Aisin Seiki Kabushiki Kaisha

Hiroaki Kawai

Kenji Asano

Kenji Tozu

Katsu Hattori

The apparatus for detecting the air pressure of the tire includes an oscillating electric signal output section for outputting an oscillating electric signal including a vibration frequency component of a tire of a vehicle. A wavelet transformation section is provided for performing wavelet transformation of the oscillating electric signal outputted by the oscillating electric signal output section. A constant extraction section is provided for calculating mean values of the wavelet coefficients calculated by the wavelet transformation section at every predetermined interval of time, for obtaining an approximate curve of the second or greater order by a method of least squares using the mean values of the wavelet coefficients at the respective predetermined frequencies at every predetermined interval of time and for extracting a constant of the approximate curve. An air pressure estimating section is provided for estimating the air pressure of the tire based on the constant.

Method and apparatus for detecting air pressure in a tire using a basic

The invention is directed to a method and apparatus for detecting a tire inflation pressure of a vehicle tire. The apparatus includes a device for producing an oscillating electric signal having a vibration frequency component of the vehicle tire. A wavelet transformer transforms the oscillating electric signal by a wavelet function into a wavelet coefficient. The wavelet function is provided on the basis of a mother wavelet function localized in time, scaled in response to a scale parameter, and shifted in response to a shift parameter indicative of a time localization. Then, an extracting device extracts a resonance frequency from the vibration frequency component of the vehicle tire on the basis of the wavelet coefficient, and an estimating device estimates the tire inflation pressure on the basis of the resonance frequency. The apparatus may further include a warning device for warning a decrease of the tire inflation pressure when the resonance frequency decreases to an extent that a difference between the resonance frequency and the reference frequency exceeds a predetermined frequency.

Method and apparatus for detecting a tire inflation pressure

An anti-skid control for use in an automotive vehicle is comprised of a brake control device for adjusting braking force of each road-wheel of a vehicle, the brake control device being set to be initiated upon receipt of a condition, a detecting device being set to be initiated upon receipt of a condition, a detecting device for measuring a load applied to the vehicle, and a changing device for less sensitivity of the initiation of the brake control device as the load decreases. Even if an instantaneous decrease of the load occurs due to the vehicle's jumping motion or turning motion, an expected initiation of the brake operation can be prevented.

Skid control system

An anti-skid control system for use in an automotive vehicle comprises a brake detecting device for detecting a braking operation of the vehicle, a deceleration detecting device for detecting an deceleration of a road-wheel during the braking operation, and a control device for controlling the braking operation in order to establish the maximum value of the deceleration. Independent of a surface of a road, the minimum braking distance is obtained.

Anti-skid control system

An anti-skid control system for use in an automotive vehicle is comprises of a real slip rate detecting device for detecting a real slip rate of the vehicle, a target slip rate setting device for setting a target slip rate of the vehicle, a braking force control device for adjusting a braking force in such a manner that a deviation between the real slip rate and the target slip rate becomes zero, a load measuring device for measuring a load applied to the vehicle, an correcting device for adding a value to the control device which is the product of a coefficient and the deviation between the real slip rate and the target slip rate and a coefficient adjusting device for decreasing the coefficient as the load decreases. If the load decreases during the vehicle's travel, the coefficient to be multiplied to the deviation between the real slip rate and the target slip rate decreases. Thus the quantity to be subtracted from the braking force is decreased and the current braking force is hardly reduced.

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Aichi, Japan

Hiroaki Kawai