| 摘要 |
PROBLEM TO BE SOLVED: To improve the accuracy of axle detection by constituting the axle detector so that the moving distance (the interval of a reflecting position) of an irradiation point in each pulse period of pulse light is sufficiently smaller than the cross-sectional height of a tire. SOLUTION: The width of a road is set up as L and it is supposed that a vehicle 24 of body width W passes a position most separated from an axle detector 21 arranged on the roadside 23 of the road at a vehicle speed V[m/sec]. When it is defined that a distance from the light projection part of the axle detector 21 up to a tire 48 is D[m] (D>-w) and the light emitting interval angle of pulse light projected from the detector 21 isΔθ[rad], the intervalΔh[m] of the reflecting position of pulse light projected from the detector 21 on the tire 48 can be approximately expressed byΔh=D.Δθ. Thereby the intervalΔh of the reflecting position of the pulse light is made sufficiently smaller than the cross-sectional height (a value obtained by subtracting the radius of an inner periphery from the radius of an outer periphery) of the tire 48 in order to improve the detection accuracy of the tire 48.
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