RU2400770C1 - Single-channel device for detecting reflective optical systems and determining range to said systems - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: surveillance object is illuminated with laser radiation and radiation reflected from said object is picked up by an optical-electronic device based on a multiple-element receiver. Besides imaging the object, the device also determines its angular coordinates and measures range. The present invention seeks to design a single-channel reception laser location imaging device for detecting reflective optical systems and determining distance to the said systems, in which angular coordinates of the reflective object and distance to the said object are determined using a single reception channel based on a photosensitive CCD matrix through phase keying of illumination pulses with defined algorithms for processing amplitude of the signal reflected from a target and without need for precision guidance to a retro-reflector.

EFFECT: possibility of imaging distant objects during night and day.

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Description

The invention relates to the field of optical instrumentation, more specifically to laser imaging systems capable of forming an image of distant objects both at night and during the day. The object of observation is illuminated by laser radiation, and when reflected from it, the radiation is recorded by an optical-electronic device based on a multi-element receiver. In addition to imaging an object, the device determines its angular coordinates (φ _x , φ _y ) and measures the range.

A special class of location objects are so-called. retroreflective objects - corner reflectors, glass spheres, optoelectronic devices with a collimation scheme, etc. When laser-scanning such objects, the probe radiation is reflected in the direction of the radiation source at wide illumination angles.

According to the patent of the Russian Federation No. 2269804 (2006, IPC G02B 23/12, G01S 17/88) a laser location device for observing a remote, including retroreflective object is known, which is the closest analogue and contains two receiving channels and one transmitting channel.

This device has the following disadvantages:

1. The presence of a separate range measurement channel, leading to a significant increase in the complexity and dimensions of the receiving channel of the device (the introduction of another receiving optical system).

2. A small field of view of the range measurement channel (2 ... 4 arcmin.), Which leads to the need for high-precision guidance of the range measurement channel on the retroreflector, requiring additional mechanisms for target selection, sighting and alignment of the range-finding channel.

3. The two-channel system requires a complex design to eliminate the parallax of the range measuring channel and the channel of measuring angular coordinates based on the FPGA matrix.

4. Additional time is required to switch the operator’s attention between the channels for measuring the range and position of the object or, in the case of an electronic guidance mechanism, to select a target.

The objective of the present invention is to provide a single-channel device for detecting retroreflective optical systems and determining the distance to them, in which the angular coordinates of the position of the retroreflective object and the distance to it are determined using a single receiving channel based on the FPSS matrix due to phase manipulation of the backlight pulses and processing the reflected amplitude from the purpose of the signal and without the requirement of high-precision guidance to the retroreflector.

The technical result achieved by the implementation of the proposed device:

- the ability to determine the range to all objects falling into the field of view of the FPGA matrix without additional devices and guidance tools,

- simplification of the design,

- reduction of accuracy requirements for targeting,

- the only receiving optical system,

- reduction in the number of matching electronic devices.

The technical result is achieved due to the fact that in the device for detecting retroreflective optical systems and determining the distance to them, containing the receiving and transmitting channels, the transmitting channel containing a semiconductor laser, the input of which is connected to the output of the laser driver, and the transmitting optical system, and in the receiving a receiving lens is installed in the channel, in the focal plane of which there is a FPGA matrix, the first output of which is connected to the input of an analog-to-digital converter (ADC), and a monitor, add no introduced a frame buffer, the frame counter, a frame memory unit, an inverter, an adder, measuring angular coordinates, the threshold device, the unit for calculating range generation unit delay time T _y, wherein the ADC output is connected to the input frame buffer, a first output connected to a first input monitor, the second output is with the input of the frame counter, the third output is with the input of the inverter, and the fourth output is from the input of the frame memory block, the outputs of the frame memory block and the inverter are connected respectively to the first and second inputs of the adder, the output of which connected to the input of the threshold device, the output of the frame counter is connected to the first input of the range calculation unit, the second input of which is connected to the first output of the threshold device, the first output of the range calculation unit is connected to the third input of the monitor, and the second to the first input of the unit of formation of the lead time T _yn the second input of which is connected to the second output of the FPGA matrix, the second output of the threshold device is connected to the angular coordinate meter, the output of which is connected to the second input of the monitor, the output of the block is formed The lead time T _{yn is} connected to the input of the laser driver, while the range calculation unit is configured to calculate the range using the formula:

L _about = [T _y0 -ΔT _y (n * -1)] c / 2,

where c is the speed of light;

T _y0 = 2L _max / s;

L _max - the maximum range measured by the device;

ΔT _y = ΔL / c;

ΔL is the error in measuring the distance to the retroreflective object;

n * is the number of the frame in which the reflected signal appeared.

A more detailed invention is illustrated by the following drawings.

Figure 1 is a block diagram of the proposed single-channel device for detecting retroreflective optical systems and determine the distance to them.

Figure 2 is a timing diagram of the operation of the device.

Figa-3B explain the selection of the signal reflected from the retroreflective system.

Figure 1 shows a block diagram of the proposed single-channel device for detecting retroreflective optical systems and determining the distance to them. The device contains one receiving and one transmitting channel. The transmitting channel contains a semiconductor laser 1, the input of which is connected to the output of the laser driver 17, and a transmitting optical system 2. A receiving lens 3 is installed in the receiving channel, in the focal plane of which there is a FPGA matrix 4, the first output of which is connected to the input of the analog-to-digital converter (ADC) 5, the output of which is connected to the input of the frame buffer 6, the first output of which is connected to the first input of the monitor 8, the second output - with the input of the frame counter 9, the third output - with the input of the inverter 11, and the fourth output - with the input frame memory 10. The outputs of frame memory 10 and inverter 11 are connected respectively to the first and second inputs of the adder 12, the output of which is connected to the input of the threshold device 13. The output of the frame counter 9 is connected to the first input of the range calculation unit 15, the second input of which is connected to the first output of the threshold device 13. The first output of the range calculation block 15 is connected to the third input of the monitor 8, and the second to the first input of the lead time formation unit T _yn 16, the second input of which is connected to the second output of the FPGA matrix. The second output of the threshold device 13 is connected to the angular coordinate meter 14, the output of which is connected to the second input of the monitor 8. The output of the lead time generation unit T _yn 16 is connected to the input of the laser driver 17. The range calculation unit is configured to calculate the range using the formula:

L _about = [T _y0 -ΔT _y (n * -1)] c / 2,

where c is the speed of light;

T _y0 = 2L _max / s;

L _max - the maximum range measured by the device;

ΔT _y = ΔL / c;

ΔL is the error in measuring the distance to the retroreflective object;

n * is the number of the frame in which the reflected signal appeared.

The detection of retroreflective optical systems and determining the distance in the proposed single-channel device for detecting retroreflective optical systems and determining the distance to them is ensured by sequentially changing the lead time of the laser pulse relative to the start of the accumulation time of an even half-frame of the FPSS matrix and applying signal processing to calculate the distance to the object. To do this, in the device during even half-frames form a sequence of backlight pulses, for which the lead time is determined by the formula:

T _yn = T _y0 -ΔT _y (n-1),

where n = 1, 2, 3 ... is the number of the frame formed by the FPSS-matrix;

T _y0 = 2L _max / s - lead time for the maximum range that the device can measure;

L _max - the maximum range that the device can measure;

c is the speed of light;

ΔT _y = ΔL / c,

where ΔL is the accuracy of measuring the distance to the object.

When n * = [(T _y0 - 2L _r / s) / ΔT _y +1],

where n * is the number of the frame in which the reflected signal appeared;

L _about - range (distance) to the object;

the signal reflected from the object will fall into the accumulation period of the even half-frame of the FPSS-matrix (see figure 2).

The signal reflected from the retroreflective object during the accumulation of an even half frame will be visible on the display device (monitor). For n <n *, the signal reflected from the retroreflective object does not fall during the accumulation of an even half-frame of the frame and, therefore, is not detected by the FPS matrix. Thus, successively changing n, and hence the lead time T _yn , it is possible to determine the value of n * by the appearance of the signal from the retroreflector on the FPGA matrix, and then determine the distance to the retroreflective object by the expression:

L _about = [T _y0 -ΔT _y (n * -1)] s / 2.

The device operates as follows.

The system starts with the fact that for the formation of a laser pulse in the range calculation unit 15, a pulse of duration T _y0 -ΔT _y (n-1) is generated, while the value n (frame number) is fed to the first input of the range calculation unit from the output of the frame counter 9 Thus, for n = 1, the lead time T _yn = T _y0 = 2L _max / c. An impulse of 2L _max / s duration from the second output of the range calculation unit 15 is transmitted to the first input of the anticipation time generation unit T _pack , the second input of which, based on the strobe of the beginning of the accumulation period, receives information about the beginning of the accumulation period T _n from the second output of the FPGA matrix 4 ( see figure 2). Knowing T _n and 2L _max / s, the lead time generation unit T _yn 16 generates a pulse of duration T _n -2L _max / s relative to the beginning of the accumulation time T _{n of the} even half frame of the FPGA matrix 4. From the output of the lead time formation block T _yn 16, the lead signal arrives at the input of the laser driver 17, which includes a semiconductor laser.

In the event that the retroreflective object 7 is at a distance L _max , i.e. L _rev = L _max , it is highlighted and the pulse reflected from it falls during the period of accumulation of an even half-frame of the FPSS matrix. In this case, the signal from object 7 will be recorded on the FPSC matrix. If L _about <L _max , then the reflected signal will arrive at the receiving optical system before the charge accumulation period of the FPSS matrix 4 begins and will not be recorded by the matrix.

Therefore, for registering object 7 with a FPSS-matrix, it is necessary to set the lead time T _yn = 2L _r / s. For this, in the proposed device, simultaneously with an increase in the frame number n, the lead time T _yn is sequentially reduced to 2L _r / s, as a result of which registration of the signal reflected from the object is obtained on the FPS matrix. To reduce the value of T _yn most appropriate with a step ΔT _y , then the error in measuring the distance does not exceed ΔL = ΔT _y s / 2.

Thus, when only one half-frame of each laser pulse 1 is formed, the probe radiation, passing through the forming transmitting optical system 2, is incident on the retroreflective object 7. A part of the radiation reflected from the object falls into the entrance pupil of the receiving lens 3 and then onto the FPS matrix 4. At the same time, on the sensitive surface of the FPGA matrix, the receiving lens 3 forms an optical image of the observed space, including the retroreflective object 7, if it is located on the corresponding far ty. From the first output of the FPGA matrix 4, the electric video signal is fed to the input of the ADC 5, the output of which is connected to the input of the frame buffer 6, from the first output of which the image signal of the half frame goes to the first input of the monitor with an adder (hereinafter referred to as the monitor) 8, from the second output of the frame buffer 6, a signal containing information about the frame number is fed to the input of the frame counter 9, from the third output of the frame buffer 6, a signal containing information about the odd half frame is fed to the input of the inverter 11, and from the fourth output, a signal containing information about the even ukadre arrives at the input of the storage unit frame 10.

Information on the current even half-frame U _even (Fig. 3a) is placed in the frame memory block, an odd half-frame (U _odd ) is processed in the inverter 11, i.e. the signal amplitude is inverted (see Fig. 3b). Then, the information from the outputs of the frame memory block and the inverter is supplied respectively to the first and second inputs of the adder 12, the output of which, in the presence of a reflected signal, produces a signal in the form of a short pulse (see Fig.3c), which is equal to the difference between the even and odd half-frames. This signal is a glare from a retroreflective object, and the image of the underlying surface is absent after subtracting half-frames. It should be noted that, when interlaced, subtraction of half-frames leads to a small error equal to the angular size of the line — the minimum size of the object should be equal to the angular size of two lines of the FPSS matrix when converted through its optical system, which, as a rule, is performed for most retroreflective objects.

Next, the signal from the output of the adder 12 is fed to the input of the threshold device 13, which determines the presence of a signal from the object (the appearance of a pulse exceeding the threshold) and transmits it (signal) through the second output to the input of the angular coordinate meter 14, where a mark is formed for display on the monitor 8 , which from the output of the angular coordinate meter 14 goes to the second input of the monitor 8. The first output of the threshold device 13 is connected to the second input of the range calculation unit 15. In the absence of a signal from the retroreflective object, the threshold troystvo 13 transmits information about this through the first output to the second input range calculation unit 15, which in this case is not calculated distance L, and the impulse duration T _y0 -ΔTy (nl), wherein the value n is supplied to a first input range calculation unit with the output of the frame counter 9. An impulse of duration T _y0 -ΔTy (n-1) from the second output of the range calculation unit 15 is transmitted to the first input of the lead time generation unit T _yn , the second input of which receives information about the beginning of the accumulation period T _n from the second output of the FPS matrices s 4. Knowing T _n and T _yn , the lead time formation unit T _yn 16 generates a pulse of duration T _n - [T _y0 -ΔTy (n-1)] relative to the beginning of the accumulation time T _{n of the} FPGA matrix 4. From the output of the time formation block lead T _yn 16 lead signal arrives at the input of the laser driver 17, the output of which is connected to the laser, which provides control of the laser with the necessary lead T _n - [T _y0 -ΔTy (n-1)] at the time of an even half frame. The laser driver 17, having received this control pulse, launches a semiconductor laser 1 to illuminate the locating retroreflective object 7.

In the presence of a reflected signal from the retroreflective object 7 (see Fig. 3a), an impulse of the form shown in Fig. 3c comes to the input of the threshold device 13 from the output of the adder 12.

In the case of determining the signal threshold device 13 (if its value exceeds the threshold), in a frame n = n * in the calculation range block 15 the impulse duration T _y0 -ΔTy (n * -1), and all subsequent frames are highlighted with a feedforward defined for n * th frame. Next, in block 15, the range is calculated by the formula:

L _about = [T _y0 -ΔT _y (n * -1)] c / 2,

where c is the speed of light;

T _y0 = 2L _max / s;

L _max - the maximum range measured by the device;

ΔT _y = ΔL / c;

ΔL is the error in measuring the distance to the retroreflective object;

n * is the number of the frame in which the reflected signal appeared.

Information about the range L _about to the retroreflective object 7 from the first output of the range calculation unit 15 is transmitted for display to the third input of the monitor 8.

It should be noted that conventional cameras are not suitable for implementing the described method, because they do not allow to accurately determine the beginning of the accumulation period T _n ; therefore, to solve the described problem, a FPS camera is required, in which a strobe of the beginning of the accumulation period T _n is displayed.

Thus, under the condition of a sufficient number of iterations, the error in determining the distance ΔL will be limited by the width of the illumination pulse t _and :

,

,

since ΔТ _у can be formally reduced to L _max / m, where

L _max - the maximum range measured by the device;

m is the number of iterations equal to the number of frames n.

Modern lasers are capable of providing t _and about 50 ns, which gives a range resolution of 7.5 meters.

Thus, the proposed single-channel device for detecting retroreflective optical systems and determining the distance to them provides the determination of the angular coordinates of the position of the retroreflective object and the distance to it using a single receiving channel based on the FPGA matrix due to phase manipulation of the backlight pulses and processing the amplitude of the signal reflected from the target and without requiring high-precision guidance to the retroreflector. At the same time, it is possible to determine the range to all objects falling into the field of view of the FPGA matrix without additional guidance devices and means, simplify the design, reduce the accuracy requirements for targeting and reduce the number of matching electronic devices.

Claims (1)

A single-channel device for detecting retroreflective optical systems and determining the range to them, comprising receiving and transmitting channels, the transmitting channel comprising a semiconductor laser, the input of which is connected to the output of the laser driver, and a transmitting optical system, and a receiving lens is installed in the receiving channel in the focal plane which contains a FPGA matrix, the first output of which is connected to the input of an analog-to-digital converter (ADC), and a monitor, characterized in that the device additionally a frame buffer, a frame counter, a frame memory block, an inverter, an adder, an angular coordinate measuring device, a threshold device, a range calculation unit, a lead time generation unit T _{yn are introduced} , the ADC output being connected to the frame buffer input, the first output of which is connected to the first monitor input , the second output is with the input of the frame counter, the third output is with the input of the inverter, and the fourth output is with the input of the frame memory block, the outputs of the frame memory block and the inverter are connected, respectively, with the first and second inputs of the adder, the output of which is one with the input of the threshold device, the output frame counter is coupled to a first input range calculation unit, a second input coupled to the first output of the threshold device, the first output range calculation unit connected to the third input of the monitor, and the other - to the first input unit for generating delay time T _yn the second input of which is connected to the second output of the FPGA matrix, the second output of the threshold device is connected to an angular coordinate meter, the output of which is connected to the second input of the monitor, the output of the forming unit lead time T _yn connected to the input of the laser driver, while the range calculation unit is configured to calculate the range according to the formula:
L _about = [T _y0 -ΔT _y (n * -1)] s / 2,
where c is the speed of light;
T _y0 = 2L _max / s;
L _max - the maximum range measured by the device;
ΔT _y = ΔL / c;
ΔL is the error in measuring the distance to the retroreflective object;
n * is the number of the frame in which the reflected signal appeared.

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