Robot Arm Cable Drum Routing to Minimize Joint Cable Wear

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Solution Overview

Problem

Existing cable guide systems for robot arms are complex to manufacture and unreliable, particularly when guiding power cables over joints, leading to potential damage and wear due to torsional loading and relative movements.

Innovation Solution

A cable guide device using a cable drum with a guide groove and connecting channel, where the cable drum is securely attached to a rotating structural component, ensuring the intermediate strand section is guided torsion-free and bend-free, with optional excess length compensation and support mechanisms to prevent wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing cable guide systems are used to guide power cables over robot arm joints, then the cable can be routed between structural parts, but the cable is subjected to torsional loading and relative movements causing wear and damage

Engineering Contradiction:
Improvecable system reliabilityVSAvoidtorsional loading and wear on cable
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A cable drum is introduced as an intermediary component between the first and second structural parts. The cable drum rotates with the second structural part and provides a guided path for the cable through connecting channels, preventing direct torsional loading on the cable while maintaining rotational flexibility.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The cable routing path is segmented into distinct sections: a first strand section in the first structural part, an intermediate strand section guided by the cable drum with connecting channels, and a second strand section in the second structural part. This segmentation allows each section to be optimized for its specific function and reduces stress concentration.

Inventive Principle:
Principle #1Segmentation

2Reliability

If a cable drum with connecting channels is used to guide the cable torsion-free, then the cable wear is minimized, but the device complexity increases

Engineering Contradiction:
Improvecable guidance reliabilityVSAvoidcable guide device complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The cable drum combines multiple functions into a single component: it rotates with the second structural part, provides guiding surfaces through connecting channels, and stores excess cable length. This integration reduces the need for separate components and simplifies the overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cable drum serves multiple purposes: it acts as a rotational coupling element, a cable guidance structure with connecting channels, and an excess length compensation mechanism. This multi-functionality reduces the number of separate components needed in the system.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3934863B1Robotic arm comprising a cable routing device
Publication Date: 2025.10.08 KUKA DEUT GMBH
  • EP3934863B1 patent drawingFigure 1
  • EP3934863B1 patent drawingFigure 2
  • EP3934863B1 patent drawingFigure 3

AI summary

The invention relates to a robotic arm (3) having a power cable run (17) with an intermediate run portion (17.3) guided in a cable routing device (20), said device comprising a cable drum (21), wherein: the cable drum (21) has a routing groove (22) which extends, at least partly, around its circumference, and in which a first run portion (17.1) of the power cable run (17) is guided in order to be at least partly wound up and unwound when the cable drum revolves (21), and the cable drum (21) has a central exit opening (23), out of which a second run portion (17.2) of the power cable run (17) is axially guided; the cable drum (21) is fastened to a second structural part and the intermediate run portion (17.3) is guided in at least one connecting channel (24) of the cable drum (21), which connects the routing groove (22) to the exit opening (23).