RU2378605C1 - Light target - Google Patents

Abstract

FIELD: weaponry.

SUBSTANCE: invention relates to targets for definition of outer ballistic parametres (coordinates, speed) of bullets and shells in case of direct fire at vertical barriers (targets). The invention concept is as follows: the light sources are grouped into two pairs with the light sources of each pair arranged in a V-shaped pattern; in one pair the light sources are dislocated relative the symmetry axis to produce identical but opposite in sense acute angles at the top, and in the other - at the bottom. Installed as opposed to the symmetry axis of each pair is an optic-and-electronic converter; the outputs of the converters are connected to the inputs of the analogue signal summator via coaxial communication lines; the summator output is connected to the selector input; the selector output is connected to the input of the digital memory oscilloscope; the output of the latter is connected to the computer input. The computer outputs are connected to the control inputs of the discrete (test) signals generator and the selector.

EFFECT: design simplification and accuracy improvement.

5 dwg

Description

The invention relates to targets for determining external ballistic parameters (coordinates, speed) of bullets and shells when firing direct fire at vertical barriers (targets) and can be used in experimental determination of accuracy and accuracy of fire and bringing weapons to normal combat, in determining speed, in training and training session.

A known method and apparatus for determining the coordinates of a bullet [US Patent No. 3487226, class. 250-222, 1996. Method and apparatus for determining bullet coordinates by measuring time intervals between successive intersection of light screens], measuring time intervals between successive intersection of a bullet of light screens - optical planes based on the use of optical systems consisting of slotted light sources located on the frame on one side of the sheaf of trajectories, and slotted photodetectors located on the other side. The slit source of each light screen contains row-mounted light sources and collimation lenses forming parallel beams of rays, from which a screen of finite thickness is cut out by a slit. The screens of each source (up to 12 pieces) are adjacent closely to each other, forming a common light screen. The slit receiver of each light screen contains focusing lenses located behind the slit opposite the corresponding light sources, in the foci of which photodetectors (photodiodes) are installed. Photodiodes are combined in groups of 6 each according to the OR circuit at the inputs of the preamplifiers of the photocurrents, the signals of the preamplifiers are combined according to the OR circuit at the inputs of the Schmidt trigger. As a result, when a part of the light flux is shaded by a passing bullet or projectile, an electrical signal is generated, which triggers the Schmidt trigger. The signal from the first light screen starts 3 chronometers, and according to the signals from the next three screens, the chronometers stop. Using the time intervals measured by the chronometers, the coordinates of the point of contact with the imaginary target (registration plane coinciding with the last screen) are calculated.

The disadvantages of the light plane based on light screens formed by slotted sources and slotted receivers are the small size of the registration field and the high probability of damage to equipment from ricochets in spite of armor protection in front of the equipment due to its close proximity to a sheaf of trajectories; the complexity and complexity of focusing the collimators and photodetectors, as well as low reliability due to the large number of light sources and photodetectors and preamplifiers of photocurrents; the complexity of shielding and protection against interference from low-current circuits, since photodetectors and preamplifiers are spaced a relatively large distance; low measurement accuracy and the ability to shoot only normal to the target due to the proximity of light sources and receivers, as well as due to the use of design ratios that are valid in the case of trajectories normal to the target plane.

The closest analogue is the light target [Light target. RF patent No. 2213320 dated 09/27/2003 by application No. 2002116940, class. F41J 5/02 of June 24, 2002. VNIIGPE / Authors Afanasyeva N.Yu., Verkienko Yu.V., Kazakov B.C., Korobeinikov VV (prototype)], containing linear extended light sources and optoelectronic converters installed on opposite sides of a sheaf of paths and pairwise forming light screens, tilted at different angles, coaxial communication lines, matching (threshold) devices, OR circuitry, and a computer, input interrupt processing which is connected to the output circuit OR.

The disadvantages of the device are a large number of sensors and, accordingly, coaxial communication lines, low accuracy of measuring the moments of suppression of zeros of light screens due to the limited capabilities of analog signal filtering and ripple of the total signal due to the ripple of the voltage of the power source of the emitters, as well as due to different delay of the sensors.

The objective of the invention is to eliminate the disadvantages of the known device by reducing the number of sensors and coaxial communication lines, converting analog signals to digital for subsequent digital processing and filtering.

The problem is solved in that the light sources are combined in two pairs, the light sources of each pair are V-shaped, and in one pair they are collapsed relative to each other at the same and opposite acute angles from above, and in the other pair from below, the light flux from each pair light sources arrive at one optoelectronic converter located on the other side of the sheaf of trajectories opposite the axis of symmetry of the pair of emitters.

Technical result - The proposed arrangement of light sources and optoelectronic converters (respectively, light screens) provides the same distance between the light sources and optoelectronic converters (respectively, the same signals and a decrease in measurement error), proximity to the ideal scheme (respectively, with a high conditionality of the system of equations model and measuring the average speed at the base in the area of the target). The transition to digital signals, digital filtering, and the use of reference signals from the first screens of each pair of screens provide the separation of signals from the second screens of each pair, which made it possible to bring the emitters closer to receive images of the light sources of each pair on a single photodetector of an optical-electronic converter, thereby reducing the number of optical -electronic converters and coaxial communication lines (respectively increasing reliability, reducing cost and reducing the error in determining coordinates and speed awst). The tilt of all screens eliminates the muzzle wave interference signal and allows the target to be used at a minimum range of 25-50 m.

Figure 1 shows a diagram of a light target, figure 2 is a layout of light sources, optoelectronic converters and a control frame in a dash; figure 3 - projection of the screens E ₁ E ₂ , E _y , E _z on the vertical XY and horizontal XZ plane, figure 4 - projection of the trajectory on the plane XY and XZ, figure 5 - signals at the output of the adder 2, generated when the bullet intersects the screens E ₁ and E ₂ .

- ордината фиктивной позиции, лежащая на касательной к траектории в точке х=0. На фиг.5 изображены: приведенный эталонный сигнал u_эпр(t), соответствующий эталонному сигналу u_э(t} на выходе сумматора 2 (фиг.1), формируемому при пролете пули через экран Э₁ со скоростью ν_э в случае выключенного источника света И₂; суммарный сигнал u_с(t), формируемый при пролете пули через экраны Э₁, Э₂ в их нижней части со скоростью ν_с, когда расстояние между экранами небольшое и сигналы от Э₁ и Э₂ накладываются друг на друга; разностный сигнал u(t)=u_с(t)-u_эпр(t), где u_эпр(t) - приведенный к сигналу от Э₁ в сумме u_c(t) по амплитуде и длительности (скорости полета пули) сигнал. Приведенный эталонный сигнал соответствует сигналу при пролете пули через экран Э₁, а разностный сигнал соответствует сигналу от пролета пули через экран Э₂.The device contains light sources And ₁ ... And ₄ , optoelectronic converters D ₁ , D ₂ , control frame KR, coaxial communication lines 1, adder of analog signals 2, selector 3, recorder (digital oscilloscope) 4, personal computer 5 with a display device information (display) and communication of the tester with the computer 6, the generator of discrete signals 7. The weapon for testing is installed on the machine 8 or held by the tester. The light sources And ₁ , ..., And _{4 are} installed in a vertical plane (along the wall of the shooting gallery), and optoelectronic converters - on the opposite side (along the other wall of the shooting gallery). The light sources of the first pair And ₁ , And ₂ are located symmetrically V - figuratively and are tilted by the angles + α and -α equal in absolute value, i.e. in the opposite direction. The light sources of the second pair of And ₃ , And _{4 are} also symmetrically V-shaped, but are angled at the bottom - α and + α, so that the light sources And ₁ And ₃ And And ₂ And _4, respectively, are parallel. Optoelectronic converters D ₁ and D _{2 are} installed opposite pairs of light sources And ₁ And ₂ And ₃ , And ₄ perpendicular to the direction of fire in the planes of symmetry of the light sources of each pair. The outputs of the optoelectronic converters are connected to the inputs of the circuit 2 for summing analog signals, the output of which through the selector 3 is fed to the input of a digital storage oscilloscope 4, the output of which is connected to a personal computer 5 connected to the device 6 for displaying information and communication of the tester with a computer. Figure 3 illustrates the method of four light screens (light wedges). The base screens E ₁ and E _{2 are} perpendicular to the X axis (parallel to the YZ plane), the E screen _{y is} rotated by an angle α relative to the Z axis, and the E screen _z is rotated by an angle β relative to the Y axis. Distances from the YZ plane to the points of intersection of the path of the bullet flying at a speed ν parallel to the X axis, respectively denoted by p ₁ , p _y , p _z and p ₂ . Figure 4 - PS - the firing plane formed by rotation relative to the vertical axis through the angle ψ, (x ₀ , y ₀ , z ₀ ) - position coordinates (y _p = z _p = 0, x _p = -D), D - firing range

- the ordinate of the fictitious position lying on a tangent to the trajectory at the point x = 0. Figure 5 shows: the reference signal u _epr (t) corresponding to the reference signal u _e (t} at the output of the adder 2 (figure 1), formed when a bullet passes through the screen E ₁ with a speed ν _e in the case of a switched off light source And ₂ ; the total signal u _с (t), formed when a bullet passes through the screens E ₁ , E ₂ in their lower part with a speed of ν _s , when the distance between the screens is small and the signals from E ₁ and E ₂ overlap each other; signal u (t) = u _c (t) -u _EPR (t), where u _EPR (t) - corrected to a signal from the sum e ₁ u _c (t) in amplitude and duration (s orosti bullet) signal. The above reference signal corresponds to a signal with a bullet passage through the screen E _1, and the difference signal corresponds to a signal from passage of the bullet through the screen E _2.

The discrete signal generator 7 is used to generate a sequence of signals that simulate the signals of the sensors and used in testing the system. Switching the signals entering the recorder is carried out using the selector 3, implemented on the relay.

The mathematical essence of the invention is as follows.

Define the screen (plane) as the equation in the traces

where a = -fgα, b = fgβ, α, β are the slope angles of the tracks (lines of intersection with the coordinate planes XY and XZ); r is the abscissa of the point of intersection of the screen with the X axis.

We define a rectilinear (in the vicinity of the target and screens) trajectory in the parametric form

where (x ₀ , y ₀ , z ₀ ) is the point of impact in the target plane (x ₀ = 0); l, m, n are the direction cosines of the trajectory equal to

Here according to figure 4

- ордината фиктивной позиции; z_р - боковая координата фиктивной позиции (z_p=0).where D is the firing range;

- ordinate of a fictitious position; z _p - lateral coordinate of the fictitious position (z _p = 0).

In (2), the parameter p physically represents the distance along the trajectory from the point (x ₀ , y ₀ , z ₀ ) to the current point (x, y, z). In the case of a constant speed p = νt and t is the flight time from the point (x, y, z) to the point (x ₀ , y ₀ , z ₀ ).

From (1) and (2) for the parameter p we have

In the case of the ideal arrangement of the screens (Fig. 3) and the path normal to the target, the distance between the screens _{y y} and _{2 2 is} proportional to the coordinate y _{0 of} the hit point, the distance between the screens _{z z} and _{2 2 is} proportional to the lateral (horizontal coordinate z _{0 of} the hit point, and the distance between the parallel screens E ₁ and E ₂ is equal to the base L and can be used to measure the average speed of the bullet, related to the middle of the base.

where k _y , k _z are instrumental coefficients equal to the ratios of the corresponding time intervals.

From (6) and (7) it follows that the screen _{y y} is functional for determining y ₀ , and _{z z} - for determining z ₀ .

ограничимся в числителях и знаменателях этих дробей линейными членами. В результате получим следующие уравнения регрессии (модель мишени)In the case of a trajectory abnormal to the target plane and an imperfect arrangement of the screens (with rotations simultaneously relative to the Y and Z axes, i.e., α ≠ 0 and β ≠ 0) when substituting in (6) and (7) the values of p ₁ , p ₂ , p _y , p _z in accordance with the formula of the general case (5) we obtain fractional rational functions. Given the fact that

we restrict ourselves to the numerators and denominators of these fractions by linear terms. As a result, we obtain the following regression equations (target model)

Since the coefficients of the model α _i , b _i , i = 0, ... 4, are unknown, we will carry out the identification. To do this, make n≥5 shots, for example, at the corners and center of the target, measure the time of the intersection of the screens in each shot and the coordinates of the holes in graph paper on the control frame. Then we solve the system of equations (8) or (9) with respect to unknown α _i , or b _i .

In the operating mode, after firing and measuring the times of crossing the screens, we will calculate the instrument coefficients k _y , k _z and then resolve the system (8), (9) with respect to the coordinates.

Rewriting equations (8), (9) in the line, we obtain a system of two linear algebraic equations with respect to y ₀ , z ₀ , which can be solved, for example, according to the Cramer rule.

Obviously, not for any arbitrary arrangement of screens the system of equations (8), (9) is solvable. If, for example, all screens are parallel, then all times will be the same for any y ₀ , z ₀ , and the system is insoluble. Mathematically, in this case, the determinant of the system is equal to zero and the system is poorly (or not at all) conditioned, and the condition number, for example, by the Euclidean norm will be equal to infinity. The minimum value of the condition number, equal to 1, will be in the case of a diagonal system, when each of the equations contains one unknown, which corresponds to the ideal arrangement and equations (6), (7).

However, in the case of short ranges (up to 25-50 m, depending on the caliber of the bullet or projectile), when the screen is parallel to the YZ plane, an interference signal appears that exceeds the useful signal from the passing bullet and is ahead of it. Physically, its appearance can be explained as follows. During the exit of powder gases from the axis of the bore, a spherical supersonic wave is formed, the radius of which increases as it propagates. Upon reaching the screen, the wave is almost flat. The wave front is a shock wave, which from an optical point of view is a lens that distorts the course of light rays. This leads to the fact that the flow from the emitter at the moment the front crosses the screen wave deviates and does not fall on the photodetector, which is equivalent to the shading of the emitter and the appearance of the signal at the output of the sensor photodetector.

It was experimentally established that in the case of a tilt of the screen by 6-8 or more degrees, the interference signal decreases to an acceptable value or practically disappears.

In order to reduce the number of sensors and coaxial communication lines, taking into account the need for tilting the screens and ensuring the conditionality of the system (approximation to the parameters of the ideal circuit using the four-screen method), an arrangement of FIG. 2 is proposed. In the scheme, all screens are tilted and the distances from the emitters to the sensors are the same, which ensures the same signals. The distance along the direction of fire (X axis) between the screens E ₁ and E ₃ or E ₂ and E ₄ (figure 2) does not depend on the lateral coordinate z, and in the case of screens E ₁ and E ₃ it increases with increasing y ₀ , and in the case of screens E ₂ and E ₄ , on the contrary, decreases. Similarly, the distance between the screens E ₁ and E ₄ or E ₂ and E ₃ does not depend on the vertical coordinate y, and in the case of screens E ₁ and E ₄ it decreases with increasing z ₀ , and in the case of E ₂ and E ₃ , on the contrary, it increases . Finally, the difference in the average distances between the screens E ₁ , E ₂ and E ₃ , E _{4 is} constant and equal to the base L. Thus, the marked distances correspond to the ideal diagram of figure 3. Taking into account the opposite dependences of the distances on the coordinates noted above, and for averaging the errors of time measurements, it is advisable to use the following instrument coefficients in equations (8), (9)

Since with a large distance between the screens of the pairs (between E ₁ and E ₂ or E ₃ and E ₄ ), the images of the emitters are not projected by optical systems onto the sensitive areas of the photodetectors of the sensors, they must be placed closer to each other. In this case, when a bullet spans in the area of their closest approach (for screens E ₁ , E ₂ - at the bottom, and for E ₃ , E ₄ - at the top, figure 2), the signals from the screens at the output of analog adder 2 (figure 1) are superimposed from each other and it is necessary from the total signal u _with (t) = u ₁ (t) + u ₂ (t) to select the signal u ₂ (t) from the second screen bullet in the direction of flight. The algorithm for extracting the second signal u ₂ (t) is as follows. Preliminarily, when the emitters I ₂ and I ₄ are turned off, the signals u _e (t) from the first screens E ₁ and E ₃ are recorded, and then they are digitally processed (smoothing) in computer 5. For each reference signal, the amplitude u _em and the duration of the positive pulse are determined τ _e (at the level of 0.1 u _em ). In the operating mode, with all emitters turned on, during the shot, the total signals u _c (t) are recorded and after their digital processing (smoothing) using the same algorithm as for the reference signal), the amplitude u _{1m of the} first positive pulse and its duration τ _{1 are} determined (at the level of 0.1 u _1m ). Then the reference signal is brought to each total signal by changing the scale in amplitude and duration, i.e.

Subtracting from the total signal the reduced reference signal, previously biased until the first positive pulses of the total and reduced reference signals coincide, find the signal from the second screen

The system operates as follows.

Preliminarily, in the digital storage oscilloscope, the start delay Q _s and the length after recording Q _{p are set} , in total not exceeding the volume of the ring buffer Q≥Q _s + Q _p .

The sampling period is determined by the velocity of the bullet V _D at the firing range D, the length of the path section L _bl blocked by the screens and the buffer volume

МГц.The speed is taken with some underestimation compared to the expected. Then the sample rate

MHz

In the identification mode, to generate the reference signals corresponding to the screens E ₁ and E ₃ , turn off the power of the light sources And ₂ and And ₄ , start the oscilloscope and fire a shot at the center of the target.

After the shot, the bullet sequentially crosses the light screens. At the intersection of each light screen, part of the light flux incident from the light source to the photodetector of the optoelectronic converter is shaded, and an electrical signal is formed at the output of the optoelectronic converter, which is transmitted through the coaxial communication line 1 to the input of signal summing circuit 2, and from it output - through selector 3 to the input of the recording of the oscilloscope 4. According to the signal generated when the first signal reaches a threshold level, recording of information from the buffer to the computer begins, starting with the history on Q _s After reaching Q _p, registration ends and information is recorded, i.e. reference signals corresponding to the first screens of the pairs from the ring buffer to the computer 5. Then, immediately after the reading light screen E ₄ , a control frame is installed with graph paper glued onto it, turn on the power of all light sources and similarly register signals corresponding to several (2-3) shots at the corners and center of the target. In this case, after each shot, the number of the next hole is marked on graph paper, and after the whole series of shots, the control frame is removed, the coordinates of all holes are measured on graph paper, they are entered into the computer, the program for processing the results and determining the regression coefficients α _i and b _{i is} called, also parameters of reference signals (amplitude and duration).

In the operating mode (operating mode), the equipment operates similarly to the identification mode. After a shot and recording in the computer memory the moments of time when the bullet crosses the light screens, the signals are filtered, the amplitude and duration of the first pulses of the total signals from the first and second pairs of screens are determined, the reference signals in amplitude and duration are converted to the total signals, determined (by subtracting the given reference from total signals) signals from the second screens of pairs. Now, according to the selected signals, the intersection times (upon reaching the threshold level) of each of the screens are determined, the instrument coefficients k _y , k _z are calculated using formulas (10), (11), and the coordinates of the hit points y are calculated from the system of equations (8), (9) ₀ , z ₀ and according to formula (12) is the average velocity ν _cp. After determining the coordinates in a series of shots, the characteristics of accuracy and accuracy of fire, the average value and the standard deviation of the speed in the series are determined. The calculation results are displayed on the monitor. If necessary, at the operator’s request, a grid of target coordinates with marked holes and their numbers in the sequence of shots is displayed on the monitor.

The proposed light target in comparison with the prototype is simpler in design, has fewer sensors and coaxial communication lines and higher accuracy due to digital signal processing.

Claims (1)

A light target with an optoelectronic recording device containing light sources located on one side of the sheaf of paths, and optoelectronic converters located on the other side of the sheaf of paths and forming together with the light sources a system of light screens, coaxial communication lines, a computer with a device for displaying information in the form of a monitor, characterized in that it is equipped with an adder of analog signals, a selector, a digital storage oscilloscope, a test signal generator c, while the light sources are combined in two pairs and installed in a V-shape in each pair, moreover, in one pair they are split apart from the axis of symmetry into equal and opposite sharp angles from above, and in the other pair from below, opposite the axis of symmetry of each pair An optical-electronic converter is installed, the outputs of the converters are connected to the inputs of the adder of analog signals by coaxial communication lines, the output of which is connected to the input of the selector, the output of the selector is connected to the input of a digital memory oscillograph, and the last output - with the computer input, the outputs of which are connected to control inputs of the test signal generator and a selector.

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