Train Occupancy Range Calculation with Dynamic Margin Adjustment
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Solution Overview
Problem
Current wireless train control systems face challenges in accurately calculating train position and occupancy range due to rotation detector failures, wear, and slip-or-skid events, which can lead to safety hazards such as train crashes.
Innovation Solution
The implementation of an on-board system with multiple rotation detectors that calculate train positions and detect slip-or-skid events, adjusting the train occupancy range by expanding the margin distances when slip-or-skid is detected to ensure a wider range that includes the no-slip-or-skid state range, thereby enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the margin distance is increased to account for position errors, then the train occupancy range becomes wider and safety is improved, but the train interval becomes excessively long and productivity decreases
Solution Approach 1:
The patent applies dynamics by making the margin distance adjustable rather than fixed. The control device dynamically changes the margin distance based on detected train states (normal operation, acceleration, deceleration, door operations). During normal operation, a smaller margin distance is used to maintain productivity, while during critical operations like door opening/closing or acceleration/deceleration, the margin distance is increased to ensure safety. This resolves the contradiction by adapting the safety buffer to actual operational needs.
Solution Approach 2:
The patent changes the parameter of margin distance based on different operational conditions. Instead of using a constant large margin distance, the system varies the margin distance parameter according to the train's operational state. The control device selects from multiple predetermined margin distance values depending on whether the train is accelerating, decelerating, at constant speed, or performing door operations. This parameter adaptation allows optimal balance between safety and productivity.
2Device complexity
If a single rotation detector is used to calculate train position, then the system complexity is reduced, but the measurement precision decreases due to wear and slip-or-skid
Solution Approach 1:
The patent applies local quality by assigning different functional roles to different rotation detectors. The control device identifies which rotation detector provides more reliable position information based on operational context. During normal operation, one detector may be primary, but during acceleration or deceleration, the system can switch to or weight the other detector more heavily. This localized optimization of detector usage improves measurement precision without requiring all detectors to be equally complex.
Solution Approach 2:
The system uses feedback from multiple rotation detectors to continuously monitor and compare position measurements. The control device receives position information from both detectors and can detect discrepancies that indicate wear or slip-or-skid events. By comparing the feedback from both sources, the system can identify and compensate for errors in one detector, thereby maintaining high measurement precision even with a relatively simple dual-detector configuration.
3Reliability
If the train occupancy range is calculated with large margin distances to ensure safety, then the risk of train crashes is reduced, but the range extends to areas extremely unlikely to include the train
Solution Approach 1:
The patent makes the occupancy range dynamic by adjusting the margin distance according to operational conditions. During critical phases like door opening/closing or acceleration/deceleration, a larger margin distance is applied to ensure safety and reduce crash risk. During stable constant-speed operation, a smaller margin distance is used to maintain accurate occupancy range information. This dynamic adjustment ensures that the occupancy range neither consistently overestimates nor underestimates the actual train position.
Solution Approach 2:
The system changes the margin distance parameter based on the train's operational state. The control device selects from multiple predetermined margin distance values depending on whether the train is in normal operation, accelerating, decelerating, or performing door operations. This parameter adaptation ensures that large margin distances are only applied when necessary for safety, while small margin distances are used when precision is more critical, thereby resolving the contradiction between risk reduction and occupancy range accuracy.
Data Source
AI summary
Whether or not slip-or-skid of a wheel on any one of a plurality of axles of a train to which pulse generators (PGs) are provided has occurred is determined on the basis of speed pulses output from the PGs. When occurrence of slip-or-skid is detected, a train occupancy range is calculated with a front end portion of the train determined on the basis of a forward-side one of train positions obtained on the basis of the speed pulses output by the PGs, and with a rear end portion of the train determined on the basis of a backward-side one of the train positions. Whether or not any of the PGs is abnormal is determined on the basis of the speed pulses or a speed and acceleration/deceleration calculated from the speed pulses.