TPMS Wheel Module Localization via Centrifugal Ripple Reconstruction
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Solution Overview
Problem
Current tire pressure monitoring systems (TPMS) face challenges in efficient localization of wheel modules due to tire rotation and position changes, which complicates identifying low-pressure tires, and existing solutions are either expensive or power-intensive.
Innovation Solution
A method utilizing ABS counter values and vehicle speed information to reconstruct the +/−1 g ripple signal, allowing for localization of TPMS wheel modules with a simpler system, reduced ADC resolution, and lower power consumption, enabling accurate tire identification across various vehicle speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If low-g sensors are used to measure the +/−1 g signal for localization, then localization capability is achieved, but the dynamic range requirement increases system complexity and cost
Solution Approach 1:
The patent uses the acceleration sensor as an intermediary to measure centrifugal acceleration during wheel rotation. By measuring the centrifugal force at different rotation angles, the system indirectly determines wheel position without requiring specialized low-g sensors. This mediator approach allows standard acceleration sensors to perform the localization function.
Solution Approach 2:
The patent replaces the need for low-g sensors with a mechanical approach using the existing acceleration sensor. Instead of directly measuring the small +/−1 g signal with specialized sensors, the system measures centrifugal acceleration (which is much larger) and uses signal processing to extract position information. This substitution eliminates the need for complex low-g sensors while achieving the same localization capability.
2Measurement precision
If frequent localization signal transmissions are implemented, then localization accuracy is improved, but power consumption increases beyond acceptable limits
Solution Approach 1:
The patent implements periodic localization measurements based on wheel rotation cycles. Instead of continuous transmission, the system measures centrifugal acceleration at specific intervals during wheel rotation and transmits localization data periodically when the wheel reaches certain positions. This periodic approach maintains localization accuracy while significantly reducing power consumption compared to continuous operation.
Solution Approach 2:
The patent makes the acceleration sensor serve multiple functions: it simultaneously monitors wheel rotation for motion detection (to conserve battery) and measures centrifugal acceleration for localization. By combining these functions in a single sensor, the system avoids the power consumption penalty of separate localization sensors while maintaining both motion-saving and localization capabilities.
3Adaptability or versatility
If tire rotation and position changes are accommodated, then system adaptability is improved, but localization reliability deteriorates due to position ambiguity
Solution Approach 1:
The patent uses feedback from the acceleration sensor to continuously monitor wheel rotation and determine current wheel position. By measuring centrifugal acceleration patterns and comparing them against expected patterns for different wheel positions, the system receives feedback about actual tire location. This feedback mechanism allows the system to adapt to tire rotations and position changes while maintaining reliable localization through continuous position verification.
Solution Approach 2:
The patent performs preliminary measurements of centrifugal acceleration during wheel rotation to establish position patterns before actual localization is needed. By pre-characterizing the acceleration patterns at different wheel positions and storing this information, the system can quickly and reliably determine current tire location when needed, even after rotations or position changes, without requiring complex real-time analysis.
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 simplifies the system, reduces power consumption, and provides stable performance over a range of vehicle speeds, enabling effective localization of TPMS wheel modules with minimal current consumption and die area, while maintaining accuracy in tire identification.
Implementation Method 1
an acceleration sensor is often included in TPMS for motion sensing by measuring the centrifugal acceleration force in g's
Implementation Method 2
This causes a signal change of +/−1 g because of the effects of gravity, which while rotating over time results in a sinusoidal ripple on top of the centrifugal acceleration signal
Data Source
AI summary
Embodiments relate to unidirectional TPMS utilizing information from a corresponding vehicle system in order to correlate with vehicle speed information to be used in a tire localization methodology. In an embodiment, the vehicle system is an anti-lock brake system (ABS), and the vehicle speed can be used in a localization scheme that reconstructs a +/−1 g ripple with waveform, amplitude, frequency and phase parameters. Because the waveform is known to be sinusoidal (due to the wheel rotation), the amplitude is known to be 2 g peak-to-peak (due to the gravitational +/−1 g), the frequency depends on vehicle speed (which can be estimated from centrifugal force measurements), and an algorithm is discussed herein for determining the phase by correlation, the +/−1 g ripple can be reconstructed and the wheels localized therefrom.