Surgical Tool Rotary Drive Transitioning Between High-Speed and High-Torque States
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Solution Overview
Problem
Robotic surgical systems face challenges in providing precise and versatile tool manipulation, particularly in achieving both high-speed and high-torque operations required for tasks like stapling and cutting, while maintaining ease of use and minimizing mechanical wear.
Innovation Solution
The implementation of a rotary drive system with a transition nut that switches between high-speed and high-torque operating states based on torque thresholds, utilizing a spring-activated ramped cam surface to engage either high-speed or high-torque gearing, allowing a single rotary drive to achieve both high speeds during grasping and high torques during clamping/cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single rotary drive is used for both high-speed and high-torque operations, then device complexity is reduced, but it becomes difficult to achieve both high-speed grasping and high-torque clamping/cutting
Solution Approach 1:
The system dynamically transitions between two operating states (high-speed and high-torque) using a transition nut that moves along a ramped cam surface. The transition nut is biased by a spring and engages with either the high-speed gear or high-torque gear based on the torque threshold, allowing a single rotary drive to adaptively provide different gear ratios for different surgical tasks
Solution Approach 2:
A single rotary drive unit is designed to perform multiple functions by selectively engaging different gear trains. The drive can operate in high-speed mode for grasping operations and switch to high-torque mode for clamping and cutting operations, making one component serve multiple surgical functions that would traditionally require separate drives
2Force
If high-torque gearing is used for clamping and cutting operations, then sufficient force is achieved, but the operation speed decreases
Solution Approach 1:
The system uses a dynamic transition mechanism where the transition nut moves along a ramped cam surface to switch between gear trains based on torque thresholds. During low-torque operations like grasping, the system engages high-speed gearing for rapid movement. When torque exceeds the threshold during clamping or cutting, the transition nut shifts engagement to the high-torque gear train, automatically adapting the speed-torque characteristics to the operational requirements
3Speed
If high-speed gearing is used for grasping operations, then operation speed is maximized, but insufficient torque is available for subsequent clamping and cutting
Solution Approach 1:
The system begins in high-speed mode during grasping operations, allowing rapid positioning and closure. As the operation progresses and torque requirements increase for clamping and cutting, the torque threshold is exceeded, causing the transition nut to shift along the ramped cam surface and engage the high-torque gear train. This dynamic transition ensures that the system automatically provides sufficient torque when needed while maintaining high-speed capability during initial grasping
4Reliability
If separate rotary drives are used for high-speed and high-torque operations, then both performance requirements are met, but device complexity and mechanical wear increase
Solution Approach 1:
The patent merges the functions of separate high-speed and high-torque rotary drives into a single rotary drive unit. The transition mechanism combines the high-speed gear train and high-torque gear train within one drive, using a transition nut and ramped cam surface to selectively engage the appropriate gear train. This integration reduces the number of separate drives and switching mechanisms while maintaining the ability to meet both high-speed and high-torque performance requirements
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
Enables seamless transitions between high-speed and high-torque operations, enhancing the robotic tool's ability to perform complex surgical tasks with reduced mechanical stress and increased efficiency.
Implementation Method 1
a spring-activated ramped cam surface to engage either high-speed or high-torque gearing
Implementation Method 2
a spring-activated ramped cam surface to engage either high-speed or high-torque gearing
Implementation Method 3
utilizing a spring-activated ramped cam surface to engage either high-speed or high-torque gearing
Data Source
AI summary
A surgical tool that comprises a surgical end effector comprising opposing jaws, an elongate shaft extending distally to the surgical end effector, and a housing defining a passage therethrough, wherein the elongate shaft extends through the passage. The surgical tool further comprises an actuation mechanism configured to selectively move the housing along the elongate shaft relative to the surgical end effector. The actuation mechanism comprises a pulley, a cable engaged with the pulley, and a lock arrangement configured to releasably lock the housing relative to the elongate shaft. The lock arrangement comprises a washer positioned around the elongate shaft. The cable is engaged with the washer. An actuation of the pulley is configured to apply a tension to the cable to pivot the washer relative to the elongate shaft from a locked orientation to an unlocked orientation.