Optical Sensor Self-Diagnosis via Control Parameter Variation
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Solution Overview
Problem
Existing methods for diagnosing optical sensors, particularly in safety-critical systems, are complex and costly, often requiring additional light sources or redundant optical systems, which compromise frame rate and increase complexity.
Innovation Solution
A method and system that utilize a photodetector and integrator in optical sensors, where control parameters such as integration time or gain are changed, and subsequent integrated signals are compared to pre-determined characteristics to diagnose faults without affecting the frame rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional light source is used for diagnosing the optical sensor, then diagnostic coverage is improved, but device complexity and cost increase
Solution Approach 1:
The optical sensor performs self-diagnosis by monitoring its own output values while changing control parameters. The sensor uses its existing photodetector and integrator to detect faults, eliminating the need for additional external light sources or diagnostic hardware. This self-service approach resolves the contradiction by achieving diagnostic coverage without increasing device complexity.
Solution Approach 2:
The existing optical sensor components (photodetector, integrator, output value generation) are made multi-functional by enabling them to perform both normal sensing operations and self-diagnosis functions. By changing control parameters during operation, the same hardware serves dual purposes, resolving the contradiction between diagnostic coverage and device complexity.
2Reliability
If an additional light source is used for diagnosing the optical sensor, then diagnostic coverage is improved, but frame rate decreases
Solution Approach 1:
The self-diagnosis is performed continuously during normal operation by dynamically changing control parameters between frames. The photodetector and integrator continue their useful action of sensing light without interruption, and the diagnosis occurs as a byproduct of normal operation. This resolves the contradiction by maintaining continuous frame rate while achieving diagnostic coverage.
Solution Approach 2:
Control parameters are changed periodically between frames to enable diagnosis without affecting the continuous frame rate. The systematic variation of parameters at appropriate intervals allows the sensor to monitor its own performance while maintaining productive operation, resolving the contradiction between diagnostic coverage and frame rate.
3Reliability
If a redundant optical system is used for diagnosing the optical sensor, then diagnostic coverage is improved, but cost and complexity increase significantly
Solution Approach 1:
Instead of using a redundant optical sensor system for diagnosis, the invention enables the single optical sensor to diagnose itself by monitoring its own output values while varying control parameters. This self-service approach eliminates the need for redundant hardware, resolving the contradiction between diagnostic coverage and system complexity.
Solution Approach 2:
The invention uses parameter changes (integration time, gain, reset timing) of the existing optical sensor to enable diagnosis. By systematically varying these parameters and monitoring output values, the sensor can detect faults without requiring a redundant system. This resolves the contradiction by achieving diagnostic coverage through parameter manipulation rather than hardware redundancy.
4Measurement precision
If control parameters are changed for diagnosis, then diagnostic accuracy is improved, but frame rate is sacrificed
Solution Approach 1:
Control parameters are changed periodically between frames rather than continuously during frame capture. This periodic parameter variation allows accurate diagnosis to be performed at specific intervals without interrupting the continuous frame rate operation. The systematic timing of parameter changes resolves the contradiction between diagnostic accuracy and frame rate.
Solution Approach 2:
The control parameters are made dynamic and adjustable during operation to enable diagnosis when needed, while returning to normal values for frame capture. This dynamic parameter adjustment allows the system to achieve high diagnostic accuracy during parameter variation phases while maintaining normal frame rate during standard operation phases.
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 effective fault detection in optical sensors without increasing complexity or cost, while maintaining continuous operation and frame rate, and can filter out changes in incoming light that might be misinterpreted as sensor failures.
Implementation Method 1
Optical sensors in general and image sensors (2D or 3D) in particular convert the amount of light into output values
Implementation Method 2
accumulating, during an integration time, a signal from circuitry which connects the photodetector with the integrator
Data Source
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Figure 3
Figure 4~5
AI summary
A method (100) for diagnosing an optical sensor which comprises a photodetector and an integrator. The method comprises exposing (110) the photodetector to incoming light; obtaining (120) an initial integrated signal at an initial frame; at least once executing the steps of changing (130) at least one control parameter of the optical sensor, exposing (110) the photodetector to incoming light, and obtaining (140) one or more subsequent integrated signals at a subsequent frame; obtaining (150) a characteristic of the optical sensor from the obtained integrated signals; comparing (160) the obtained characteristic with a pre-determined characteristic of the optical sensor to diagnose the optical sensor.