JPS63100318A - Method and device for measuring unevenness of road surface - Google Patents

Abstract

PURPOSE:To remove the adverse influence of a noise effectively and to improve measurement accuracy by determining a threshold value matching with the circumferential condition of a measurement point and taking a measurement. CONSTITUTION:A light signal transmission part 1A and a photosensor part 1B are provided, and the sensor part 1B detects the height position of spot light projected on the road surface from the transmission part 1A; and its detection signal is converted into a binary signal to obtain unevenness information on the road surface, which is supplied to a recording and display part 23. In this case, the output of a semiconductor laser element 10 is turned on (off) through an on-off control circuit 31 and a driving circuit 11 under the control of a CPU. A threshold value setting means 30 inputs the output of the linear CCD sensor 18 through a buffer 20 and determines a proper threshold value. Then, the driving circuit 11 is operated to output laser light and the photodetection signal of the sensor 18 is inputted through the buffer 20 to convert the contents of the buffer 20 into a binary signal on the basis of the determined threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and device for measuring road surface unevenness, and more particularly to a method and device for measuring road surface unevenness, which includes an optical signal transmitter and an optical sensor.

[Conventional technology]

In an optical road surface unevenness measuring device, a signal related to the height of the road surface detected by an optical sensor is binarized based on a predetermined threshold, and then arithmetic processing is performed using a predetermined method. Generally, a method of recording and displaying information on the unevenness of the road surface is generally adopted.

[Problem that the invention seeks to solve]

However, in the conventional example described above, the dark current generated in the optical sensor part increases or decreases relatively largely due to the influence of the ambient temperature at the measurement point and the heat generation temperature of the optical sensor part itself caused by continuous use for a long time. Therefore, if the threshold value for binarizing the output signal of the optical sensor section is fixed, noise often remains in the data after binarization, making it difficult to determine the correct spot position (distance to the road surface). This caused the inconvenience of not being able to ask for it.

[Purpose of the invention]

The present invention improves the disadvantages of the conventional example, and in particular effectively eliminates the adverse effects of noise caused by an increase in dark current even if the surrounding measurement conditions change, and improves measurement accuracy. Its purpose is to provide a measuring method and apparatus.

[Means for solving problems]

Therefore, the present invention is provided with an optical signal transmitter and an optical sensor, the optical sensor detects the height position of the spot light irradiated onto the road surface from the optical signal transmitter, and the detected signal is appropriately transmitted. In a road surface unevenness measurement method in which the height of the road surface at the measurement point is determined based on the binarized signal after the signal is binarized using a threshold value, the height of the road surface at the measurement point is The objective is to be achieved by determining an appropriate threshold value that matches the surrounding conditions of the point, and then turning on the output of the optical signal transmitter and starting measurement.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

In FIG. 1, 1 indicates a laser beam transmitting/receiving section as a signal transmitting/receiving section, and 2 indicates a signal processing section.

The laser beam transmitting/receiving section 1 includes an optical signal transmitting section IA and an optical sensor section IB. Of these, the optical signal transmitter IA includes a semiconductor laser element 1o, a laser drive circuit 11 that drives the semiconductor laser element 1o, a lens unit 12 that focuses the laser light output from the semiconductor laser element 10, and this lens. part 12 and semiconductor laser element 1o
and a support member 13 that integrally supports the.

Therefore, when the laser drive circuit 11 operates, the laser beam focused into a spot by the action of the lens section 12 is output with its optical axis TR (parallel rays) substantially perpendicular to the road surface A. It is designed to illuminate measurement points on the road surface.

Further, the optical sensor section IB of the laser beam transmitting/receiving section 1 is connected to the road surface A.
Interference filter 16 sequentially from the side. A condensing lens 17 and a -dimensional CCD sensor 18 are installed in this order. Of these, -
The dimensional CCD sensor 18 is also provided with a CCD drive circuit. The signal processing section 2 is provided on the output side of the -dimensional CCD sensor 18. Further, the light receiving axis RE of the sensor part IB is on the road surface A at the reference height.
It is arranged so as to change at an angle of θ with respect to the above-mentioned transmission optical axis TR. In this case, the laser spot on the road surface A is captured on the -dimensional CCD sensor 18 at a level as shown in FIG. 2, for example.

The signal processing section 2 includes a line buffer 20 that stores data for one scan of the -dimensional CCD sensor 18, a first arithmetic circuit 21 that calculates the center position of the output signal of the line buffer 20, and the first and a second calculation section 22 that calculates the height of the measurement point based on the output of the calculation circuit 21. The road surface unevenness information calculated by the second calculation section 22 is recorded and displayed on the recording display section 23.

The first calculation unit 21 binarizes the output of the line buffer 20 based on a threshold value of a predetermined level determined by the threshold setting means 30, and the above-mentioned center position is set based on this. It looks like this. In Figure 3, one-dimensional C
The relationship between the output of the CD sensor 18 and the threshold value and an example of a binarized signal are shown respectively. In this case, the threshold setting means 3o is capable of outputting thresholds of multiple levels depending on the situation. Specifically, this threshold setting means 30 has a function of detecting the level of dark current and setting a threshold of a predetermined level to cut it, and a function of outputting a start signal for laser driving vI. have. The threshold output 30A from the threshold setting means 30 is sent to the first calculation unit 21 as described above, and the activation signal 30B for laser on/off control is used to turn on/off the laser drive circuit 11. The signal is sent to the control circuit 31. When the on/off control circuit 31 receives the output of the threshold value setting means 30, it takes this as an activation signal and immediately activates the laser drive circuit 11. As shown in FIG. 6, the output state of this laser beam is 1! while the optical signal transmitter/receiver 1 moves on the road surface at the measurement point. Continued.

Next, the operation of the signal processing system in the above embodiment will be explained.

When the road surface E is irradiated with laser light, the road surface E diffusely reflects the laser light. Therefore, when viewed from the optical sensor unit IB, the portion of the road surface irradiated with the laser light is observed like a spot-shaped laser light source. In this case, when the reference plane A (see Fig. 1) is irradiated with laser light, that point P is
Since the light receiving axis RE of B passes through, the center of the image of the laser spot formed on the reference plane A is focused on the center point Q of the -dimensional CCD sensor 18 . On the other hand, h from the reference height
When the laser beam is irradiated onto the road surface A' at a higher position, the center of the laser spot image at that time is shifted by δ from the center (0 point) on the -dimensional CCD sensor 18. image at the position. The relationship between δ and h at this time is
If the center of the condensing lens 17 is R, then h=δ・R lower/(δ・cos θ+QR・sin θ)
...(11) The calculation of this equation +11 is performed in the second calculation section 22 described above.

In addition, the center position of the laser spot image, that is, the center position of the image formed on the one-dimensional CCD sensor 18 described above, is determined as the center of the image formation line (same processing as the center in FIG. 2) even if there is an overall shift. It can be grasped simply. This calculation is performed in the first calculation section 21 described above.

Furthermore, in this embodiment, as described above, the interference filter 16 is provided on the light input side of the condenser lens 17.

This interference filter 16 is one that allows only light having a wavelength near the laser wavelength (for example, 780 nm in this embodiment) to pass therethrough in order to prevent the influence of sunlight. Therefore, there is an advantage that measurement can be continued even during the day.

Specifically, the signal processing system shown in FIG. 1 is entirely controlled by a CPU 50 according to a predetermined program (see FIG. 4). FIG. 5 shows the flowchart.

To explain this in more detail, in this embodiment, first, the CPU 50
controls the laser drive circuit 11 via the output port 51 in the on/off control circuit 31 to turn off the output of the semiconductor laser element 10.

Next, in this state, the threshold setting means 30 inputs the output of the one-dimensional CCD sensor 18 via the line buffer 20 serving as a memory, checks the contents of the memory, and determines an appropriate threshold ( For example, "maximum value in memory + α" or "average value in memory + α") When this threshold value is determined, the laser drive circuit 11 is immediately activated via the on/off control circuit 31 as described above, Output laser light. Then, with the laser beam turned on, the light reception signal from the one-dimensional CCD sensor 18 is taken in via the line buffer 20, and the contents of the line buffer 20 are binarized using the previously determined threshold value. The following steps are similar to those described above.

〔Effect of the invention〕

Since the present invention is configured and functions as described above, even if noise due to an increase in dark current is detected due to the ambient temperature or heat generation of the optical sensor part, the height measurement data obtained from the road surface cannot be changed. It is possible to provide an unprecedented and excellent method and apparatus for measuring road surface irregularities, which can substantially completely eliminate the effects of the above and continuously perform high-precision measurements.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a signal processing system in one embodiment of the present invention, FIG. 2 is an explanatory diagram showing the imaging situation in a one-dimensional CCD sensor as an optical sensor, and FIG. 3)
are an explanatory diagram showing the relationship between the line buffer output and the threshold value and the binarized signal shown in Fig. 1, Fig. 4 is an explanatory diagram showing the operation system for turning on and off the laser beam transmitter, and Fig. 5 This figure is a flowchart showing the operation of FIG. 4, and FIG. 6 is an explanatory diagram showing the on/off status of the laser beam transmitter at the measurement point (patient 1.IVk12). 1... Signal transmission/reception section, IA... Optical signal transmission section, IB... Optical sensor section, 17...
・Condensing lens, 18-dimensional CCD sensor,
20...Line buffer as memory, 30
. . . Threshold setting means, 31 . . . On/off control circuit. Patent applicant Tokyo Keiki Co., Ltd. Agent Patent attorney Isamu Takahashi Figure 1 I3 Figure 3 Figure 4<n Figure 5

Claims (2)

[Claims] (1) comprises an optical signal transmission section and an optical sensor section, the optical sensor section detects the height position of the spot light irradiated onto the road surface from the optical signal transmission section, and the detected signal is sent to an appropriate threshold. In a road surface unevenness measurement method in which the height of the road surface at a measurement point is specified based on the binarized signal after the value is binarized, the height of the road surface at the measurement point is determined by A road surface unevenness measuring method characterized by determining an appropriate threshold value that meets the conditions, and then turning on the output of an optical signal transmitter to start measurement. (2) It has an optical signal transmitting section that irradiates a measurement point on the road surface with a spot, and an optical sensor section that detects the measurement position of the road surface irradiated with the spot, and the optical sensor section is provided with a signal processing part. a threshold value setting means, and a signal for binarizing the signal output from the optical sensor section based on the output of the threshold value setting means and calculating the height of the road surface based on the binarized signal. A road surface unevenness measuring device comprising a processing circuit, wherein the threshold value setting means is configured to output threshold values of different levels depending on the environment of the measurement point, and the threshold value setting means is configured to output threshold values of different levels depending on the environment of the measurement point, and A road surface unevenness measuring device characterized in that an on/off control circuit is provided between the value setting means and the on/off control circuit for controlling the operation of the optical signal transmitting section on or off according to the signal output of the threshold value setting means. .