Angle Sensor Autocalibration for Offset and Amplitude Correction
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Solution Overview
Problem
Existing angle sensor calibration methods, such as multipoint calibration, are costly and time-consuming due to the need for extensive programming and reference points, particularly for automotive applications, and do not efficiently compensate for mechanical misalignments like x, y movement and magnetization inclination.
Innovation Solution
An angle sensor with an autocalibration function that includes a processor to determine offset and amplitude correction values during a dedicated calibration mode, allowing for efficient EoL calibration without external references, using sensor elements sensitive to different magnetic field components to correct rotation angle estimations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multipoint calibration methods are used to compensate for mechanical misalignments, then angle accuracy is improved, but calibration time and cost increase significantly
Solution Approach 1:
The patent extracts only the essential calibration parameters (offset values and amplitude correction values) needed for angle sensor calibration, rather than using comprehensive multipoint calibration. This allows calibration to be performed with minimal sample points (as few as 2-4 points), dramatically reducing calibration time while maintaining adequate accuracy for automotive applications.
Solution Approach 2:
The patent applies partial calibration by determining offset and amplitude correction values without performing full multipoint calibration across all possible angles. This partial approach focuses only on the critical parameters that have the greatest impact on angle accuracy, reducing the number of required sample points from 32+ to just 2-4 points.
2Measurement precision
If more sample points are programmed during multipoint calibration, then angle accuracy is improved, but chip surface area and programming time increase
Solution Approach 1:
The patent extracts and stores only the essential calibration parameters (offset values and amplitude correction values) in on-chip memory, rather than storing correction values for multiple sample points. This minimal parameter storage requirement significantly reduces the EEPROM memory space needed on the chip, allowing adequate calibration with minimal sample points.
3Measurement precision
If multipoint calibration is performed to achieve acceptable angle accuracy, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The angle sensor performs self-calibration by automatically determining offset values and amplitude correction values during a brief calibration routine. This self-calibration capability eliminates or reduces the need for expensive external calibration equipment and manual calibration procedures, significantly reducing manufacturing costs while maintaining adequate angle accuracy.
4Measurement precision
If comprehensive multipoint calibration is used to account for all mechanical misalignments, then angle accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts and compensates for only the two most critical sources of error: offset errors and amplitude errors. By focusing on these two primary error sources rather than attempting to correct all possible mechanical misalignments, the calibration system remains simple while achieving adequate accuracy for automotive applications.
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 simplifies the calibration process, reduces costs, and improves angle accuracy by enabling on-chip storage of compensation parameters, potentially eliminating the need for multipoint calibration and reducing chip surface area requirements.
Implementation Method 1
a first sensor element designed to output a first sensor signal on the basis of a magnetic field, which is dependent on an angle of rotation of a measurement object, at the location of the first sensor element
Data Source
AI summary
The present disclosure relates to a design for operating an angle sensor. A first sensor signal is output from a first sensor element on the basis of a magnetic field, which is dependent on an angle of rotation of a measurement object, at the location of the first sensor element. A second sensor signal is output from a second sensor element on the basis of the magnetic field that is dependent on the angle of rotation of the measurement object at the location of the second sensor element. During a calibration mode of the angle sensor, in which a rotation of the measurement object is performed, a first offset value of the first sensor signal, a second offset value of the second sensor signal and an amplitude correction value are determined on the basis of signal amplitudes of the first and second sensor signals. The first and second offset values ascertained during the calibration mode and the amplitude correction value are stored for use in an operating mode of the angle sensor.