Electric Power Steering Current Estimation Malfunction Detection
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Solution Overview
Problem
Existing electric power steering apparatuses face challenges in accurately controlling current flow through motors, particularly in detecting malfunctions in torque sensors and current detectors, which can lead to abnormal operations.
Innovation Solution
An electric power steering apparatus that includes a torque sensor, a current detector, and an electronic control unit to estimate the current flowing through the motor based on detected torque, compare it with measured current, and stop operation if a critical difference is found, indicating a malfunction in the torque sensor or current detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electric power steering apparatus uses a torque sensor and current detector to control motor current, then the steering control accuracy is improved, but the risk of malfunction detection failure increases
Solution Approach 1:
The patent applies feedback by having the electronic control unit continuously compare the measured current from the current detector with the estimated current calculated from torque sensor data. This feedback mechanism enables real-time detection of discrepancies indicating sensor malfunction, allowing the system to maintain reliability while preserving measurement precision through cross-validation of multiple sensing sources.
2Reliability
If the apparatus compares measured current with estimated current to detect malfunction, then the system reliability is improved, but the device complexity increases
Solution Approach 1:
The electronic control unit performs self-diagnosis by automatically comparing measured and estimated current values and detecting its own malfunctions without external intervention. The system uses its existing computational resources to monitor its own health, eliminating the need for separate dedicated monitoring hardware and thus limiting the increase in device complexity while improving reliability.
3Object-affected harmful factors
If the control unit stops operation when current difference exceeds critical value, then the safety is improved, but the productivity decreases
Solution Approach 1:
The patent implements beforehand cushioning by establishing a critical value threshold in advance that triggers safety shutdowns only when genuine malfunctions occur. This pre-set threshold acts as a protective buffer against false shutdowns caused by normal operational variations, thereby maintaining system productivity while ensuring safety. The threshold is calibrated to distinguish between acceptable operational deviations and actual sensor failures requiring intervention.
Data Source
AI summary
Disclosed is an electric power steering apparatus. The electric power steering apparatus includes: a torque sensor configured to detect a torque applied to a steering wheel; a current detector configured to measure a current flowing through a driving motor; and an electronic control unit configured to estimate a current flowing through the driving motor depending on the detected torque and compare the estimated current with the measured current to judge a malfunction of the torque sensor or the current detector.