Distance-Measuring Sensor False Positive Reduction
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Solution Overview
Problem
Distance-measuring monitoring sensors used in safety-critical applications often generate false-positive object detection signals due to small particles like dust, chips, or raindrops, leading to unwanted shutdowns and reduced machine availability, as these particles can mask larger objects or move quickly through the monitored field.
Innovation Solution
A method that classifies objects based on size and motion within a two-dimensional protected field divided into sector-shaped monitored fields, generating an object detection signal only when a large object is consistently present or a particle remains stationary for a predefined number of cycles, thereby distinguishing between safety-critical and non-critical objects to minimize false positives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small particles are detected in the protected field, then object detection signals are generated to ensure safety, but false-positive signals increase causing unwanted shutdowns and reduced machine availability
Solution Approach 1:
The patent applies local quality by differentiating detection criteria based on spatial location. Particles close to the sensor (within a defined proximity threshold) are evaluated differently from distant particles. Close particles that remain stationary across multiple measurement cycles trigger shutdown signals, while moving particles do not, creating location-dependent detection quality that resolves the contradiction between safety and availability
Solution Approach 2:
The patent implements dynamics by introducing temporal evaluation through multiple measurement cycles. Instead of static single-cycle detection, the system dynamically evaluates particle behavior over time by tracking whether particles remain stationary or move across cycles. This dynamic approach allows the system to distinguish between hazardous stationary particles and benign moving particles, maintaining safety while reducing false positives
2Measurement precision
If particles close to the sensor are detected, then object detection signals are generated to prevent masking of larger objects, but false-positive signals increase reducing machine availability
Solution Approach 1:
The patent applies local quality by implementing location-dependent detection thresholds and evaluation criteria. Particles within a specific proximity threshold to the sensor are subject to different evaluation rules than distant particles. This localized quality control ensures accurate recognition of close particles that could mask larger objects while applying more lenient criteria to distant particles, thereby maintaining measurement precision without excessive false positives
Solution Approach 2:
The patent uses dynamics by introducing temporal tracking across multiple measurement cycles for particles close to the sensor. The system evaluates whether close particles remain stationary or move over time, using this dynamic behavior information to distinguish between hazardous stationary particles requiring detection and benign moving particles. This dynamic evaluation maintains high measurement precision for close particles while reducing false-positive shutdowns
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 increases the availability of the monitoring sensor or machine by reducing false-positive object detection signals without compromising safety, as it accurately differentiates between large objects and small, non-critical particles, ensuring reliable recognition of safety-critical objects.
Implementation Method 1
A transmitted light beam generated by a light transmitter, e.g. by a laser or the like, is directed via a light deflection unit into the protected field to be monitored and is reflected or remitted there by an object that may be present. The reflected or remitted light moves back to the monitoring sensor again and is detected by the light receiver there.
Implementation Method 2
The distance between the monitoring sensor and the detected object can be determined in a manner known per se on the basis of the time of flight or of the phase shift between the transmitted light and the received light.
Data Source
AI summary
The present invention relates to a method of operating a distance-measuring monitoring sensor for monitoring an at least two-dimensional protected field that is divided into a plurality of sector-shaped, cyclically scannable monitored fields, wherein the monitoring sensor comprises at least one light transmitter and at least one light receiver. The invention further relates to a monitoring sensor.