Patent ID: 6711508
Filing Date: 2004-03-23
Classification: B60C,G01H,G01L,G01N

Abstract:
An apparatus for estimating tire air pressure of a vehicle based on a wheel speed signal, the apparatus comprisingan extracting component for extracting a resonance frequency or a spring constant of the tire based on a wheel speed signal including frequency components of vibration of the tire in operating the vehicle; a first estimating component for estimating the tire air pressure based on the resonance frequency or the spring constant of the tire extracted by the extracting component; a deriving component for deriving a dynamic load radius of the tire based on the wheel speed signal: a second estimating component for estimating the tire air pressure based on the dynamic load radius derived by the deriving component; and a switching component for selectively switching estimation of the air pressure by the first estimating component and the second estimating component in accordance with a statistic value based on the resonance frequency or the spring constant of the tire at a plurality of time points, wherein the statistic value is any one of a variance value, a standard deviation value, bias, and a kurtosis of the resonance frequency or spring constant at the plurality of time points.