METHOD AND APPARATUS FOR MEASURING SPEED OF VEHICLE

• Main Author: TAKANASHI ISAO
• Format: Patent
• Language: English
• Published: 21.11.1991
• Subjects: INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT; MEASURING; MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION,OR SHOCK; PHYSICS; TESTING

PURPOSE:To facilitate installation by simple constitution by calculating the time lag between two points of time when the output of the loop coil arranged to a vehicle running path coincides two different set values and calculating the speed of a vehicle from the time lag and the distance between two corresponding positions. CONSTITUTION:The vehicle detection signal of the frequency corresponding to the inductance of a loop coil 1 obtained when a vehicle passes on the loop coil 1 arranged to a road surface is outputted from the vehicle detection circuit 9 of a vehicle detector 2 and the signal from a frequency measuring circuit 5 is inputted to an inductance calculation circuit 12 through a gate circuit 11. The circuit 12 issues the output corresponding to the frequency changed by the effect of the vehicle to comparing circuits 13, 14. The first and second threshold values are set to the circuits 13, 14 and the value of the former is small. When the output of the circuit 12 increases, an FF 15 is set at first by the output of the circuit 13 and a clock circuit 16 starts clocking operation. Next, when the output of the circuit 12 exceeds the second threshold value, the FF 15 is reset by the output of the circuit 14 to stop the operation of the circuit 16 and a speed calculation circuit 17 calculates the speed of the vehicle from the time data of the circuit 16 to output the same.