Tire pressure decrease detection apparatus, method, and computer readable medium therefor

A method for detecting a decrease in tire pressure based on a resonance frequency of a tire installed in a vehicle, including:

• a rotation information detection step for detecting rotation information of the tire,
• a resonance frequency estimate step for estimating the resonance frequency of the tire from the rotation information of the tire, and
• a judgment step for judging the decrease in the tire pressure by comparison between the resonance frequency estimated in the resonance frequency estimate step and a reference frequency preliminarily determined by learning at the time of initialization,
• wherein an effective speed region when the reference frequency is determined at the time of the initialization is a first speed and less, the first speed being the upper limit of the effective speed region, and
• wherein the method further includes an effective speed region change step for extending the upper limit of the effective speed region from the first speed to a second speed which is larger than the first speed at the time of shifting to judgment of the decrease in the pressure after learning of the reference frequency is completed.

A non-transitory computer readable medium encoded with a computer program containing instructions stored therein which causes a computer, for detecting a decrease in tire pressure based on a resonance frequency of a tire installed in a vehicle, to function as

• resonance frequency estimate means for estimating the resonance frequency of the tire from rotation information obtained by rotation information detection means for detecting the rotation information of the tire, and
• judgment means for judging the decrease in the tire pressure by comparison between the resonance frequency estimated by the resonance frequency estimate means and a reference frequency preliminarily determined by learning at the time of initialization,
• wherein an effective speed region when the reference frequency is determined at the time of the initialization is a first speed and less, the first speed being the upper limit of the effective speed region, and
• wherein the program further causes the computer to function as effective speed region change means for extending the upper limit of the effective speed region from the first speed to a second speed which is larger than the first speed at the time of shifting to judgment of the decrease in the pressure after learning of the reference frequency is completed.