Tire Distance Measurement Using Crown-Normal Acceleration
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Solution Overview
Problem
Existing methods for determining the distance traveled by a tire casing are either energy-inefficient, require complex angular precision, or are affected by temperature corrections due to their placement on the wheel or tread, leading to inaccurate and power-hungry measurements.
Innovation Solution
A method involving a sensor mounted plumb with the tire crown, measuring normal acceleration to calculate distance traveled efficiently in real-time, using a threshold to filter noise and correct for temperature-independent centrifugal acceleration, with computations optimized for energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an accelerometer is mounted on the wheel to measure distance travelled, then the measurement accuracy is improved, but the device complexity and power consumption increase
Solution Approach 1:
The invention extracts the accelerometer from the wheel assembly and relocates it to the tire casing. This separation allows the measurement function to be maintained while reducing the complexity of the wheel-mounted TPMS device. The accelerometer becomes an independent component integrated into the tire structure rather than being part of the complex wheel assembly.
Solution Approach 2:
The accelerometer in the tire casing serves multiple functions: it measures both the rotational speed of the tire and the vertical acceleration for distance calculation. This multi-functionality reduces the need for additional sensors and simplifies the overall device architecture while maintaining measurement accuracy.
2Measurement precision
If temperature correction is applied to accelerometer signals, then the measurement accuracy under extreme conditions is improved, but the device complexity and computational requirements increase
Solution Approach 1:
The invention extracts the temperature sensor from the wheel assembly and places it in the tire casing near the accelerometer. This co-location allows for direct measurement of the accelerometer's operating temperature, enabling simple temperature compensation without complex thermal modeling or multiple sensors distributed throughout the wheel assembly.
3Use of energy by moving object
If an accelerometer is used to detect wheel rotation status, then the power saving capability is improved, but the device complexity increases
Solution Approach 1:
The accelerometer serves dual purposes: it continuously monitors the vertical acceleration to detect wheel rotation status (enabling power management) and simultaneously provides the data needed for distance calculation. This eliminates the need for separate rotation detection sensors and reduces overall device complexity while achieving power savings.
Solution Approach 2:
The system uses feedback from the accelerometer signals to determine wheel rotation status and adjust power consumption accordingly. When the wheel is stationary or rotating very slowly, the system can reduce sampling frequency or enter low-power mode, while maintaining full functionality during active rotation. This feedback-based power management optimizes energy usage without requiring additional control hardware.
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
Provides accurate, energy-efficient distance measurement by filtering noise and correcting for temperature effects, enabling long-term tire wear monitoring without high power consumption.
Implementation Method 1
at least one sensor (3) having a radial position RC with respect to the natural axis of rotation in its on-wheel mounted state and able to generate at least one output signal proportional to the acceleration experienced by said sensor in the tyre casing
Data Source
AI summary
A method for obtaining the distance travelled by a tire comprises fixing a sensor, to the right of the crown with a radial position Rc, capable of generating a signal proportional to the acceleration experienced; rolling the tire at a rotation speed W, subject to a load Z; acquiring, after a time T, a first signal Sigi comprising the acceleration amplitude in the direction normal to the crown, wherein the values below a threshold N represent less than 40 percent of the length of the first signal; identifying a reference value Vireference, being the square root of the average value of the first signal Sigi; and determining the distance travelled D during the time T from the following formula: D=A*T*Vireference, where A is proportional to the square root of the rolling radius of the tire.