Vehicle Detection Device

Abstract

To provide a vehicle detection device that enables adjustment of a mounting angle of a head unit that transmits and receives ultrasonic signals to be easily completed.SOLUTION: A control unit controls the flashing and lighting of a light-emitting unit 1f via a light emitting unit drive circuit when a reception level p is greater than a first set reception level P1. The difference between a second set reception level P2 and the reception level p is calculated, and the light-emitting unit 1f is blinked at intervals according to this difference. The smaller the difference, the shorter a blinking interval shall be controlled. As an operator gradually tilts a head unit in the direction in which the head unit should be tilted, the reception level p increases and the blinking interval of the light-emitting unit 1f becomes shorter. When the reception level p becomes greater than the second set reception level P2, the light-emitting unit 1f lights up continuously, allowing the operator to know that an optimum mounting angle has been reached, and angle adjustment is completed by fixing the head unit in place.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a vehicle detection device that detects vehicles by transmitting and receiving ultrasonic signals from a head unit to a road surface. [Background technology]

[0002] Ultrasonic vehicle detectors, which detect vehicles traveling on the road by placing a head unit directly above the road surface, transmitting an ultrasonic signal from this head unit to the road surface directly below, and receiving the reflected wave of the ultrasonic signal from vehicles traveling on the road surface, are widely used at intersections and other locations.

[0003] When introducing such a vehicle detection device, after installing the head unit, it is necessary to adjust the mounting angle so that the receiving sensitivity of the reflected wave is equal to or greater than a threshold value.

[0004] Patent Document 1 discloses a vehicle detection device that is brought to a work site. This portable vehicle detection device has an oscilloscope placed inside the device, and it is possible to adjust the mounting angle of the ultrasonic head while checking the waveforms and the like displayed on the oscilloscope's display panel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-180940 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the vehicle detection device of Patent Document 1, the worker must bring the vehicle detection device to the work site and connect it to the ultrasonic head each time the mounting angle is adjusted, and there is a problem that if the vehicle detection device is not available, the mounting angle cannot be adjusted.

[0007] Furthermore, with the vehicle detection device of Patent Document 1, the operator must check the waveform displayed by the oscilloscope to determine whether or not the adjustment is complete from the waveform, which requires the operator to have a certain degree of experience and skill in order to read the waveform. Furthermore, when adjustments are made during the day, sunlight enters the display panel, making it difficult to check the waveform, which is a problem.

[0008] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to solve the above-mentioned problems and to provide a vehicle detection device that eliminates the need for an operator to carry an adjustment device to the work site and enables easy adjustment of the mounting angle of the head unit. [Means for solving the problem]

[0009] In order to achieve the above object, vehicle detection according to the present invention Device is a vehicle detection device including a control unit that is connected to a head unit that is installed directly above a road surface and transmits and receives ultrasonic signals to and from the road surface directly below, and a notification unit that is connected to the control unit and issues notifications, and the control unit controls the notification unit to either intermittently notify, continuously notify, or not issue any notification based on a reception level of a reflected wave of the ultrasonic signal from the road surface input from a receiving unit of the head unit and a preset set reception level. the set reception level is composed of a first set reception level and a second set reception level that is higher than the first set reception level, and the control unit starts control of the intermittent notification by the notification unit when the reception level exceeds the first set reception level, and when the reception level exceeds the first set reception level and is equal to or lower than the second set reception level, calculates a difference between the second set reception level and the reception level, and controls the notification unit to shorten the interval at which the notification is made intermittently as the difference becomes smaller. The present invention is characterized by the above. Effect of the Invention

[0010] With the vehicle detection device of the present invention, the worker does not need to bring an adjustment device to the work site, and can easily complete the adjustment of the mounting angle of the head unit by checking intermittent and continuous notifications from notification units such as the light-emitting unit, speaker, and vibration. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram of a vehicle detection system. [Diagram 2] FIG. 2 is an explanatory diagram illustrating vehicle detection by the vehicle detection system. [Diagram 3]11 is an explanatory diagram for explaining the angle adjustment of the head part when installed. FIG. [Figure 4] 13 is an explanatory diagram for explaining how to adjust the angle of the head part after installation. FIG. [Diagram 5] 13 is a flowchart of the control unit when adjusting the angle of the head unit. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Figure 1 is a block diagram of a vehicle detection system, which consists of a vehicle detection device 1 installed in a box-shaped housing and a head unit H connected to the vehicle detection device 1 and which transmits and receives ultrasonic signals s to and from the road surface R directly below.

[0013] The head unit H includes a transmitting unit H1 that radiates an ultrasonic signal s toward the road surface R, and a receiving unit H2 that receives the reflected wave of the ultrasonic signal s and converts it into an electric signal.

[0014] The vehicle detection device 1 is composed of a control unit 1a that performs various processes, an ultrasonic driving circuit 1b that is arranged between the control unit 1a and the transmission unit H1 and drives and controls the ultrasonic signal s that is radiated via the transmission unit H1, an amplifier 1c and an A / D converter 1d that are arranged between the control unit 1a and the reception unit H2, and a light emitting unit driving circuit 1e and a light emitting unit 1f that are connected to the control unit 1a.

[0015] The control unit 1a controls the transmitting unit H1 of the head unit H via the ultrasonic driving circuit 1b, and an electrical signal converted from a reflected wave from the road surface R is input via the receiving unit H2 of the head unit H. The control unit 1a also controls light emission such as blinking and continuous lighting of the light emitting unit 1f via the light emitting unit driving circuit 1e.

[0016] The amplifier 1c amplifies the electrical signal of the reflected wave, and the A / D converter 1d converts the amplified received signal into a digital signal. The amplifier 1c and the A / D converter 1d may be provided on the head unit H side.

[0017] The light emitting unit 1f functions as a notification unit that notifies the worker, and can be, for example, an LED element, and the light emitting unit drive circuit 1e can control the blinking and continuous lighting of the light emitting unit 1f. As described later, other aspects of the notification unit can include a speaker as a voice generating unit and a vibration as an oscillation unit.

[0018] The light-emitting unit 1f is positioned so that the blinking, continuous lighting, etc. can be visually confirmed by an operator who adjusts the angle of the head unit H. When the light-emitting unit 1f is also stored inside a box-shaped housing, visual confirmation is performed with the door of the housing open.

[0019] The light emitting unit 1f may be disposed outside the housing so that it can be seen from outside without opening or closing the door, or a window made of a transparent material may be provided in the housing. In addition, by using a highly luminous red LED element as the light emitting unit 1f, the blinking state of the light emitting unit 1f can be seen even in the daytime.

[0020] 2 is an explanatory diagram illustrating vehicle detection by the vehicle detection system. The vehicle detection device 1 installed in a box-shaped housing is attached to, for example, a pillar K, and a head part H connected to the vehicle detection device 1 is attached to the lower side of an arm part A extending horizontally from the pillar K.

[0021] Then, from the transmitter H1 of the head H placed at a predetermined height, an ultrasonic signal s with a frequency of 27 kHz and a transmission time of 2 ms is repeatedly transmitted at a cycle of 80 ms.

[0022] Based on the time difference d0 between the ultrasonic signal s emitted from the transmitting unit H1 and the reflected ultrasonic signal s, and the time difference d1 which is a threshold value, it is determined whether the state is as shown in Figure 2(a) or (b), i.e., whether or not a vehicle C is present.

[0023] If the time difference d0 is within a predetermined time difference d1, it can be assumed that the ultrasonic signal s has been reflected by the vehicle C. The predetermined time difference d1 is set appropriately according to the height at which the head unit H is installed.

[0024] Next, the duration during which the repeatedly emitted ultrasonic signal s is detected within the time difference d1 is measured. This duration corresponds to the detection time for one vehicle C, and it is also possible to calculate the traveling speed of the vehicle C based on this detection time and the average vehicle length of the vehicle. In this way, it is possible to measure the number of passing vehicles in a given time and the average traveling speed obtained by averaging the traveling speeds of each vehicle C.

[0025] 3 is an explanatory diagram for explaining the angle adjustment of the head part H during installation. When attaching the head part H, after temporarily fixing the head part H as shown in (a), the angle of the head part H is adjusted from the state in (a) where it is tilted by an angle θ until the ultrasonic signal s is perpendicular to the road surface R as shown in (b), that is, until the angle θ becomes 0.

[0026] As shown in Figure 3(b), the angle is adjusted so that the emission direction of the irradiated ultrasonic signal s is parallel to the reflection direction on the road surface R, that is, so that the reception level p of the receiving unit H2 of the reflected wave of the ultrasonic signal s from the road surface R is equal to or greater than a predetermined value. In this state, the head unit H is fixed in place, completing the installation of the head unit H.

[0027] 4 is an explanatory diagram showing the angle adjustment of the head unit H when ruts or the like occur due to aging of the road surface R after the head unit H is installed. As shown in (a), when ruts or other depressions occur on the road surface R directly below the head unit H due to aging, the ultrasonic signal s emitted from the transmitter H1 will be reflected by the road surface R in a direction different from the incident direction. When reflected in a different direction, the reception level p of the receiver H2 decreases according to the shift in the reflection direction, and the reflected wave of the ultrasonic signal s may not be detectable by the receiver H2.

[0028] In such a case, as shown in (b), it is necessary to adjust the angle of the head unit H again and tilt it by an angle θ so that the emission direction of the irradiated ultrasonic signal s is parallel to the reflection direction on the road surface R, i.e., so that the reception level p of the reflected wave is equal to or greater than a predetermined value.

[0029] Incidentally, when the head portion H is tilted by the angle θ in this manner, the reflected wave when a vehicle C having a substantially horizontal ceiling or the like passes by will be reflected at a shifted reflection angle; however, this does not pose any particular problem since the distance is short and the reception level p of the reflected wave is detected as being strong.

[0030] 5 is a flow chart of the control unit 1a when adjusting the angle of the head unit H when and after the head unit H is installed. In step ST1 after starting, the control unit 1a compares the reception level p of the reflected wave input from the amplifier 1c and the A / D converter 1d with a first set reception level P1. The first set reception level P1 is set in advance as a reception level lower than a second set reception level P2 described later. The reception level p of the reflected wave is an average value of the most recent 10 times, for example 50 times.

[0031] If the reception level p is greater than the first set reception level P1, the process proceeds to step ST2, and if the reception level p is less than the first set reception level P1, the operator continues adjusting the angle.

[0032] When the reception level p of the reflected wave is greater than the first set reception level P1, the control unit 1a controls the blinking and lighting of the light emitting unit 1f via the light emitting unit drive circuit 1e. In step ST2, the reception level p of the reflected wave is compared with a second set reception level P2 that is greater than the first set reception level P1.

[0033] The first set reception level P1 is a threshold value at which the light-emitting unit 1f starts to flash, and the second set reception level P2 is a threshold value at which the light-emitting unit 1f starts to light continuously, and indicates that a reception level has been reached at which sufficient reflected waves can be detected, as shown in Figures 2(a) and 3(b).

[0034] In step ST2, if the reception level p of the reflected wave is smaller than the second set reception level P2, the process proceeds to step ST3, and if the reception level p is larger than the second set reception level P2, the process proceeds to step ST4.

[0035] In step ST3, the difference between the second set reception level P2 and the reception level p of the reflected wave is calculated, and the light-emitting unit 1f is blinked at intervals according to this difference. As the difference becomes smaller, the blinking interval is shortened.

[0036] When the angle adjustment is started gradually in one direction, steps ST1 to ST3 are repeated and, as the reception level p increases, the blinking interval of the light-emitting portion 1f gradually becomes shorter after the blinking starts.

[0037] In addition, when performing blinking control to shorten the blinking interval according to the difference between the second set reception level P2 and the reception level p, the reception level p and the blinking interval are set according to a linear function, but it may be set according to a quadratic function or an exponential function. Alternatively, the blinking interval may be controlled in three stages: long, normal, and short.

[0038] By repeating steps ST1 to ST3, the worker adjusts the angle of the head unit H by predicting in which direction the head unit H should be tilted based on the relationship between the direction of irradiation of the ultrasonic signal s and the road surface, and tilts the head unit H in an appropriate direction.

[0039] When the reception level p exceeds the first set reception level P1, the light emitting portion 1f starts to flash, thereby notifying the operator in which direction the head portion H should be tilted.

[0040] Furthermore, as the worker gradually tilts the head part H in the direction in which it should be tilted, the reception level p increases and the blinking interval of the light emitting part 1f becomes shorter. This allows the worker to know the optimal mounting angle of the head part H.

[0041] The worker adjusts the angle of the head part H so that the blinking interval of the light-emitting part 1f becomes shorter, and when the optimal mounting angle is reached, the reception level p becomes greater than the second set reception level P2, which is the reception level at which sufficient reflected waves can be detected, and the process moves from step ST2 to step ST4.

[0042] In step ST4, the light emitting unit 1f is continuously lit, so that the operator can know that the optimum mounting angle has been achieved, and the head unit H is fixed in place to complete the angle adjustment.

[0043] It is preferable that the light-emitting unit 1f always lights up when the head unit H is at the optimal mounting angle. In this way, if the light-emitting unit 1f is flashing or not lit, it becomes possible to easily confirm that a problem has occurred with the mounting angle of the head unit H.

[0044] In addition to the light emitting unit 1f, a speaker unit may be provided. This speaker unit controls the buzzer to emit an intermittent buzzer sound when the reception level p is greater than a first set reception level P1, and to emit a continuous buzzer sound when the reception level p is greater than a second set reception level P2.

[0045] Furthermore, the light emitting unit 1f and the above-mentioned speaker unit do not necessarily need to be provided in the vehicle detection device 1, and a wireless unit may be arranged in the vehicle detection device 1 to wirelessly control a terminal device held by an operator, such as a smartphone. In this case, vibration can be used instead of sound from the speaker unit.

[0046] In this way, according to the vehicle detection device of the present invention, the worker does not need to bring an adjustment device to the work site. Also, the control unit 1a controls the notification unit to notify intermittently, continuously, or not at all based on the difference between the reception level p input from the receiving unit H2 of the head unit H and the first and second preset reception levels P1 and P2, allowing the worker to easily complete the adjustment of the mounting angle of the head unit H. [Explanation of symbols]

[0047] 1 Vehicle detection device 1a Control section 1f Light emitting part H Head H2 Receiver p Reception level P1 First setting reception level P2 Second setting reception level R Road surface s Ultrasonic signal

Claims

1. A vehicle detection device including a control unit that is connected to a head unit that is installed directly above a road surface and transmits and receives ultrasonic signals to and from the road surface directly below, and a notification unit that is connected to the control unit and issues notifications, the control unit performs control to intermittently notify, continuously notify, or not notify at all via the notification unit based on a reception level of a reflected wave of the ultrasonic signal from the road surface input from the receiving unit of the head unit and a preset set reception level; the set reception level includes a first set reception level and a second set reception level that is greater than the first set reception level, the control unit starts control of the notification unit to perform the intermittent notification when the reception level exceeds the first set reception level; A vehicle detection device characterized in that, when the reception level exceeds the first set reception level and is equal to or lower than the second set reception level, a difference between the second set reception level and the reception level is calculated, and the smaller the difference becomes, the shorter the interval at which the notification unit makes intermittent notifications is controlled.

2. 2. The vehicle detection device according to claim 1, wherein the control unit starts the control of making the continuous notification when the second set reception level is exceeded.

3. 3. The vehicle detection device according to claim 1, wherein the notification unit is a light emitting unit that flashes for intermittent notification and lights continuously for continuous notification.

Images