Power Steering Column Pinch Detection Using Slew Rate Signals
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Solution Overview
Problem
Existing vehicle steering systems, particularly those with powered steering columns, face challenges in detecting pinch events due to the variability in physical properties and the reliance on additional sensors or hardware, which increases complexity and cost, making it difficult to implement effective pinch detection and prevention.
Innovation Solution
A method and system for real-time pinch detection in powered steering columns using current and speed slew rates to determine pinch events, allowing for immediate motor control adjustments such as stopping or reversing the column operation for calibration, and communicating messages to operators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors or hardware are used for pinch detection, then detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The motor controller uses the motor's own existing current and speed sensors to detect pinch events through slew rate analysis, eliminating the need for additional dedicated pinch detection sensors. The system serves its own detection needs using already-present components.
Solution Approach 2:
The patent introduces slew rate analysis as an intermediary computational method that transforms existing current and speed data into pinch detection capability. This mathematical intermediary allows accurate pinch detection without direct physical contact sensors.
2Measurement precision
If additional sensors or hardware are used for pinch detection, then detection accuracy is improved, but cost increases
Solution Approach 1:
The motor controller uses the motor's own existing current and speed sensors to detect pinch events through slew rate analysis, eliminating the need for additional dedicated pinch detection sensors. The system serves its own detection needs using already-present components.
Solution Approach 2:
The patent replaces expensive additional hardware sensors with computational analysis of existing signals. The 'detection mechanism' becomes software-based slew rate calculation rather than physical sensor additions, significantly reducing component costs.
3Reliability
If motor stops or reverses on pinch detection, then safety is improved, but operational continuity may be affected
Solution Approach 1:
The system applies partial reversal action (reversing for a calibrated time period) rather than complete operation termination. This partial action provides safety by clearing the pinch condition while allowing quick resumption of normal operation, balancing safety with operational continuity.
Solution Approach 2:
The motor controller continuously monitors current and speed slew rates during and after reversal to detect when the pinch condition has cleared. This feedback mechanism allows automatic resumption of normal operation once safety conditions are met, maintaining operational continuity.
Data Source
AI summary
A method includes determining a current slew rate associated with a motor of the steering column, determining a speed slew rate associated with the motor, determining a current and speed slew rate threshold for the motor, and determining whether the current slew rate or the speed slew rate indicates a pinch event based on a comparison of the current slew rate, the speed slew rate, and the current and speed slew rate threshold. The method also includes, in response to a determination that at least one of the current slew rate and the speed slew rate indicates a pinch event, selectively instructing the motor to one of stop operation and reverse operation for a calibration period and, in response to the pinch event having a magnitude that is less than a pinch event threshold, selectively instructing the motor to continue operation.