Tire Tread Wear Measurement via Internal Capacitance Oscillation
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Solution Overview
Problem
Existing methods for monitoring tire tread thickness and wear, especially in autonomous vehicles, face challenges in accuracy and reliability due to the need for human visual inspection and the complexity of measuring tire wear through indirect parameters like tire pressure and vibration frequencies.
Innovation Solution
A device with at least two electrodes affixed to the inside of a tire, connected to an oscillator, where the oscillator frequency depends on capacitance between the electrodes, allowing for real-time measurement of tire tread height and aging by detecting changes in capacitance as the tread wears or ages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency scanning method is used to measure tread depth, then measurement can be performed, but the method is complex and requires correlating specific frequency to tread depth
Solution Approach 1:
The patent changes the measurement parameter from frequency scanning to direct capacitance measurement. By using an RC oscillator where the oscillation frequency is directly determined by the capacitance between electrodes (which varies with tread depth), the system eliminates the need for frequency scanning and correlation algorithms, simplifying the measurement process while maintaining precision
Solution Approach 2:
The patent replaces the mechanical/electrical frequency scanning system with an electronic capacitance-based oscillation system. The RC oscillator circuit automatically converts capacitance changes (caused by tread depth variations) into frequency changes, eliminating the need for external frequency scanning equipment and complex signal processing
2Measurement precision
If indirect measurement based on tire pressure and vibration frequency is used, then tire wear can be estimated, but accuracy is reduced
Solution Approach 1:
The patent extracts the measurement function from indirect parameters (pressure, vibration) and places sensors directly at the measurement location - inside the tire cavity. By positioning electrodes between the tire cavity and external environment, the system directly measures the parameter of interest (tread depth via capacitance) rather than inferring it from secondary effects
Solution Approach 2:
The patent introduces capacitance as an intermediary physical quantity that directly relates to tread depth. The capacitance between internal and external electrodes varies with the distance to the tread surface, providing a direct measurement link without requiring inference from pressure or vibration data
3Measurement precision
If magnetic field sensors and magnetizable particles are used to measure tread depth, then measurement is possible, but special tires with magnetic particles are required
Solution Approach 1:
The patent uses homogeneous dielectric material (air or gas) in the tire cavity instead of requiring heterogeneous magnetic particles embedded in the tread. This approach maintains tire manufacturing simplicity while achieving accurate measurement through capacitance changes that occur naturally as the tread wears
Solution Approach 2:
The patent copies the measurement function from magnetic field interaction to electric field interaction. Instead of using magnetizable particles in the tread, the system uses electrodes that sense the dielectric properties of the tire structure, eliminating the need to modify tire composition while maintaining measurement capability
4Measurement precision
If contact patch length is used to determine tread depth, then measurement can be performed, but contact patch varies with tire pressure and load making extraction difficult
Solution Approach 1:
The patent creates a controlled measurement environment inside the tire cavity that is isolated from external variations in pressure and load. By positioning electrodes within the sealed tire cavity and measuring capacitance to external references, the system achieves consistent measurements that are not affected by operating conditions
Solution Approach 2:
The patent segments the measurement function from the variable operating conditions by placing sensors inside the tire cavity. This isolation allows the measurement system to capture only the tread depth information while filtering out the effects of pressure and load variations that occur during tire operation
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 solution provides a reliable and accurate method for monitoring tire tread thickness and wear, reducing downtime and enhancing safety by using capacitance-based frequency changes to indicate tire health, and can also detect road conditions like wetness, snow, or ice.
Implementation Method 1
an oscillator connected to a tire such that the oscillator frequency depends on the capacitance between the electrodes and such that the frequency is a measure to the tread height or tire aging
Implementation Method 2
transmitting an oscillating signal from a first pad, through the material with some dielectric property, to a second pad, and measuring the signal reflected to the first pad
Data Source
AI summary
A tire with a treads depth measuring device that includes a first electrode and a second electrode that are fixed to internal surface of the tire, and an oscillator that is electrically connected to the electrodes so that capacitance between the electrodes affects frequencies of the oscillator. Changes in frequencies of the oscillator can be used to detect and calculate changes in thickness of the tire and changes in depth of treads in the tire.