Surgical Manipulator Link Mechanism Drive

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Solution Overview

Problem

Conventional manipulators with multiple degrees of freedom for minimally invasive surgery face issues such as frequent wire replacement, limited control accuracy, and difficulty in sterilization due to wire elongation, breakage, and directional power transmission limitations.

Innovation Solution

A manipulator with multiple degrees of freedom utilizing a link mechanism as the drive power transmitting means, providing high stiffness and ease of sterilization, with three degrees of freedom including relative opening/closing and rotation around two axes, eliminating the need for wires and simplifying attachment and detachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wire is used as drive power transmitting means, then the manipulator can be driven, but the wire needs frequent replacement due to elongation or breakage

Engineering Contradiction:

ImprovedurabilityVSAvoidservice life of wire

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent replaces the wire-based mechanical drive system with a cable-driven parallel mechanism using rigid cables and pulleys. The cables are enclosed in a protective sheath that prevents elongation and breakage, eliminating the need for frequent wire replacement while maintaining the manipulator's driving capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a protective sheath (flexible shell) to enclose the cables. This sheath protects the cables from damage, prevents them from elongating or breaking, and allows them to be easily sterilized and cleaned, thereby extending their service life and improving reliability

Inventive Principle:

Principle #30Flexible shells and thin films

2Measurement precision

If wire is used as drive power transmitting means, then the manipulator can be driven, but the control accuracy is limited due to wire elongation or contraction

Engineering Contradiction:

Improvecontrol accuracyVSAvoidprecision maintenance

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the flexible wire system with a rigid cable-based parallel mechanism. The cables, enclosed in protective sheaths, maintain their length and shape during operation, eliminating the elongation and contraction problems of wires. This substitution enables precise control of the manipulator's articulation and gripping portion movements

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent divides the drive system into multiple independent cable segments, each enclosed in its own protective sheath. These segmented cables are attached to the manipulator at multiple points, allowing precise control of each degree of freedom independently while maintaining overall structural integrity and accuracy

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If wire is used as drive power transmitting means, then the manipulator can be driven, but the wire is difficult to sterilize and clean

Engineering Contradiction:

Improveease of sterilizationVSAvoidsterilization complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent encloses the cables in a protective sheath that is designed to be easily sterilized and cleaned. The sheath acts as a barrier that protects the internal cable structure while allowing standard surgical sterilization procedures to be applied effectively, thereby simplifying the sterilization process compared to exposed wire systems

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent replaces the wire-based system with an enclosed cable-driven system where the cables are protected within sheaths. This substitution allows the entire manipulator assembly to be sterilized as a unit using standard surgical methods, reducing the complexity of sterilization procedures while maintaining driving functionality

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Adaptability or versatility

If wire is used as drive power transmitting means, then the manipulator can be driven, but wire can only transmit drive power in one direction (pulling direction)

Engineering Contradiction:

Improvepower transmission capabilityVSAvoidoperational flexibility

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent replaces the one-way wire system with a cable-driven parallel mechanism where multiple cables can be tensioned and controlled independently. The pulley system allows cables to transmit force in multiple directions, enabling bidirectional control of the manipulator's articulation and gripping motions, thereby improving operational flexibility

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a universal cable-driven parallel mechanism where the same cable system can perform multiple functions: driving articulation bending, controlling gripping opening/closing, and enabling rotation around multiple axes. The cable tensioning mechanism can operate in different directions and modes, providing versatile control capabilities

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7819894B2Manipulator with multiple degrees of freedom

Publication Date: 2010.10.26 MITSUISHI

AI summary

A bending forceps 1 has at least three degrees of freedom including relative opening/closing of a pair of gripping members 11a, 11b, rotation of both the gripping members around a first axis 15 and rotation of both the gripping members around a second axis 42 existing on an imaginary plane substantially perpendicular to the first axis 15. A drive power from an actuator is converted to each motion of the opening/closing of the gripping members, rotation thereof around the first axis and rotation thereof around the second axis by first to third link mechanisms 5, 6 and 7. The present invention enables the durability and control accuracy to be raised by employing a link mechanism as a drive power transmitting means. Further, the present invention facilitates sterilization, cleaning and attachment/detachment to/from a driving means.