Steering Wheel Angle Sensor Signal Correlation Filter
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Solution Overview
Problem
Existing methods for determining the absolute angular position of a motor vehicle's steering wheel are sensitive to external influences such as dirt and electromagnetic interference, leading to incorrect measurements due to additional contrast differences and edges in the output signal.
Innovation Solution
The output signal of the sensor array is subjected to a convolution operation with a reference signal in a first correlation filter to reconstruct the code track, and the resulting bit pattern is then convolved with a reference bit pattern in a second correlation filter to determine the best match and validate the angle value, using correlation threshold values to filter out interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the output signal is evaluated by detecting edges or contrast differences, then the angle value can be determined, but the measurement becomes sensitive to external influences such as dirt and electromagnetic interference
Solution Approach 1:
A correlation filter is introduced as an intermediary between the sensor array output and the angle determination. This filter processes the raw sensor signal by comparing it with reference signals, effectively mediating the measurement process to reject interference while preserving the actual angle information.
Solution Approach 2:
The system uses feedback by comparing the sensor output signal with stored reference signals that represent the expected code track pattern. The correlation filter continuously adjusts the measurement by referencing the known code structure, allowing it to distinguish between actual angle changes and interference artifacts.
2Reliability
If plausibility checking processes are used to recognize erroneous measurements, then incorrect measurements can be identified, but the measurement results cannot be corrected
Solution Approach 1:
The system performs preliminary action by pre-storing reference signals that represent the expected code track pattern at different angles. Before determining the angle, the correlation filter compares the current sensor output against these pre-prepared references, enabling both error detection and correction in advance rather than requiring post-processing plausibility checks.
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 significantly increases the insensitivity to external influences, providing reliable and accurate angle measurements by filtering out interference and correcting for errors, with an improved resolution of up to a tenth of a degree.
Implementation Method 1
a transmitter/receiver unit comprising a light source and a sensor array having a large number of optoelectronic transducer elements
Data Source
AI summary
The method involves representing associated segment of coding of angular value on a sensor array. An output signal is evaluated for determination of an actual angular value of a corresponding code word. The signal is subjected for reconstruction of the represented segments of the code-sign in a correlation filter (KF2) of the convolution operation with a reference signal, which represents a short section of an ideal code signal.