Patent application number | Description | Published |
20090282906 | APPARATUS AND METHOD FOR DETECTING DECREASE IN TIRE AIR PRESSURE AND PROGRAM FOR DETECTING DECREASE IN TIRE AIR PRESSURE - An apparatus for detecting a decrease in a tire air pressure includes: a rotation velocity information detection means for periodically detecting tire rotation velocity information for the respective wheels of a vehicle; a frequency characteristic estimate means for estimating, based on this rotation velocity information, a frequency characteristic of the rotation velocity information; and a judgment means for judging, based on the estimated frequency characteristic, a decrease in the air pressure of the tire. The frequency characteristic estimate means includes, with regard to a time-series signal including the rotation velocity information, a parameter estimate means for subjecting parameters of a three-order or more linear model to a time-series estimate; an input signal estimate means for estimating, based on the estimated linear model and the rotation velocity information that is an output signal of the linear model, an input signal to the linear model; a parameter identification means for identifying, based on the estimated input signal and the rotation velocity information, parameters of a linear model caused to have a lower order of a second order; and a resonant frequency estimate means for estimating, based on the parameters identified based on the model caused to have a lower order of the second order, a resonant frequency of the tire in a torsional direction. | 11-19-2009 |
20100013616 | APPARATUS AND METHOD FOR DETECTING DECREASE IN TIRE AIR PRESSURE AND PROGRAM FOR DETECTING DECREASE IN TIRE AIR PRESSURE - The invention includes: a rotation velocity information detection means for regularly detecting tire rotation velocity information regarding the respective wheels of a vehicle; a frequency characteristic estimation means for estimating a frequency characteristic of the rotation velocity information based on the rotation velocity information obtained from the rotation velocity information detection means; and a determination means for determining a decrease in the air pressure of the tire based on the estimated frequency characteristic. The frequency characteristic estimation means is configured to extract a resonance peak of the rotation velocity information by calculating a gain corresponding to an arbitrary frequency. | 01-21-2010 |
20100013617 | APPARATUS AND METHOD FOR DETECTING DECREASE IN TIRE AIR PRESSURE AND PROGRAM FOR DETECTING DECREASE IN TIRE AIR PRESSURE. - An apparatus for detecting a decrease in a tire air pressure includes; a rotation velocity information detection means for regularly detecting tire rotation velocity information regarding the respective wheels of a vehicle; a resonance frequency estimation means for estimating a resonance frequency of the rotation velocity information based on the rotation velocity information obtained by the rotation velocity information detection means; and a determination means for determining, based on the estimated resonance frequency, a decrease in the tire air pressure. The apparatus includes a data rejecting means for rejecting data of rotation velocity information hindering the estimation of the resonance frequency. | 01-21-2010 |
20100217542 | APPARATUS, METHOD, AND PROGRAM FOR DETECTING ROTATION SPEED INFORMATION, AND APPARATUS, METHOD, AND, PROGRAM FOR DETECTING TIRE HAVING DECREASED PRESSURE - A rotation speed information detection apparatus, including: a wheel sensor for detecting passage of teeth of a gear provided in association with tires of a vehicle; a number-of-teeth calculation means for calculating the number of teeth of the gear passed per a sampling cycle set in advance; and a wheel speed calculation means for regularly calculating rotation speed information of the tire with using the number of teeth calculated. The number-of-teeth calculation means is configured to use a ratio between time information at the point and a remaining time until the time at which the next sampling cycle is started is reached to thereby calculate the number of remaining teeth to calculate the number of teeth passed during the sampling cycle. The wheel speed calculation means is configured to calculate tire rotation speed information based on an interval between neighboring teeth in the gear, the number of teeth passed during the sampling cycle, the number of remaining teeth calculated by the number-of-teeth-calculation means, and the sampling cycle. | 08-26-2010 |
20100225463 | APPARATUS AND METHOD FOR DETECTING TIRE HAVING DECREASED PRESSURE, AND PROGRAM FOR DETECTING TIRE HAVING DECREASED PRESSURE - An apparatus for detecting a tire having a decreased pressure based on resonance frequency of tires attached to respective wheels of a vehicle. The apparatus includes a storage means for storing information regarding a distribution of resonance frequencies respectively corresponding to a plurality of air pressure statuses, an initialization means for estimating a frequency characteristic of the rotation speed information or the rotation acceleration information, a frequency estimation means for estimating a frequency characteristic of the rotation speed information or the rotation acceleration information of a running vehicle, and a Bayesian estimation means for subjecting a tire pressure status at a certain time to a Bayesian estimation based on the resonance frequency during the initialization, a resonance frequency at the certain time obtained from the frequency estimation means, and distribution-related information stored in the storage means. | 09-09-2010 |
20110107828 | APPARATUS AND METHOD FOR DETECTING TIRE HAVING DECREASED PRESSURE, AND PROGRAM FOR DETECTING TIRE HAVING DECREASED PRESSURE - The detection appatatus includes means for detecting rotation speed information of the respective wheels of a vehicle; means for estimating, a frequency characteristic of the wheel rotation speed information; and means for determining, based on the estimated frequency characteristic, a tire having a decreased air pressure. The frequency characteristic estimate means includes, to a time-series signal including the wheel rotation speed information: means for time-series estimating a third order or more linear model parameter; means for generating pseudo input data; means for estimating, based on the estimated linear model parameter and the pseudo input data, output data to a linear model; means for identifying, based on the pseudo input data and the estimated output, a linear model parameter for which the order is reduced to a second order; and means for estimating, based on the identified parameter for which the order is reduced to the second order, a resonance frequency of a tire torsional direction. The decreased air pressure determination means is so configured as to determine a tire having a decreased air pressure based on the estimated resonance frequency of the tire torsional direction. | 05-12-2011 |
20120245787 | APPARATUS, METHOD AND PROGRAM FOR VEHICLE MASS ESTIMATION, AND APPARATUS, METHOD AND PROGRAM FOR DETECTING DECREASE IN TIRE AIR PRESSURE - A vehicle mass estimation apparatus includes a wheel rotation speed information detection device configured to detect rotation speed information regarding the respective wheels of the vehicle; a frequency characteristic estimation device configured to calculate wheel acceleration information based on the rotation speed information of the wheels to estimate a frequency characteristic of the wheel acceleration information; and a vehicle mass estimation device configured to estimate a vehicle mass based on the estimated frequency characteristic. The frequency characteristic estimation device calculates an integrated value of frequency gain magnitudes of the respective frequency domains of front wheels and rear wheels of the vehicle, and the vehicle mass estimation device estimates the vehicle mass based on the ratio among the respective integrated values of the front wheels and rear wheels and a relation calculated in advance between the ratio and the vehicle mass. | 09-27-2012 |
20120304754 | SYSTEM, METHOD, AND PROGRAM FOR DETECTING DEFLATED TIRES - A system detects deflated tires based on a resonance frequency of tires with a vehicle and a relative comparison value of rotation speeds of the tires. The system includes: a rotation information detection means for detecting rotation information of the tires; a rotation speed calculation means for calculating rotation speeds of the tires; a resonance frequency assumption means for assuming a resonance frequency of the tires; and a determination means for detection of deflated tires using a decreased pressure determination index calculated by a relative comparison of the rotation speeds of the tires and the resonance frequency. The determination means is so configured as to reduce the second threshold to be compared with the decreased pressure determination index to a value equal to or higher than 1% and equal to or lower than 90% and to detect deflated tires when the decreased pressure determination index exceeds the reduced threshold. | 12-06-2012 |