| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and device for detecting a drop in internal pressure of a tire with high accuracy by collecting data on a traveling state of a vehicle while utilizing GPS positioning information only when a stable dynamic load radius can be measured, and by comparing GPS speed information and tire rotating speed information to calculate an exact dynamic load radius. SOLUTION: Speed of a traveling vehicle is calculated based on the information obtained by a GPS device, and the speed of the vehicle calculated by the GPS device is successively compared with the tire rotating speed obtained by tire rotating speed detecting devices installed in rotating portions of four tires of the vehicle, thereby calculating an apparent dynamic load radius of the tire during traveling. Only when it is determined based on the GPS positioning information that the vehicle is traveling, at constant speed, on a flat road, effectivity of a dynamic load radius value is determined. The dynamic load radius value is compared with an initial value previously stored as the dynamic load radius in a normal state of the internal pressure, and, based on the magnitude of the change of the dynamic load radius, the drop in the internal pressure of the tire is determined. COPYRIGHT: (C)2007,JPO&INPIT
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