JPS583484A - Detector for mobile body - Google Patents

Abstract

PURPOSE:To perform the detection of a travelling body in a high speed, the measurement of speed and discrimination of the shape, by arithmetic processing a video signal from a television camera and a space filter function from a memory. CONSTITUTION:A memory 3 stores a space filter function in response to each picture element of a television camera 1. A control circuit 2 reads out a space filter function in response to each picture element from the memory 3 in synchronizing with the scanning of the television camera 1. The space filter function read out and a video signal from a television camera 1 are multiplied at a multiplication circuit 5, integrated at an integration circuit and inputted to a CPU4 via an A/D conversion circuit 7 to calculate travelling body information.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a moving object detection device, more specifically, a moving object detection device, which detects a moving object by capturing an image of an object with a television camera and processing a video signal output from the television camera. The present invention relates to a moving body detection device that determines the speed of the cave and its shape.

One type of moving object detection device is one that utilizes a spatial filter effect. A spatial filter is basically configured at the image plane of an object lens that transmits infrared or visible light or a reflector that reflects it, and suppresses the influence of radiation from the background other than the object included in the field of view. It improves the detection ability for objects and is also effectively used for speed measurements. Specifically, the spatial filter is constituted by a reticle placed on the image plane of the optical system, or a detector constituted by a large number of light conversion elements arranged parallel to each other. In addition to the grid-like reticle 8, there is also an electro-optical reticle that is controlled to move in one direction with opaque parts and transparent parts arranged alternately. However, with such a reticle or photodetector array,
Since the spacing between the arrays of these components is constant, the spatial frequency is fixed to the value specified by the spacing, and there is a problem that only specific frequency components of the target can be detected, resulting in a lack of versatility. .

An object of the present invention is to provide a moving object detection device/apparatus that can select any spatial frequency component and is highly versatile.

Another object of the present invention is to provide a moving object detection device that is capable of high-speed processing and can also handle high-speed moving objects.

A further object of the present invention is to provide a moving object detection device that can obtain separate moving object information for each of a plurality of moving objects included within the field of view of a television camera.

Embodiments of the present invention will be described in detail below with reference to the drawings.

In this invention, a television camera is used as a detector for detecting an object. The image pattern of the object projected onto the television camera through the lens system is expressed by the function f(
x, y).

Letting the spatial frequency function of this video pattern be F(U, ■), it can be expressed by the following equation.

F(U,V) = H,f(X+y)@eXP(-j(UaX+V@
y)) @dX11dy' +161
1 +11 Here, S indicates the area to be integrated, and TV
The area of the image projected onto the camera or a smaller area. eXP(-j(Usx+V·y)) is called a spatial filter function. U and V are spatial frequency components (angular velocities) in the x and y directions, respectively, and if λX and λy are wavelengths in the x and 7 directions, respectively, they are expressed by the following equation.

U=2π/λX...(2)V=2
'r/λy (3) Furthermore, the spatial frequency Φ and the direction θ of its vector with respect to the X-axis direction are expressed by the following equation.

Φ=f】74...(4) When equation (1) is expressed using trigonometric functions, the following equation is obtained.

F(U,V) =JJ8f(x,y) @(008(U11X+V@)l)−jsin(U@x
+V@y month sdx@dy= ff 8f (X, y) ac
os(U@x-1-V*y)*dx@dy-j')')
8 f(x,y)ssin(Uex+V*y)sdi@
dy...(61) This function F(U, V) is the output of a spatial filter constructed isometrically by an electric circuit, which will be described later, and is therefore referred to as a spatial filter output.

When an object within the field of view of the television camera is moving, this spatial filter output F(U, V) changes sinusoidally at a frequency proportional to the moving speed of the object. F
Since (U, V) are complex numbers, they can be expressed as vectors on the complex plane as shown in FIG. Here, Q = Jf8 f(x, y) ecos(Bx+Vs
y)*dxsdy-・-(71 R=-') ding, f(x, y)*5in(Usx
+V11y) dx*dy...(8) (Z = tBn ``DanQ...(9) This phase angle α'' is obtained for each scan of one screen, and by calculating its change △α, the target The moving speed W of an object is obtained by the following equation.

Here, τ is the scanning time for one screen, and is approximately 16.7 m8 in the case of one field. The direction of movement of the object is
This can be determined by the polarity (positive or negative) of Δα.

If the wavelength of the spatial frequency (the pitch of the spatial filter) is P, and the period at which the output F (U, V) changes is T, then the speed W can also be obtained from the following equation.

W=P/T
...2 Oll However, p=17f strain shoulder is back.

Since the spatial frequency Φ is defined by the values of U and V, the spatial frequency Φ can be changed by changing these U and V.

This is equivalent to changing the interval between the components of the reticle and light receiving element array that constitute the above-mentioned spatial filter. In this invention, as described below, since the values of U and V can be arbitrarily set, any spatial frequency component of the object can be obtained, and the invention is versatile.

FIG. 2 is a block diagram showing the configuration of the moving object detection device. The output signals of each of these blocks are shown in FIG. FIG. 3a shows each signal of one field, FIG. 3b shows an enlarged horizontal l-scan signal, and FIG. 3C shows a further enlarged signal of one pixel. The television camera (1) captures an image of an object and outputs its video signal (Al), and is controlled by a control circuit (2). ,y
). The video signal (A) is passed through a high band pass filter (its low frequency component and filter 101). As shown by the broken line in Figure 5, the video signal (Al contains many low frequency components and DC components. This is mainly due to the brightness of the background of the object. The second video signal (A1) is shown by a solid line in FIG.

It is preferable to use a filter (lO) to cut components whose frequency is lower than the spatial frequency in the Y direction to be extracted. Scanning frequency of TV camera (1) (approximately 60H2
) It is also effective to cut the following frequency components. Specifically, as shown in FIG. 4, the filter (lO) is composed of a differentiator circuit consisting of a capacitor 051 and a resistor (161), and an amplifier α'71. As a result of the components being cut off, multiplication and integration, which will be described later, can be performed accurately.

The control circuit (2) outputs a vertical synchronization signal and a horizontal synchronization signal to control the video camera (1), and also outputs a vertical address signal (Bl) and a horizontal address signal (C1) in synchronization with these synchronization signals. The control circuit (2) also generates a reset signal (DJ and gate signal (g)), which will be described later.

Storage device (hereinafter simply referred to as RAM) (3) is No. (7)
and (U S X + V @ y ) in equation (8)
(radians) (hereinafter simply referred to as declination data) and area designation data. RAM [3]
2. As shown in the 5th all, the TV camera (1
), and each of these locations has a storage capacity of the number of bits that can represent the argument data and the specification data. Horizontal scanning direction (X
The number of pixels (number of memory locations) in the vertical scanning direction (
The number of pixels in the X direction is Ny. RA, M 131 is also divided into multiple regions. In this example, R
A M +31 is divided into four regions 0 to 3, and each region is all rectangular. Since RAM +31 corresponds to the imaging plane (field of view) of the television camera (1), the fact that RAM +31 is divided into multiple areas means that the field of view of the television camera (1) is the same area. It means that it is divided into. As will be clear from what will be described later, the calculation of the +61st expression or the +71st to +81st expressions is performed for each region, and a spatial filter output is obtained for each region. Therefore, the TV-camera (1
), if a moving object exists in each divided area of the field of view, a spatial filter output for each moving object will be obtained separately. It goes without saying that these regions are not necessarily rectangular as shown in the drawings, but may be trapezoidal, circular, or any other arbitrary shape. Each storage location in the RAM (31) stores the declination data (U * x −1−V @y ) at the corresponding pixel (“py”) of the television camera (1) and its Area designation data indicating the area in which pixels are included is stored.RAM (Each storage location of 31 is stored in the control circuit (2).
The data output from the address signal (81 (C1) and stored in synchronization with the scanning of the camera (1) is read out. Fl) (F2).

ROM +81 and (9) are declination data (U-X+
008 (U11x + v11y) (
(hereinafter simply represented as [CO8]), and -Bin (Ue
x 0 V @ y) (hereinafter simply expressed as (Sin)). [cog) or (8in) takes positive and negative values. In ROM +81 or (9), [cos] or (-i-) is represented by, for example, 8 bits, the most significant digit (MSB) of which represents a positive or negative sign, and the other 7 bits. The number is [Co5
) or [8in). ROM
A more detailed configuration of +81191 is shown in Figure 7.
The signal (Fl) output from bRAM +31 is input to decoder a9, and from the value of the declination data input here, the location where [co8] or [8in] corresponding to that value is stored is specified. The address is decoded, and [coB] or (sin) of the address specified by the decoding result is read.The read data is transmitted to the signal (G
) and four.

The multiplier circuit (5) receives the video signal (A1) of the television camera (1) and a signal (G) indicating the value of [C08] or (8in) read from the ROM +81 (91).
H) is input, and f(xty)·[co8] or f(x, y)·[8in] is calculated.

An example of this multiplication circuit (5) is shown in FIG.

The video signal (A1) is an analog signal, and [008] and [8in] are digital signals.

The multiplication circuit (5) has a DA conversion function and outputs the multiplication result as an analog signal +IHJI. The multiplier circuit (5) receives the video signal (A1) as input, is connected to each output terminal of this resistor circuit Q2+ of the ladder-like resistor circuit α having eight output terminals, and is connected to each output terminal of the resistor circuit Q2+ of the ladder-like resistor circuit α having eight output terminals. An analog changeover switch controlled by
, a first adding circuit consisting of an inverting amplifier r31) and a resistor, which adds the outputs of the terminals talN of these switches, and the output of this first adding circuit and the output of the terminal tbl of the switch. It consists of a second adding circuit consisting of an inverting amplifier (support) and a resistor (toward), which performs addition.
The output of the adder circuit becomes the output signal (Il (Jl). The signal (G) (H) is weighted (a power of 2) according to each digit.
have. The resistance circuit 04 divides the video signal (AI) according to these weights. If the current flowing into the switch handle is I, then a current of 27I flows into the switch (2). Only the MSB of the signal (Gl (H)) is inverted by the N01 circuit (2), and this inverted bit controls the switch (A).The signal fG
When a certain bit of l(Hl is 0, the corresponding analog switch except switch (5) is connected to the +bl side, and when it is ■, it is switched to the (Al side. Switch ■
~In the situation shown in FIG. 8, the signal (F') is ooo-
This is the case of oooooo. In this case, each resistance country (to) and increase width so that the signal side becomes 0. vessel ant
The value of the resistor (to) connected between the output terminal of amplifier (2) and the inverting input terminal of amplifier (2) is determined. Input signal (G) (
signal (I) (or (J)) corresponding to the value of
) is as follows. MS here
When B is 0, [C0-) (or (, 1n)) is positive, and when B is 1, it is negative.

41 (or (H)) (Il (or (J)) MSB LSB 01111111 - (Al)X127/12B?
? 00000001 → (Al)X 1/128o
ooooooo → 0 11111111 → (A 1 ) X (-1/
12B)? ? 10000001 → (AI) x (-127
/128) 10000000 → (Al)X (
-1) The integrating circuit (6) receives the output signal (
Il or (Jl is integrated for each region 0 to 3.

A typical example of the integrating circuit (61) is shown in FIG. 9. The integrating circuit (6) is composed of integrating circuits (6a) to (6d) provided for each area. The integrating circuits (6a) to (6d) are all amplifiers (41).
, whose input resistance (47J) is connected to the capacitor connected between the inverting input terminal and the output terminal of the amplifier (41).
4'lJ and the switch connected between the inverting input terminal +
441, and a switch for shorting the capacitor. A reset signal (D) is output at the start of scanning one screen (one field or one frame), and the switch (49) is turned on by this reset signal (D+).

When the switch (451) is turned on, the charge on the capacitor is discharged, so each integrating circuit is set.

The switch (441) is switched on by the area designation signals (EO) to (F3) output from the decoder (11).

Controlled off. Decoder 01) has RAM +3)
decode the area designation data signal (F2) read from
Only when this decoding result is input to the gate signal (G) output from the control circuit (2), the signals (EO) to (F3
). Signal (EO) ~ (F3)
represent regions O to 3, respectively. The scanning period for one screen includes a blanking period in which there is no video signal. In addition, as shown in FIG. 3C, there is a time delay (TD, 1) for reading each data from RAM (3),
There is a time delay (TD2) for reading [COs], [:8in] from +81 +91 and a delay (TD3) for the multiplier circuit (5). Gate signal stop) eliminates such retrace period and delay time and determines the integration period to integrate only valid human input signals, and only during this integration period, the area specified by signal (F2) switch +44] of the integrating circuit is turned on, and the signal [1
1 [Jl enters. Output of integral circuit +61 (KO) ~
(K3) and (LO-(F3)) represent Q and R of the +71st and +81st expressions for each region 0 to 3, respectively.These output signals (KO) to (L3) are the output signals of the AD conversion circuit. (7), it is converted into a digital signal and sent to the CPU (4
1.

The CPU (Central Processing Unit) (4) performs processing such as writing each data to the RAM (31) and calculating the moving speed of the object based on the data read from the AD conversion circuit (7).CPU, +41 is preferably a microprocessor.

Figure 10 shows the field of view (511) of the television camera (1).
The lens group in the television camera (1) and the RAM +31 corresponding to the image formed on the television camera (1) are shown. RAM [31 has a number (N x X
There is a memory location for Ny). The length of the field of view (51) corresponding to the length of one pixel in the horizontal direction is represented by Mx, and the length of the field of view (51) corresponding to the length of one pixel in the vertical direction is represented by M7.

The horizontal and vertical lengths of the field of view (5)1 are (LMx @NX, M)' @Ny, respectively.

FIG. 11 shows the address of the storage location for area 0 of RAM +31. Figure 12 in the X direction of area 0 is
It shows the process of writing each data into area 0 of RAM (3) by CPU +41. This process
Performed during initial processing of U(41.RAM
Let Cx and Cy represent address-counters that specify the addresses in the X direction and the X direction of each storage location of +31,
The contents are represented by (Cx゛) and (C'y), respectively. Further, the value obtained by dividing the above-mentioned spatial frequency component U%V by 2π represents the number of pairs in the specified region of the spatial filter electrically configured with the circuit shown in FIG. This U and V
is assumed to be set in advance. Further, the above-mentioned magnifications Mx and My are also set in advance.

Referring to FIG. 12, first, (Axe-Axs -1-
1) -M X, and (Ay e-Ay 8+1)
* By calculating M y, the sizes AX and Ay of area 0 are calculated (steps (61) and (62)). These Ax, Ay are loaded into appropriate registers. next,
A start address Ays%Axe is set in each address counter Cy, Cx (step (6)
3X64) ). The contents of these counters (Cx) (
The values obtained by multiplying Cy) by the magnification Mx and My are X, Y
and is placed (step (65)). X% of these
Y, using the above U, V, Ax, and Ay, (U. RAM addressed in %Cy
(Written to memory location in 31 (step (67)
). The contents of counter Cx are incremented by 1 (step (6)
8) ), the new (Cx) is the end address AX6
(step (69))
). If NO in step (69), step (65)
, and the above process is repeated using a new (Cx). If YES in step (69), one horizontal scan has been completed for area 0, so the contents of counter cy are incremented by 1 (step (70)), and this new (Cy) exceeds Aye. is examined (step (71)). NO at step (71)
If so, return to step (64) and change (Cx) to Axs
l Strain and process the stamps (64 to (69)).
It is repeated A x e - A x e +l ) times.

If YES in step (71), RAM (3)
The writing of each data for all storage locations in area 0 of is completed.

It will be well understood that the writing of declination data and area designation data to each storage location of other areas 1 to 3 can be performed using exactly the same method. In this case, 1 to 3 are written as the area designation data in step (67).

Since the field of view of the television camera (1) is discontinuously divided by each memory location of RAM f31, and the size of area 0 is Ax%Ay, Equations (7) and (8) ) is modified as follows for region O.

...(12) ...(131) Fig. 13 shows the process of calculating the moving speed W of the object by the CPU (41) for one area. This process is started by a manual interrupt from the AD conversion circuit (7) every time one screen is scanned, and is executed for each interrupt.The scanning period for one screen is set to τ (for example, 16.7m8) as described above. The data corresponding to the signals (KO) to (K3) and (LO) to (L3) read from the AD conversion circuit (7) for each side input, respectively, are represented by CAD)K and (AD)L. Furthermore, it is assumed that the pitch P of the spatial filter has been calculated in advance.Furthermore, it is assumed that the phase angle calculated during the previous screen scan is α1.

Referring to FIG. 13, AD-converted data (AD) K and (ADIL) are read from the AD conversion circuit (7), and CP
Each register Ra%Rb in U (41 is loaded (step (81)). Next, each register R
The phase angle α is calculated by equation (9) using the data of a and Rb (step (82)). The change Δα is calculated from this phase angle α and the previous phase angle α1 (step (83)), and the current phase angle is used for the next calculation.
1 (step (84)).
The speed W is calculated by calculating the αα formula (step (
85)). As described above, the moving direction of the object can be detected by checking the polarity of Δα.

In the above embodiment, the declination data and area specification data are stored in the RAM (31), but two such RAMs are provided, and (co8), (8in) and area specification data are stored in these and the RQ M (81+91 may be omitted.Also, although the calculations of equations (7) and (8) are performed by the multiplier circuit (5) and the integration circuit (6), the video signal (Al) After AD converting and importing into the CPU (41), these calculations are
It is also possible to use U+41.

As explained in detail above, according to the present invention, the pitches U and V can be set arbitrarily, so compared to a moving object detection device using a conventional spatial filter, it is much more versatile. be. Also, the scanning time of a television camera is usually 1
The field size is approximately 16.7 mg, and one frame is approximately 33.3 mg,
At least the moving speed and direction of the moving body can be detected from the scanning information of one screen, and high-speed processing is possible. Therefore, it can immediately respond to moving objects that make complex movements or move at high speed. Furthermore, by setting an arbitrary area of the TV/camera's field of view, moving object information in this area can be obtained, so if the TV/camera's field of view is divided into multiple areas, information on multiple moving objects can be obtained separately for each area. can be obtained. Therefore, for example, information about a plurality of vehicles traveling on a road can be obtained with a single television camera, which is very useful for measuring traffic flow.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the spatial filter output in a complex plane, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is a time chart showing the output signal of each block in FIG. 2, and FIG.
The figure is a circuit diagram showing an example of a high band pass filter, Figure 5 is a graph showing frequency components of a video signal, and Figure 6 is a RAM
Figure 7 is a diagram showing the configuration of ROM, Figure 8 is a diagram showing the configuration of ROM.
Figure 9 is a circuit diagram showing an example of a multiplication circuit, Figure 9 is a circuit diagram showing an example of an integrating circuit, Figure 10 is a diagram showing the relationship between the field of view of a television camera and RAM, and Figure 11 shows the address of RAM. FIG. 12 is a flow chart showing the procedure for writing into the RAM, and FIG. 13 is a flow chart showing the procedure for measuring the moving speed. (1)...TV camera, (2)...control circuit,
(3)...RAM, +41...CPU, +51...
- Multiplication circuit, +61 (6a) to (6d) -6 integration circuit, (8) (9) sea RAM, +I11. ．． ·decoder. Patent applicants: Tateishi Electric Co., Ltd. and 4 others 1QIrT11! Q--- Figure 6a Ny-1 Figure 6b Rei and Mr. and Mrs. Ceremony for 4

Claims (2)

[Claims] (1) A television that captures an image of an object and outputs the video signal.
A memory that stores a spatial filter function corresponding to each pixel of a camera, a TV camera, and a means for specifying a preset area on the imaging surface of a TV camera (/J) from memory in constant scanning synchronization. means for reading a spatial filter function corresponding to each pixel; a multiplication means for multiplying the read spatial filter function by a video signal from a television camera; an integration means for integrating the multiplied signal over a specified region; A moving object detection device comprising calculation means for calculating required moving object information from an integral result. (2) A mobile object according to claim (1), wherein data specifying a preset area of an imaging surface of a television camera is stored in a memory together with a spatial filter function corresponding to each pixel. Detection device.