Angle Sensor Calibration Without Full Rotation
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Solution Overview
Problem
Angle sensors with less than full rotations (e.g., 360°) face challenges in accurately determining angular positions due to the inability to calculate calibration parameters, leading to inaccuracies in angle accuracy, which is critical for achieving high Automotive Safety Integrity Levels (ASIL) in applications like electronic power steering.
Innovation Solution
The angle sensor collects signal values corresponding to magnetic field components at known calibration points, performs ellipse regression on overdetermined equations, and calculates calibration parameters to normalize sensor data, enabling accurate angle determination even with less than full rotations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the angle sensor uses less than full rotations (e.g., 360°), then the device complexity is reduced, but the measurement precision deteriorates due to inability to calculate calibration parameters
Solution Approach 1:
The patent applies preliminary action by performing calibration at known angular positions before actual measurement. The sensor collects signal values at predetermined calibration points (e.g., 0°, 90°, 180°, 270°) and calculates calibration parameters in advance. This allows the sensor to achieve accurate angle measurement within a limited rotation range by using pre-established calibration data, thereby resolving the contradiction between reduced device complexity and maintained measurement precision.
2Reliability
If the angle sensor operates without full rotation, then the reliability is improved by reducing mechanical wear, but the measurement precision deteriorates due to inaccurate calibration
Solution Approach 1:
The patent replaces mechanical full-rotation calibration methods with a mathematical approach. Instead of requiring the sensor to physically rotate through 360° to establish calibration, the system uses signal values collected at specific angular positions and applies ellipse regression calculations to determine calibration parameters. This substitution of mechanical operation with mathematical processing enables accurate calibration without mechanical rotation, thereby improving reliability while maintaining measurement precision.
3Measurement precision
If the angle sensor collects data at multiple calibration points, then the measurement precision is improved through better calibration, but the loss of time increases due to additional calibration steps
Solution Approach 1:
The patent applies partial action by collecting calibration data at specific key angular positions (e.g., 0°, 90°, 180°, 270°) rather than continuously throughout the entire rotation range. This selective sampling at critical points provides sufficient calibration information for accurate ellipse regression calculations while significantly reducing the time required compared to full-rotation data collection. The excessive action principle is applied by using more than the minimum required calibration points to ensure robust calibration parameters.
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 allows for precise angle accuracy determination, ensuring compliance with high ASIL requirements by accounting for factors like vibration and sensor offset, thereby enhancing functional safety in applications with partial rotations.
Implementation Method 1
a set of sensing components that sense a strength of different components (e.g., an x-component and a y-component) of a magnetic field produced or distorted by a target object
Data Source
AI summary
In some implementations, a sensing device associated with less than a 360 degree measurement range may obtain a set of signal values. The sensing device may be configured to sense a magnetic field present at the sensing device and collect sensor data based on the magnetic field. The set of signal values may be included in the sensor data collected by the sensing device and may correspond to one or more components of the magnetic field present at the sensing device. The sensing device may determine, based on the set of signal values, a set of calibration points and a set of angular positions. The sensing device may calculate a set of calibration parameters based on the set of calibration points and the set of angular positions. The sensing device may utilize the set of calibration parameters to perform one or more safety checks.