Vehicle Power Steering Redundancy via Dual Detection Circuits
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Solution Overview
Problem
The existing steering systems that use motors for power steering face challenges in accurately calculating the steer angle and ensuring redundancy, particularly when an angle sensor is abnormal, which can hinder motor control and affect the accuracy of steering operations.
Innovation Solution
A steering system with a dual detection circuit configuration, where two detection circuits with independent power sources calculate the steer angle, allowing for redundancy and high accuracy by comparing parameters from different power supply paths to determine abnormality and ensure reliable steer angle calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single detection circuit is used to calculate the steer angle, then the device complexity is low, but the reliability is insufficient when the angle sensor is abnormal
Solution Approach 1:
The patent applies local quality by creating two independent detection circuits (first and second detection circuits) with separate power supply paths. Each circuit independently calculates the steer angle, and the system selectively uses the reliable calculation result. This local differentiation of detection paths ensures that a failure in one circuit does not compromise the entire system, thereby improving reliability while maintaining manageable complexity through modular design.
Solution Approach 2:
The detection system is segmented into two independent detection circuits, each with its own power supply path. This segmentation allows the system to isolate failures to individual circuits rather than having a single point of failure. The control unit segments the decision-making process by comparing results from both circuits and selecting the reliable one, thus improving overall system reliability without proportionally increasing complexity.
2Measurement precision
If redundant detection circuits are introduced to ensure calculation accuracy, then the reliability improves, but the device complexity increases
Solution Approach 1:
The patent implements preliminary action by having both detection circuits continuously calculate the steer angle in advance, storing their respective results. When an abnormality is detected in one circuit, the system already has a pre-calculated reliable result from the other circuit available for immediate use. This preliminary calculation and storage of multiple results ensures measurement precision is maintained without requiring complex real-time switching mechanisms.
Solution Approach 2:
The detection circuits perform self-service by independently calculating and validating their own steer angle results. Each circuit operates autonomously with its own power supply, and the control unit enables them to self-diagnose through comparison of their outputs. This self-service capability improves measurement precision through cross-validation while minimizing the need for additional complex control mechanisms.
3Reliability
If multiple power supply paths are used for detection circuits, then the reliability improves through redundancy, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies universality by designing the dual detection circuit system to serve multiple functions: normal steer angle detection, abnormality detection, and automatic failover. The same hardware infrastructure (two detection circuits with separate power paths) simultaneously provides redundancy for reliability and a mechanism for detecting abnormalities. This multi-functionality reduces manufacturing cost by avoiding the need for separate redundant systems for each function.
Data Source
AI summary
A steering system in a vehicle includes a plurality of subsystems provided with a control unit. The control unit includes a storage unit storing steer angle information regarding a steer angle of one of a steering mechanism and a steered mechanism when the steering mechanism or the steered mechanism stops, an abnormality determiner determining abnormality of the motor rotation detection value and the detection circuit in the plurality of subsystems at a start time of a motor based on a comparison of at least two parameters, and a steer angle calculator calculating the steer angle based on the parameters having been determined by the abnormality determiner as not abnormal.