Rail Carriage Speed Estimation Using Observer-Based Sensor Fusion
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Solution Overview
Problem
Current methods for determining the speed of rail vehicles face significant measurement errors due to noise in satellite navigation, wheel diameter inaccuracies, wheel slip during braking or acceleration, and drift in acceleration sensors, which affect the accuracy of position, speed, and acceleration measurements.
Innovation Solution
A method using an observer model, preferably a Luenberger observer or Kalman filter, that acquires and processes sensor data such as longitudinal acceleration, wheel speed, and braking/drive forces to continuously determine the carriage speed, adapting to specific vehicle conditions and compensating for measurement errors through sensor fusion and drift correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If satellite navigation (GPS, Galileo, GLONASS) is used to determine position, then position information can be obtained, but measurement accuracy is drastically reduced in poor reception conditions such as tunnels
Solution Approach 1:
The patent introduces an intermediary system consisting of a local reference position determination device and a movement detection device that mediates between the unreliable satellite navigation and the need for accurate position/speed determination. This local system uses inertial sensors and wheel speed sensors to determine position and speed independently of satellite reception conditions.
2Measurement precision
If train control systems are used for position determination, then position can be determined at specific points or sections, but continuous evaluation is not possible
Solution Approach 1:
The patent implements continuous determination of position and speed by continuously processing sensor data from acceleration sensors and wheel speed sensors through integration and observer models. This provides uninterrupted position and speed information throughout the entire measurement period, enabling continuous evaluation rather than discrete point measurements.
3Speed
If wheel slide protection speed signals are used, then speed can be determined from wheelsets, but systematic measurement inaccuracy is caused by unknown wheel diameter changes over time
Solution Approach 1:
The patent employs an observer model that uses feedback from multiple sensors (acceleration sensors, wheel speed sensors) to continuously estimate and correct the actual vehicle speed. The system compares the integrated acceleration data with the wheel speed sensor data and uses this feedback to compensate for wheel diameter changes and provide accurate speed determination.
4Measurement precision
If non-driven and unbraked reference wheelsets are used to minimize slip measurement errors, then measurement errors from wheel slip are reduced, but additional components and assembly work are required and unbraked wheelsets are undesirable
Solution Approach 1:
The patent makes the driven/braked wheelsets self-sufficient for accurate speed measurement by equipping them with both acceleration sensors and wheel speed sensors. The system processes data from these sensors through an observer model to determine accurate vehicle speed without requiring separate unbraked reference wheelsets, thus eliminating the additional components and assembly work.
5Ease of manufacture
If pulse generator signals are used to measure longitudinal acceleration, then acceleration can be measured cost-effectively, but accuracy is reduced due to sampling rate limitations and gravity compensation requirements
Solution Approach 1:
The patent merges multiple measurement approaches by combining data from pulse generators (wheel speed sensors) and acceleration sensors in an observer model. This fusion of measurement methods compensates for the individual limitations of each sensor type, providing accurate acceleration and speed determination while maintaining cost-effectiveness.
Data Source
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AI summary
Disclosed is a method for determining a carriage speed (vcarriage) of a carriage, said method comprising the following steps: sensor data available in the carriage are sensed as an input variable for an observer model (1, 2); the input variables are input into the observer model (1, 2); and the carriage speed (vcarriage) is continuously determined by the observer model (1, 2). A device, a vehicle and a computer program product for carrying out said method are also disclosed.