Maypole Tube Cable Compensation for Robotic Surgical Instrument Roll

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Solution Overview

Problem

Existing surgical instruments face challenges in efficiently articulating and firing staples while maintaining precise control and tension in robotic surgeries, particularly due to the complexity of cable management and articulation during roll and yaw movements.

Innovation Solution

The surgical instrument incorporates a shaft assembly with a rotatable outer shaft and a maypole tube, featuring articulation cables that can rotate about a pitch and yaw axis, and a control device that adjusts cable length to maintain tension, using a cable compensation mechanism to ensure precise articulation and firing of staples.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If articulation cables are used to enable end effector movement with two degrees of freedom, then the surgical instrument achieves precise 360-degree movement capability, but the cable management becomes complex and cable tension control becomes difficult during roll and yaw movements

Engineering Contradiction:

Improveend effector movement capabilityVSAvoidcable management complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The cable system is divided into multiple independent articulation cables (first, second, third, and fourth cables) that are routed through separate channels in the shaft assembly. Each cable is independently tensioned and controlled, allowing complex end effector movements to be achieved through coordinated action of segmented cable components rather than a single complex cable system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The maypole tube serves as an intermediary structure that guides and organizes the articulation cables as they wrap around during roll movements. The shaft assembly acts as an intermediary mechanism that coordinates cable tension changes, preventing direct interference between cables while enabling smooth 360-degree end effector articulation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the outer shaft rotates about a roll axis to enable rolling movement, then the surgical instrument achieves enhanced positioning flexibility, but the articulation cables wrap around the maypole tube causing tension changes that affect articulation precision

Engineering Contradiction:

Improvepositioning flexibilityVSAvoidarticulation precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The system incorporates sensors that detect the roll angle of the outer shaft and provide feedback to the control system. Based on this feedback, the control system dynamically adjusts cable tension (through cable compensation mechanisms) to maintain constant tension during roll movements, thereby preserving articulation precision despite the wrapping effect.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control system preemptively adjusts cable tension before and during roll movements by calculating the expected tension changes based on roll angle. This preliminary action compensates for the wrapping effect before it degrades articulation precision, maintaining accurate end effector positioning throughout the movement.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If multiple articulation cables are routed through the shaft assembly to enable two degrees of freedom, then the surgical instrument achieves comprehensive articulation capability, but maintaining constant cable tension becomes challenging during dynamic movements

Engineering Contradiction:

Improvearticulation capabilityVSAvoidcable tension consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Tension sensors monitor the force in each articulation cable in real-time and provide feedback to the control system. The control system processes this feedback and dynamically adjusts cable tension through compensation mechanisms (such as variable friction elements or active tensioning devices) to maintain constant tension during articulation and roll movements, ensuring reliable and predictable end effector positioning.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12484900B2Systems and subsystems for rolling a surgical instrument including articulation cables

Publication Date: 2025.12.02 CILAG GMBH INTERNATIONAL

AI summary

A surgical instrument designed to operate with a robotic platform is disclosed. The surgical instrument assembly includes a shaft, an end effector, a knife firing subsystem to actuate functions of the end effector, an articulation subsystem that is actuatable to articulate the end effector, an articulation joint about which the end effector articulates, a roll subsystem to roll the shaft, and a housing that couples to the robotic platform. A maypole tube is further provided, around which one or more articulation cables can wrap when the end effector is rotated.