Electronic Compass Calibration for Dynamic Tire Rolling Radius
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Solution Overview
Problem
Current parking and maneuvering systems face inaccuracies due to uncertainties in tire rolling radii, leading to errors in distance and angle measurements, which affect the precision of parking maneuvers and increase the number of corrective moves required by drivers.
Innovation Solution
A method that couples an electronic compass with a parking system to algorithmically process angle information and wheel impulse data, allowing for the accurate estimation of tire rolling radii and stabilization of angle changes, thereby improving target position compliance and reducing corrective moves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tire rolling radius parameters are used for distance calculation, then the parking system can determine distance and angle, but measurement precision deteriorates due to tire manufacturing tolerances (up to 4%) and tread wear (up to 2%)
Solution Approach 1:
The system uses the electronic compass as an independent reference sensor to provide feedback on actual vehicle orientation and position. This feedback loop allows the system to detect deviations caused by inaccurate tire rolling radius parameters and compensate for them, thereby maintaining measurement precision despite tire variations.
Solution Approach 2:
The electronic compass acts as an intermediary sensor that indirectly measures vehicle position and orientation without being affected by tire rolling radius variations. By using the compass as a mediator, the system bypasses the reliability issues of tire-based distance calculation while still achieving accurate parking guidance.
2Measurement precision
If electronic compass is coupled with parking system, then angle information processing accuracy improves, but device complexity increases
Solution Approach 1:
The electronic compass serves multiple functions within the parking system: it provides angle information for orientation determination, serves as a reference for correcting distance measurements, and enables compensation for tire rolling radius inaccuracies. This multi-functionality justifies the added device complexity by delivering comprehensive measurement improvements.
Solution Approach 2:
The system merges the electronic compass data with the existing tire-based distance calculation and ultrasound sensor data into a unified processing algorithm. By combining these different measurement sources and processing them together, the system achieves improved angle measurement precision without requiring completely separate systems.
Data Source
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AI summary
The present invention relates to a method for improving parking precision in driver assistance systems comprising an electronic compass (30). The following method steps are performed: An electronic compass (30) is coupled to the driver assistance system. Rolling radii are calibrated on tyres (20, 22) mounted on the vehicle (10) on the basis of path pulses (36, 38), a track width (24) and a distance dWIC covered per wheel pulse (36, 38). A change in angle Delta phiWIC is then determined, whereupon an absolute change in angle Delta phiKompass is performed using the electronic compass. Finally a corrective factor is determined for the distance covered per wheel pulse.