Robot Arm Cable Fastening Joint for Reduced Bending Wear

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Solution Overview

Problem

Existing cable routing devices on robot arms experience wear and mechanical stress due to rigid attachment, leading to high bending angles and reduced service life when the robot arm moves extensively.

Innovation Solution

A fastening device for cable routing devices that allows movement in two rotational degrees of freedom perpendicularly to the extension direction, enabling the cable guide device to follow the cable section and reduce bending angles, comprising a first and second connection body with angled seat surfaces forming a tilting hinge and a joint that restricts excessive rotation, allowing for flexible alignment with the robot arm's movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the cable guide device is rigidly attached to the robot arm, then the mounting structure is simple and stable, but the cable guide device experiences high wear and reduced service life due to high bending angles during robot arm movement

Engineering Contradiction:
Improveservice life of cable guide deviceVSAvoidcomplexity of mounting structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by transitioning from a rigid static mounting to a dynamic articulated mounting. The fastening device includes a joint with two rotational degrees of freedom that allows the cable guide device to move relative to the robot arm, adapting to the cable's bending movements and reducing wear while maintaining structural integrity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent segments the mounting structure into multiple independent components: a first connecting body, a second connecting body, and a joint mechanism. This segmentation allows each component to perform its specific function (rigid connection, rotational movement, degree of freedom control) independently, resolving the contradiction between structural simplicity and device reliability.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If the cable guide device is rigidly attached to the robot arm, then the mounting structure is simple, but the cable section experiences high bending angles and increased mechanical stress during robot arm movement

Engineering Contradiction:
Improvemechanical stress on cable sectionVSAvoidcomplexity of fastening device
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The joint mechanism with two rotational degrees of freedom enables the cable guide device to dynamically follow the cable section's movement, reducing bending angles and mechanical stress on the cable while the robot arm moves through its workspace.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The fastening device acts as an intermediary between the rigid robot arm structure and the flexible cable guide device. The joint mechanism mediates the mechanical stress by allowing controlled relative movement, protecting the cable section from high bending angles while maintaining stable mounting.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the cable guide device is mounted with two rotational degrees of freedom, then wear on the cable guide device is reduced, but the mounting structure becomes more complex

Engineering Contradiction:
Improvewear resistance of cable guide deviceVSAvoidcomplexity of joint mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The joint mechanism is segmented into distinct functional components: the first connecting body for rigid attachment to the robot arm, the second connecting body for rigid attachment to the cable guide device, and the joint mechanism itself providing two rotational degrees of freedom. This segmentation manages complexity by distributing functions across independent components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the mounting parameters from fixed rigid connection to articulated connection with two rotational degrees of freedom. This parameter change enables the cable guide device to adapt its orientation dynamically, reducing wear while the modular design keeps the implementation manageable.

Inventive Principle:
Principle #35Parameter changes

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 solution reduces wear on the cable routing device by minimizing bending angles and enhancing the service life of the cable guide system, ensuring the cable section is aligned closely with the robot arm's contour during movement.

Implementation Method 1

a joint (12) designed to mount the second connecting body (10) movably relative to the first connecting body (8) in two different degrees of rotational freedom

Methodology Applied
Scientific EffectHinge mechanism: Hinge

Implementation Method 2

the first seat surface (21) of the first connecting body (8) has two first partial seat surfaces (21.1, 21.2) angled towards each other, and/or the second seat surface (22) of the second connecting body (10) has two second partial seat surfaces (22.1, 22.2) angled towards each other, such that the tilting first seat surface and second seat surface determine one of the two degrees of rotational freedom

Methodology Applied
Scientific EffectGeometric constraint: Geometry

Data Source

PatentEP3781371B1Fastening device and robot arm having such a fastening device
Publication Date: 2022.01.05 KUKA DEUT GMBH
  • EP3781371B1 patent drawingFigure 1
  • EP3781371B1 patent drawingFigure 2
  • EP3781371B1 patent drawingFigure 3

AI summary

The invention relates to a fastening device (7) for a line guiding device (4) which has a receiving compartment (5) in which a line section (6.1) is supported so as to be extendable in a direction of extension (A), for supporting the line guiding device (4) on a robot arm (1) having a plurality of elements (2) and joints (3) which move the elements (2) with respect to one another. A joint of the fastening device (7) is designed to support a second connecting body (10) so as to be movable relative to a first connecting body (8) in two different rotational degrees of freedom (D1, D2) in each case oriented perpendicularly to the direction of extension (A). Moreover, the invention relates to a robot arm (1) having such a fastening device (7).