Yaw Rate Sensor Calibration Using Polynomial Interpolation
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Solution Overview
Problem
Current calibration methods for yaw rate sensors in motor vehicles do not provide sufficient accuracy for zero offset error compensation, especially due to manufacturing tolerances, temperature variations, and aging effects.
Innovation Solution
A method that uses a polynomial of nth order to interpolate and correct the zero offset error by determining and storing coefficients during a predefined temperature profile, allowing for continuous adaptation and improvement of calibration accuracy during the sensor's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear interpolation is used for zero point correction based on reference points, then the calibration process is simple, but the accuracy of zero offset error compensation is insufficient
Solution Approach 1:
The patent changes the mathematical model from linear interpolation to polynomial interpolation of nth order. This transforms the correction function from a simple linear relationship to a more complex polynomial relationship that can capture non-linear temperature dependencies, thereby improving accuracy while maintaining computational feasibility
Solution Approach 2:
The patent extends the calibration approach from using discrete reference points in one dimension (temperature) to using a polynomial function that operates across multiple dimensions (temperature and its powers up to nth order). This dimensional extension allows for more flexible and accurate modeling of the temperature-compensation relationship
2Ease of manufacture
If the sensor is calibrated only during manufacture, then the initial zero offset error is corrected, but aging effects cause accuracy degradation over time
Solution Approach 1:
The patent performs preliminary calibration during manufacture to establish baseline polynomial coefficients. This preliminary action provides an initial accurate calibration that can later be refined through adaptation, combining the benefits of early correction with subsequent improvements
Solution Approach 2:
The patent implements a feedback mechanism where the polynomial coefficients are continuously adapted during the sensor's operational life based on actual performance data. This feedback loop allows the system to compensate for aging effects by updating the calibration parameters, thereby maintaining accuracy over time
Data Source
AI summary
The invention relates to a method of calibrating a sensor, in particular a yaw rate sensor, in which sensor values (Ysensor) and associated temperature values (T) are stored in the shape of reference points in a non-volatile memory of the sensor, in which case the values (Ysensor, T) are determined during a calibration mode in which the sensor is exposed to a predefined temperature profile. In order to further improve the accuracy of the calibration, the invention discloses that the values (Ysensor, T) determined in the calibration mode are used to determine coefficients (C0, . . . , Cn-1, Cn) of a polynomial of nth order, and these coefficients are stored.