JPS588032B2 - Wheel number measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measurement method for determining the number of tires on a front wheel or a rear wheel (single tire or double tire) at a toll gate of a toll road or the like.

The number of wheels is generally measured by using a large number of contact sensors embedded in the road to detect the number of wheels being stepped on.

However, this method has the following drawbacks.

i Requires a large number of sensors.

n Short lifespan.

徂 Road construction is required for sensor installation and maintenance.

The present invention provides a measurement method using a non-contact sensor that solves the above-mentioned drawbacks.

Examples thereof will be described below.

In Fig. 1, beams A and B between the two pairs of near-infrared emitters SA, SB and light receiver RA'RB are both parallel to the road surface at a height of 5 to 10 c/rL above the road surface, and beam A is moving toward the vehicle. beam B is at an angle θ with the vehicle traveling direction.
Set it so that However, the angle θ must satisfy the following relationship for all two-axle vehicles.

In addition, each code is as follows.

X: TF-W, or. Smaller value of one kite Y:T
FW or 8-W3, whichever is larger TF: Front wheel tread TB: Rear wheel tread B: Wheelbase WF: Front wheel tire width W8: Rear wheel tire width (including tire gap in case of double tires) L: Length of tire that blocks beam A Now, if the vehicle to be measured passes through beams A and B at speed V, the time relationship in which beams A and B are blocked by the front and rear wheels is shown in Figure 2. shall belong to.

In other words, the time when beam A is blocked by the front wheels and rear wheels of the vehicle is T, , T2, respectively, the time when beam B is blocked by the front wheels is T2, T, and the time when beam B is blocked by the rear wheels is T5. , T6.

Then, the following relationship holds true between Le W, , W, # θ, and ■.

(2L (3)# If the result calculated using equation (5) from equation (4), and equation (7) from equation (6) is close to "1", the rear wheel is a single tire "2" similar to the front wheel. If it is close to , the number of wheels can be measured by determining that it is a double tire.

Note that the number of axles can be measured from the number of times the beam A is interrupted.

Furthermore, in the above description, even if the vehicle running speed V is constant or, for example, the acceleration is constant, there will be no error.

However, if the vehicle to be measured stops with the beam cut off, measurements will not be possible.

This problem can be solved by increasing the number of measurement systems using the two pairs of light emitting/receiving sections SA, SB, RA, and RB.

Note that the above-mentioned light emitters are an oscillator that generates a signal with a constant frequency fo, a driver that modulates the amount of light emitted by the light emitting element with the output of this oscillator, a light emitting diode as the light emitting element, and a sharp light emitting diode. It consists of lenses, etc. to focus the beam into a light beam.

The light receiving section RA t RB includes a lens for condensing incident light onto a light receiving element, a phototransistor as a light receiving element, a band amplifier for band amplifying a signal having a frequency component fo in the output of the phototransistor, and a band amplifier for band amplifying a signal having a frequency component fo in the output of the phototransistor. It consists of a rectifier circuit that rectifies the amplifier output, a level comparator that outputs "0" when the output of the rectifier circuit is above a certain level, and output "1" when it is below a certain level.

As described above, the vehicle counting method according to the present invention does not require road construction, and can count the number of wheels using a small number of non-contact sensors.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a device using a wheel number counting method according to an embodiment of the present invention, and FIG. 2 is a signal waveform diagram thereof. SA, SB ...... Light projecting section, "A, R13...
····Light receiving section.

Claims (1)

[Scope of Claims] 1. It has two pairs of light emitting/receiving parts, and the light beam emitted from each light emitting part crosses the road parallel to the road surface and is received by each corresponding light receiving part, and one of the light beams ( Beam A) is set to be perpendicular to the road traveling direction, and the other beam (beam B) is set to form an angle θ with the road traveling direction, and the time when the beam A is interrupted by the front wheel of the wheel to be measured is T1, after which Calculate the time when the beam A is blocked by the wheels as T2, the time when the beam B is blocked by the front wheels as T2, T3, and the time when the beam B is blocked by the rear wheels as T5, T6, and calculate the calculation result R. This wheel count measurement method is characterized by determining that the rear wheel is a single tire if it is close to "1", and that it is a double tire if it is close to "2".