Train Braking Thresholds Based on Distance Sensing and Stopping Margin
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Solution Overview
Problem
Conventional rail transit systems face a high risk of rear-end collisions due to reliance on driver experience and the limitations of radar auxiliary protection systems after ATP is cut-off.
Innovation Solution
A method and device for braking a vehicle that acquires the distance between the vehicle and a preceding vehicle, issues alarms based on thresholds, and implements braking commands at preset decelerations, with thresholds determined by equivalent virtual stopping distances and emergency braking distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radar auxiliary protection system is used after ATP cut-off, then the system can measure distance in real time, but the risk of rear-end collision remains high due to insufficient braking safety margin
Solution Approach 1:
The system performs preliminary actions by issuing progressive alarms (first alarm at distance ≤ first threshold, second alarm at distance ≤ second threshold) before actual collision occurs. This allows the driver sufficient time to react and apply brakes progressively, transforming the reactive braking system into a proactive safety system that prevents collisions through advance warning and staged intervention.
Solution Approach 2:
The system changes parameters by establishing multiple thresholds (first threshold based on emergency braking distance, second threshold based on first threshold plus minimum alarm interval) and corresponding deceleration rates (first preset deceleration for emergency braking, second preset deceleration for normal braking). This multi-parameter approach creates a graduated response system that adapts to the severity of the approaching collision risk.
2Length of stationary object
If emergency braking is applied at high deceleration, then the stopping distance is reduced, but the comfort and safety of passengers deteriorates due to sudden deceleration
Solution Approach 1:
The braking process is segmented into two distinct phases: normal braking (second preset deceleration, lower deceleration rate) for routine distance maintenance, and emergency braking (first preset deceleration, higher deceleration rate) for critical collision avoidance. This segmentation allows the system to apply the appropriate level of force based on the situation, avoiding unnecessary harsh braking while ensuring rapid stopping when truly needed.
Solution Approach 2:
The system dynamically adjusts the braking deceleration rate based on the current distance to the preceding vehicle. When distance exceeds the second threshold, no braking is applied. When distance falls between first and second thresholds, normal braking with second preset deceleration is applied. When distance falls below the first threshold, emergency braking with first preset deceleration is applied. This dynamic adjustment optimizes both stopping distance and passenger comfort.
Data Source
Figure 1~2
AI summary
A vehicle braking method and device (200), and a train. The braking method comprises: obtaining the distance between a vehicle and a front vehicle (101); providing an alarm if the distance is smaller than or equal to a first threshold (102); receiving a first braking instruction triggered by a user, and braking the vehicle at a first preset deceleration according to the first braking instruction, wherein the first threshold is obtained according to the sum of a target idling stopping distance and an emergency braking distance, the target idling stopping distance is obtained according to at least one of a first idling stopping distance and a second idling stopping distance, the first idling stopping distance is the traveling distance of the vehicle in the process of obtaining the distance between the vehicle and the front vehicle, the second idling stopping distance is the traveling distance of the vehicle in the process of the user triggering the first braking instruction, and the emergency braking distance is the traveling distance for braking the vehicle at the first preset deceleration (103). The beneficial effects are that: a braking threshold is determined by considering the distance measuring capacity and the braking performance of a train, the rear-end collision risk with a front vehicle can be effectively reduced, and the running safety of the train is improved.