Wheel Speed Sensor Dual Data Packets Low Speed Resolution
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Solution Overview
Problem
Existing wheel speed sensors face challenges in achieving higher resolution without compromising repeatability and magnetic field strength, particularly at low speeds, due to limitations in the number of pole pairs and signal frequency.
Innovation Solution
A wheel speed sensor that sends data packets of two types: one type indicative of pole transitions for high-speed operations and another type indicating signal amplitude for increased resolution at low speeds, allowing the electronic control unit to calculate wheel speed with higher accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of encoder pole pairs is increased to improve resolution, then measurement precision is improved, but repeatability performance (jitter) deteriorates and bandwidth requirements increase
Solution Approach 1:
The patent segments the measurement task into two parts: using pole transition detection for coarse position measurement and signal amplitude measurement for fine position measurement. This segmentation allows achieving high resolution without increasing pole pairs, thus maintaining repeatability performance while improving measurement precision.
Solution Approach 2:
The patent introduces signal amplitude as an intermediary parameter to achieve high resolution. Instead of relying solely on pole transitions, the amplitude of the signal between pole transitions serves as a mediator to provide fine-grained position information, enabling high resolution without increasing the number of poles.
2Measurement precision
If the number of encoder pole pairs is increased to improve resolution, then measurement precision is improved, but magnetic field strength is reduced
Solution Approach 1:
The patent segments the measurement task into coarse measurement (pole transitions) and fine measurement (signal amplitude). This allows maintaining a lower number of pole pairs with sufficient magnetic field strength while achieving high resolution through amplitude-based fine measurement, thus resolving the contradiction between resolution and magnetic field strength.
Solution Approach 2:
The patent changes the measurement parameter from relying solely on pole transition frequency to incorporating signal amplitude. By utilizing amplitude as an additional measurement parameter, the system achieves high resolution without needing to increase pole pairs, thereby maintaining adequate magnetic field strength.
3Measurement precision
If the number of encoder pole pairs is increased to improve resolution, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the resolution achievement into two independent components: pole transitions for coarse position and signal amplitude for fine position. This segmentation avoids the complexity of designing and manufacturing encoders with high pole pair counts, as the fine resolution is achieved through amplitude measurement rather than physical pole multiplication.
Solution Approach 2:
The patent substitutes the mechanical approach of increasing pole pairs with an electrical/signals-based approach of measuring signal amplitude. This replacement reduces mechanical/physical encoder complexity while achieving the same resolution goal through signal processing.
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 provides a significantly increased resolution for low-speed applications like automated parking while maintaining performance at high speeds, avoiding issues related to jitter and magnetic field strength loss.
Implementation Method 1
the sensing unit can preferably be a magnetic sensing unit, e.g. a coil
Data Source
Figure 1~3
AI summary
The invention relates to a wheel speed sensor being configured to send two types of data packets, wherein data packets of one type contain instantaneous sensor signal amplitude information. The invention relates further to a wheel speed sensing system comprising such a wheel speed sensor. The amplitude information represents e.g. the current bridge voltage of the sensor and allows to determine speed and position with high resolution at low speed, where the time between pole transitions can be very long. The amplitude data can also be representative of an interpolated angular position signal, derived e.g. from the sinusoidal current sensor signal of the sensor.