Self-Calibrating Angle Measuring Device Using Fourier Series
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing angle measuring systems require external reference systems for accurate calibration, especially for low-order harmonic errors, which complicates the calibration process and makes it difficult to recalibrate after installation or in response to environmental changes.
Innovation Solution
The method involves arranging multiple reading heads at fixed, known angular distances to determine absolute position codes and error coefficients, allowing the system to self-calibrate without external aids, using a Fourier series to correct harmonic errors up to the 11th order, and storing coefficients for continuous online correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external reference systems are used for calibration, then measurement precision for low-order harmonic errors is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The angle measuring device performs self-calibration using its own multiple reading heads and the absolute position code without requiring external reference systems. The device determines angular position values from different reading heads and uses these to calculate and correct harmonic errors autonomously, eliminating the need for complex external calibration equipment.
Solution Approach 2:
The multiple reading heads serve dual functions: they perform normal measurement tasks and simultaneously enable self-calibration. The same reading heads that detect absolute position codes during operation are used to determine angular errors and generate correction values, making the calibration function integrated into the existing measurement system.
2Measurement precision
If external reference systems are used for calibration, then measurement precision is improved, but ease of operation and adaptability deteriorate
Solution Approach 1:
The device can be recalibrated at any time during operation without requiring external reference systems or specialized calibration procedures. The self-calibration function is continuously available through the evaluation unit, allowing the device to adapt to environmental changes or maintain precision throughout its service life.
Solution Approach 2:
The calibration process is dynamic and can be performed continuously or periodically during normal operation. The system can switch between measurement mode and calibration mode as needed, allowing flexible timing of calibration operations without requiring separate static calibration sessions with external equipment.
3Adaptability or versatility
If multiple reading heads are used for self-calibration, then adaptability and ease of operation are improved, but device complexity increases
Solution Approach 1:
The multiple reading heads are already present in the device for normal measurement operations, so adding self-calibration functionality utilizes existing components rather than requiring additional specialized elements. The same reading heads perform both measurement and calibration functions.
Solution Approach 2:
The calibration function is merged with the measurement function. The evaluation unit combines the processing of absolute position codes from multiple reading heads with the calculation of harmonic error corrections, integrating calibration operations into the existing signal processing workflow rather than creating a separate calibration subsystem.
4Measurement precision
If Fourier series are used to correct harmonic errors, then measurement precision is improved, but use of energy and computational requirements increase
Solution Approach 1:
The system uses Fourier series expansion to represent harmonic errors, which provides a comprehensive mathematical model for correcting systematic errors. By expressing the error as a sum of sinusoidal components with different frequencies and amplitudes, the system achieves high precision correction while the computational complexity is managed through efficient algorithms.
Data Source
Figure 1a~1b
Figure 2
Figure 3a~3b
AI summary
The invention relates to a calibration method that can be carried out without a reference system for an angle measuring device having a code carrier (2) carrying an absolute position code, and at least two reading heads (1a and 1b) comprising a fixed, known angle position (4) at an angular distance, in particular of more than (50) degrees, relative to each other, in particular wherein at least one of the angle distances between adjacent reading heads (1a,1b,1c,1d) differs from the other angle distances, and each detecting the position code at least partially, such that an absolute angle position value of each reading head can be determined relative to the code carrier, wherein the code carrier can be rotated (3) relative to the reading heads, and different angle positions of the code carrier relative to the reading heads can thus be captured, comprising the steps of: determining the angle position values of the reading heads (1a and 1b) in an angular setting; determining an angular error by comparing the difference of the angle position values of the reading heads to the known angular location (4) of the reading heads (1a and 1b) relative to each other; repeating the determining of the angle position values and the angular error for a plurality of varying angle settings, and performing a mathematical analysis method, comprising determining the parameters of a mathematical function quantifying the angular error, and determining calibration parameters as parameters of the quantifying mathematical function or as a correction or code table derived from the parameters.