| 摘要 |
PURPOSE:To perform the control in consideration of the braking condition and to inexpensively detect the frictional coefficient of the road surface by emitting an ultrasonic wave and measuring the pulse width of the reflected wave from the road surface. CONSTITUTION:A short pulse electric signal having an ultrasonic frequency is generated by a transmitter 1. This electric signal is sent to a transmitter- receiver 3 through a transmission/reception switch 2 and is radiated to air from the transmitter-receiver 3 as an ultrasonic pulse. This ultrasonic pulse is propagated in air and reaches the road surface and is reflected on the road surface and is received as the reflected wave by the transmitter-receiver 3. Since the frictional coefficient of the road surface is related to the hardness of the road surface and this hardness is related to the reflection coefficient of the ultrasonic wave, the pulse width of the reflected wave is measured by a pulse width measuring part 5 to detect the frictional coefficient of the road surface. |
