Safety Laser Scanner Sensitivity Adjustment

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Solution Overview

Problem

Conventional safety laser scanners face issues with sensitivity adjustment due to reference target degradation, leading to potential undetected failures in detecting objects, especially dark or distant targets, and increased downtime due to incorrect self-diagnosis.

Innovation Solution

The safety laser scanner adjusts its sensitivity based on the reference signal level, compensating for changes by increasing sensitivity when the reference signal becomes too weak and maintaining robustness against external light, within a limited scope to ensure continued functionality and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If sensitivity is adjusted to compensate for reference target degradation, then detection capability for dark or distant targets is improved, but the risk of false positives from extraneous light increases

Engineering Contradiction:
Improvedetection capabilityVSAvoidfalse positives from extraneous light
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the sensitivity parameter dynamically based on the measured reference signal level. When the reference signal degrades over time, the system automatically increases sensitivity to maintain detection capability, while implementing safeguards to prevent excessive sensitivity that would cause false positives from extraneous light sources.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system continuously monitors the reference signal level and uses this feedback to adjust the sensitivity parameter. This closed-loop control ensures that sensitivity adjustments are based on actual system performance rather than fixed预设 values, allowing the system to adapt to gradual degradation while maintaining safety margins.

Inventive Principle:
Principle #23Feedback

2Reliability

If the system shuts down on reference target measurement failure, then safety is ensured, but availability decreases due to unnecessary downtime

Engineering Contradiction:
ImprovesafetyVSAvoidavailability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent transitions from a static shutdown-on-failure approach to a dynamic response system that adjusts sensitivity in real-time based on reference signal quality. This allows the system to maintain operation during gradual degradation while still ensuring safety, rather than immediately shutting down at the first sign of reference target issues.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements a buffer zone where sensitivity adjustments can compensate for reference target degradation before actual detection failures occur. This cushioning approach prevents unnecessary shutdowns by maintaining adequate detection margins even when the reference signal is degraded, while still triggering safety shutdowns when degradation exceeds compensable limits.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If a contiguous angular range is reserved for reference target measurement, then self-test functionality is ensured, but the dead zone increases reducing measurement coverage

Engineering Contradiction:
Improveself-test functionalityVSAvoidmeasurement coverage
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent makes the reference target serve multiple functions: it provides both the traditional self-test capability and simultaneously enables sensitivity adjustment based on measured signal levels. This multi-functionality justifies the angular space requirement while providing additional benefits that improve detection capability without requiring additional hardware or angular ranges.

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

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 enhances the system's robustness against systematic fluctuations, reducing incorrect self-diagnosis and extending the device's operational stability, while maintaining safety standards, by allowing limited positive adjustments in sensitivity to compensate for reference target degradation.

Implementation Method 1

the distance of the object from the laser scanner is determined from the light travel time, using the speed of light

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Implementation Method 2

The light is remitted by objects in the surveillance area

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

the continuously transmitted light is modulated, and the phase shift of the received light compared to the transmitted light is evaluated

Methodology Applied
Scientific EffectPhase modulation: Phase Modulation

Data Source

PatentEP3637136B1Security laser scanner and method for maintaining functionality
Publication Date: 2024.03.20 SICK AG
  • EP3637136B1 patent drawingFigure 1

AI summary

A safety laser scanner (10) for detecting objects in a monitoring area (20) is specified, comprising a light transmitter (12) for emitting a light beam (16) into the monitoring area (20), a light receiver (26) for generating a received signal from the light beam (22) emitted by the objects, a rotatable deflection unit (18) for periodically deflecting the light beam (16, 22) in order to scan the monitoring area (20) during movement, an internal reference target (40) that reflects the emitted light beam (16) back within the safety laser scanner (10) to the light receiver (26) to generate a reference signal, and a control and evaluation unit (36) designed to detect objects based on the received signal and to check the functionality of the safety laser scanner (10) based on the reference signal.The control and evaluation unit (36) is designed to change the sensitivity of the detection depending on the reference signal.