Rail Wheel Resolver Sensor for Low-Speed Position and Slip Detection
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Solution Overview
Problem
Current systems for determining wheel speed and position in rail vehicles face challenges such as inability to detect rotation direction, unreliable low-speed signals, high latency, and increased wear and energy consumption in precision stopping, particularly in automatic train operations.
Innovation Solution
A signal processing method and sensor system using a resolver with orthogonal windings to measure induced voltages, providing precise rotation speed and position calculations, and enabling low-latency control for improved brake performance and real-time diagnostics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pole-wheel-based encoder is used for wheel speed and position determination, then the system works well according to EN norms, but the signal quality becomes unreliable below 3 km/h
Solution Approach 1:
The patent replaces the mechanical pole-wheel-based encoder with an electromagnetic sensor system that measures wheel speed and position through electromagnetic induction. This substitution eliminates the mechanical contact limitations of the encoder, enabling reliable measurement down to zero speed while maintaining accuracy across the full speed range.
Solution Approach 2:
The patent changes the measurement parameter from mechanical position detection to electromagnetic field detection. By measuring the electromagnetic signature of the wheel rim instead of mechanical encoder pulses, the system achieves reliable low-speed and zero-speed measurement capability.
2Loss of time
If the latency of signal processing is reduced for fast interventions, then control precision and brake distance reproducibility improve, but the system complexity increases
Solution Approach 1:
The patent performs preliminary calculations of wheel speed and acceleration directly in the sensor unit before data leaves the sensor. This pre-processing approach reduces the computational burden on higher-level control systems and minimizes signal processing latency, enabling faster control responses without significantly increasing overall system complexity.
3Ease of operation
If precision stopping is achieved using only brake system, then stopping position control is simplified, but brake wear increases significantly
Solution Approach 1:
The patent provides high-resolution wheel position and speed feedback that enables precise control of the brake system. This accurate feedback allows the brake system to achieve precision stopping with minimal brake force application, significantly reducing brake wear compared to traditional methods that require stronger braking to compensate for measurement limitations.
4Measurement precision
If the wheel speed measurement resolution is increased for precision stopping, then the stopping position accuracy improves, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical measurement systems with an electromagnetic sensor that achieves high measurement resolution through signal processing rather than mechanical complexity. The electromagnetic approach provides fine measurement resolution for wheel position and speed without the mechanical complexity of high-resolution encoders or multiple sensor systems.
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
The solution enables precise and reliable wheel speed and position measurements, reducing latency and wear, improving brake reproducibility, and allowing for real-time diagnostics and adhesion curve measurement, enhancing precision stopping and automatic train operations.
Implementation Method 1
Excitation of a first winding (1) by an AC voltage, the first winding being provided on a wheel (W)... Measuring a first induced voltage in a second winding (2)
Implementation Method 2
Measuring a second induced voltage in a third winding (3)... wherein the middle axes of the second winding (2) and the third winding (3) are not parallel
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a signal processing method and a sensor (S), which comprises a first winding (1) being provided on a wheel (W), wherein the first winding (1) can include any angle (θ) with a reference position (R), a second winding (2), and a third winding (3), wherein the directions of the second winding (2), and a third winding (3) are not parallel; a signal generation and processing unit (8), adapted to provide an AC voltage to the first winding (1) and to receive the a first induced voltage (Vs) of the second winding (2) and the second induced voltage (Vs) of the third winding (2). With such system, wheel speeds / positions can be measured very accurately. In a further aspect the invention relates to a use of said sensor for determining rotational speeds of wheels of a rail vehicle (V) and/or determining wheel slips of wheels of a rail vehicle.