Electric Power Steering Controller Torque Sensor Abnormality Detection
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Solution Overview
Problem
Existing electric power steering systems face challenges in distinguishing between torque sensor abnormalities and main microcomputer failures, leading to potential misjudgment and inappropriate system control, which requires costly redundant configurations and higher-performance monitoring microcomputers.
Innovation Solution
An electric power steering controller with a main microcomputer and an external device that includes a torque sensor abnormality detector, allowing for the detection of torque sensor issues and appropriate system control by using dual torque signals and an external device to differentiate between sensor and microcomputer abnormalities, enabling continued operation with abnormal torque sensor conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a monitoring microcomputer is used to detect main microcomputer failures, then failure detection capability is improved, but system cost and complexity increase
Solution Approach 1:
The patent extracts the failure detection function from a separate monitoring microcomputer and integrates it into the main microcomputer itself. The main microcomputer periodically stops execution to allow an inspection circuit to verify its operational state, eliminating the need for a dedicated monitoring microcomputer while maintaining failure detection capability.
Solution Approach 2:
The main microcomputer performs self-inspection by periodically halting execution and allowing the inspection circuit to verify its state. This self-service mechanism enables the system to detect failures without requiring external monitoring resources, reducing system complexity and cost.
2Reliability
If a dually redundant main microcomputer is configured for comparison, then failure detection accuracy is improved, but system cost increases
Solution Approach 1:
The patent extracts the redundancy function from a separate dual microcomputer configuration and implements it within the single main microcomputer through periodic execution stops and inspection circuit verification. This eliminates the need for duplicate microcomputer hardware while maintaining failure detection accuracy.
Solution Approach 2:
Instead of using a physical duplicate microcomputer for redundancy, the system creates a virtual copy of the inspection process by periodically halting execution and verifying the microcomputer state against expected values. This virtual redundancy approach achieves the same safety goal without duplicating expensive hardware.
3Reliability
If redundant code logic is configured in the main microcomputer, then self-check capability is improved, but development time and cost increase
Solution Approach 1:
The patent segments the microcomputer operation into execution phases and inspection phases. During inspection phases, the microcomputer stops execution and allows the inspection circuit to verify its state. This temporal segmentation provides self-check capability without requiring complex redundant code logic, simplifying development.
Solution Approach 2:
The inspection circuit acts as an intermediary between the main microcomputer and the failure detection function. Instead of implementing complex self-check logic within the microcomputer code, the external inspection circuit performs verification during execution stops, reducing development complexity while maintaining reliability.
4Measurement precision
If torque sensor abnormalities are not distinguished from microcomputer failures, then system control accuracy deteriorates, but system complexity increases
Solution Approach 1:
The patent implements dynamic response strategies that adapt to the type of abnormality detected. When torque sensor abnormalities are detected, the system responds differently than when microcomputer failures are detected. This dynamic control approach improves detection accuracy without requiring complex static differentiation mechanisms.
Solution Approach 2:
The system uses feedback from the inspection circuit to determine the appropriate control response. By continuously monitoring microcomputer execution state and comparing it against expected behavior, the system can distinguish between torque sensor issues and microcomputer failures, enabling accurate abnormality detection with manageable control complexity.
Data Source
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Figure 6~7
AI summary
The present invention provides an electric power steering controller and an electric power steering system that allow appropriate operation even when the operation of their torque sensors is abnormal. The controller 100 of a main microcomputer 1-1 outputs motor drive signals 3 to a drive circuit 5 based on first and second torque signals detected by a torque sensor 2 that detects steering force. The drive circuit 5 drives a motor 6 to generate assistive torque. A torque sensor abnormality detector 101 is installed within the main microcomputer 1-1 and detects abnormalities of the torque sensor 2 based on the first and second torque signals. An excessive torque detector 102 is installed within an external device 1-2 and outputs a motor stop signal when either of the first and second torque signals exceeds a given value.