Vehicle Wheel Radial Acceleration Calculation via Rotation Period
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Solution Overview
Problem
Radial acceleration sensors used in vehicle wheel monitoring systems become saturated at high speeds, rendering them unable to measure radial acceleration, which is essential for tire pressure monitoring and load estimation, leading to incomplete tire footprint detection and wear monitoring.
Innovation Solution
A method that calculates radial acceleration by determining the distance between the wheel axis and the wheel unit using the period of rotation, allowing for radial acceleration calculation even when the sensor is saturated, through formulas Zcalc = R × ω^2, where R is the stored distance and ω = 2 × π / T, with T being the wheel's period of rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radial acceleration sensor is used to measure wheel acceleration, then measurement precision is improved at low speeds, but the sensor becomes saturated at high speeds making measurement impossible
Solution Approach 1:
The invention changes the measurement parameter from direct radial acceleration measurement to period of rotation measurement. By measuring the period T of wheel rotation instead of directly measuring radial acceleration Z, the system avoids sensor saturation while maintaining the ability to determine wheel dynamics. The period measurement remains reliable across all speed ranges including high speeds where the original sensor fails.
2Productivity
If the vehicle speed increases beyond the saturation threshold, then productivity is improved through higher speed operation, but the radial acceleration measurement becomes unavailable
Solution Approach 1:
The invention introduces an intermediary measurement approach where the period of rotation T serves as a mediator to indirectly obtain information about wheel acceleration. Instead of directly measuring radial acceleration which becomes unavailable at high speeds, the system measures the period of rotation and uses it to calculate the necessary parameters, thus preserving information flow across all operating conditions.
3Reliability
If a tangential acceleration sensor is used instead of radial acceleration sensor, then saturation problem is avoided, but the required functions for tire pressure monitoring and load estimation cannot be performed
Solution Approach 1:
The invention inverts the conventional approach by not using an alternative sensor type (tangential acceleration sensor) but rather by fundamentally changing what is measured (from acceleration to period of rotation). This inverted approach maintains compatibility with the original radial acceleration measurement system while avoiding its limitations, thereby preserving all required functions for tire pressure monitoring and load estimation.
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
Enables continuous measurement of radial acceleration across all vehicle speeds, ensuring accurate tire pressure monitoring and load estimation, and preventing tire wear monitoring issues caused by sensor saturation.
Implementation Method 1
radial acceleration sensors of microelectromechanical system type (also called 'MEMS'), in particular piezoelectric accelerometers
Implementation Method 2
calculating said radial acceleration Zcalc using the following formula: Zcalc=R×ω2 where: R being the distance between the axis of rotation of the wheel and the wheel unit defined and stored in step 1) of the method according to the invention and T being the period of rotation determined in step 2a)
Data Source
AI summary
A method for determining a vehicle wheel's radial acceleration for a tyre pressure monitoring system, having a central electronic unit. The wheels each including a wheel unit attached to a rim or to a valve or the tyre tread's inner face, and including at least one radial acceleration sensor at a distance from the wheel's rotational axis, to measure the wheel's radial acceleration when it is not saturated, and a microprocessor, including: when the radial acceleration sensor is not saturated, measuring the radial acceleration of the wheel using the radial acceleration sensor; determining the wheel's rotation period; deducing, from the radial acceleration and the period, the distance of the wheel unit; storing the distance in the wheel unit's memory; and when the radial acceleration sensor is saturated, determining the wheel's rotation period, and calculating the radial acceleration from the rotation period and the stored distance.