JPH0367589B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an optical wide-area situation monitoring device that monitors the situation in a monitoring area by detecting light from a detected object.

[Background Art] Conventionally, most optical situation monitoring devices of this type detect whether or not a detected object exists within a monitoring area, and since the position of the detected object cannot be determined, accurate monitoring is difficult. was difficult. Therefore,
So-called active type optical distance measuring means (e.g., triangulation method, focus detection method, positioning method, There are monitoring devices that use a phase difference detection method, etc., but in either case, they only detect objects within the detection area in the front direction of the monitoring device, so it is difficult to detect objects over a wide area. When detecting the distance and direction of a vehicle, it is necessary to provide a large number of monitoring devices, which poses a problem in that the device becomes larger and the cost increases. It is also possible to rotate the monitoring device, but in the case where the monitoring device including the light projecting means is rotated, the rotational drive system becomes large, making it difficult to put it into practical use. On the other hand, as a passive optical distance measuring method that does not require a light projecting means, for example,
As seen in Japanese Patent Application Laid-Open No. 57-211007, an optical system is driven back and forth in a direction orthogonal to the optical axis, and a plurality of photodetecting elements are arranged on the focal plane of the optical system in the direction of movement of the formed image. There was a system in which the light from the detected object was received by each photodetecting element, and the position of the detected object was detected based on the output of each photodetecting element. However, since a means for reciprocating the optical system is required, the monitoring device itself becomes large, and when rotating the device to monitor a wide area, the overall structure of the device becomes complicated and large, which increases cost. There was a problem with the price being high.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to detect the distance and direction to a detected object over a wide area and determine the position of the detected object. To provide a wide area situation monitoring device capable of making judgments, having a simple configuration of the entire device, and reducing cost.

[Disclosure of the Invention] (Structure) The present invention comprises: a rotating optical system 1 that rotates at a constant speed and receives light from a detected object X; a direction detecting means 2 that detects the viewing direction of the rotating optical system 1; A detection element array 3 in which a plurality of light detection elements 30 and 31 are arranged on the locus of the focal point of the rotating optical system 1 and arranged in the movement direction of the formed image, and the detection element array 33 detects adjacent light from the detection element array 33. Adding means 4 for adding the outputs of the detection elements 30 and 31 with their polarities alternately reversed; a calculating means 5 for calculating the distance R to the detected object X based on the frequency of the output of the adding means 4; and direction detecting means. and a situation determining means 6 that determines the situation based on the direction information output from the calculation means 2 and the distance information output from the calculation means 5. The position of the detected object X can be determined by detection.

(Example 1) Figures 1 to 5 show an example of the present invention, in which a rotating optical system 1 that rotates at a constant speed and receives light from an object to be detected X is driven by a motor at a constant speed. The center part of a support rod 11 is attached to the upper end of the rotation shaft 10 to be rotated, and a convex lens 12 is installed upright at one end of this support rod 11, and a window plate 13 with a window 13a bored at the other end is attached as a convex lens. The convex lens 1 is vertically formed so that the optical axis of the lens 12 passes through the center of the window 13a.
2 and the window 13a, an image of the object to be detected X is formed on the sensing element array 3. Note that the window 13a determines the duration of light reception from one detected object Effective for improvement. In addition, it goes without saying that a concave mirror, a pinhole, etc. can be used in place of the convex lens 12. Although a pinhole has inferior light-gathering ability, it simplifies the configuration and reduces costs, and also allows for light weight and rotation. The mechanism can now be simplified. The direction detection means 2 for detecting the viewing direction of the rotating optical system 1 includes a rotating plate 21 attached to the rotating shaft 10 and having a slit 22 for detecting a reference position of the azimuth angle, and a rotating plate 21.
A photo interrupter consisting of a light emitting element 23 and a light receiving element 24 arranged opposite to each other with the light emitting element 2
The light from 3 passes through the slit 22 to the light receiving element 24.
A waveform shaper 25 that shapes the waveform of the signal output when the light is received by the waveform shaper 25 to form a reference position pulse.
and a counting circuit 27 that counts the reference clock that is reset by the reference position pulse and generated by the clock circuit 26, and outputs direction information indicating the rotation angle of the rotating optical system 1 with respect to the reference position as the output of the counting circuit 27. are output sequentially. Note that another photo interrupter is provided on the circumference of the rotary plate 21, on which a large number of rotation detection slits 22a are arranged in rows at equal intervals, and a light receiving element is provided oppositely to the rotation detection slit 22.
The reference clock may be a pulse signal corresponding to the pulsed light received by the light receiving element through the reference clock a. In this case, it is possible to prevent a decrease in direction detection accuracy due to uneven rotation of the rotating optical system 1. The detection element array 3 is arranged on the locus of the focal point, which is the image formation point of the rotating optical system 1, and includes a plurality of light detection elements 3 arranged in an arc shape in the moving direction of the formed image.
0,31, and in the adding means 4,
Adjacent photodetecting elements 30 of the detecting element array 3,
31 outputs are added by alternately reversing the polarity (for example,
The outputs of the odd-numbered photodetecting elements 30 are combined to form a positive polarity signal, and the outputs of the even-numbered photodetecting elements 31 are combined and added as a negative polarity signal to obtain a bipolar signal. In the figure, the photodetecting element 30 whose output is not inverted is shown as "+", and the photodetecting element 31 whose output is inverted is shown as "-". In the embodiment, the photodetecting elements 30 and 31 are A pyroelectric element is used that can detect infrared rays from a high-temperature object X such as the location where the infrared rays are generated, and does not require cooling. Further, the adding means 4 is formed using a differential amplifier, and a photodetecting element 3 is connected to both input terminals.
By inputting the 0 and 31 outputs, both outputs can be inverted and added, and an amplifier circuit may be provided at the subsequent stage if necessary. It goes without saying that photodiodes for detecting visible or near-infrared light may be used as the photodetecting elements 30 and 31.

Next, calculation means 5 that calculates the distance to the detected object X based on the frequency of the output of the addition means 3 uses an inverter 51 that inverts the output of the addition means 3, and waveform-shapes the output Va of the addition means 3 and its inverted signal. waveform shapers 52a, 52b, and waveform shaper 52
The gate circuits 53a, 53b controlled by the outputs Vb, 52b and the clock signal Vf output from the clock circuit 55 are connected to the gate circuits 53a, 52b.
Counting circuits 54a and 54b that count via 3b
, level determination circuits 56a and 56b, a zero-crossing point detection circuit 57 for detecting the zero-crossing point of the output Va of the addition means 3, and a storage means 59, and calculates the average frequency of the effective component of the output Va of the addition means 3 based on the output of each circuit. (detailed operation will be described later), and an arithmetic circuit (microcomputer) 58 that calculates the distance based on the measured frequency. Further, the situation determining means 6 determines the situation based on the direction information output from the direction detecting means 2 and the distance information output from the calculating means 5.

The operation of the embodiment will be described below. 6 and 7 are diagrams for explaining the principle of distance measurement according to the present invention. Now, the object to be detected X exists on the optical axis of the convex lens 12 at the position indicated by the solid line in FIG. 12 is rotated about the rotation axis 10 at a rotation radius a (cm) and an angular velocity ω (rad/sec), the distance from the object to be detected If the distance to the image plane Y is r (cm), when the convex lens 12 rotates by Δθ (rad) during Δt (sec) and moves to the position shown in the imaginary image, the distance to the image plane Y by the convex lens 12 is The image point formed by the incident light of
The displacement angle of X″ from the optical axis is Δα (rad), the imaging point X′,
If the moving distance of X'' is Δx (cm), then θ=ωΔt (1), assuming that Δθ and Δα are minute, and using the triangular formula, the following relationship is obtained.

RΔα=aΔθ ...(2) Δx=(R+r)Δα ...(3) Next, let V (cm/sec) be the moving speed of the images X′, X″ of the detected object X on the imaging plane Y. Then the above
Using equation (3), V=Δx/Δt=(R+r)Δα/Δt...(4) From equations (1), (2), and (4), the moving speed V of images X′ and X″ is as follows. It is transformed like this.

V=a(R+r)/RΔθ/Δt=aω(1+r/R)
...(5) Solving the above equation (5) for the distance R gives the following.

R=raω/(V-aω) (6) From the above equation (6), the distance R can be obtained by finding the moving speed V.

Next, the moving speed V of the images X′ and X″ of the detected object
The seventh method describes how to obtain the
The operation will be explained based on the operation explanatory diagram shown in the figure. Figure 7a
As shown in the figure, the adjacent photodetecting elements 30 and 31 of the detecting element array 3 are so-called polar detecting elements whose outputs are inverted and added to each other, and their arrangement pitch is l (cm). There is. The object to be detected
When the image X' moves in the direction of the arrow at a moving speed V, a bipolar signal as shown in FIG. 7b is obtained as the output Va of the adding means 4. If the period of this bipolar signal is T (sec), then T = 2l/V...(7), and from the above equation (7), the frequency (Hz) of the output Va of the adding means 4 is =V/2l... (8) becomes. Here, from equations (6) and (8), the relationship between the frequency and the distance R to the detected object X is given by the following equation.

R=raω/(2l-aω) (9) That is, by finding the frequency of the output Va of the adding means 4, the distance R to the detected object X can be calculated.

Hereinafter, a specific distance measuring operation in the embodiment will be explained using FIG. 8. FIG. 8a shows the addition means 4
The signal waveform of the output Va is shown, and the rotating optical system 1
Due to the effect of the window 13a provided in the center, the amplitude is maximum near the center and becomes smaller as it approaches the left and right ends. The calculating means 5 of the embodiment in FIG. 4 is a circuit that obtains the periods between the zero crossing points of the output Va of the adding means 4 and determines the frequency from the average value. First, the output Va of the adding means 4 is waveform shaped. 52a, only the positive signal waveform is shaped into a positive pulse signal Vb as shown in FIG. 8b.
is output. On the other hand, the output Va is from the inverter 51
The waveform shaper 52b shapes only the negative signal waveform to produce a negative pulse signal as shown in FIG. 8c.
Vc is output. This positive and negative pulse signal Vb,
The clock generated by the clock circuit 55 via the gate circuits 53a and 53b controlled by Vc.
Counting circuit 5 in which Vf (shown in Figure 8 f) is reset (described later) at the zero-crossing point of the output Va of the adding means 4
4a, 54b, and the counting circuit 54
The time width of one pulse of the positive and negative pulse signals Vb and Vc (for example, "H" level time) is determined by a and 54b.
is now measured (clock period x number of counts). Next, the zero cross point detection circuit 32
The zero-crossing signal detected at is input to the arithmetic circuit 58, and when this zero-crossing signal is obtained, the counting results of the counting circuits 54a and 54b are read into the arithmetic circuit 58, and the level judgment circuits 56a and 54, which will be described later, After the counting result determined to be valid based on the output from the counting circuit 56b is stored in the storage means 59, the reset signal of the counting circuits 54a and 54b is sent to the arithmetic circuit 58.
It is now output from . Next, in the level determination circuits 56a and 56b, the output of the adding means 4 is
When the level of Va exceeds the threshold voltages V _T , -V _T , as shown in FIG. 8 d and e, judgment signals V d and Ve indicating valid signals are latched and output. The arithmetic circuit 58 calculates this judgment signal Vd, at the time when the zero-cross signal is obtained.
Ve is checked, and if the judgment signals Vd and Ve are "1", the measurement results of the time widths of the positive and negative pulse signals are regarded as valid and stored in the storage means 59 as described above, and the valid pulses are Count up the pulse number counter. At this time,
From the calculation circuit 58 to the level determination circuits 56a and 56b
A reset signal is output for the determination signals Vd and Ve latched to the level determination result, and the level determination result is reset in preparation for the next level determination. On the other hand, it goes without saying that when the judgment signals Vd and Ve are "0", the measured time width is canceled as invalid data, and in this case, the counting circuit 54
Although it is necessary to reset the latch circuits a and 54b, it is not particularly necessary to reset the latch circuits of the level determination circuits 56a and 56b, but they may be reset. In this way, the number of effective pulses and the time width (period) between the zero crossing points of each effective pulse are sequentially stored in the storage means 59, the average value of the time widths is calculated, and the output Va is calculated based on this average time width. The frequency (=1/2T) is calculated. This frequency is data corresponding to the distance R to the detected object X, and the frequency data output from the arithmetic circuit 58 is input to the situation determining means 6 as distance information. Note that the output Va of the adding means 4 contains unnecessary frequency components, and if these unnecessary frequency components are removed by a band filter, highly accurate frequency measurement can be performed. In the example, since it is essential to maintain the zero volt point, a band filter for removing unnecessary waves is added in the adding means 4. Further, in this embodiment, the frequency is determined based on the time width between the zero cross points of the output Va of the adding means 4, but it is also possible to determine the frequency based on the time width between the peak points of the output Va. It is also possible to A/D convert the signal waveform of the output Va, obtain a frequency spectrum by digital calculation such as the FFT method or the MEM method, and obtain the frequency from its maximum value.

Next, the situation determining means 6 synchronizes and takes in this distance information and the direction information output from the direction detecting means 2 to make them correspond to each other, and accurately determines the position of the detected object X based on both pieces of information. Then, based on the preset monitoring area information and the position information of the detected object In some cases, an abnormality detection signal that drives an output device such as an alarm means is output. Note that the monitoring area can be arbitrarily set within the effective field of view (180°) of the rotating optical system 1 and the detection limit distance, and it is possible to easily set a complex monitoring area. Further, it is also possible to determine the number of detected objects X within the range of angular resolution determined by the configurations of the rotating optical system 1 and the sensing element array 3.

(Example 2) FIG. 9 shows another example, in which the rotating optical system 1 is
A mirror 14 for changing the optical path is erected in place of the window plate 13, and the detection element array 3 consisting of the light detection elements 30 and 31 is formed in an annular shape, and the rotating optical system 1
The light collected by the convex lens 12 is reflected obliquely upward by the mirror 14 and is sequentially imaged on the photodetecting elements 30 and 31. Moreover, this mirror 14 is
It has the same angular resolution determining function and hood effect as the window 13a in . Note that the other configurations and operations are completely the same as those of the first embodiment, so explanations will be omitted.

Here, in the first embodiment, the effective field of view of the rotating optical system 1 is obtained only in the front (180°), and the optical path of the rotating optical system 1 is blocked by the sensing element array 3 at the rear. It became a blind spot, making it impossible to monitor the situation in a wide area in all directions (360 degrees).
In this example, since the optical path is changed by a mirror, there are no blind spots, and the monitoring area can cover all directions (360 degrees), making it possible to achieve wide-area situation monitoring. ing.

[Effects of the Invention] As described above, the present invention includes a rotating optical system that rotates at a constant speed and receives light from an object to be detected, a direction detection means that detects the viewing direction of the rotating optical system,
A detection element array in which a plurality of light detection elements are arranged in a row in the direction of movement of a formed image arranged on the locus of the focal point of a rotating optical system, and outputs of adjacent light detection elements of the detection element array are alternately arranged. an addition means for inverting the polarity and adding it; and an arithmetic means for calculating the distance to the detected object based on the frequency of the output of the addition means;
It is composed of a situation determining means that determines the situation based on the direction information output from the direction detecting means and the distance information output from the calculating means. The distance and direction to the detected object are detected by moving the image of the detected object formed on the sensing element array placed on the imaging plane of the system, so the distance and direction of the detected object can be detected over a wide area. The position can be determined, and since the effective field of view of the optical system and the image on the sensing element array are moved by the same rotation mechanism, the overall configuration of the device can be simplified and costs can be reduced. There is an effect that it can be done.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic structure of an embodiment of the present invention, FIG. 2 is a perspective view showing the main structure of the same as above,
3 is a schematic top view of the main parts of the same as the above, FIG. 4 is a block circuit diagram of the main parts of the same as the above, FIG. 5 is a schematic block diagram of the main parts of the same as the above, and FIGS. FIG. 9 is a perspective view showing a schematic configuration of main parts of another embodiment. 1 is a rotating optical system, 2 is a direction detection means, 3 is a detection element array, 4 is an addition means, 5 is a calculation means, and 6 is a situation determination means.

Claims (1)

[Claims] 1. A rotating optical system that rotates at a constant speed and receives light from an object to be detected, a direction detection means that detects the viewing direction of the rotating optical system, and a rotating optical system that is arranged on the locus of the focal point of the rotating optical system and that forms an image. a sensing element array in which a plurality of light sensing elements are arranged in a row in the moving direction of the image; an adding means for adding outputs of adjacent light sensing elements of the sensing element array while alternately reversing polarities; and the adding means. Consisting of a calculation means for calculating the distance to the detected object based on the frequency of the output, and a situation determination means for determining the situation based on the direction information output from the direction detection means and the distance information output from the calculation means. Wide area situation monitoring device.