Force-Feedback Closure Driver Velocity Control in Surgical End Effectors
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Solution Overview
Problem
Existing robotic surgical instruments face challenges in accurately controlling the speed of cutting members to adapt to varying tissue thickness, leading to inconsistent stapling and cutting performance.
Innovation Solution
A control circuit is employed to detect conditions at the end effector during closure and firing phases, adjusting motor velocities based on actual closure force and position feedback to ensure precise control of the firing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the cutting member speed is controlled based on initial tissue thickness measurement, then the stapling and cutting performance can be optimized for that specific tissue thickness, but the system cannot adapt to varying tissue thickness during the procedure
Solution Approach 1:
The system continuously monitors closure force during the closure phase and uses this feedback to determine tissue thickness. The control circuit adjusts the firing member speed based on the measured closure force, enabling real-time adaptation to varying tissue thickness while maintaining consistent stapling and cutting performance throughout the procedure.
Solution Approach 2:
The system transitions from static speed control to dynamic speed adjustment. The firing member speed is not fixed but is continuously adjusted during the firing phase based on real-time closure force measurements, allowing the system to adapt to tissue thickness variations while maintaining optimal performance consistency.
2Manufacturing precision
If a single fixed speed is used for the firing member, then the system structure remains simple, but the stapling and cutting performance becomes inconsistent across different tissue thicknesses
Solution Approach 1:
The control circuit incorporates feedback from the closure force sensor to dynamically adjust firing member speed. This feedback mechanism enables precise control of stapling and cutting performance across different tissue thicknesses while adding only moderate system complexity through the integration of sensors and control algorithms.
Solution Approach 2:
The system changes the operational parameter of firing member speed based on measured tissue properties. By adjusting speed as a variable parameter rather than using a fixed value, the system achieves precise stapling and cutting performance across different tissue thicknesses without requiring complex mechanical adjustments.
3Reliability
If the closure member applies sufficient force to ensure reliable tissue compression, then the stapling reliability improves, but the closure member velocity must be reduced to prevent tissue damage
Solution Approach 1:
The control circuit divides the closure phase into distinct periods: initial closure at reduced speed to compress tissue, followed by a firing phase at higher speed. This periodic action pattern allows the closure member to achieve reliable tissue compression while maintaining overall procedural efficiency through the rapid firing phase.
Solution Approach 2:
The system dynamically adjusts closure member velocity during the procedure. The control circuit monitors closure force in real-time and adjusts speed accordingly, enabling sufficient compression force for reliable stapling while minimizing tissue damage risk through controlled velocity adjustment.
4Productivity
If the firing member moves at high speed to improve productivity, then the stapling efficiency increases, but the precision of cutting and stapling decreases due to inability to adapt to tissue variations
Solution Approach 1:
The system employs dynamic speed control where the firing member operates at high speed during the firing phase to maintain productivity, while the control circuit independently adjusts closure member velocity based on real-time tissue properties. This dynamic adjustment enables both high productivity and high precision by optimizing each component's speed for its specific function.
Solution Approach 2:
The control circuit performs preliminary measurement of tissue properties during the closure phase before the firing phase. By pre-characterizing the tissue based on closure force, the system can then execute the firing phase at optimized high speed with confidence in maintaining precision, as the tissue parameters are already known and accounted for.
Data Source
AI summary
A surgical system comprising an end effector, a closure driver, a force sensor, and a control circuit is disclosed. The end effector comprises a first jaw and a second jaw rotatable relative to the first jaw between an open position and a closed position. The closure driver is configured to apply a closure force to the second jaw to rotate the second jaw toward the closed position. The force sensor is to measure a parameter indicative of the closure force. The control circuit is to receive an output of the force sensor indicative of the parameter and set a velocity of the closure driver based on the received output and a force threshold.