Surgical Instrument Worm Drive Linkage for Low-Friction Actuation

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Solution Overview

Problem

Conventional surgical instruments require improvements in actuation components to enhance efficiency and reduce complexity, particularly in translating rotational input to translational movement for end effectors, while minimizing parts and maintaining low friction for effective force transmission.

Innovation Solution

A force transmission mechanism incorporating a worm drive and lever arm system that converts rotational movement into translational movement through a follower member engaged with the worm drive, allowing efficient actuation of surgical instrument end effectors with reduced parts and low friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional actuation components are used to translate rotational input to translational movement, then the surgical instrument can actuate end effectors, but the device complexity and number of parts increases

Engineering Contradiction:

Improveactuation of end effectorVSAvoidnumber of parts

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines the worm drive and lever arm into a single integrated force transmission mechanism. The lever arm is directly coupled to the worm drive, eliminating the need for separate coupling components. This merging of functions reduces the total number of parts while maintaining the ability to translate rotational movement to translational movement for end effector actuation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The force transmission mechanism serves multiple functions: it converts rotational motion to translational motion, provides mechanical advantage through the worm drive, and directly actuates the end effector through the lever arm. This multi-functionality reduces the need for additional specialized components, thereby reducing overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Power

If conventional force transmission mechanisms are used, then rotational input can be transmitted, but friction increases reducing efficiency

Engineering Contradiction:

Improveforce transmission efficiencyVSAvoidfriction

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent replaces traditional high-friction mechanical coupling mechanisms with a worm drive system. The worm drive utilizes sliding contact between the worm threads and the lever arm, which generates controlled friction that provides self-locking capability while maintaining efficient force transmission. This substitution reduces energy loss compared to conventional gear or linkage systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If more components are added to improve actuation precision, then end effector control improves, but manufacturing costs increase

Engineering Contradiction:

Improveend effector control precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The force transmission mechanism is segmented into distinct functional elements (worm drive, lever arm, actuation element) that can be manufactured separately using standard machining processes. Each component is relatively simple in geometry, allowing for cost-effective manufacturing. The segmented design also enables modular assembly, reducing overall manufacturing complexity while maintaining precision through controlled interfaces between segments.

Inventive Principle:

Principle #1Segmentation

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 mechanism efficiently translates rotational motion to translational motion with low friction, conserving space and reducing manufacturing costs, enabling precise and reliable actuation of surgical instruments with high torque and back-drivability.

Implementation Method 1

The force transmission mechanism may include a worm drive and a lever arm. The lever arm may include a follower at a first end of the lever arm. The follower may engage the worm drive and be driven by the worm drive.

Methodology Applied

Scientific EffectWorm drive: Worm Drive

Implementation Method 2

Rotational movement of the worm drive may be converted to translational movement of an actuation element for actuation of a surgical instrument with high torque

Methodology Applied

Scientific EffectMechanical advantage: Mechanical Advantage

Implementation Method 3

The follower member engages the worm drive and is configured to be driven by the worm drive... enabling precise and reliable actuation of surgical instruments with high torque and back-drivability

Methodology Applied

Scientific EffectFriction reduction: Friction

Data Source

PatentUS20250213317A1Force transmission mechanism for surgical instrument, and related systems and methods

Publication Date: 2025.07.03 INTUITIVE SURGICAL OPERATIONS INC

AI summary

A method of actuating an actuation element to transmit force along an instrument shaft, comprising driving rotational movement of a worm drive of a force transmission mechanism at a proximal end portion of the instrument shaft; converting the rotational movement of the worm drive into linear translational movement of a linkage of the force transmission mechanism, the linkage engaged with the worm drive; and converting the linear translational movement of the linkage to linear translational movement of the actuation element.