Surgical End Effector Force Sensing with Dual FBG Distortion Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In master-slave robot systems used for endoscopic surgery, existing force-detecting mechanisms face challenges in accurately measuring forces on end effectors due to interference from cable-driven mechanisms, leading to potential sensitivity deterioration and calibration difficulties.

Innovation Solution

The system incorporates a dual distortion detection mechanism using FBG sensors on optical fibers attached to both sides of the end effector blades and links, allowing for precise calculation of forces acting on the end effector by detecting distortions on both inner and outer sides, and utilizing a processing unit to account for temperature changes and orthogonal forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a force sensor is arranged between the end effector and the driving unit in a cable-driven system, then force detection capability is provided, but the cable pulling force interferes with external force measurement causing sensitivity deterioration and calibration difficulty

Engineering Contradiction:

Improveforce detection accuracyVSAvoidcable interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful cable pulling force from the force measurement system by using a cable-driven mechanism that applies force through the cable, while the force sensor measures only the external force applied to the end effector. The cable force is separated as a known actuation mechanism rather than being conflated with external force measurements, thereby eliminating interference.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary mechanism - the cable-driven actuation system - that mediates between the driving unit and the end effector. The cable transmits driving force while the force sensor, positioned to detect external forces, uses the cable mechanism as an intermediary that does not interfere with measurement, allowing separate measurement of external forces applied to the end effector.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the end effector is miniaturized for endoscopic surgery, then surgical applicability is improved, but the structure becomes more fragile and harder to instrument

Engineering Contradiction:

Improvesurgical applicabilityVSAvoidminiaturization difficulty

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical force sensing mechanisms with optical fiber-based FBG sensors. This substitution allows for miniaturization of the end effector because the optical sensors can be integrated into thin structures without adding mechanical complexity, enabling the end effector to be small enough for endoscopic surgery while maintaining force detection capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses optical fibers as flexible sensing elements that can be integrated into the thin-walled structure of the miniaturized end effector. The optical fibers conform to the thin film structure without compromising structural integrity, allowing the end effector to maintain both miniaturized dimensions and force sensing functionality.

Inventive Principle:

Principle #30Flexible shells and thin films

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

This approach enhances the accuracy of force detection on end effectors, reducing mechanical noise and improving sensitivity, enabling precise control and feedback in surgical operations without interfering with the cable-driven mechanism.

Implementation Method 1

distortion detecting elements including FBG sensors formed on optical fibers attached to the inner side and the outer side of the first blade, and distortion detecting elements including FBG sensors formed on optical fibers attached to the inner side and the outer side of the second blade

Methodology Applied

Scientific EffectFiber Bragg Grating (FBG) sensor effect: Bragg Diffraction

Data Source

PatentUS11779411B2Operation system, surgical system, control device, distortion generating body, surgical instrument, and external force detecting system

Publication Date: 2023.10.10 SONY GROUP CORP

AI summary

An operation system, a surgical system, a control device, a distortion generating body, a surgical instrument and the like for detecting a force acting on an end effector are provided.The surgical system includes an arm including one or more links, an end effector arranged at a tip end of the arm, a first distortion detecting unit that detects distortion generated in the end effector, a second distortion detecting unit that detects distortion generated in the link, and a processing unit that calculates a force acting on the end effector in a living body on the basis of detection results of the first distortion detecting unit and the second distortion detecting unit.