Rail Braking Parameter Modeling for Fluid-Affected Wheel Adhesion
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Solution Overview
Problem
Existing methods for determining braking behavior parameters in rail vehicles fail to accurately account for the influence of fluid conditions, particularly when simulating scenarios like water-soap mixtures on railway tracks, leading to inadequate simulation of anti-slip test drives and increased need for complex and expensive real-world testing.
Innovation Solution
A physical model that considers the influence of fluid on a wheel by calculating fluid reduction caused by a preceding wheel, using auxiliary characteristic curves to determine frictional contact and control parameters for slip controllers, allowing precise simulation of braking behavior under various conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods for determining braking behavior parameters are used, then the determination process is simple, but the accuracy of fluid condition simulation is insufficient
Solution Approach 1:
The physical model pre-calculates and stores braking behavior parameters for various fluid conditions before actual braking events occur. The model determines friction coefficients, adhesion values, and braking characteristics for different fluid depths and compositions in advance, allowing the control system to quickly retrieve and apply appropriate parameters during real braking operations without performing complex real-time calculations.
Solution Approach 2:
The patent introduces a fluid depth detection device as an intermediary element that measures the actual fluid depth on the track and feeds this information to the physical model. This intermediary sensor bridges the gap between the physical braking environment and the simulation model, enabling accurate selection of braking parameters based on real-time fluid conditions without requiring direct complex measurement of braking forces.
2Reliability
If fluid conditions are not accurately accounted for, then the simulation process is simpler, but the simulation accuracy of anti-slip test drives deteriorates
Solution Approach 1:
The physical model dynamically adjusts braking behavior parameters based on detected fluid depth. When fluid depth exceeds a threshold, the model changes friction coefficients, adhesion values, and braking force distribution parameters to reflect reduced wheel-rail adhesion conditions. This parameter adaptation allows the simulation to accurately represent different fluid conditions (dry, wet, contaminated) without requiring completely different simulation models for each scenario.
3Measurement precision
If real-world testing is performed without accurate simulation, then validation is more direct, but testing costs and complexity increase
Solution Approach 1:
The patent creates a virtual copy of the braking system with integrated physical model that replicates real-world braking behavior under various fluid conditions. This virtual braking system allows comprehensive testing of anti-slip control algorithms, braking force distribution, and safety functions in simulated environments before deploying to physical test tracks. The virtual model reproduces fluid effects, wheel slip characteristics, and braking responses, enabling extensive validation without repeated expensive real-world testing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables highly accurate simulation of braking behavior, reducing the need for costly real-world tests by ensuring compliance with standards like EN15595, even under challenging fluid conditions, and optimizing slip controller parameters for realistic operation.
Implementation Method 1
a physical model is used to determine the at least one parameter relevant to the braking behavior, which takes into account the influence of a wheel preceding a wheel to be braked, specifically with regard to an influencing effect that the preceding wheel exerts on the frictional connection between the trailing wheel to be braked and the rail
Implementation Method 2
the frictional connection between the trailing wheel to be braked and the rail
Data Source
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AI summary
The invention relates to a method for determining at least one braking-behavior-relevant parameter relevant to the open-loop or closed-loop control of a braking system (210) of a rail vehicle (200). According to the invention, a physical model (PHYSM) is used in the determining of the at least one braking-behavior-relevant parameter, the physical model taking into account the influence of a wheel (10) which leads a wheel (20) to be braked (20), specifically with respect to an influence effect which the leading wheel (10) has on the traction between the trailing wheel (20) to be braked and the rail (30).