements from affecting the overall robotic system while ensuring precise control of the knife along the guide track
2Measurement precision
If control algorithms are used to control knife position, then precision is improved, but unintended movement of any component frustrates the control algorithm
Solution Approach 1:
The radial load reactors and aligned drive rod configuration provide beforehand cushioning against off-axis loads and unintended movements. By preemptively designing the mechanism to resist lateral forces and prevent tilting, the patent ensures that the knife drive components remain stable and do not frustrate the control algorithm during surgical operations
3Device complexity
If a simple drive mechanism is used, then device complexity is reduced, but off-axis loading causes tilting and unintended movement
Solution Approach 1:
The patent addresses off-axis loading by introducing radial load reactors that operate in a dimension perpendicular to the primary drive direction. The drive rod is aligned in a plane with the longitudinally driven gear, creating a geometric arrangement that inherently resists tilting and unintended movements caused by lateral forces, thus improving reliability without excessive complexity
Data Source
AI summary
A surgical tool includes a drive housing, a drive input rotatably mounted to a bottom of the drive housing, a capstan assembly arranged within the drive housing to rotate a drive gear about a rotational axis and within a drive plane orthogonal to the rotational axis, a longitudinally driven gear engageable with the drive gear, and a drive rod operatively coupled to the longitudinally driven gear and extending from the drive housing to a knife extendable within end effector of the surgical instrument. The drive rod is aligned within the drive plane such that translation of the longitudinally driven gear induces a corresponding longitudinal translation of the drive rod within the drive.