Steering Control Unit Neutral Point Correction
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Solution Overview
Problem
Existing electric power steering systems face inaccuracies in calculating steering absolute angles due to deviations between theoretical and actual specific strokes caused by dimensional or assembly tolerances, leading to discrepancies in motor neutral points.
Innovation Solution
A steering control unit that includes a steering angle calculation circuit, which calculates a correction amount for the motor neutral point based on the deviation between theoretical and actual specific strokes, ensuring accurate calculation of the steering absolute angle by reflecting this correction in the motor neutral point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the motor neutral point is calculated using the conversion value based on the theoretical specific stroke, then the calculation process is simple, but the accuracy of the steering absolute angle deviates due to dimensional or assembly tolerances
Solution Approach 1:
The patent applies preliminary action by pre-calculating correction amounts for the motor neutral point based on expected deviations from theoretical specific stroke. These correction values are stored in advance and applied during operation to compensate for dimensional and assembly tolerances, eliminating the need for complex real-time calculations while maintaining high accuracy.
Solution Approach 2:
The patent implements feedback by using the detected steering absolute angle to calculate a correction amount that compensates for deviations between theoretical and actual specific stroke. This correction is fed back into the motor neutral point calculation, creating a closed-loop system that continuously improves accuracy based on actual operating conditions.
2Ease of manufacture
If the theoretical specific stroke is used for conversion, then the system is easier to implement, but the motor neutral point deviates from the actual value due to manufacturing tolerances
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the specific stroke parameter from its theoretical value to an corrected value that accounts for dimensional and assembly tolerances. The correction amount is calculated based on the deviation between theoretical and actual relationships, allowing the system to adapt to manufacturing variations while maintaining simple implementation.
3Productivity
If the motor neutral point is calculated without correction, then the calculation is faster, but the steering control precision deteriorates due to the deviation between theoretical and actual specific stroke
Solution Approach 1:
The patent uses preliminary action by pre-computing correction amounts that can be quickly applied during operation. This approach maintains high calculation speed while improving precision, as the complex correction calculations are performed in advance or using simplified lookup tables rather than full real-time computations.
Data Source
AI summary
A steering angle calculation circuit of an ECU includes a neutral point calculation circuit, a correction amount calculation circuit, an adder, and an absolute angle calculation circuit. When started, the neutral point calculation circuit calculates a motor neutral point from a steering angle detected through a steering sensor and a motor rotation angle detected through a relative angle sensor. The correction amount calculation circuit calculates a correction angle that is a difference between a conversion value and an actual value of the motor rotation angle with respect to the steering angle. The conversion value is obtained by converting the steering angle in terms of the motor rotation angle by taking into account a theoretical specific stroke. The adder calculates a final motor neutral point by adding the correction angle calculated by the correction amount calculation circuit to the motor neutral point calculated by the neutral point calculation circuit.