JPH07229727A - Road surface detection device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an inexpensive road surface detection device with a simple configuration. A road surface detection device includes a light emitting element 2 that irradiates a plurality of light beams obliquely downward and forward of a moving device 1 at different irradiation angles, and a light receiving element 3 that detects reflected light from the road surface of the irradiated light beam. And signal processing means 4 for detecting the road surface shape of the moving body based on the distance between the light emitting element and the road surface calculated from the output signal from the light receiving element and the predetermined irradiation angle. It is a composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road surface detecting device for detecting a road surface state in a moving direction of a moving device.

[0002]

2. Description of the Related Art A conventional self-propelled moving device has been used in a limited environment such as a factory where the road surface is flat and there is no step. The road surface detection method is guided by a predetermined traveling route such as detecting a magnetic tape or an optical reflection tape installed on the floor with a dedicated device. However, recently, a mobile device having a degree of freedom instead of a determined route has been studied. When traveling, it is necessary to judge in advance whether or not the mobile device can safely travel not only on a flat place but also on a complicated road surface having slopes, steps, stairs, and the like.

[0003] Conventionally, as a road surface detecting device for detecting a road surface state in a moving direction of a moving device in advance, for example, there is one disclosed in Japanese Patent Laid-Open No. 62-162112. Further, as a conventional example for detecting a detailed road surface condition by slit light, there is one disclosed in Japanese Patent Application Laid-Open No. 1-163806. This road surface detection method irradiates a slit-shaped light on the road surface at an angle and reflects the reflected light by T
It is intended to obtain information on the road surface condition by taking a picture with a V camera, a two-dimensional sensor or the like, and using the principle of triangulation from the position of the projected slit image.

[0004]

However, although the moving device is equipped with the road surface detecting means in the above-mentioned Japanese Laid-Open Patent Publication No. 62-162112, no specific disclosure of the detecting method is made. Further, the method utilizing slit light, which is the road surface detection method disclosed in Japanese Patent Laid-Open No. Hei 1-163806, has some problems in practical use.

One of the problems is that the brightness of the slit light is not sufficient, and it is difficult to accurately detect the image of the slit light on the road surface under daylight such as an external environment. The reason is,
In this type of method, a semiconductor laser, a light emitting diode, or the like is used as a light emitting source, but the brightness is not so high originally, and since it is used by expanding it in a slit shape with an optical system, the brightness per unit area at a distance is large. This is because it is inevitable. Further, the method using the slit light has a drawback that the apparatus cost is increased because a TV camera, a two-dimensional sensor, etc. are required to detect the two-dimensional image of the slit light. Further, in this type of method, as described above, the number of data to be processed is large because the two-dimensional image is used, and when processing at high speed, it becomes difficult to perform real-time processing particularly in accordance with the speed of the mobile device. There was a drawback that

Further, in the method of this type, since the number of data to be processed is large because the two-dimensional image is used as described above, in the case of high speed processing, it is necessary to perform the real-time processing particularly in accordance with the speed of the mobile device. It had the drawback of becoming difficult. In order to solve such a problem, in the present invention,
First, in order to ensure sufficient brightness of the detected light, the light beam projected from one light emitting element is not expanded like slit light, but rather is condensed at a single point on the road surface by an optical system, I tried to measure the distance to that one point.

Further, in order to measure the condition of the road surface with high accuracy, it is possible to increase the number of measurement points as much as possible.
In order to increase the signal processing speed thereafter, the minimum number of detection points should be suppressed. Therefore, considering that it is important to measure the inclination angle and height level of the road surface,
We decided to use a method that linearly approximates from at least two detection points. Furthermore, in order to know the current road surface condition of the mobile device, it is necessary to measure at least two points for the last measurement and at the front two points for predicting the road condition further ahead. Good. Further, in order to provide such a detection device at a low cost, one light receiving element for the detection light is provided, and a means for detecting while detecting each emission beam is also provided.

It is an object of the present invention to provide an inexpensive and simple road surface detecting device by using a method of accurately and rapidly processing a small amount of road surface information obtained from the front of a moving device.

[0009]

To achieve the above object, a road surface detecting device according to the present invention comprises a light emitting element for irradiating a plurality of light beams obliquely downward and forward of a moving device at different irradiation angles. A light receiving element that detects the reflected light of the irradiated light beam from the road surface, the moving device based on the distance between the light emitting element and the road surface calculated from the output signal from the light receiving element, and the predetermined irradiation angle. And signal processing means for detecting the road surface shape.

[0010]

According to the present invention, the distance detecting device for the moving device comprises a plurality of light emitting elements and an element for receiving the reflected light from the road surface of the light beam from the light emitting elements. Measure the distance to a plurality of points in a determined direction, and from the obtained distance information of each point and the angle at which each light beam is projected, the road surface at each measurement point as the road surface condition in front of the moving device. Information about the height of
As a result, it is possible to detect changes in the inclination angle of the road surface, steps, and the like.

Further, according to the present invention, one light source is used to form one light beam, and since only one point is measured, the device can be used with high brightness, so that it can be sufficiently detected even in the presence of daylight. In addition, since the distance is measured at only one point, a one-dimensional PSD (position detection element) can be used as a light receiving element,
The equipment cost can also be significantly reduced. Further, although it should not be mentioned, since the detection of only one point is repeated a plurality of times, signal processing can be performed at high speed, and even when the moving device is moving at high speed, it is possible to cope with it in real time.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a conceptual explanatory view of a moving device equipped with a road surface detecting device according to the present invention. In the figure, 1 is a moving device main body, 2 is a light emitting element portion in which a plurality of light emitting elements are incorporated so as to form a constant irradiation beam, and 3 is a light receiving element portion for receiving the reflected light of the emission beam on the road surface. 4 is a signal processing unit.

FIG. 2 shows an example of signal processing relating to the road surface condition obtained by the road surface detecting apparatus according to the present invention. Figure 2 (a)
Is the case where all the beams in the moving direction hit and the road surface is a constant slope. Each light emitting element projected on the road surface emits a beam at a constant angle, and the detected distances are, for example, S1, S2, S3 and S4. Further, the projection angles of the respective emitted beams are θ1, θ2, θ3, and
Let θ4 be the position where each emitted beam hits the road surface.
1, P2, P3, P4, the height Hi (i = 1 to 4) from the detection device to the road surface can be easily calculated from the following equation.

Hi = Si · cos (θi) (i = 1 to 4) Further, the moving direction distance from the detection device to each road surface detection point Pi is Pi = Si · sin (θi) (i = 1 to 4) Therefore, the height information of the front road surface can be expressed as shown in FIG. In this case, the height of the road surface (the angle of the inclined surface of the road surface) is constant, and thus the road surface becomes straight.

Next, FIG. 2 (a) shows a case where the road surface in the moving direction is upwardly inclined from the middle. At this time, as can be seen from the figure, the distance values of S3 and S4 in which the inclination of the inclined surface is changed are shorter than those when the road surface is originally a constant inclined surface.
It can be clearly recognized on the graph that the slopes of the straight lines formed by the heights at P1 and P2 and the heights at P3 and P4 are different as shown in FIG. 4 (b). Especially, in this case, since the light emission beam is composed of four beams, the two points (P1, P
By comparing the slopes of two straight lines connecting 2) and the front two points (P3, P4) respectively, the road surface condition can be detected easily and with high reliability.

Further, FIG. 2 (b) shows a case where the road surface in the moving direction inclines downward from the middle. In this case, the distance values of S3 and S4 are more than those in the case where the road surface is a constant inclined surface. It is easily understood that it is measured long. Therefore, the slope of the road surface is different between the straight line formed by P1 and P2 and the straight line formed by P3 and P4 as shown in FIG. Therefore, it is possible to detect that there is a road surface with a downward slope ahead.

Further, FIG. 3 shows an example in which there is a climbing step ahead. As can be seen from the figure, in this case, the distance values of S3 and S4 are measured shorter than the original road surface. Further, the height from the detection device is shown in FIG. 5 (b). It can be seen that the straight lines formed by H1 and H2 and the straight lines formed by H3 and H4 have different heights but are in a parallel relationship with each other. You can see that there is a climbing step on the road and the road ahead is flat. Further, although not particularly described, it is obvious that even when there is a step of descending ahead, it can be detected from the difference in height values similarly detected.

Next, an embodiment of the signal processing means of the road surface detecting device of the present invention will be described. FIG. 6 is a circuit block diagram for explaining a signal detection method by time division lighting according to the first embodiment. It shows a method of detecting signals by time division using four light emitting elements and one light receiving element.
The light-emitting elements LED1 to LED4 are divided by a time-division lighting circuit 11 and are lit in synchronization with a synchronous clock 12 at a timing as shown in FIG.

The light emitted from the light emitting elements LED1 to LED4 is reflected on the road surface as shown in FIG. 1 and enters the light receiving element PSD1. The signal from the light receiving element PSD1 is the head amplifier 1
After being sent to the I / V conversion circuit 14, the current signal is converted into a voltage signal. The converted voltage signal is calculated by the analog calculation circuit 15 and becomes distance information. Further, it is sent to the A / D conversion circuit 16 and is latched as digital information by the latch circuit 1.
7 and the synchronous clock 12 from the clock circuit 21
2 and 3 at the timings shown in FIG. 5 by the latch timing command circuit 23 with reference to FIG.
Are latched as the distance information data of S1 to S4.

Distance information S latched in the latch circuit 17
1 to S4 are received by the CPU 19 of the arithmetic processing unit 22 via the I / O port 18, and the data is received by the equations for obtaining the angle values of θ1 to θ4 shown in FIGS. 2 and 3 and the above Pi and Hi. The distances from the element to the points P1 to P4 and the heights H1 to H4 from the position of each light receiving element to the road surface are obtained. Further, the CPU 19 obtains the obtained P1 to P4 and H1 to H4.
The data shown in FIG. 4 and FIG. 5 are analyzed, and the distance X from the light receiving element in front of the road surface as shown in FIG.
It is possible to detect that there is a step of height Y at the position of and the angle α of inclination.

FIG. 9 is a circuit block diagram for explaining a signal detection method using modulated light according to the second embodiment. The numbers of the light emitting elements and the light receiving elements are the same as those in the above-described embodiment, but the light emission of the light emitting elements LED11 to LED14 are modulated at different frequencies and simultaneously emitted. The modulated light is reflected by the road surface as shown in FIG. 1 and enters the light receiving element PSD11. The signal from the light receiving element PSD11 passes through the head amplifier 25 and is I / V.
It is sent to the conversion circuit 26 and converted from a current signal to a voltage signal.

The signal converted into a voltage is a bandpass filter 27 which is adjusted to each frequency of the light emitting element.
˜30, and further demodulation circuits 31 to 3
4, demodulated, converted into distance information through the analog operation circuits 35 to 38, and sent to the A / D conversion circuits 39 to 42.
Converted to digital information. The converted S1 to S of FIG.
The distance information corresponding to 4 is taken into the CPU 44 of the arithmetic processing unit 43 via the I / O port 45. After that, arithmetic processing is performed in the same manner as in the case of the time division described above, and similar data can be obtained.

Although the embodiment of the present invention has been described in the case where there are four emission beams for distance detection, the inclination state of the road surface where the self-propelled mobile device is currently placed is at least two detection beams in front. It is convenient that the linear approximation can be performed with the above, and the changing road surface state can be performed with the above-mentioned at least two detection beams. Of course, it is obvious that the road surface condition can be detected more accurately by increasing the number of these detection beams. However, if the number of detection beams is increased too much, the cost of the apparatus as a whole becomes high and it takes time to process the data. Therefore, as described in the item of the problem, a two-dimensional image is obtained using the conventional slit light. Since the superiority to the method of performing the treatment cannot be exhibited, it is considered that the number of emission beams is practically suitable to be about 4 to 10, preferably about 4 to 6.

[0024]

As described above, according to the present invention, as compared with the slit light projection method and the two-dimensional image processing means which have been conventionally used as means for detecting the road surface state related to the moving direction in the self-propelled moving device, The device can be configured simply and inexpensively, and since it can detect with a small amount of information, the processing time is short, and it is possible to operate in real time, which has a great practical effect. In addition, since the light beam from the light emitting element is condensed and used in a point shape, the intensity of light is not reduced as compared with the conventional method of expanding to slit light and the like, and a signal with a high S / N ratio is obtained. There is an advantage that can detect. Therefore, it is possible to perform road surface detection in a general environment where daylight is present, which is highly reliable and which is impossible in the past.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a configuration in which a road surface detection device of the present invention is mounted on a moving device.

FIG. 2 is an operation explanatory view when the road surface state of the road surface detection device of the present invention is a slope.

FIG. 3 is an operation explanatory diagram when the road surface state of the road surface detection device of the present invention has a step.

FIG. 4 is a diagram illustrating a relationship between a moving distance of the road surface detection device of the present invention and an output signal detected according to a road surface state.

FIG. 5 is a diagram illustrating a relationship between a moving distance of the road surface detection device of the present invention and an output signal detected according to a road surface state.

FIG. 6 is a circuit block diagram for explaining a signal detection method by time division lighting which is a first embodiment of the road surface detection device of the present invention.

FIG. 7 is a diagram showing a time chart of signal detection by time division lighting which is a first embodiment of the road surface detection device of the present invention.

FIG. 8 is a diagram illustrating road surface information obtained from an output signal detected according to a road surface state of the road surface detection device of the present invention.

FIG. 9 is a circuit block diagram illustrating a signal detection method using modulated light that is a second embodiment of the road surface detection device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Moving device main body 2 Light emitting element 3 Light receiving element 4 Signal processing means

Claims (3)

[Claims] 1. A light emitting element that irradiates a plurality of light beams obliquely downward and forward of a moving device at different irradiation angles, a light receiving element that detects reflected light from the road surface of the irradiated light beam, and a light receiving element from the light receiving element. A road surface detecting device, comprising signal processing means for detecting the road surface shape of the moving device based on the distance between the light emitting element and the road surface calculated from the output signal of the vehicle and the predetermined irradiation angle. . 2. The plurality of light emitting elements respectively irradiate the light beams with a fixed time interval and sequentially emit the light beams, and the light receiving element detects each reflected light from the road surface of the light beam in a time division manner. The road surface detection device according to claim 1. 3. The light emitting element simultaneously irradiates a plurality of light beams with light beams modulated at different frequencies, and the light receiving element simultaneously detects reflected light from the road surface of the light beams. The road surface detection device according to claim 1, which is characterized.