JPH0120360B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aiming device that automatically controls a gun that fires with direct aiming, mainly a tank gun, by using a combination of techniques in the fields of optics and electronics. .

Conventionally, guns with relatively short ranges have been controlled by one of the following three methods. The first method is to use an optical distance meter that uses triangulation to input distance information to the target into a trajectory calculator by the person operating the distance meter, and use a coordinate system with the horizontal axis as the standard. It represents the line of sight of the target as seen from the launcher, and that angle is input into a trajectory calculator to determine the firing angle of the gun. In the second method, the distance data in the first method is obtained from the time required for the pulsed laser beam with a short time width to travel back and forth the distance between the launcher and the target, and is automatically input into the trajectory calculator.
This method not only eliminates the shortcomings of the first method, namely the skill level of the operator and the time required to operate an optical measuring device, but also the lack of distance measurement when measuring distances exceeding 1 km. This greatly improved the accuracy and greatly improved the accuracy of the gun. The distance measuring device used here is
It is generally referred to as a laser distance meter or laser range finder, and the laser oscillator and oscillation wavelength used therein were a ruby laser at the early stage of development, and its wavelength was visible light with a wavelength of 0.694 μm. In the later stages, the wavelength is 1.06μm with YGA laser.
It was invisible light. The third method is a so-called open-loop control system that basically performs control without incorporating impact effects or aiming errors up to the point of firing, whereas the third method Alternatively, it was a closed-loop control system that incorporated aiming errors and corrected them, with an emphasis on correcting the next bullet. Specifically speaking, the steps up to firing the first shot are the same as the second method, but after firing the shell, the speed is determined by the speed of the shell and the distance to the target. At the same time, the angle between the target and the shell or its impact point as seen from the firing device is automatically measured using an imaging device and a video signal processing device, and a high-level system is used to set the firing angle of the second shot. The image pickup device and the video signal processing device that processes the image are added to the aiming device.

In the above explanation, for the sake of simplicity, we will assume that the firing angle of the gun is determined solely by the distance from the firing device to the target and the angle between the line of sight and the horizontal axis when looking at the target from the firing device. As has been expressed, meteorological observation quantities such as wind direction, wind speed, and temperature in the space up to the target, as well as equipment-related observation quantities such as gun wear and shell initial velocity, are added as higher-order correction quantities. Of course.

Since the conventional aiming device embodies the above three methods, it has the following drawbacks. First, as already mentioned in the explanation of the second method, the accuracy of distance measurement deteriorates especially when measuring long distances, and the first method requires a long time and a high degree of skill on the part of the operator. Furthermore, there were many points that made it unsuitable for practical use, such as the fact that neither the optical distance meter nor the operator should be subject to vibration during measurement. The second method is that the pulsed laser light used in the laser range finder is so intense that it can be easily detected when it is irradiated on an opponent, or that it can cause injury if it is accidentally irradiated on a teammate. In addition to the remaining risks, the laser transmitter is composed of a large number of expensive optical and electrical components, making it less reliable and less economical than receiving-only equipment. The third method was a closed-loop version of the gun control in the second method, so it retained the drawbacks of the second method. By the way, in an effort to prevent the irradiated pulsed laser light from being easily detected by the other party, the wavelength of the irradiated laser light is changed from 0.694 μm, which is visible light, to 1.06 μm, which is near-infrared light, and furthermore, oscillates mid-infrared light. This was achieved by increasing the wavelength of pulsed light from a carbon dioxide laser (wavelength: 10.6 μm). This effort to lengthen the wavelength was also advantageous in terms of preventing damage caused by laser light, but with the rapid progress of electro-optic composite technology, it is now possible to arrange elements in a planar manner even with pulsed mid-infrared light. With the development of such a light receiving element, the direction of arrival thereof can be easily detected, and the confidentiality has been reduced. However, in order to reduce damage to allies and effectively maximize the results of the cannon, it is necessary to measure the distance with high secrecy, control the cannon based on the results, and modify the amount of control after the second shot. There are high demands for a gun control system that satisfies these three requirements.

This invention attempts to eliminate the drawbacks of the aiming device based on the conventional control method described above by applying electronic circuit technology and optical technology that are becoming smaller, lighter, more integrated, and faster. This will be explained in detail using

Before going into detailed explanations, the gist of the present invention can be summarized in bullet points. First, a target image is formed on a plurality of high-resolution linear light-receiving elements by separate optical systems, and the two light-receiving elements are The second step is to determine the direction that gives the maximum correlation from the cross-correlation function of the obtained video signal and calculate the distance by triangulation.The second step is to calculate the distance, initial velocity, and altitude difference of the cannonball using the method described above. ,
Determine the time when the shell will reach the target point from air resistance, weather factors, etc., and calculate the time when the shell will reach the target point, including the target and the shell.
The third step is to capture and store the image seen from the launcher and automatically measure the angle between the target and the shell.
After evaluating and examining the above-mentioned measured angle, it is added as a correction amount to the anticipatory angle when firing the next bullet. FIG. 1a is a diagram showing the launcher, target object, and line of sight before the first shot is fired, where 1 is the launcher, 2 is the target, 4 is the line of sight, and 10 is the terrain near the target. FIG. 1b shows the trajectory and impact point of a cannonball fired with an anticipated angle determined by inputting the various quantities observed in FIG. 1a into the impact calculator in the firing device 1. In the figure, 3 is the trajectory of the shell, 9
is the impact point, and 12 is the expected angle. Figure 1c is a diagram showing the trajectory of the second shell when the angular errors in the elevation angle and turning angle direction observed at the time when the shell passes the target point are incorporated as correction amounts, as determined by the method described later. be. In the figure, 5 is a virtual line of sight that incorporates the angular error of the first shot as a correction amount, 6 and 7 are the elevation angle error and turning angle error of the first shot, and 8 is a target perpendicular to line of sight 4. Surface containing object 2, 1
1 is the modified trajectory of the second bullet with an anticipation angle of 12.

FIG. 2 is a diagram showing the principle of the distance measuring section of the aiming device according to the present invention, the basic configuration of the optical system, and the distance dependence of measurement accuracy. In FIG. 2, 11 is the optical system of the distance measuring section, 12 and 13 are linear light receiving elements in which a plurality of image sensors are arranged in a linear manner with high density, and 1
4 and 15 are imaging lenses having a focal length f that are arranged parallel to each other, and 16 is a distance D between both imaging lenses. Now, the target object 2 is on the optical axis of one of the imaging lenses 14, and the imaging lens 14 and the target object 2 are
If the distance to R is R, then the other imaging lens 15
The image forming position of the target object 2 on the image forming plane is located at a distance d from the optical axis of the image forming lens 15, and is in the relationship with each of the above-mentioned quantities in equation (1).

d=D・f/R...(1) FIG. 3 shows the configuration of an electronic circuit for automatically measuring the above-mentioned d. In the figure, 17 and 18 are the linear light receiving elements 12 and 13 drive circuits, 19 and 20 are memories for storing the signals of the linear light-receiving elements 12 and 13, and 21 is a partial video signal extracted from the image signal of the target object 2 of the linear light-receiving element 12 and a linear light-receiving circuit. 22 is a correlation length setting circuit for cutting out a partial video signal; 23 is a maximum correlation coordinate detection circuit; 24 is a memory for storing the detected maximum correlation coordinate; 25 is an averaging circuit for averaging the stored contents of the memory 24 to reduce the effect of time fluctuation of the maximum correlation coordinate due to noise generated in the process of signal processing, and 26 is the (1st) maximum correlation coordinate from d to
This is a distance conversion circuit that converts the distance R to the target object 2 using the relationship of the formula.

FIG. 4 shows the image formed on the linear light receiving elements 12 and 13 of the distance measuring circuit shown in FIG. FIG. 3 is a diagram depicting the electrical signals generated by the electronic circuit and the output of the subsequent electronic circuit in correspondence with the above-mentioned input image. In FIG. 4, 27 and 28 are optical images,
Since the image of the target object 2 is located at a short distance, it is observed to be shifted laterally. 29 and 30 are regions to be converted into electrical signals, 31 and 32 are corresponding electrical signals, 33 is a reference signal cut out by the correlation length setting circuit, and 34 is a reference signal 33 on the left side of the coordinate axis of the electrical signal 32. This is the correlation signal obtained by moving to the right from , and performing the correlation calculation of equation (2), and is the output of the correlation calculation circuit 21.

Ci=1/k _k/2 〓 ^j=-k/2 Sj・R _j+i (2) 35 indicates the maximum value of the correlation signal 34 on the corresponding coordinates, and 36 indicates the storage in the memory 24. The content is expressed as a histogram, and 3
7 indicates the average value of the maximum correlation coordinates obtained therefrom, which is the output of the averaging circuit 25. In addition, Section (2)
In the formula, Sj indicates the electrical signal 32, R _j+i indicates the reference signal 33, and Ci indicates the correlation signal 34. Subscripts i, j, and k each indicate coordinates, and k is half the width of the reference signal 33. Further, the double-headed arrow d shown below the average value 37 of the maximum correlation signal is an amount corresponding to the displacement amount d in equation (1).

Now, the displacement d in equation (1) has been obtained in the above manner, but the relationship between the measurement resolution △d of d and the accuracy △R/R of the distance R determined by equation (1) is found. This is equation (3).

△R/R=-(△d/f・D)・R...(3) Now, the results of calculating the accuracy by substituting f=400mm, D=1m, and △d=5μm are shown in Figure 2 b. As shown, accuracy △R/R=2.5% for distance R=2000m
It can be seen that the following results can be obtained.

FIG. 5 is a diagram showing the configuration of a landing error angle measuring section that measures the error at the time when the shell reaches the vertical plane 8 including the target object 2, which is the second component of the aiming device according to the present invention. . In Figure 5, 38
3 is a distance measurement signal processing circuit shown in FIG. 3, 39 is a trajectory calculator that calculates the expected angle from the distance to the target object 2, the altitude angle to the target object, the initial velocity of the shell, the wind direction, the wind speed, etc., and 40 is the initial velocity. and a correction amount input terminal for wind direction, wind speed, etc., 41 is an interface circuit that generates a signal to control a gate 45, which will be described later, from the flight time calculated by the trajectory calculator 39, and 42 is a digital input terminal for the flight time of the cannonball. A clock oscillator that generates the time signal necessary for measurement, 4
3 is a shell firing time detection circuit necessary for starting clock signal measurement, 44 is a gate, 45 is a gate for ending clock signal measurement, and 46 is a
From video signals sent from a TV camera or an infrared imaging device using a planar image sensor, a video immediately before the shell is fired and a video at the time of impact of the shell are stored in the subsequent frame memory 1 and frame memory 2 in the form of electrical signals. memory control circuit for storing data in 47
48 is a frame memory 1 that stores a video signal immediately before firing, and 48 is a vertical plane 8 in which a cannonball includes a target object 2.
The frame memories 2 and 49, which store video signals at the time of passing through the bullet (hereinafter referred to as the impact time), are used to store video signals such as those shown in FIG. A point detection circuit, 50 is a correlation calculation circuit that measures the angle change of a TV camera, etc., which will be described later, before and after the gun is fired from two images in the frame memory 147 and the frame memory 248, and 51 is a bullet determined by the bright spot detection circuit 49. An angular error detection circuit that subtracts the angular change determined by the correlation calculation circuit 50 from the center coordinates of the bullet to determine the angular error in the vertical plane 8 at the time of impact; 52 is a gun controller that controls the pointing angle of the gun; , 53
54 is a push button switch that is pressed when the operator who is searching for the target object 2 by changing the pointing angle of the sight glasses captures the target object in the center of the sight glasses; 54 records the video signal at this time in the frame memory 147; A lock-on signal generator 55 generates a trigger signal for detecting the target object 2 on the imaging surface of a TV camera, etc.
56 is an imaging device such as a TV camera or an infrared imaging device using an image-shaped imaging device; 57 is an imaging device that limits the aperture of the lens 55 based on the average value of the video signal of the imaging device 56; An aperture drive circuit 58 is used to prevent signal saturation, and a signal determination circuit 58 determines whether or not to transmit the signal from the angle error detection circuit 51 to the trajectory calculator 39.

Since the landing error angle measuring section is configured as described above, the operator first captures an image of the target object 2 on the optical axis of the imaging device 56 and the lens 55 as shown in FIG. When the user presses the push button 53 whose distance was measured by the distance measuring section shown in FIG. 3, a video signal as shown in FIG. 7 is stored in the frame memory 147. Note that, in order to clarify the amplitude of the video signal, FIG. 8 shows the amplitude three-dimensionally in the Z-axis direction. Next, the signal from this push button 53 is transmitted to the cannon's firing device and becomes a trigger signal for firing the cannonball, causing the cannonball to be fired. By the way, since the flight speed of the shell and the distance to the target are known in advance, the time at which it reaches the vertical plane 8 containing the target 2 can be determined, and the video signal of the imaging device 56 at that time is as described above. The frame memory 248 can be stored in the frame memory 248 according to the method. The contents are shown in Figure 6. When expressed three-dimensionally in the same way as FIG. 8, it becomes as shown in FIG. 9, and it can be seen that the video signal in the shell portion is the strongest. Therefore, the function of the bright spot detection circuit 49 that determines the coordinates of the shell is to extract the maximum amplitude from a limited portion of the video signal shown in FIG. 6 stored in the frame memory 248, excluding the horizontal synchronization signal and vertical synchronization signal. The given scanning line number and the time from the horizontal synchronizing signal, that is, the distance in the Y-axis direction and the distance in the X-axis direction in FIG. 9 are determined. Let these values be X ₂ and y ₂ . By the way, the optical axis of the optical system determined by the imaging device 56 and the lens 55 changes during aiming and landing due to impact during firing, control error of the optical axis stabilizing mechanism, etc. The bullet coordinates (X ₂ , y ₂ ) determined by the output circuit 49 do not give a landing error, and the amount of change in the optical axis must be subtracted. The correlation calculation circuit attempts to measure the amount of change in the optical axis using the correlation processing method shown in FIGS. 3 and 4. The correlation calculation in Figure 4 is performed only in the horizontal direction, but since the optical axis changes with two degrees of freedom in the images shown in Figures 6 and 7, it can also be applied in the vertical direction. It is necessary to perform a correlation calculation. The correlation calculation in this case is shown in equation (4).

CiI=1/kK _K/2 〓 ^J=-K/2 _k/2 〓 ^j=-k/2 S _j , J・R _j+i , J+I ...(4) Now, the result of this correlation calculation is determined. The true impact error (△X, △y) is given by the coordinates of the optical axis and X ₁ and y ₁ .
is obtained using the fifth equation.

△X _{= X 2 -} The amount of correction to the anticipation angle during firing is -ΔX, while △y is the error angle in the direction of elevation and depression, and the amount of correction is -△y. Of course, △X and △y are the displacement amounts on the image sensor surface of the imaging device 56, and in order to use them as correction amounts for the viewing angle, it is necessary to convert them into angles by dividing them by the focal length f of the lens 55. .

△θ=△X/f, △=△y/f...(6) By the way, in the above explanation, as shown in Figure 9,
The intensity of the image signal of the cannonball and the image signal of the target are at a comparable level, and both of them have the automatic aperture control signal 57.
The figure shows a case where the output is properly controlled and the output is not saturated; however, as the distance to the target gets closer, the image of the saturated bullet becomes much brighter than the background, causing the video signal to be output. Not only will the image become saturated, but in extreme cases, a comet-like bright area may appear in the part of the scanning line that is scanned later than the actual position of the shell, or in the case of a solid-state image sensor. may cause a linear bright area in the area where the transfer line exists. 10 to 12 are examples of images reproduced from the image signal of the imaging device 56. FIG. In the case of such an image, it is impossible to measure the position of the shell at all, but even if it were possible, the detection accuracy would be reduced, so an optical filter with wavelength characteristics that darkens only the image of the shell is placed in front of the lens 55. It is necessary to provide

FIG. 10 is an example in which a videcon is used as the image sensor of the image sensor 56, FIG. 11 is an example in which a CCD, which is a type of solid-state image sensor, is used, and FIG. 12 is an example in which a solid-state image sensor is used. CID (Charge) is a type of
This is an example of using an Injection Device.

Next, the signal determining section, which is the third component of the aiming device according to the present invention, will be explained. The function of this part is to automatically determine whether or not the impact error angle measured by the impact error angle measurement unit is significant, and only if it is significant, transmit it to the trajectory calculator 39.
If it is not significant, the bright spot detection circuit 49, the correlation calculation circuit 50, and the memory control circuit 46 issue a command to calculate the landing error angle again according to a separately prepared method.
It is to put it out to. For convenience of explanation, in the explanation of FIG. 5, a case is described in which the signal determination circuit 58 assumes that the above-mentioned determination result is significant, but the operation thereof will be described below for each determination content.

Whether or not the aiming device according to the present invention can demonstrate the expected performance depends first on whether the lateral movement speed of the target as seen from the gun control device is a constant value including zero at the time of firing the first bullet and the time of firing the next bullet. secondly, the frame memory 248 stores an image of the time when the shell is within the vertical plane 8 including the target object 2;
Thirdly, the two frame memories 47 and 48 appropriately store images before and after firing, and fourthly, the circuits constituting the device including the correlation calculation circuit 50 and the angle error detection circuit 51 are It depends on things like normal functioning. First, the speed of the first lateral movement is determined by the memory control circuit 4 using signals from the lock-on signal generating circuit 54 in each period before firing the first bullet and before firing the next bullet.
6 is activated and before stopping the rewriting of the memory contents of the two frame memories 47 and 48, the lateral movement speed of the target image within the screen is measured, and only when the two match, the angular error detection circuit is activated. This is done by transmitting the signal 51 to the trajectory computer 39. The moving speed is set at a constant time rate by the imaging device 5.
6, by performing the same processing as that performed by the correlation calculation circuit 50 explained in FIG. 5, and for this purpose, the correlation calculation circuit 50 is used. Next, the determination as to whether the image of the cannonball is stored in the second frame memory 248 is based on the possibility that the image of the cannonball saturates the image signal of the imaging device as shown in FIGS. 10 to 12. Therefore, the video signal of the frame memory 147 was subtracted from the video signal of the frame memory 248 by taking into account the deviation of the optical axes of the lens 55 and the imaging device 56 determined by the correlation calculation circuit 50. This is done depending on whether or not there is a brightness area that is sufficiently higher than noise in the video signal. Furthermore, the determination as to whether or not the third appropriate brightness level is stored is based on whether the saturation level is reached within the entire screen of the video signal stored in the frame memory 147 or within a relatively narrow screen centered on the optical axis. This is done based on whether there are any high-luminance areas, and whether the video signal stored in the frame memory 248 is binarized using a plurality of threshold values and whether the center of gravity of the binary video has the same coordinates. Figure 13 shows the image extracted from the video signal shown in Figure 9, where only the full video portion is binarized using three threshold values, and its center of gravity with brackets. , FIG. 13a shows whether there is no signal saturation or even if there is signal saturation, the bright spot detection circuit 4
9 shows the case where the landing error angle can be determined with high accuracy, and FIG. 13b shows the case where there is signal saturation as shown in FIG. 11. Finally, it is determined whether the correlation calculation circuit 50, angle error detection circuit 51, etc. that constitute the fourth device are functioning normally.
Difference between the coordinates determined by the two circuits 50 and 51 △
This is done depending on whether the absolute values of X and Δy are large enough to exceed a predetermined value taking into account the pointing error of the gun. The operation of this signal judgment section can be performed by using the components of the impact angle measurement section shown in Fig. 5 before or after the shell is fired, or by comparing the outputs of the components with preset reference values. The signal determination circuit 58, which is the main component of the signal determination section, is a small electronic computer.

In addition, in the above explanation, the correlation calculation circuits 21 and 50
has been assumed to execute the so-called product correlation shown in equation (2), but in the case of a mobile device that emphasizes shortening calculation time and reducing the equipment scale, equations (7) and (8) are used. )
It is effective to carry out the so-called absolute value correlation of differences as shown in Eq. The meanings of the symbols in the formula are the same as in formula (2).

Ci=1/k _k/2 〓 ^j=-k/2 |Sj−Rj+i| ...(7) C _iI =1/kK _K/2 〓 ^J=-K/2 _k/2 〓 ^{j=-k/ 2} |S _j , J−R _j+i , J+I | ...(8) Equation (7) is the absolute value correlation of the one-dimensional difference,
Equation (8) is two-dimensional and corresponds to Equation (2) and Equation (4), respectively.

As described above, in the aiming device according to the present invention,
Since it is possible to accurately measure the distance to a target without sending out light waves or radio waves, it is possible to aim while maintaining high secrecy, and it is also possible for the shell to be located on a vertical plane that includes the target. The error angle at the time when the bullet passes above can be accurately measured even if the optical axis of the imaging device changes before and after the bullet is fired, and the measurement result of the impact error angle can be calculated based on the characteristics of the imaging device and the distance measurement unit. The act of correcting the next bullet itself was made effective because it was evaluated using a signal judgment method and signal judgment circuit that were determined by taking into account the characteristics and the characteristics of the gun's firing device.

[Brief explanation of drawings]

Fig. 1 is a diagram showing how the device is used, Fig. 2 is a diagram showing the principle of the distance measuring section of the aiming device according to the present invention, the basic configuration of the optical system, and the distance dependence of the accuracy of distance measurement. 4 is a diagram showing the configuration of the electronic circuit of the distance measuring section, FIG. 4 is a diagram depicting the output of each part of the electronic circuit in FIG. 3 in correspondence with the image on the linear light receiving element, and FIG. FIGS. 6 and 7 are diagrams showing the configuration of the impact error angle measuring unit of such an aiming device, and show images of the target direction of the shell before firing, captured by the image sensor that is the input sensor of the impact error angle measurement unit. A schematic diagram of an image in the direction of the target at the time when the shell passes through a plane that includes the target and is perpendicular to the line of sight of the imaging device. Figures 8 and 9 are video signals corresponding to Figures 6 and 7. Figures 10 to 12 are three-dimensional representations of the amplitude of the Z-axis video signal and the X- and Y-axes as coordinates on the image sensor. Figures 10 to 12 show cases where the imaging conditions of the imaging device were inappropriate and the image of the shell was saturated. Figure 10 is a video image when using a videocon, Figure 11 is a CCD, Figure 12 is a diagram when using a CID, and Figure 13 is used when determining the significance of the detected error angle. FIG. In the figure, 12 and 13 are linear light receiving elements, 14 and 1
5 is an imaging lens, 19 and 18 are memories, 21 is a correlation calculation circuit, 22 is a correlation length setting circuit, 23 is a maximum correlation coordinate detection circuit, 24 is a memory, 25 is an averaging circuit, 26 is a distance conversion circuit, 38 39 is a distance measurement signal processing circuit, 39 is a trajectory calculator, 41 is an interface circuit, 42 is a clock oscillator, 43 is a firing time detection circuit, 44 and 45 are gates, 46 is a memory control circuit, 47 and 48 are frame memories, 49 50 is a bright spot detection circuit, 50 is a correlation calculation circuit, 51 is an angular error detection circuit, 52 is a gun controller, 53 is a push button, 54 is a lock-on signal generator, 55 is a lens, 56 is an imaging device, and 57 is an aperture drive circuit, 58
is a signal judgment circuit. It should be noted that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Scope of Claims] 1. The amount of correction to the anticipation angle when firing the next shell is determined by the direction of the target and the shell as seen from the gun at the time when the gun reaches a plane perpendicular to the line of sight connecting the gun and the target. In the aiming device that measures the difference between
After arranging the optical axes of these optical systems and the linear light-receiving elements to be parallel to each other, the cross-correlation of the outputs of the two linear light-receiving elements is measured between the two linear light-receiving elements in a plane perpendicular to the optical axis. a distance measuring unit having a function of a triangulation method to determine the distance to a target by taking the coordinates in the arrangement direction of Consists of a light-receiving element that scans the focal plane using one or more image sensors, and a lens that can change the brightness of the image by changing the angle of a built-in filter using an external signal. An image including the optical system and the target before the shell is fired, and an image including the shell and the target at the time when the shell passes through the vertical plane are extracted and stored in two frame memories, and the cross-correlation of both images is calculated. In this way, the amount of movement of the target is determined, and the direction of existence of the shell is determined from the measurement of the center of gravity of the binary image, which is binarized based on the intensity of the latter image amplitude. A sighting device consisting of a bullet impact error angle measurement unit whose component is an electronic circuit system that outputs a correction amount when firing a bullet. 2 The signal judgment unit uses the image information stored in the two frame memories to subtract the pre-launch image from the post-launch image, taking into account changes in the line of sight before and after the gun is fired, and determines whether there is a high brightness area within the screen. 2. The aiming device according to claim 1, wherein an electronic computer is used which has a function of not transmitting the results of the impact error angle measuring section to the trajectory computer when there is no error angle of impact. 3. As a signal determination unit, the video signal of the latter frame memory in which the image of the cannonball is stored is binarized using multiple threshold values, the center of gravity of these multiple binary images is calculated, and the center of gravity of each image does not match. 2. The aiming device according to claim 1, wherein an electronic computer is used which has a function of not transmitting the results of the impact error angle measuring section to the trajectory computer when the impact error angle is measured.