Train Speed Correction During Wheel Slip and Idling

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Solution Overview

Problem

Existing train protection systems struggle to accurately calculate the speed of a train when wheel slip or idling occurs, leading to inaccuracies in speed correction.

Innovation Solution

The system combines rotation speed data from a wheel detection device with ground speed data from a ground speed detection device, using a calculation unit to correct speed estimates during slip or idling events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If wheel rotation speed is used to calculate train speed, then the speed can be obtained from the rotation system device, but the speed calculation becomes inaccurate when wheel slip or idling occurs

Engineering Contradiction:
Improvespeed measurement accuracyVSAvoidspeed data reliability during slip/idling
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent introduces an intermediary correction mechanism that detects wheel slip/idling conditions and applies correction values to the speed calculation. When slip or idling is detected, the system uses the rotation system device speed as a baseline and adds correction values derived from acceleration sensor data to obtain the actual train speed, thereby resolving the inaccuracy caused by wheel-track friction changes

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent supplements the mechanical rotation-based speed measurement with an acceleration-based correction system. By using acceleration sensors to detect changes in motion and calculating correction values, the system replaces the unreliable mechanical wheel rotation measurement with a hybrid approach that accounts for slip and idling conditions

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If all speed data is replaced with maximum speed when wheel slip is detected, then early detection of wheel slip is achieved, but the speed data deviates from actual speed every time slip or idling occurs

Engineering Contradiction:
Improvewheel slip detection reliabilityVSAvoidspeed measurement precision
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the parameter used for speed correction from a static maximum speed value to a dynamic correction value based on acceleration data. Instead of replacing speed data with a fixed maximum value, the system calculates correction values from acceleration sensor measurements and applies them to the rotation system device speed, allowing the correction to adapt to varying slip and idling conditions

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If wheel rotation data is used for speed calculation, then the system can operate with simple rotation detection, but the speed cannot be accurately calculated when wheel slip or idling occurs

Engineering Contradiction:
Improvespeed detection system complexityVSAvoidspeed calculation accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent merges the simple rotation system device with an acceleration sensor system to create a hybrid speed measurement approach. The rotation device provides baseline speed data while the acceleration sensor provides correction information, combining both systems to achieve accurate speed measurement during slip and idling without completely redesigning the original simple system

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3988376B1Train security system, train security control method, and on-train device
Publication Date: 2025.02.19 HITACHI LTD
  • EP3988376B1 patent drawingFigure 1
  • EP3988376B1 patent drawingFigure 2
  • EP3988376B1 patent drawingFigure 3

AI summary

Provided, is a train protection system. The train protection system includes a control device 6 that controls movement of a vehicle 8 based on a block section and an on-rail position X of the vehicle 8 in the block section, a first device 1 that detects rotation of at least one of a wheel 4 and an axle of the wheel 4 and outputs the rotation to the control device 6 as a first detected value P1, and a second device 2 that inputs second, detected values P2 and P3 obtained by detecting a moving state of the vehicle 8 to the control device 6. The control device 6 calculates a speed V of the vehicle 8 based on the first detected value P1, calculates a moving, distance L of the vehicle 8 based on the speed V, calculates the on-rail position X of the vehicle 8 based on the moving distance L, detects slip or idling of the wheel 4 based on the first detected value P1, and corrects the speed V of the vehicle 8 during the slip or idling based on the second detected values P2 and P3 when slip or idling is detected in such a manner.