Inductive Proximity Sensor Pulse Sampling for Interference Checking
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Solution Overview
Problem
Existing inductive proximity sensors face challenges in accurately detecting metallic objects and distinguishing between actual changes in the sensor coil's inductance and external interference, leading to potential errors in distance determination and material identification.
Innovation Solution
An inductive proximity sensor unit that employs individual pulse-shaped signals to induce eddy currents in metallic objects, with an evaluation unit measuring voltage or current at multiple sampling times to determine an actual time series signal, which is then compared to stored reference signals to identify deviations and determine the presence of a metallic body or potential faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse evaluation method is used to detect metallic objects, then detection capability is improved, but susceptibility to external interference increases
Solution Approach 1:
The patent applies preliminary action by storing reference impulse response signals before actual detection occurs. These reference signals are captured under known conditions (with and without metallic objects) and stored in memory. During operation, the actual impulse response is compared against these pre-stored references to identify deviations caused by external interference, thereby maintaining detection accuracy despite harmful factors.
Solution Approach 2:
The patent implements feedback by continuously comparing the actual impulse response signal against stored reference signals and using this comparison to correct or reject measurements. The evaluation unit analyzes deviations between actual and reference signals, and this feedback mechanism enables the system to distinguish between genuine object detection signals and external interference, improving reliability.
2Measurement precision
If impulse response sampling is performed to determine object properties, then measurement accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies copying by creating simplified representations of the impulse response through comparison with stored reference signals. Instead of performing complex real-time analysis of the entire impulse response waveform, the system compares key features against pre-stored reference patterns, significantly reducing computational requirements while maintaining accurate object property determination.
3Reliability
If multiple sampling points are used to analyze voltage or current values, then detection reliability is improved, but processing time increases
Solution Approach 1:
The patent applies preliminary action by pre-storing reference impulse response signals captured at multiple sampling points under known conditions. This allows the system to perform rapid comparison-based evaluation during operation without needing to process all sampling point data in real-time, thus maintaining high detection reliability while minimizing processing time.
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 approach allows for reliable detection of metallic objects and identification of faults by analyzing the functional relationship between actual and reference time series signals, providing high reliability and quick response times with minimal computational effort.
Implementation Method 1
a sensor coil (12) which is supplied with individual pulsed signals spaced apart in time
Implementation Method 2
Based on the superposition, i.e., from the deviation of the sensor coil signal from the decay behavior of the self-induction voltage pulse without the induction of the sensing body, the presence of the sensing body and/or the distance and/or at least the achievement of the switching distance can be determined.
Data Source
Figure 1a~1c
Figure 2a~2b
Figure 3a~3l
AI summary
An inductive proximity sensor unit for detecting a detection body, wherein the detection body has metallic properties, comprising a sensor coil supplied with individual, time-spaced pulsed signals, an evaluation unit, wherein the evaluation unit is configured to measure values for voltage or current of the pulsed signal at several sampling times and to determine an actual time series signal from the measured values, a storage unit, wherein at least three values of a reference time series signal are stored in the storage unit for the detection body, wherein the evaluation unit is configured to check the actual time series signal for a disturbance by determining a functional relationship between the actual time series signal and the reference time series signal.