Range Measurement System Calibration via Internal Delay Compensation
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Solution Overview
Problem
Existing range measurement systems for vehicles face challenges in accurately determining the position and speed due to inconsistencies in manufacturing and environmental factors, particularly in calibrating the internal delays of on-board and wayside range measurement devices, which affect the reliability of wireless signal propagation times.
Innovation Solution
The system calibrates by comparing measured travel times of signals between on-board and wayside range measurement devices with pre-determined times, accounting for internal delays to ensure accurate propagation time measurements, and performs calibration procedures when deviations exceed thresholds, using methods that involve multiple signal routes and health checks to maintain system integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If internal delays of range measurement devices are not calibrated, then the system is simpler to operate, but the measurement precision deteriorates due to manufacturing inconsistencies and environmental factors
Solution Approach 1:
The patent performs calibration measurements in advance to determine internal delays of range measurement devices. Pre-determined times for signal propagation between devices are calculated and stored before actual range measurements are taken. This preliminary calibration action eliminates the need for complex real-time delay compensation during operation, resolving the contradiction between measurement precision and device complexity.
2Measurement precision
If calibration procedures are performed frequently to maintain accuracy, then measurement precision improves, but loss of time increases due to repeated calibration operations
Solution Approach 1:
The system performs calibration measurements once beforehand to establish pre-determined signal propagation times between all pairs of range measurement devices. These calibration results are stored and reused for multiple subsequent range measurements, eliminating the need for frequent recalibration. This approach maintains high position determination accuracy while minimizing time loss by performing calibration only once rather than repeatedly.
Solution Approach 2:
The patent creates a copy of the calibration data (pre-determined times) that can be reused across multiple measurement operations. Instead of repeating the full calibration process each time, the system references the stored calibration copy, significantly reducing the time required while maintaining measurement precision.
3Reliability
If multiple signal routes are used for calibration, then reliability improves through comprehensive system checking, but device complexity increases due to additional measurement pathways
Solution Approach 1:
The calibration system divides the overall calibration process into separate measurement segments, each evaluating specific pairs of range measurement devices using individual signal routes. By segmenting the calibration into discrete device-pair measurements rather than attempting to calibrate all devices simultaneously through a single complex procedure, the system achieves comprehensive reliability checking while keeping each individual calibration step manageable and clear.
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
This approach enhances the accuracy and reliability of range measurements, ensuring the system meets Safety Integrity Level (SIL) 4 standards by accurately accounting for internal delays and maintaining system health, thereby improving position determination and speed measurement precision.
Implementation Method 1
measuring a time of flight (TOF) for a signal to travel from an internal component of the on-board range measurement device to an antenna of the on-board range measurement device, to an antenna of the wayside range measurement device, and to an internal component of the wayside range measurement device
Data Source
AI summary
Systems and method of calibrating a range measurement system for a vehicle mounted on a guideway are disclosed. In some embodiments, a method includes: measuring a first time of transmission (TOT) between a first internal component of an on-board range measurement device and a second internal component of a wayside range measurement device. The first TOT is compared with a first pre-determined time. A health of the range measurement system is determined based on a difference between the first TOT and the first pre-determined time.