Sensor Calibration Using Dual Reference Media
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Solution Overview
Problem
High-quality calibration media with standardized references are expensive and prone to age-related changes, making reliable self-calibration of sensors challenging, especially for sensitive measurements like detecting banknotes, and existing methods fail to account for deviations from the actual measuring point and environmental influences.
Innovation Solution
A method involving two calibration steps: first, using a high-quality calibration medium with a standardized reference outside the sensor housing to cover the entire detection area for initial calibration, and second, using a non-standardized calibration medium within the sensor housing to account for deviations and environmental changes, allowing for precise and long-term stable calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-quality calibration medium with a standardized reference is used for self-calibration, then measurement precision is improved, but calibration costs increase and the calibration medium is prone to age-related changes
Solution Approach 1:
The calibration process is divided into two independent steps: first calibration using a standardized reference medium to establish baseline parameters, and second calibration using a non-standardized reference medium to account for environmental influences and aging. This segmentation allows each calibration medium to serve its specific purpose optimally.
Solution Approach 2:
A non-standardized reference medium is introduced as an intermediary between the sensor and the measurement object. This intermediary accounts for environmental influences and aging effects, allowing the standardized reference medium to maintain its precision without being directly exposed to harsh conditions.
2Measurement precision
If a high-quality calibration medium with a standardized reference is used, then measurement precision is improved, but the cost of calibration increases
Solution Approach 1:
The second calibration medium uses inexpensive, non-standardized reference objects that can be easily manufactured and replaced. These cheap references handle the demanding task of compensating for environmental influences, allowing the expensive standardized reference to be used only once for initial calibration.
Solution Approach 2:
Instead of using expensive standardized references for every calibration operation, the system creates a calibration model during first calibration that captures the relationship between the standardized reference and actual measurement conditions. This model is then applied during subsequent calibrations using cheaper reference media.
3Reliability
If the calibration medium is accommodated inside the sensor housing and folded into the beam path, then the calibration medium is protected from environmental influences, but there is always a deviation from the actual measuring point
Solution Approach 1:
The system performs preliminary calibration in a controlled environment inside the sensor housing where the reference medium is protected from environmental influences. This preliminary calibration establishes baseline parameters that are then used to correct measurements taken in the actual measurement position, compensating for the spatial deviation.
Solution Approach 2:
The system measures and compensates for the spatial deviation between the calibration position inside the housing and the actual measurement position. By detecting the deviation parameters and applying correction factors, the system maintains measurement precision despite the physical separation between calibration and measurement locations.
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 method reduces calibration costs by using a high-quality calibration medium only once and allows for precise calibration of all sensor systems of a type, while the non-standardized medium accounts for environmental changes and deviations, ensuring stable and comparable measurement signals over time.
Implementation Method 1
mit einem Anregungssignal anregt und ein aufgrund des Anregungssignals vom Standardreferenz der ersten Kalibrierungsvorrichtung erzeugtes Signal von mindestens einem Sensor des Sensorsystems detektiert wird
Data Source
Figure 1a~1b
Figure 2a~2b
AI summary
The invention relates to a method for calibrating a sensor system. The method according to the invention provides for using two calibration media. A high-quality first calibration medium (1), having a standardized reference that is independent of the sensor system to be calibrated, is used once, such as upon manufacture or after a repair of the sensor system, for a first calibration step, in which the sensor system is calibrated and adjusted. In an immediately subsequent second calibration step, a second calibration medium having a non-standardized reference and being part of the sensor system is used in order to generate and store measurement signals from the second calibration medium (6) by means of at least one sensor (3) of the sensor system. In the calibration mode, the second calibration medium is used exclusively in the subsequent calibration of the sensor system, in order to generate new measurement signals from the second calibration medium by means of the sensor (3). If the measurement signals generated in the subsequent calibrations deviate from the stored measurement signals of the second calibration step, the sensor (3) is adjusted, correction factors being determined, for example, to compensate for the detected deviations.