Capacitive Sensor Cable Spacing to Prevent False Obstacle Detection
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Solution Overview
Problem
Collaborative robots equipped with capacitive sensors face interference and accuracy issues due to electrical cables, which can be detected as obstacles and disrupt sensor operation, and moving cables away poses a risk of collision with objects.
Innovation Solution
Positioning electrical lines at specific distances from capacitive measurement electrodes, using a spacer to maintain a minimum and maximum distance that avoids coupling capacitance with the electrodes, thereby preventing detection errors and collision risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electrical cables are placed close to capacitive sensors, then cable management is simplified, but sensor accuracy deteriorates due to false detection of cables as obstacles
Solution Approach 1:
The patent introduces a guard electrode as an intermediary element positioned between the capacitive sensor and the electrical cable. This guard electrode is polarized at the same potential as the cable, creating an equipotential region that shields the sensor from the cable's electric field. The intermediary structure allows the cable to remain in close proximity to the sensor without causing false detections, thus resolving the contradiction between ease of cable management and sensor accuracy.
2Measurement precision
If electrical cables are moved away from capacitive sensors, then sensor accuracy is improved, but collision risk increases between cables and objects
Solution Approach 1:
The guard electrode serves as a mediator that enables the cable to maintain its protective position close to the sensor. By creating an equipotential shielding effect, the intermediary structure allows the cable to remain in a location that provides mechanical protection against collisions while not interfering with sensor operation, thus resolving the contradiction between sensor accuracy and collision risk mitigation.
3Measurement precision
If electrical cables are positioned at intermediate distances, then both sensor accuracy and collision protection are maintained, but device complexity increases due to additional positioning means
Solution Approach 1:
The patent merges the positioning function with the existing sensor housing or cable routing structure. The guard electrode is integrated into the device's structural components rather than being a separate, standalone element. This merging approach allows the positioning function to be achieved while minimizing additional complexity, as the same structural elements serve both mechanical support and electrical shielding functions.
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
This solution effectively prevents electrical lines from being detected by capacitive sensors while ensuring objects are detected, thus maintaining safety and accuracy without risking collisions.
Implementation Method 1
capacitive detection electronics, connected to said measurement electrodes, to detect a signal relating to a capacitive coupling between said object and at least one measurement electrode
Implementation Method 2
an electrical line, referred to as a reference, with a predetermined dimension, generates a coupling capacitance with the at least one measurement electrode
Data Source
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AI summary
The invention relates to an apparatus (200) comprising: - at least one capacitive measuring electrode (108), - at least one electronic unit for capacitive sensing (100), and - an electric line (202) comprising at least one electric wire, in said sensing area (126); said apparatus (200) further comprising at least one means for spacing (204) said electric line (202) between: - a minimum distance (Dmin) corresponding to the distance beyond which a reference electric line generates a coupling capacitance with the at least one measuring electrode that is less than a predetermined threshold capacitance; and - a maximum distance (Dmax) corresponding to the distance beyond which a predetermined reference object generates a coupling capacitance with the at least one measuring electrode (108) that is less than said threshold capacitance.