Railway Velocity Compensation During Wheel Slide
Solution Overview
Problem
Current methods for detecting and calculating the travel velocity of railway vehicles during wheel slide phenomena are inaccurate due to the lack of difference in signals from speed sensors and integration of noise from acceleration sensors, leading to errors in velocity calculation and prolonged braking distances.
Innovation Solution
A travel velocity compensation apparatus and method that includes a velocity measurement unit, a velocity estimation unit using dynamic models and non-linear observation, and a detection unit to determine wheel slide, allowing for selection of accurate travel velocity and compensation during sliding, thereby enhancing accuracy and reducing noise impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If velocity is calculated using tachometer information from wheel axis, then velocity measurement is simple, but accuracy deteriorates when wheel slide occurs because wheels do not rotate properly
Solution Approach 1:
The patent introduces an accelerometer as an intermediary measurement device to detect velocity indirectly through acceleration integration. When wheel slide occurs and tachometer-based measurement becomes unreliable, the accelerometer provides an alternative measurement path, acting as a mediator to maintain velocity measurement accuracy without being directly affected by wheel rotation status.
Solution Approach 2:
The patent changes the measurement parameter from direct wheel rotation speed (tachometer) to acceleration (accelerometer). By measuring acceleration and integrating it over time, the system obtains velocity information that is independent of wheel rotation, thus resolving the contradiction between measurement simplicity and accuracy during slide conditions.
2Reliability
If velocity is calculated by integrating acceleration information from accelerometer, then velocity can be obtained independently of wheel rotation, but noise from sensor is also integrated resulting in deteriorated accuracy
Solution Approach 1:
The patent merges two different measurement methods (tachometer-based and accelerometer-based) into a unified velocity measurement system. By combining the outputs of both sensors and using their complementary strengths, the system achieves reliable velocity measurement during slide conditions while mitigating the noise integration problem through fused estimation rather than simple integration.
Solution Approach 2:
The patent implements feedback mechanisms where the measured velocity from tachometer and the integrated velocity from accelerometer are continuously compared and adjusted. The system uses feedback to detect discrepancies caused by noise integration and corrects the velocity estimate, maintaining accuracy while preserving the reliability benefit of accelerometer-based measurement.
3Quantity of substance
If four speed sensors are used to detect wheel slide by comparing signals, then velocity measurement is available, but slide detection fails when slide occurs simultaneously on all four wheel axes
Solution Approach 1:
The patent uses accelerometer as an intermediary device to detect wheel slide by comparing its output with tachometer output. This intermediary measurement approach allows slide detection even when all four wheels slide simultaneously, because the accelerometer provides an independent reference that is not affected by universal wheel rotation loss.
Data Source
AI summary
Disclosed is a travel velocity compensation apparatus for railway vehicles and a method thereof for compensating a travel velocity when there is generated a slide between a wheel and a railway, the apparatus including a velocity measurement unit measuring a travel velocity of a railway vehicle, a velocity estimation unit estimating the travel velocity using travel information of railway vehicle and rail information received from at least one sensor, a detection unit generating wheel slide information by determining whether wheels of the railway vehicle slide, using the travel velocity of the railway vehicle measured by the velocity measurement unit and the travel velocity estimated by the velocity estimation unit, and a selection unit selecting, as a travel velocity, any one of the travel velocity measured by the velocity measurement unit using the wheel slide information generated by the detection unit and the travel velocity estimated by the velocity estimation unit.