Rail Vehicle Roll Motion Detection via Dynamic Bandpass Filtering
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Solution Overview
Problem
Existing methods fail to reliably detect permanent rolling movements of a rail vehicle body relative to the chassis, distinguishing them from transient movements, which can be intentionally induced by passengers or due to mechanical issues, posing safety risks, especially in driverless vehicles where these conditions are not immediately apparent.
Innovation Solution
A method involving a signal proportional to the car body's rotation about the longitudinal axis, filtered using a bandpass filter tuned to the natural rolling frequency, with a timer counting limit value violations to differentiate between transient and persistent rolling movements, triggering a warning signal for persistent vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bandpass filter is used to detect roll motion, then measurement precision is improved, but false alarms from transient movements increase
Solution Approach 1:
The system dynamically adjusts the center frequency of the bandpass filter to match the actual roll natural frequency of the vehicle, which varies with load conditions. This dynamic adaptation ensures accurate detection while maintaining reliability across different operating conditions.
Solution Approach 2:
The system uses feedback from pressure sensors monitoring the air springs to continuously track the roll natural frequency and adjust the filter parameters accordingly. This feedback mechanism enables the system to distinguish between transient disturbances and genuine roll motions, reducing false alarms while maintaining detection precision.
2Adaptability or versatility
If the roll natural frequency is adjusted based on air spring pressure, then adaptability is improved, but device complexity increases
Solution Approach 1:
The system automatically determines the roll natural frequency by monitoring the pressure differences in the air springs, eliminating the need for manual calibration or complex external adjustment mechanisms. The system self-adjusts the filter parameters based on the measured pressure data, maintaining adaptability while minimizing added complexity.
3Manufacturing precision
If pressure differences in air springs are used to measure roll angle, then manufacturing precision is improved, but reliability decreases due to out-of-phase movements
Solution Approach 1:
The system combines the roll angle measurements from both left and right air springs by summing their pressure differences. This merging approach ensures that out-of-phase roll movements cancel each other out, while in-phase movements (indicating genuine roll) are reinforced, thereby improving reliability without sacrificing measurement precision.
Data Source
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Figure 3
AI summary
The invention relates to a method and to a device for detecting roll motion of a rail vehicle car body (1) relative to the bogie (2) of a rail vehicle (3), wherein a signal ( S ) proportional to the roll motion is bandpass-filtered and the magnitude of the bandpass-filtered signal ( S filter) is compared with a limit value ( S lim) and rolling is determined on the basis of the limit value ( S lim) being exceeded several times within an observation time period ( T ).