Rail Brake Controller Using Axle Adhesion Validation
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Solution Overview
Problem
Existing rail vehicle braking systems face challenges in achieving optimal brake load distribution due to varying adhesion conditions along the length of long rail vehicles, especially in conditions like leaves or snow on the tracks.
Innovation Solution
A controller that determines and compares adhesion parameters for each wheel of a rail vehicle, ensuring that only similar adhesion parameters are reported for common wheel axles, allowing for a distributed brake force application for efficient braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-uniform brake load distribution is applied to account for varying adhesion conditions along the rail vehicle, then brake performance is improved, but the complexity of determining accurate adhesion parameters for each wheel increases
Solution Approach 1:
The system divides the rail vehicle into multiple independent wheel units, each with its own adhesion parameter determination and brake control. This segmentation allows each wheel to be controlled individually based on its specific adhesion conditions, enabling optimal brake load distribution across the entire vehicle while maintaining manageable complexity through modular architecture.
Solution Approach 2:
The system implements local quality by determining adhesion parameters specifically for each wheel based on local track conditions rather than applying a uniform brake load distribution. Each wheel's brake force is independently adjusted according to its measured adhesion characteristics, allowing the system to adapt to varying local conditions along the rail vehicle's length.
2Measurement precision
If adhesion parameters are determined and reported for each wheel independently, then measurement precision is improved, but the reliability decreases due to potential random hardware failures in individual sensors
Solution Approach 1:
The system merges data from multiple wheels' adhesion parameter measurements to determine the track section's overall adhesion characteristics. By combining information from multiple independent measurements, the system achieves both high measurement precision for individual wheels and high reliability through redundancy, as the failure of a single sensor does not compromise the overall system.
Solution Approach 2:
The system implements feedback mechanisms where adhesion parameters are continuously monitored and compared across multiple wheels. When discrepancies or anomalies are detected in individual wheel measurements, the system can identify potential hardware failures and compensate through feedback from other wheels, maintaining reliable operation even when individual sensors fail.
3Strength
If wheel slide protection (WSP) system is used to reduce brake force when sliding occurs, then wheel damage is prevented, but the brake force is rapidly reduced which may be misleading for determining true friction coefficients
Solution Approach 1:
The system performs preliminary action by determining adhesion parameters through controlled wheel slide events before applying full brake force. By intentionally inducing minor, controlled sliding and measuring the resulting adhesion characteristics, the system obtains accurate friction coefficient data without causing actual wheel damage, thus preventing the problem before it occurs.
Solution Approach 2:
The system applies partial action by using only the minimum necessary brake force to induce controlled sliding for measurement purposes, rather than applying full brake force that would trigger WSP intervention. This partial action allows accurate friction coefficient determination while staying below the threshold that would cause harmful wheel sliding and WSP activation.
Data Source
Figure 1a
Figure 1b
Figure 2a~3
AI summary
A controller (140) controls a set of electrically operated brake units (141a, 151a; 141b, 151b; 142a, 152a; 142b, 152b; 143a, 153a; 143b, 153b; 144a, 154a; 144b, 154b) of a rail vehicle (100), which has wheels arranged in pairs of first and second wheels on a respective common wheel axle (131, 132, 133, 134), where each wheel is individually braked via a respective brake unit in the set of electrically operated brake units. The controller (140) repeatedly determines a respective adhesion parameter (µ1a, µ1a, µ2a, µ2b, µ3a, µ3b, µ4a, µ4b) reflecting a friction coefficient between each wheel (101a, 101b, 102a, 102b, 103a, 103b, 104a, 104b) of the rail vehicle (100) and a rail upon which the wheel travels. The controller (140) compares repeatedly compares the respective adhesion parameters (µ1a, µ1b, µ2a, µ2b, µ3a, µ3b, µ4a, µ4b) pairwise to one another. In each pair, first and second adhesion parameters (µ1a ,µ1b; µ2a, µ2b ; µ3a, µ3b; µ4a, µ4b) are compared to one another, which adhesion parameters have been determined for the first and second wheels on the common wheel axle (131, 132, 133, 134). The controller (140) reports a respective adhesion parameter (µ1, µ2, µ3, µ4) for one of said common wheel axles (131, 132, 133, 134) if and only if a ratio (µa/µb) between the first and second adhesion parameters (µ1a, µ1b; µ2a, µ2b; µ3a, µ3b; µ4a, µ4b) is within a first predefined threshold interval (EQ1) around a factor one.