Steering Column Jam Detection Using Motor Current Slope
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Solution Overview
Problem
Existing methods for detecting jamming situations during the adjustment of a steering column in a motor vehicle often result in false detections, particularly due to mechanical influences, which can lead to incorrect identification of pinch points.
Innovation Solution
A method that evaluates the slope of the current signal from the electric motor during adjustment, using predefined limits defined by a first and second slope profile to distinguish between actual and false jamming situations, and includes simulation of obstacles to set these limits accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current signal threshold is set to detect jamming situations, then safety detection capability is improved, but false detections due to mechanical influences increase
Solution Approach 1:
The patent transitions from a static threshold detection method to a dynamic slope-based detection method. Instead of comparing current values against a fixed threshold, the system calculates the slope (rate of change) of the current signal over time. This dynamic approach allows the detection system to adapt to varying mechanical conditions during steering column adjustment, distinguishing between normal mechanical resistance (which produces gradual current changes) and actual jamming situations (which produce abrupt current slope changes).
Solution Approach 2:
The patent changes the detection parameter from absolute current value to current signal slope (derivative). By evaluating the rate of change of current rather than the current magnitude itself, the system can effectively filter out false alarms caused by mechanical influences such as friction and resistance during normal adjustment operations. The slope parameter captures the temporal characteristics of current variations, enabling discrimination between benign mechanical effects and genuine jamming conditions.
2Measurement precision
If the detection sensitivity is increased to identify all jamming situations, then detection coverage is improved, but the number of false alarms increases
Solution Approach 1:
The patent implements a feedback mechanism where the detected current signal is continuously monitored and its slope is evaluated in real-time during the adjustment process. The control unit receives the slope information and uses it to dynamically adjust the detection decision. This feedback loop enables the system to maintain high detection sensitivity while filtering out false alarms, as the slope evaluation provides continuous information about the actual mechanical state of the steering column adjustment.
3Device complexity
If a simple threshold-based detection method is used, then device complexity is reduced, but detection accuracy deteriorates
Solution Approach 1:
The patent replaces a complex mechanical detection system with an electrical signal processing approach. Instead of using mechanical sensors or switches to detect jamming conditions, the system uses the existing electric motor's current signal and processes it through slope calculation and evaluation. This substitution maintains device simplicity by utilizing already-present electrical components while achieving superior detection accuracy through signal processing techniques.
Data Source
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AI summary
The present invention relates to a method for detecting a jamming situation during the electromechanical adjustment of a steering column (1) in a motor vehicle by means of at least one electric motor, wherein during an adjustment process a current signal is detected for the at least one electric motor and the slope of the current signal is evaluated, wherein during the evaluation of the slope of the current signal it is checked whether the slope of the current signal lies within predetermined limits, wherein a jamming situation is then detected if the slope of the current signal lies within the predetermined limits.Furthermore, the invention relates to an adjustable steering column (1) for a motor vehicle comprising a support unit (4) by which an actuating unit (2) is adjustably held, and an adjusting device (7) configured for adjusting the actuating unit (2) relative to the support unit (4), wherein the adjusting device (7) for adjusting the actuating unit (2) comprises at least one electric motor (55, 65) and a control unit (8) is associated with the steering column (1). The steering column (1) is configured to carry out the aforementioned method.