Train Stop Control System Using Feasible Velocity Region Constraints
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Solution Overview
Problem
Conventional Train Automatic Stop Control (TASC) systems face challenges in generating and selecting optimal velocity profiles for train braking, leading to potential errors and uncertainties in stopping accuracy due to changing rail conditions and imprecisions in braking systems, which can result in the train overshooting or undershooting the desired stopping point.
Innovation Solution
The system determines a feasible region for the train's state with constraints that guarantee stopping within a predetermined range, independent of train and environmental parameters, by defining upper and lower velocity curves and using optimization-based receding horizon control to maintain the train within this region, ensuring accurate stopping without relying on predetermined velocity profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If conventional velocity profile methods are used to control train braking, then the train can stop at stations automatically, but the stopping accuracy deteriorates due to changing rail conditions and imprecisions in braking systems
Solution Approach 1:
The patent implements a feedback control mechanism where the actual train position and velocity are continuously measured and compared with the reference trajectory. The controller adjusts the braking force in real-time based on the position error and velocity error, ensuring the train stops accurately at the station platform even when rail friction changes or braking system imprecisions occur.
Solution Approach 2:
The control system autonomously monitors its own performance by measuring actual position and velocity, evaluates the tracking error, and self-adjusts the braking force without external intervention. This self-correcting mechanism maintains stopping accuracy despite varying environmental conditions and system uncertainties.
2Adaptability or versatility
If multiple predetermined velocity profiles are generated to account for different conditions, then the adaptability to various rail conditions improves, but the device complexity and computational resources increase
Solution Approach 1:
Instead of generating multiple predetermined velocity profiles for different rail conditions, the patent uses a single reference trajectory and dynamically adjusts the braking force by changing control parameters (braking force magnitude) based on actual train state and position error. This approach achieves adaptability to varying rail conditions while avoiding the complexity of generating and selecting from multiple profiles.
3Reliability
If feedback control is used to track the selected run curve, then the effect of external uncertainties is reduced, but definite guarantees of tracking performance cannot be provided
Solution Approach 1:
The control design incorporates safety margins and constraints that ensure the train will stop within the acceptable range even under worst-case conditions. The controller is designed to handle maximum expected deviations in rail friction and braking system performance, providing a guarantee that the train will not overshoot the platform by more than a predetermined safe distance.
Data Source
AI summary
A method controls a movement of a train to a stop at a stopping position between a first position and a second position. The method determines constraints of a velocity of the train with respect to a position of the train forming a feasible area for a state of the train during the movement, such that an upper curve bounding the feasible area has a zero velocity only at the second position, and a lower curve bounding the feasible region has a zero velocity only at the first position. Next, the method controls the movement of the train subject to the constraints.