Robot Arm Capacitive Sensor Shielding for Cable Interference

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Solution Overview

Problem

Cables interfere with capacitive sensors in robots, leading to deteriorated detection accuracy.

Innovation Solution

A robot design that includes a housing with a detection electrode, a shield member, and a circuit board, where cables extend through a passage between the housing and the detection electrode, and are shielded by a cover member to prevent interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cables are routed through the robot arm body, then cable connectivity is achieved, but detection accuracy of capacitive sensor deteriorates due to cable interference

Engineering Contradiction:
Improvecable connectivityVSAvoiddetection accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The robot arm structure is segmented into distinct functional zones: a sensor protection space containing the capacitive sensor, and a cable passage space for cable routing. The shield member divides these spaces, allowing cables to be routed through the arm while preventing cable interference with the sensor, thus resolving the contradiction between cable connectivity and detection accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A shield member is introduced as an intermediary component between the cables and the capacitive sensor. This shield member, combined with the sensor protection space, acts as a mediator that isolates the sensor from cable interference while still allowing cables to pass through the robot arm structure, maintaining both connectivity and detection accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If shield member is added to protect detection electrode, then detection accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvedetection accuracyVSAvoidstructure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The shield member is merged with the housing structure, and the sensor protection space is integrated into the existing arm design. The cable passage is formed within the shield member itself, combining multiple protective and routing functions into a single integrated component, thereby reducing overall device complexity while maintaining detection accuracy.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The shield member serves multiple functions simultaneously: it protects the detection electrode from cable interference, provides a structure for cable routing through the arm, and defines the sensor protection space. This multi-functionality reduces the need for separate components, thereby reducing device complexity while improving detection accuracy.

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

3Ease of operation

If cable passage is formed in shield member, then cable routing is facilitated, but electromagnetic shielding effectiveness may be reduced

Engineering Contradiction:
Improvecable routingVSAvoidelectromagnetic interference
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The shield member has different structural characteristics in different regions: it includes a cable passage for routing purposes, but the passage is designed with specific dimensions and positioning that maintain electromagnetic shielding effectiveness. The local quality of the shield member varies to accommodate both cable routing needs and shielding requirements, preventing excessive electromagnetic interference while facilitating cable installation.

Inventive Principle:
Principle #3Local quality

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

Prevents compromise of capacitive sensor detection accuracy by cables, facilitating cable replacement and routing while maintaining sensor operation and compactness.

Implementation Method 1

a shield member that is located between the housing and the detection electrode and has a passage through which a cable extends from the outside of a space between the housing and the detection electrode to the inside of the space passes

Methodology Applied
Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 2

Some collaborative robots are equipped with a capacitive sensor for detecting humans and other objects nearby

Methodology Applied
Scientific EffectCapacitive sensing: Capacitance

Data Source

PatentEP4703097A1robot
Publication Date: 2026.03.04 NACHI FUJIKOSHI CORP
  • EP4703097A1 patent drawingFigure 1
  • EP4703097A1 patent drawingFigure 2
  • EP4703097A1 patent drawingFigure 3

AI summary

Provided is a robot (2) that can prevent a drop in the detection accuracy of a capacitive sensor (4) due to a cable (22, 62). The robot (2) includes a housing (20, 60) constituting a fourth arm (A4), a detection electrode (8d, 66d) that is disposed on the housing (20, 60) and constitutes a capacitive sensor (4), and a shield member (27, 68) that is located between the housing (20, 60) and the detection electrode (8d, 66d) and has a conduit (33, 73) through which a cable (22, 62) leading from outside a space between the housing (20, 60) and the detection electrode (8d, 66d) to inside the space passes.