Torque Sensor Failure Detection in Motor-Driven Power Steering
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Solution Overview
Problem
Existing motor-driven power steering systems fail to detect torque sensor failures accurately when external environmental factors, such as water or corrosion, cause a torque sensor to transmit a voltage within a normal range, leading to potential self-rotation and unsafe vehicle operation.
Innovation Solution
An apparatus and method that utilize dual torque sensors, with a processor to analyze main and sub-torque signals, calculate differences, and determine sensor failures based on reference torque values and times, applying electric current to measure torque changes, enabling accurate detection of sensor failures even when damaged by external factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If voltage range checking is used for torque sensor failure detection, then detection simplicity is improved, but detection accuracy deteriorates when sensors are damaged by external factors like water or corrosion
Solution Approach 1:
The failure detection process is segmented into multiple stages: initial voltage range checking for quick identification of obvious failures, followed by differential comparison between dual torque sensors for subtle anomalies, and finally dynamic response monitoring during motor activation to detect sensors damaged by external factors. This multi-stage segmentation resolves the contradiction by combining simple and complex detection methods.
Solution Approach 2:
The system performs preliminary voltage range checking on torque sensor signals before proceeding to more complex differential comparison analysis. This preliminary action quickly filters out sensors with obvious failures while preparing the system for more accurate detection methods if needed, balancing simplicity and accuracy.
2Reliability
If dual torque sensors are used for redundancy, then system reliability is improved, but device complexity increases
Solution Approach 1:
The system merges the functions of two torque sensors not only for redundant measurement but also for mutual validation through differential comparison. By combining both sensors' data processing and cross-checking their outputs, the system achieves enhanced reliability while managing complexity through integrated control logic that automatically selects or switches between sensors based on their health status.
Solution Approach 2:
The system monitors parameter changes in torque sensor outputs over time, including voltage levels, signal stability, and response characteristics during motor activation. By detecting parameter deviations that indicate sensor degradation from external factors, the system maintains high reliability without requiring overly complex real-time analysis, as it focuses on key parameter thresholds.
3Ease of operation
If voltage threshold checking is used for failure detection, then ease of operation is improved, but detection capability deteriorates for sensors transmitting normal-range voltages despite damage
Solution Approach 1:
The system implements feedback mechanisms where torque sensor readings are continuously monitored and compared against expected values during normal operation and motor activation. When a sensor's output deviates from the feedback pattern (even if within voltage thresholds), the system flags potential failure. This feedback loop maintains ease of operation while improving detection capability for subtly damaged sensors.
Solution Approach 2:
The detection system transitions from static voltage threshold checking to dynamic monitoring that observes sensor behavior during motor activation and steering operations. By evaluating how sensor outputs change dynamically under different operating conditions, the system can detect sensors damaged by external factors that still output normal-range voltages, balancing operational simplicity with enhanced detection capability.
Data Source
AI summary
Disclosed are apparatuses and methods for detecting a failure of a torque sensor for a motor-driven power steering system, the apparatus including a processor configured to detect a failure in a first torque sensor and a second torque sensor based on main torque signals and sub-torque signals, compare a first torque value of the first torque sensor and a second torque value of the second torque sensor, in response to the first torque sensor and the second torque sensor being normal, measure an amount of change in first torque of the first torque sensor and an amount of change in second torque of the second torque sensor by applying electric current to a motor, in response to the comparison result being abnormal, and determine a failure in the first torque sensor and the second torque sensor based on the amount of change in first torque and second torque.