Medical Instrument Shaft With Meshing Sections For Precision Control

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Solution Overview

Problem

Medical instruments with shafts composed of multiple sections that pivot via pull cables face challenges in achieving precise movements due to dependence on adjacent tissue contact, making them unsuitable for robot-based surgical systems.

Innovation Solution

A medical instrument with shaft sections that mesh or engage via toothing or frictional surfaces, allowing for defined, slip-free rolling movements, enabling precise control and positioning, particularly through the use of arcuate teeth and friction surfaces with corresponding contact surfaces and tension elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If shaft sections are connected via cable-driven pivot joints, then the instrument achieves flexibility and adaptability for minimally invasive surgery, but the movement precision and definability deteriorate because individual shaft sections do not perform precisely defined movements relative to each other

Engineering Contradiction:

ImproveflexibilityVSAvoidmovement precision

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The shaft is divided into multiple shaft sections (first shaft section, second shaft section, etc.) that can move relative to each other. Each section is segmented with specific engagement features (teeth, friction surfaces) that enable controlled movement while maintaining overall flexibility of the instrument shaft.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The engagement surfaces between shaft sections utilize arcuate (curved) geometries. The teeth have arcuate profiles and the friction surfaces are arcuate, allowing the shaft sections to pivot smoothly relative to each other while maintaining precise defined movement through the curved engagement geometry.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Ease of operation

If shaft sections are connected via cable-driven pivot joints, then the instrument achieves ease of operation for minimally invasive procedures, but the reliability and controllability deteriorate because movements depend on how sections lie against adjacent tissue

Engineering Contradiction:

Improveease of operationVSAvoidcontrollability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The cable-driven flexible joint system is replaced with a mechanical engagement system between shaft sections. Instead of relying on cables and flexible deflection, the invention uses positive engagement through teeth or friction surfaces that provide deterministic mechanical control over shaft section movement relative to each other.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The engagement characteristics between shaft sections are changed by introducing specific geometric parameters (tooth profiles, friction surface curvature, engagement forces). These parameter changes ensure that the shaft sections perform precisely defined movements regardless of external tissue forces, maintaining reliable controllability.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If arcuate teeth and friction surfaces are used for engagement, then the instrument achieves precise and defined movements between shaft sections, but the device complexity increases

Engineering Contradiction:

Improvemovement precisionVSAvoiddevice complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The engagement features (teeth, friction surfaces) are integrated directly into the shaft sections themselves rather than being separate components. The arcuate teeth and friction surfaces are formed as part of the shaft section structure, merging the engagement mechanism with the shaft structure to reduce overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The shaft sections are designed with multi-functionality: they provide structural support for the instrument, enable flexible positioning through relative movement, and incorporate the engagement mechanism (teeth or friction surfaces) for precise movement control. This universal design reduces the need for separate specialized components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

The instrument achieves defined and precise movements between shaft sections, enhancing its usability in robot-based surgery by ensuring consistent and controlled positioning of the distal end, even in flexible and minimally invasive procedures.

Implementation Method 1

engage with each other in a frictional-locking manner, so that they roll against each other without slippage

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

engage with each other via toothed connections in a positive-locking meshing manner

Methodology Applied

Scientific EffectGear mechanism: Gear

Data Source

PatentEP2877100B1Shaft for medical instruments, comprising movable sections

Publication Date: 2021.01.20 RICHARD WOLF GMBH

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AI summary

The invention relates to a medical instrument comprising a shaft that includes at least two adjacent shaft sections which are movable relative to one another. The invention is characterized in that the at least two movable shaft sections are engaged with each other so as to roll off one another in a frictionally locking manner or so as mesh with each other by means of teeth.