Robotic Surgical Instrument Closed-Loop Feedback for Tissue Thickness

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Solution Overview

Problem

Robotic surgical instruments face challenges in accurately measuring tissue thickness and adjusting cutting speed in real-time to ensure optimal stapling and cutting performance, as existing systems lack precise feedback mechanisms to adapt to varying tissue conditions.

Innovation Solution

The implementation of sensors, such as Hall effect sensors and strain gauges, embedded within the surgical end effector to measure tissue thickness and force, coupled with a control circuit that adjusts the speed of the cutting member based on real-time feedback, allowing for adaptive control of the stapling and cutting process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If real-time feedback mechanisms are implemented to measure tissue thickness and adjust cutting speed, then surgical precision and tissue handling consistency are improved, but device complexity increases due to additional sensors and control circuits

Engineering Contradiction:
Improvesurgical precisionVSAvoiddevice complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements closed-loop feedback by using sensors (Hall effect sensors, strain gauges) to measure tissue thickness and force in real-time, then feeding this information back to the control circuit which adjusts the cutting member speed accordingly. This ensures precise control while managing complexity through integrated sensor-controller-actuator loops.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces traditional mechanical measurement systems with electronic sensors (Hall effect sensors for position, strain gauges for force). This substitution reduces mechanical complexity while improving measurement precision and enabling real-time digital control of the cutting process.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If the speed of the cutting member is adjusted in real-time based on tissue conditions, then tissue damage risk is reduced, but the response time and control system complexity increase

Engineering Contradiction:
Improvetissue damage riskVSAvoidresponse time
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The control circuit continuously monitors tissue thickness and force measurements and immediately adjusts cutting member speed in real-time. This closed-loop feedback minimizes response time by using direct sensor-to-controller connections and rapid processing, preventing tissue damage while maintaining surgical efficiency.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary measurements of tissue thickness before the cutting member engages, allowing the control circuit to pre-calculate and prepare the optimal speed adjustment. This anticipatory action reduces actual response time during the critical cutting phase by having control parameters ready in advance.

Inventive Principle:
Principle #10Preliminary action

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 precise control of the stapling and cutting process, ensuring consistent tissue handling and reducing the risk of tissue damage by accurately adjusting the speed based on real-time tissue conditions, thereby improving surgical efficiency and accuracy.

Implementation Method 1

A Hall effect sensor may be used to sense the position of the closure member

Methodology Applied
Scientific EffectHall effect: Hall Effect

Implementation Method 2

A strain gauge sensor can be used to measure the force on the tissue

Methodology Applied
Scientific EffectStrain gauge effect: Piezoresistive Effect

Data Source

PatentEP3420920B1Robotic surgical instrument with closed loop feedback techniques for advancement of closure member during firing
Publication Date: 2024.05.22 ETHICON INC
  • EP3420920B1 patent drawingFigure 1
  • EP3420920B1 patent drawingFigure 2
  • EP3420920B1 patent drawingFigure 3

AI summary

A control system for a robotic surgical system is disclosed. The control system includes a control circuit configured to determine a closure force applied to a closure member, determine a position of a firing member, and set a new closure force based on the closure force applied to the closure member and the position of the firing member.