Fine Interpolator Calibration for Transit Time Range Finding
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Solution Overview
Problem
Existing optoelectronic contactless range finding methods using the transit time principle face challenges in achieving high measuring accuracy due to nonlinearities and drifts in fine interpolators, which are costly to correct and require time-consuming calibration processes.
Innovation Solution
The method involves automatic calibration of fine interpolators using statistical evaluation of multiple measurements, assuming an equal probability distribution of measured values, to correct for nonlinearities and drifts, eliminating the need for separate calibration modes and reducing the demand for precise linearity and drift behavior in components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fine interpolators are used to determine initial and final time differences, then measurement precision is improved, but nonlinearities and drifts in the components reduce reliability
Solution Approach 1:
The system performs self-calibration by automatically determining correction values for fine interpolator nonlinearities and drifts through multiple measurements and statistical evaluation, eliminating the need for external calibration equipment and manual intervention. The calibration process is integrated into the normal operation, allowing the system to self-correct its measurement errors.
Solution Approach 2:
The system implements a feedback mechanism where multiple measurements are taken and statistically evaluated to determine correction values. These correction values are then applied to compensate for nonlinearities and drifts in subsequent measurements, creating a closed-loop system that continuously improves measurement accuracy based on accumulated data.
2Measurement precision
If traditional calibration methods are used to correct nonlinearities and drifts, then measuring accuracy is improved, but the calibration process requires time-consuming separate calibration modes
Solution Approach 1:
The system performs calibration actions preliminarily by taking multiple measurements and determining correction values in advance through statistical evaluation. This preliminary calibration data is stored and applied to subsequent measurements, eliminating the need for time-consuming separate calibration modes and allowing rapid successive measurements without repeated calibration overhead.
Solution Approach 2:
The calibration process is integrated into the continuous measurement operation rather than being a separate discrete step. Multiple measurements are continuously taken and statistically evaluated to determine correction values, which are then immediately applied. This continuous process eliminates idle calibration modes and maintains productive operation throughout.
3Measurement precision
If high precision components are used to minimize nonlinearities and drifts, then measuring accuracy is improved, but device complexity and costs increase
Solution Approach 1:
Instead of using expensive high-precision components that are difficult to manufacture and maintain, the system employs standard fine interpolators with acceptable precision characteristics. The measurement accuracy is improved not through component quality but through the statistical evaluation method that determines correction values from multiple measurements, effectively replacing expensive precision components with a computational correction approach.
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 measuring accuracy by precisely correcting random drifts and nonlinearities, leading to cost savings and faster calibration, while using the same detector for echo and reference pulses to eliminate component tolerance errors and improve measuring precision.
Implementation Method 1
an optical measurement pulse reflected by the object
Implementation Method 2
a detector for detecting light pulses
Data Source
AI summary
The invention relates to a method for optoelectronic contactless distance or range measurement or finding according to the transit time principle, in which a distance of an object from a sensor unit is determined from a time difference between a starting signal and an echo signal, which is derived from an optical measurement pulse reflected by the object and where for determining the time difference the following steps are performed: a) by comparing the starting signal and echo signal with a digital clock a digital raw value is obtained, b) with the aid of at least two fine interpolators an initial time difference between the starting signal and the beginning of the digital raw value as well as a final time difference between the echo signal and the end of the digital raw value is determined, c) to the fine interpolators are in each case supplied analog signals corresponding to the initial time difference or final time difference, respectively, and converted into a digital initial time difference or digital final time difference, respectively. The method is characterized in that for the automatic calibration of the fine interpolators a plurality of measurements according to steps a) to c) are carried out and, assuming an equal distribution for the probability with which the values in a given value interval for the initial time difference and final time difference are measured, corrections for nonlinearities and/or drifts of the characteristics of the fine interpolators are calculated. The invention also relates to an apparatus for optoelectronic contactless distance or range measurement according to the transit time principle.