Asymmetric Joint Structure for Stiff, Accurate Articulation

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Solution Overview

Problem

Existing joint structures in instruments, such as medical and industrial tools, face challenges in maintaining accuracy and stiffness during articulation, are susceptible to environmental intrusion, and suffer from path length changes in actuation elements due to bending, leading to reduced stiffness and potential buckling under loads.

Innovation Solution

The joint structures incorporate asymmetrical actuation element paths through guide channels with varying termination points relative to the longitudinal axis, providing differential support regions and minimizing environmental interference, thus maintaining stiffness and preventing slack development.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If actuation elements are routed through off-centerline positions in joint structures, then articulation control is achieved, but path length changes during bending occur leading to reduced stiffness and positioning accuracy

Engineering Contradiction:

Improvearticulation controlVSAvoidpositioning accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The guide channel is positioned asymmetrically relative to the joint centerline, with its longitudinal axis offset from the joint's rotational axis. This asymmetric configuration allows the actuation element to follow a more consistent path length during joint articulation, reducing the path length changes that cause positioning errors and stiffness variations.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The system dynamically compensates for path length changes by adjusting actuation parameters. The controller monitors joint position and actuation element path length, then modifies actuation forces or element tension to maintain consistent positioning accuracy despite variations in element length during articulation.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If actuation elements undergo repeated bending during articulation, then joint flexibility is achieved, but changes in path length and susceptibility to buckling occur

Engineering Contradiction:

Improvejoint flexibilityVSAvoidstiffness under load

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system replaces purely mechanical actuation elements with a hybrid approach combining flexible elements and magnetic actuation. Magnetic fields can actuate the joint without physical contact or bending of traditional mechanical elements, eliminating buckling risks while maintaining flexibility through controlled magnetic forces.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The actuation elements use composite material construction combining flexible polymers with embedded reinforcement structures. This composite design allows the elements to bend repeatedly for joint articulation while maintaining sufficient structural integrity and resistance to buckling under operational loads.

Inventive Principle:

Principle #40Composite materials

3Reliability

If protective covers are added to prevent environmental intrusion, then reliability is improved, but overall instrument diameter increases

Engineering Contradiction:

Improveresistance to environmental intrusionVSAvoidinstrument diameter

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The system uses thin flexible protective membranes or coatings that provide environmental protection against contamination while maintaining minimal thickness. These thin-film barriers prevent intrusion of environmental materials into the joint structure without significantly increasing the overall instrument diameter.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The protective features are nested within the existing joint structure geometry rather than added as external covers. Environmental protection elements are integrated into the hollow chambers or internal spaces of the joint links, providing protection without increasing the external dimensions of the instrument.

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS12558179B2Joint structures and related devices and methods

Publication Date: 2026.02.24 INTUITIVE SURGICAL OPERATIONS INC

AI summary

A joint structure includes a first link and a second link coupled to one another by a joint. The first link and the second link are articulatable relative to each other about the joint. An actuation element extends through a first guide channel in the first link and a second guide channel in the second link. The first guide channel terminates in an opening where the actuation element extends from the first link to extend across the joint to the second link. A first edge portion of the opening is at a first location along a longitudinal axis of the first guide channel, and a second edge portion of the opening is at a second location different from the first location along the longitudinal axis of the first guide channel. Systems and devices include related joint structures.