RU2812755C2 - Device for determining object coordinates - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: invention can be used to determine the location of moving objects using the angular-rangefinder method from an aerial vehicle (AV). In the claimed device for determining the coordinates of objects, the elements of the ground control point are transferred to the AV board. The mode of operation of the camera, autonomous from the AV, is used, the spatial orientation of which is determined using an inertial measurement unit (IMU). An increase in the accuracy characteristics of the latter is achieved through periodic correction of its readings based on satellite navigation system data and refinement of the estimates obtained by the IMU using a Kalman filter.

EFFECT: expansion of the boundaries of the controlled area and the reduction of time spent on detecting and determining the coordinates of specified objects.

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Description

The inventive device relates to the field of radio engineering, namely to passive location and can be used in navigation, direction finding, and location aids for visual detection and determination of the coordinates of a priori unknown moving objects from flight-lifting equipment (FLS). Further, by LPS we will understand airplanes and helicopters of various modifications.

The devices are known according to Pat. RF No. 2251712, IPC G01S 13/66; Pat. RF No. 2359288, IPC G01S 5/02. Analogs provide determination of the coordinates of objects using optical-electronic means. However, they have a significant drawback: they are placed on the earth's surface, as a result of which they have a small radius of action.

A device for determining the coordinates of objects is known. RF No. 2323851, IPC V64S 31/06 “Earth surface surveillance system with an unmanned aerial vehicle”, publ. 05/10/2008.

The analog contains a tightening winch, an unmanned aerial vehicle (UAV) and a ground control point (GCP), and the UAV consists of a series-connected controller, a steering gear and aerodynamic rudders, an autopilot, a group of information inputs of which is connected to a second group of information outputs of the controller, the first group of information the inputs of which are connected to the group of information outputs of the autopilot, the propulsion system, the group of information inputs of which is connected to the third group of information outputs of the controller, the video surveillance unit, the group of information inputs of which is connected to the fourth group of information outputs of the controller, and the group of information outputs is connected to the second group of information inputs of the controller , and the first transceiver module, the group of information inputs of which is connected to the fifth group of information outputs of the controller, the third group of information inputs of which is connected to the group of information outputs of the first transceiver module, and the ground control station is made containing a series-connected control unit, the second receiving and a transmitting module and a device for processing and displaying information, the second group of outputs of the control unit is the NPU control bus, and is connected to the tightening winch.

The analogue is intended for obtaining photographs of the earth's surface from a height of about 100 meters. However, this device does not provide measurement of the coordinates of visible objects due to the lack of high-precision UAV navigation systems and determination of the direction to them.

The closest in its technical essence to the claimed invention is a device for determining the coordinates of objects (see RF Patent No. 2513900, IPC G01S 13/42, G01S 3/14, publ. 07/20/2014, Bulletin No. 11).

The prototype device contains an LPS, for which a UAV is used, and an NPU, and the UAV is made containing a series-connected controller, a steering gear and aerodynamic rudders, an autopilot, a group of information inputs of which is connected to the second group of information outputs of the controller, the first group of information inputs of which is connected to a group of autopilot information outputs, a propulsion system, the group of information inputs of which is connected to the third group of information outputs of the controller, the first transceiver module, the group of information inputs of which is connected to the fourth group of information outputs of the controller, the second group of information inputs of which is connected to the group of information outputs of the first receiver -transmitting module, and a video surveillance unit, and the ground control point is made containing a series-connected first control unit, designed to generate take-off, flight and landing control commands for the LPS, a second transceiver module and a first information processing and display device, a transmitting module, a navigation unit LPS and a storage device, wherein the first group of information inputs of the storage device is connected to a group of information outputs of the video surveillance unit, the second group of information inputs is connected to a group of information outputs of the LPS navigation block, and the group of information outputs of the storage device is connected to a group of information inputs of the transmitting module, and in the ground control station is equipped with a series-connected receiving module and a second processing and display device, a second control unit designed to set initial data and generate a command to determine the coordinates of objects, the group of information inputs of which is combined with the first group of information inputs of the second information processing and display device, and a group of information outputs - with a second group of information inputs of a second device for processing and displaying information.

The prototype device improves the accuracy of measuring the coordinates of objects from the LPS board.

However, the prototype has disadvantages that limit its use. The main one is the limited range of action, determined by the line of sight range between the NPU and the LPS. The results of measurements of the spatial location and orientation of the LPS, the video image of the monitored object and its location on the camera are transmitted over a high-speed communication channel (more than 4 Mbit/s) at frequencies of 2.5 MHz and higher.

In addition, the rigid attachment of a camera (video surveillance unit) to the LPS board sharply reduces the field of view during flight of the LPS, which entails an increase in the time spent searching and determining the coordinates of a given object. Additional problems arise when determining the coordinates of moving objects, leading to a decrease in the accuracy of the prototype. The latter are associated with the detected object not falling into the center of the camera image, averaging the sequence of measurement results of moving objects over the time interval Δt.

The technical result that the claimed device is aimed at achieving is expanding the boundaries of the controlled area and reducing the time spent on detecting and determining the coordinates of specified objects.

The technical result is achieved in that the device for determining the coordinates of objects, located on a standard flight-lifting device, and containing a transmitting module, a video surveillance unit, a sequentially connected navigation unit and a storage device, the second group of information inputs of which is connected to a group of information outputs of the video surveillance unit, the LPS additionally houses an information processing and display device, a control unit, a reference rotary device and an inertial measurement module, wherein the video surveillance unit and the inertial measurement module are placed together on the reference rotary device, a group of information outputs of the inertial measurement module is connected to a third group of information inputs of the storage device, the group of information outputs of which is connected to the group of information inputs of the control unit and the first group of information inputs of the information processing and display device, the second group of information inputs of which is connected to the group of information outputs of the control unit, and the group of information outputs is connected to the group of information inputs of the transmitting module, and on the preparatory stage and in the “correction” device operating mode, a group of information inputs of the inertial measurement module is connected to a group of information outputs of the navigation block.

Airplanes and helicopters of various modifications are used as LPS. The transfer of some of the elements of the ground control point and the operator on board the LPS and the introduction of additional elements made it possible to expand the boundaries of the controlled area and reduce the time spent on detecting and determining the coordinates of given moving objects by optimizing the spatial orientation of the video surveillance unit during the flight of the LPS.

The main problem that arose during the implementation of the proposed device is determining with the required accuracy the spatial orientation of the video surveillance unit (camera). For this purpose, in small-sized objects, inertial measurement systems (IMS) based on micromechanical sensors (MEMS), which are characterized by insufficient accuracy characteristics, are used. The sensors are not sensitive to the Earth's rotation, have high noise levels and inconsistent drift. Thanks to the joint use of the navigation unit, which makes it possible to measure the aircraft drift angle with high accuracy, and using signals from the navigation satellite system, and the IIS, a significant increase in the accuracy characteristics of the proposed device is ensured.

The proposed device is illustrated by drawings in which:

in fig. 1 - shows a generalized block diagram of a device for determining the coordinates of objects:

a) at the preparatory stage, in the “correction” mode (setting the initial data);

b) in measurement mode;

in fig. 2 - illustrated:

a) a camera illumination spot on the earth's surface with an object O _j located in it;

b) the reason for errors in determining the coordinates of an object in the absence of taking into account the terrain;

in fig. 3 - explains the procedure for preliminary determination of object coordinates;

in fig. 4 - illustrates the procedure for determining the coordinates of an object with a given accuracy;

in fig. 5 - generalized algorithm of operation of the device for determining the coordinates of objects;

in fig. 6 - the algorithm of operation of the video surveillance subsystem is shown;

in fig. 7 - appearance of the camera (block 1):

a) the position of the camera’s components;

b) location of the ADIS 16488A inertial sensor;

in fig. 8 - block diagram of the information processing and display device 7;

in fig. 9 - shows the operating algorithm of control unit 8;

in fig. 10 - illustrates the algorithm of operation of the sixth computer for determining the direction vector to an object in the camera coordinate system

in fig. 11 - shows the operating algorithm of the seventh computer 18;

in fig. 12 - shows the operating algorithm of the third control unit 22;

in fig. 13 - block diagram of inertial measurement module 6;

in fig. 14 - algorithm of operation of computer 26.

The device for determining the coordinates of objects, located on the standard LPS, contains a series-connected video surveillance unit 1, a storage device 4, a control unit 8, an information processing and display device 7 and a transmitting model 9, a navigation unit 5, a reference rotary device 3 with a control bus 2, inertial measurement model 6, jointly placed with the video surveillance unit 1 on the reference rotary device 3, the group of control inputs of which is the input bus 2 of the device for determining the coordinates of objects, and the group of information outputs of block 6 is connected to the third group of information inputs of the storage device 4, the first group of information the inputs of which are connected to a group of information outputs of the navigation block 5, and the group of information inputs of the control unit 8 is combined with the first group of information inputs of the information processing and display device 7, and at the preparatory stage and in the “correction” device operating mode, a group of information inputs of the inertial measurement module 6 connected to a group of information outputs of navigation block 5.

The block diagram of the device for determining the coordinates of objects is shown in Fig. 1, where:

1 - video surveillance unit (VSU);

2 - input bus of the device for determining the coordinates of objects;

3 - supporting rotary device (ROD);

4 - storage device (storage device);

5 - navigation block (BN);

6 - inertial measurement module (IMU);

7 - information processing and display device (IDD);

8 - control unit (CU);

9 - transmitting model.

The operation of the device (see Fig. 1a, b, 5) is as follows. At the preparatory stage, video surveillance unit 1 (camera), inertial sensor ADIS 16488A (unit 25) and computer 26 (see Fig. 13) from module 6 are jointly placed on the supporting rotary device 3. These elements are installed under the fuselage of the LPS (in this case The operator controls block 3 using a remote control panel) or on the glazing of the aircraft on the inside. Then direct (manual) control of block 3 (camera 1) becomes available to the operator.

At the preparatory stage, the position of block 3 (blocks 1 and 6) is fixed and the orientation of camera 1 relative to the side of the LPS is determined. Measurement results fixed (see Fig. 13) in block 6 (block 26). Here - angle of roll, pitch and heading of block 1. In this position, the further operation of the proposed device (see Fig. 1a) basically coincides with the operation of the prototype device. The difference is that the decision to determine coordinates is made by the operator on board the LPS. In addition, all operations for determining coordinates are also performed on the aircraft using blocks 1, 4, 5, 7 and 8, the implementation of which is basically similar to the corresponding blocks 5, 6, 7, 16 and 18 of the prototype. Block 7 (block 16 of the prototype) has undergone changes due to the fact that its operation does not require information about the spatial orientation of the LPS. The latter are used in block 6 to correct data on the spatial orientation of BV 1. For this purpose, a group of information outputs of BN 5 is connected to a group of information inputs of IIM 6 (see Fig. 13). Rigid fixation of video surveillance unit 1 with LPS allows you to track spatial orientation with the accuracy realized by unit 5. In addition, in block 7, averaging of the sequence of measurement results of the coordinates of a moving object is excluded. Taking into account the relative orientation of the camera 1 in the initial position and the LPS is performed by block 6. The results of measuring the coordinates of the detected object are transmitted to the consumer using block 9 via a low-speed communication channel. This becomes possible due to a sharp reduction in the volume of transmitted information. In this case, equipment operating in the HF range of radio waves, satellite radio communications, etc., which has no restrictions within specified limits on the communication range, can be used as block 9. For this purpose, the regular LPS command communication channel can also be used.

If it is necessary to change the orientation of the camera (block 1) relative to the LPS board during flight, the proposed device switches to autonomous navigation mode. At the first stage, when the j-th object is visually detected, the operator decides on the need to measure its coordinates, and block 1 is pointed in its direction. For this purpose, the location of the object in the camera frame is initially set (determined) by the operator using a viewfinder.

Received coordinates of the j-th object on the frame (see Fig. 2a), by analogy with the prototype, are specified in pixels, and they are counted from the upper left corner of the frame.

At the next stage, it is necessary to transform the coordinates of the j-th object in the frame to the direction towards the object in the camera coordinate system This operation is performed in accordance with the expression

Where ƒ - focal length of the camera lens, converted into pixels of the matrix (frame), (с _x , с _у ) ^T - coordinates of the center of the matrix in pixels, k ₁ , k ₂ , k ₃ - measured lens distortion coefficients (see Szeliski, Richard. Computer: Algorithms and Applications - Sprintger, 2010). Having redesignated expression 1 takes the form

Where . Vector determined based on known camera parameters and coordinates of the j-th object in the frame

Thus, denoting we obtain an equation whose solution is the desired vector

Numerical value of the vector found by simple iteration method.

Direction to j-th object determined without taking into account the orientation of the camera in space. Due to the above reason, in the proposed device, at the first stage, the orientation of the camera in the direction of the j-th object and the coordinates of the LPS at the time of taking measurements t _i are taken into account. The spatial orientation of the camera is measured using an inertial measurement module 6. At the second stage of determining the coordinates of objects, the terrain features of the measurement area are taken into account. These stages are covered quite fully in Pat. RF No. 2419106, IPC G01S 13/46, publ. 05/20/2011 and Pat. RF No. 2458360 IPC G01S 13/46, 5/02, 3/14, publ. 1.08.2012.

LPS coordinates and, consequently, cameras 1, measured by block 5 at time t _i , are converted into a geocentric coordinate system:

where B _lps , L _lps , H _lps are the latitude, longitude and altitude of the LPS location, respectively.

In transforming the direction vector to the jth object the camera orientation measured by block 6 is taken into account. Correction carried out in the plane of three Euler angles: roll pitch and declinations Source vector successively multiply by three the rotation matrices corresponding to the Euler angles (see Fig. 2)

Where

Refined azimuth values and elevation angle determined from expression (6) as follows:

Here is the vector is in the normal coordinate system: OX ⁺ - direction to the north, OY ⁺ - to the east, OZ ⁺ - to the center of the Earth.

To find the distance between the LPS and the j-th object it is necessary to take into account the spherical nature of the Earth's surface. Otherwise, this problem can be interpreted as finding the distance , on which the vector will intersect with the “round” Earth at a height meters:

where D is the discriminant of the quadratic equation: R is the radius of the Earth, R=6370000 m. It should be noted that the distance can be determined under the condition D≥0. Otherwise, a new cycle of measuring the spatial parameters of the j-th object begins And

The normal coordinate system in which the vector is located at this stage located with some rotation, which depends on the latitude and longitude of the location of the LPS. For the final transition to the geocentric coordinate system, it is necessary to rotate the vector to LPS latitude and π/2 minus LPS longitude using rotation matrices, and then transfer the center of the coordinate system to the center of the Earth using the geocentric coordinates of the LPS. As a result, we have the true vector directions to the j-th object

Where

This completes the first stage of measurements.

At the next stage, the results of the elevation angle calculations are compared with the threshold value Δβ, which determines the specified potential accuracy of measuring the location of objects. It should be noted that the elevation angle to the source corresponds to the horizon, corresponds to the zenith.

The coordinates of an object on the “round” Earth in the geocentric coordinate system in direction and distance at height H ₀ can be found using the expression:

Transition from (11) to a more convenient geographic coordinate system carried out as follows:

Where

At small values (low accuracy of measuring object coordinates is ensured), and also when threshold conditions are met and there is no digital terrain map of the measurement area, the coordinates of the intersection point of the true direction vector to the j-th object are determined with a “round” Earth, which are then output and used as the desired quantity.

When threshold conditions are met and the availability of a digital relief map of the measurement area, it becomes possible to more accurately measure coordinates, which in turn is performed in two stages. At the first stage, a sequential set of height values {H _i,m }, m=1, 2, ..., M is formed, which correspond to uniformly distributed coordinates on the segment connecting the coordinates of the LPS and the j-th object (B _j , L _j ) (see Fig. 3). In this case, the number of named points M is found from the relation: , where Δd is the scanning step along the direction vector to the j-th object at time t _i . The value of Δd is determined by the specified accuracy of determining the coordinates of the object at the first (preliminary) stage of measurements, for example, Δd=500 m. The coordinates are calculated corresponding to discretely selected terrain heights H _im . For the preliminary coordinates of the j-th object take the first partition point of the vector located below the level of the terrain.

At the second stage of measurements, the location of the j-th object is specified by selecting a neighboring partition point located above the terrain (see Fig. 4). Line segment direction vectors for the j-th object are divided at δ equal intervals, Δδ<<Δd, where Δδ is the scanning step along the selected segment of the true direction vector . The latter is determined by the final specified accuracy of measuring the coordinates of objects and the resolution (discreteness) of a digital terrain map. For the named points, coordinates are calculated and the corresponding values of terrain heights H _j,m,δ . Based on linear interpolation, the exact coordinates of the j-th object are taken to be located between neighboring points p and p-1, p∈δ, located above and below the terrain

Where

Results of coordinate calculations converted into a convenient geographic coordinate system in accordance with expression (12). The corresponding value of H _jδ is taken from the array of digital terrain maps.

When performing measurements over the sea surface, the successive climb {H _i,rn }, m=1, 2, …, M, is a constant stationary value m ₁ =m ₂ …=m _M =0, and the need to perform operation (13) disappears.

The proposed device is designed to determine the coordinates of moving objects, for example, ships. In this regard, increasing the accuracy of the device by jointly processing a sequence of video frames, as proposed in the prototype, is impossible.

Thus, on board the LPS it is possible to quickly determine the coordinates of objects based on video images (see Fig. 6). The last received by block 1, together with data on the spatial orientation of the camera (determined by block 6) and its spatial location (measured by block 5) through storage device 4 (buffer memory) are sent to the information inputs of blocks 7 and 8. Thanks to camera telemetry data and the position of the object on In the frame in block 7, the geographic coordinates of the object of interest are calculated.

The functions of block 4 include joint recording of video frames from block 1 and corresponding data on the spatial position of the camera from the outputs of blocks 5 and 6.

The inventive device is alternately in two stable states: the “correction” mode (setting the initial state of block 6 and clarifying its readings) and the operating (autonomous) mode lasting up to 10 minutes. In the first of them (see Fig. 1a), camera 1 is in the initial (fixed) position with an a priori known orientation relative to the side of the LPS. At the same time, determining its current orientation in space carried out by block 26 (see Fig. 1a and 13) based on measurements And . In this mode, the group of information outputs 5 is connected to the group of information inputs of block 6 (block 26). The integrated system of blocks 5 and 6 ensures maximum accuracy in measuring the spatial orientation of camera 1.

In the autonomous operation mode of block 1 (see Fig. 1b), determination of its spatial orientation is carried out by block 6 for a limited time (up to 10 minutes). This is due to the limited drift stability readings of the gyroscope of block 25. The joint use of inertial meters (block 25) in conjunction with the Kalman filter (which evaluates the errors of block 25 against the background of the measurement results of the satellite navigation system of block 5) allows us to maximize the accuracy of determining the coordinates of objects in offline mode " from the hand."

All functional elements and blocks of the proposed device are widely covered in the literature and are mass-produced.

Video surveillance unit 1 (see Fig. 7a) can be implemented using a digital camera “Peresvet-25”, produced by LLC “Special Technology Center”. The latter is built on the basis of a modern light-sensitive sensor Gpixel Gmax 0505. Thanks to the use of a matrix with an optical format of 1.1 inches, it is possible to equip the camera with lenses based on the C-mount mount. The latter allows you to reduce the working distance (rear focal length) to 17 mm. As a result, the size of the camera itself and its weight have decreased.

The adopted photosensitive sensor is based on global shutter technology, which makes it possible to exclude an external shutter device from the camera, increasing its resource. Due to the exposure of all lines of the image at the same time, there is no distortion of objects characteristic of cameras with a rolling shutter (Rolling shutter). The latter do not allow exceeding the accuracy of coordinateometry based on an orthomosaic of 1 meter. The appearance of the camera (block 1) is shown in Fig. 7a, b.

The rotary support device 3 is designed to jointly place on it a camera 1 and an inertial measurement module 6 (blocks 25 and 26) for the latter to measure the spatial orientation of block 1. Currently, they are widely represented on the market (see the Internet resource bic-in- form.ru/products/oporno-povorotnyie-ustrojstva/vzryivozashhishhyonnyie-oporno-povorotnyie-ustrojstva/ptr-407ex/ Arr. 01/16/2022).

The navigation unit 5 is designed for high-precision determination of the location of the LPS (camera 1) and its spatial orientation. Its output generates data on the latitude B _lps , longitude L _lps and height H _lps of the location of the LPS (B _lps , L _lps , H _lps ) _i and its spatial orientation (k _lps , l _lps , ζ _lps ) _i at the moment of time, where k _lps - roll angle, l _lps - pitch and ζ _lps - declination. Performed for various operating conditions in accordance with Pat. RF No. 2514197, No. 2553270 or No. 2740606.

The inertial measurement module 6 is designed to continuously determine in real time the spatial parameters of the video surveillance unit 1: linear speed and acceleration, angular orientation (true course, declination ζ _k , roll k _k and pitch l _k , angular velocity of rotation). It can be implemented (see Fig. 13) based on a series-connected tactical-grade inertial sensor 25 with ten degrees of freedom ADIS 16488A from Analog Devices Inc. (see online resource www.analog.com/ru/products/adis16488a. Rev. 01/13/2022) and computer 26. The procedure for using inertial sensors is discussed in the article by I. Nagin, D. Malafeeva. MEMS accelerometers, magnetometers and orientation angles (see online resource habr.com/ru/post/491476. Sample 01/13/2022).

The main components of block 25 are three gyroscopes and three accelerometers located along three different mutually perpendicular axes, which makes it possible to measure the acceleration and angular velocity of rotation of an object in three-dimensional space. Blocks 25 and 26 are placed directly in camera 1 (see Fig. 7b). To start the operation of block 6, it is necessary to enter from the group of information outputs of block 5 the initial values of the coordinates of the location of the LPS, its speed and orientation parameters into the computer 26.

In addition, at the preparatory stage, the spatial orientation of the video surveillance unit 1 (camera) is measured and stored in block 26 relative to the side of the LPS when it is in its original (fixed) position. Here - roll, pitch and heading angles, respectively.

Determining the angular position of block 25, and, consequently, camera 1, in relation to the navigation coordinate system used is the essence of the correction mode of block 6 and the device as a whole. After completion of this process, the inertial module 6 can switch to navigation mode, and the inventive device to the mode of autonomous “hand-held” determination of object coordinates (see Fig. 1b). The most important element of the inertial measurement module 6 is the Kalman filter, implemented in the computer 26. It solves the problem of estimating the errors of block 25 against the background of measurements of the satellite navigation system (block 5). For this purpose, the Kalman filter contains an error model of blocks 25 and 5 (see Appendix).

The “correction” mode is performed at the preparatory stage of the device’s operation and periodically during a uniform straight flight lasting no more than 7 minutes. In this case, the group of information outputs BN 1 is connected to the group of information inputs BAT 6 (block 26). During this time, in block 26, the values of the spatial parameters of the camera obtained by block 25 are replaced on . The latter are calculated in block 26 based on the a priori known orientation of block 1 and data from block 5 on the spatial orientation of the LPS at the i-th moment of time . This operation is performed in the plane of the three Euler angles by multiplying the rotation matrices around the roll, pitch and declination axes of camera 1 installation angles relative to the side of the LPS by the rotation matrices around the orientation angles of the LPS at the i-th moment of time (by analogy with expressions (6) and (7 ) prototype device) and originating in the shooting coordinates (with coefficients [1,0,0] ^T ).

After completion of the “correction” mode, video surveillance unit 1 (camera) can leave its original position and go into autonomous operation mode (Fig. 16) for up to 10 minutes. Next, the angular position of the camera is predicted using the inertial data of block 25. In block 26, the orientation angles of block 1 are clarified in the Kalman filter. After the completion of transient processes, valid measurements are obtained at its output

At the end of the named time interval, block 1, together with block 6, is returned to its original position to perform correction of the data of block 25.

To reduce the weight and size characteristics of the current consumed, it is advisable to implement the computer 26 on a specialized processor TMS320c6416 (see TMS320c6416: http//focus/ti/com/docs/prod/fold-ers/print/ TMS320c6416/html), the operating algorithm of which is shown in Fig. 14.

The functions of block 4 include joint recording of video frames from the output of block 1 and the corresponding LPS navigation parameters from the output of block 5 and data on the orientation of camera 1 from the output of block 6. It is a buffer storage device.

The information processing and display device 7 (see Fig. 8) is designed to determine the coordinates of objects (the decision is made by the operator, the command for execution of which is generated using block 8), implementing operations in accordance with expressions 1-13, presenting measurement results in a given form . It contains a first computer 10, a second computer 11, a third computer 12, a fourth computer 13, a fifth computer 14, a sixth computer 15, a second memory device 16, a clock generator 17, a seventh computer 18, an eighth computer 19, a switching unit 20, a comparison unit 21 , the third control unit 22, the first memory device 23 and the display unit 24.

The information processing and display device 7 operates as follows.

At the preparatory stage, using control unit 8 (the latter can be a laptop operating in accordance with the algorithm presented in Fig. 9), the initial data are set:

measured camera lens distortion coefficients, k ₁ , k ₂ , k ₃ ;

threshold values Δβ, Δd and Δδ;

number of iterations when solving the equation of transition from the coordinates of an object in the frame (x _r , y _r ) ^T to the direction vector towards it

digital map of the measurement area with boundary characteristics of the terrain.

During operation, the video image from the output of block 4 is read by blocks 7 and 8. When a given object is detected, information about it from the output of block 8 is sent to the first group of information inputs of the sixth computer 15 in the form of coordinates . The functions of block 15 (see Fig. 10) include the transformation of object coordinates in pixels to the direction vector towards it in the coordinate system of camera 1 in accordance with expressions 1-4.

At the same time, information about the spatial position of the LPS , and And arrives at the group of information inputs of the first computer 10. Its functions include the transformation of spatial parameters of the LPS to geocentric coordinate system in accordance with expression (5).

Calculation results are supplied to the first group of information inputs of the second computer 11, and to the second group of its information inputs - the value from the group of information outputs of block 15. The functions of computer 11 include correction of the direction vector to the j-th object based on the orientation of the camera 1 measured by unit 6. The latter is supplied from the first group of information inputs of the device 7 to the inputs of the second memory device 16, which is a buffer memory device. From the information outputs of block 16 values follow to the third group of information inputs of the second computer 11. Corrected vector found by sequentially multiplying the vector into three rotation matrices corresponding to the Euler angles in accordance with (6).

Corrected value of the direction vector to the j-th object from the information outputs of block 11 it then goes to the first group of information inputs of the third computer 12. The functions of the latter include determining the updated values of the azimuthal angle , elevation angle and removing the j-th object from the LPS . Spatial angles and find in accordance with expressions (7) and (8), respectively. Distance between the LPS and the j-th object is determined in accordance with (9). To ensure calculations, the second group of information inputs of block 12 receives the value from the first group of information inputs of device 7. The radius of the Earth is known, and its value is contained in block 12. If it is impossible to determine the distance At the zeroing output of the third calculator 12, a signal is generated that is sent to the zeroing inputs of the first 10 and second 11 calculator. As a result, the values of the vectors And in these blocks are reset, and the inventive device begins a new cycle of operation.

For measuring value c the group of information outputs of block 11 through block 12 is supplied to the group of information inputs of the fourth computer 13. Its functions include the transformation of the refined direction vector to the j-th object, located in the normal coordinate system, into the true direction vector in a geocentric coordinate system. This operation in block 13 is carried out in accordance with expression (10). To do this, the values are supplied to the second group of information inputs of the fourth computer 13 And from the first group of information inputs of block 7.

At the next stage of operation of the proposed device, vector transformation is carried out . The latter is supplied to the second group of information inputs of the fifth 14 and the fifth group of information inputs of the seventh 18 computers and the second group of information inputs of the third control unit 22.

The purpose of the fifth computer 14 is to determine the coordinates of the intersection point of the vector with a “round” Earth and converting the geocentric coordinates of the j-th object into geographic ones . The first of these functions in block 14 is performed in accordance with expression (11). For this value , generated by the first computer 10, is supplied to the first group of information inputs of the fifth computer 14. In addition, the value , found by block 12, through block 13 enters the second group of information inputs 14. Next, a transition is made from the geocentric vector of coordinates of the j-th object to its geographic coordinates B _j and L _j in accordance with (12). Calculation results from the outputs of block 14 they go to the second group of information inputs of the switching block 20.

At the same time (with block 13) in block 18, the coordinates of the j-th object are determined in two stages with a given accuracy. This operation is performed in conjunction with the control unit 22 and the storage device 23. At the preparatory stage, a digital map of the terrain of the measurement area is recorded in the storage device 23. This operation is performed using block 8 via the second group of information inputs of block 7. At the same time, via the same bus, control unit 22 is set to the boundary values of the DEM (B _a , L _a ) and (B _b , L _b ) and the number of partition points J, and in block 18 - the number of scanning steps along the vector at the preliminary Δd and final Δδ stages. In block 23, an ordered (at given addresses) recording of a digital terrain map is carried out. The matrix covers an area of the earth's surface limited by the coordinates (B _a , L _a ) and (B _b , L _b ). The purpose of the control unit 22 is to transform part of the vector , limited by points and (B _j , L _j ) into a line of addresses {A _i,j,δ } corresponding to the heights {H _i,j,δ } of the terrain uniformly distributed along its length. For this purpose, the first group of information inputs of block 22 receives the coordinates of the LPS . The second group of information inputs of the control unit 22 is supplied with the value of the direction vector to the j-th object from the outputs of block 13. The third group of information inputs of control block 22 contains a coordinate value , received from the output of the fifth computer 14. In block 22, the named vector segment converted into a sequence of addresses {A _i,j,δ }, which are supplied to the address inputs of the storage device 23. The latter are used to form an address line A _i,j,δ at its input. As a result, the third group of information inputs of the seventh computer 18 receives a sequence of terrain heights {H _i,j,δ } corresponding to a given segment of the true direction vector The capacity of the height sequence {H _i,j,δ } is determined by the value M=max{J,δ}, where J=d(H ₀ ) _ij /Δd, δ=Δd/Δδ. In fig. Figure 11 shows the operating algorithm of block 18 for searching for preliminary and accurate (with a given accuracy) determination of the coordinates of objects .

The geocentric coordinates of the j-th object are then sent to the information inputs of the eighth computer 19. In block 19, the geocentric coordinates are converted to geographic in accordance with expression (13).

The calculation results from the output of block 19 are sent to the first group of information inputs of the switch 20.

Deciding which coordinates will go to the input of block 24 (approximate , obtained on a “round” Earth or accurate taking into account the terrain) receives the comparison block 21. At the preparatory stage (using block 8), the value Δβ is written into the comparison block 21, which determines the given potential accuracy of determining the coordinates of objects. During operation of the inventive device, in block 21 the next measured value is compared with a threshold value Δβ. If the current value turned out to be less than the threshold level Δβ, block 21 generates a control signal supplied to the control input of switching block 20. As a result, the coordinate value from the output of block 14 through block 20 it goes to the group of information inputs of block 24. Otherwise the input of block 24 receives the value from the output of block 19.

If a situation arises in which there is no information about the terrain and block 18 operates according to the algorithm (see Fig. 11) in accordance with expression (12), and the input of block 24 receives the approximate coordinates of the j-th object from the output of block 14. The synchronization of all operations is ensured by the clock pulse generator 17.

The proposed device is designed to measure the coordinates of moving objects. Therefore, their refinement by averaging the resulting sequence is not provided. As a result, the need for image processing units 31 and averaging 34 (Fig. 11 of the prototype) is eliminated. The obtained measurement results from the group of information outputs of block 24 in a given form are sent to the group of information outputs of block 7 (contain the appearance of the j-th object, its coordinates and the time of their measurement in UTC).

The first 10, second 11, third 12, fourth 13 and sixth 15 calculators are designed to determine the true direction vector to the j-th object in a geocentric coordinate system, as well as And and removing the object from the LPS (see Fig. 8). This is achieved by taking into account the orientation of the camera in space and determining the location of the object in the frame of camera 1. Each of the computers performs strictly defined operations in expressions (1-11), the implementation of which does not cause difficulties. The implementation of these blocks is known (see RF Patent No. 2513900, published on July 20, 2014), they are performed on read-only memory devices K541 and K500 series of microcircuits. Algorithms for the operation of computers 10, 11, 12 and 14 are shown in Fig. 18-22 of the prototype, and the sixth computer 15 in FIG. 15.

To reduce weight and size characteristics and current consumption, it is advisable to implement these blocks on a specialized processor TMS320c6416 (see TMS320c6416: http://focus/ti/com/docs/prod/folders/print/TMS320c6416.html).

The fifth 14, seventh 18 and eighth 19 calculators are implemented similarly to the corresponding blocks in Pat. RF No. 2458360, publ. 08/10/2012. The fifth computer 14 is designed to determine the coordinates of the intersection point of the vector with a “round” Earth and geocentric coordinate transformations to geographical in accordance with (11) and (12).

The implementation of the block does not cause any difficulties. Can be implemented on read-only storage devices K541 and K500 series of microcircuits.

The seventh computer 18 is designed to determine the location of an object with a given accuracy in a geocentric coordinate system . Block 18 performs this function in two stages in accordance with the algorithm shown in FIG. 11 and expression (13). It can be implemented by analogy with the corresponding block (see RF Patent No. 2458360, published on August 10, 2012) based on the 16-bit K1810 VM86 microprocessor.

The eighth computer 19 is designed to convert the geocentric coordinates of the object to geographical in accordance with expression (12).

The implementation of block 19 is known and does not cause any difficulties. Block 19 can be implemented on discrete elements based on TTL signal levels, for example 555, 1533 series of microcircuits, etc.

The third control unit 22 is designed to convert part of the vector , limited by points and, (B _j , L _j ) into a line of addresses {A _i,j,δ } corresponding to uniformly distributed heights {H _i,j,δ } of the terrain. The implementation of block 22 is known and does not cause any difficulties. Can be implemented on a microprocessor assembly with sufficient speed (see Shevkoples B.V. Microprocessor structures. Engineering solutions: Handbook. - 2nd ed., revised and supplemented. - M.: Radio and Communications, 1990. - 512 pp. .), which implements the algorithm shown in Fig. 12. The latter determines the order of performing operations to preliminary determine the coordinates of objects. In the mode of measuring coordinates with a given accuracy, the order of operation of block 22 is preserved (the algorithm has a similar form).

It is advisable to implement the functions of blocks 15-24 using a second signal processor (see TMS320c6416: http://focus/ti/com/docs/prod/folders/print/TMS320c6416.html).

In addition, blocks 7, 8 and 26 can be simultaneously implemented on a personal computer. The minimum requirements for it can be defined as follows: Core i5 2000 MHz processor, 1 GB of RAM, 200 MB of free hard disk space. Software component: operating system Windows XP SP2 and higher, library.NetFrameWork 4.0, digital map of the area with information about the relief and format compatible with maps of the Panorama Group.

An analysis of the accuracy and time characteristics of the proposed device has been carried out. When blocks 1 and 6 are in the initial (fixed) state, the device operates in the integrated mode of blocks 5 and 6 (“correction” mode). In this state, the accuracy characteristics of the device are determined by block 5. When the latter uses an antenna system for receiving signals from a satellite navigation system with a base of 1 m (course measurement accuracy 0.8°), the accuracy characteristics of the device (see Fig. 1a) are shown in Table 1.

After changing the orientation of block 1, the device switches to autonomous operation mode (see Fig. 1b), navigation block 5 is disconnected from block 6. The device predicts the spatial orientation of camera 1 based on the inertial data of block 6. The drift stability of block 25 declared by the manufacturer is 5°/ hour, which is realistically achievable only in laboratory stationary conditions. If we assume a realistic value for the stability of gyroscope drifts of 10°/hour, then within 10 minutes of autonomous operation the angle prediction error will be 1.7°. For elevation angle this means an error of 2°, for heading 2.5°. The error in determining the geographic coordinates of the survey object relative to the location of the FPS at a slant range of 3000 m will be 167 m. By adding the error in determining the absolute coordinates of the aircraft equal to 6 m, we obtain an absolute error in determining the geographic coordinates of the survey object of 173 m.

In most cases, detection, fixation and identification of objects is carried out not at nadir, but at an angle of camera 1 of at least 45°. The latter is attached to an aircraft with an inclination along the roll axis of 45°, which will allow flight near a given object, and not above it (in many cases this is prohibited), and along the course - at 90°.

An analysis was made of the dependence of the error in determining the coordinates of objects located in the center of the camera frame (FC) and at its edge. To simplify the calculations, we exclude the stage of intersection of the beam with the terrain (we consider the water surface), the length module of which is equal to 3000 m. Let us fix the angles of the field of view of camera 1 relative to the LPS. Based on the required resolution of block 1 of 0.025 m/squeak and an observation range of 3000 m, the necessary FC parameters were determined, such as matrix size and lens focal length 400 mm, field of view angle 1.8 × 1.8 degrees. Based on them, the data presented in Table 2 was obtained.

The presented results indicate that the error in the aircraft's own orientation should not exceed 2° along each of the axes.

Performing an assessment of the time spent on detecting an object and determining its coordinates for both modes of operation of the device: “correction” and “hands-on” (autonomous operation of the FC). Based on a given observation distance of 3000 m and a fixed observation angle of 45°, the shooting altitude should be 3000-45° = 2120 m. The projection size of the observation field at this range is 130 m. This leads to the fact that the operator can detect a given object, but the latter may not immediately fall into the field of view of the camera. As a result, the aircraft is required to make a turn, a return flight and another turn and set a line of repeated flight (pass) near the object with an accuracy higher than 65 m. Thus, in the case of a successful choice of a repeated pass of the LPS, obtaining one measurement will require time equal to the total time of two tacks and two turns.

For measurements in offline FC 1 mode, the flight altitude and distance to the object can be reduced. As a result, more than one measurement can be taken in a single pass. The time gain from using the autonomous mode of using FC is 3 times or more.

Application

The procedure for determining the parameters of the Kalman filter for correcting an inertial navigation system based on complex processing of information from external sensors

In the proposed device, determining the location of the flight-lifting means and its spatial orientation the navigation unit 5 performs with high accuracy. In turn, the measurement of the spatial orientation of the video surveillance unit 1 (camera) is carried out by the inertial measurement module 6 based on a tactical class inertial sensor 25. The small dimensions of the camera 1 make it difficult to determine its spatial orientation with sufficient accuracy. To eliminate this drawback, the device regularly switches to the “correction” mode after at least 10 minutes of operation. As a result, the readings of block 25 are corrected in block 26 by block 5 obtained with high measurement accuracy based on the use of satellite navigation system (SNS) signals.

An important role in the development of the Kalman filter operating algorithm (block 26) is given to the sensor error model and equations implemented in the inertial navigation system (INS). The following can be selected as variable parameters of the initial equations:

where V ^N , δV ^N are the vectors of the object’s velocity and the errors in its determination in the navigation coordinate system (SC) N; R ^N , δR ^N - vectors of object coordinates and errors in their determination in the navigation system N; Ψ ^N is the error vector for determining orientation in space, expressed in the navigation system N; (Ψ ⁿ ×) is an oblique matrix corresponding to the vector Ψ ⁿ ; δω _IB is the vector of error in determining the angular velocity measured by gyroscopes; δa _IB is the error vector for determining the acceleration measured by accelerometers.

Using the equations of object dynamics and the proposed errors in the parameters, we can write the error equations in the following form (see Savage P.G. Strapdown Analytics Parts 1 and 2, Maple Plain, MN: Strapdown Associates, 2000):

To connect the parameters with the geographic coordinate system, you can use the matrix of rotation of the navigation coordinate system relative to the geographic trihedron by angle α :

Measured values And Taking into account the main components of the errors of gyroscopes and accelerometers, they can be rewritten as:

where Δа, Δω are the zero displacements of accelerometers and gyroscopes, respectively, ϑ _a , ϑ _ω are random measurement errors of accelerometers and gyroscopes.

The displacements of the error zeros of accelerometers Δа and gyroscopes Δω can be considered in a first approximation (see O.A. Babich. Information processing in navigation systems - M.: Mashinostroenie, 1991. - 512 pp.) as autocorrelated random variables with an exponential correlation function

where t is the current time, , τ _μ - correlation time, - error dispersion, μ - index related to the corresponding sensitive element of the inertial measurement module (IMU) (μ=ω corresponds to the accelerometer; μ=ω - gyroscope).

Random errors with an exponential correlation function correspond to a first-order Gaussian Markov process:

where σ is the standard deviation of random errors; ϑ∈N(0,1) - Gaussian noise with zero mean value and correlation function R(t, τ)=δ(t-τ), δ(⋅) - delta function.

In this case, the state vector to be estimated can be represented in the following form, taking into account the main components of the errors of gyroscopes and accelerometers:

δХ=[(δV ^N ) ^T ,(Ψ ⁿ ) ^T ,(δR ^N ) ^T ,(Δω) ^T ,(Δa) ^t ] ^t ;

and the error equation will take the following form in the continuous case

or

δX _k+1 =F _k δX _k +ϑ _k

after sampling.

A natural assumption in such problems is the independence of the noise vector at different times, i.e.

We write the measurement vector z _k in the form

z _k =H _k δX _k +ξ _k ,

where H _k is the measurement matrix, ξ _k is the random measurement error with the covariance matrix R _k , i.e.

Assuming that the correction is carried out from the SNS in coordinates and velocities, we can obtain the measurement equation:

where δz _R is the correction vector for coordinates, δz _v is the correction vector for speed,

Now we can write the traditional Kalman filter structure with the initial conditions: δХ ₀ , Р ₀ =Е [δХ ₀ (δХ ₀ ) ^Т ] (see Savage PG Strapdown Analytics Parts 1 and 2, Maple Plain, MN: Strapdown Associates, 2000; Simon D. Optimal State Estimation (Kalman, Hoo and Nonlinear Approaches, John Wiley & Sons, Inc., Hoboken, New Jersey, 2006).

Predicted state vector and its calculation errors at time t _k+1 :

δX _k+1 -F _k δX _k ,

At the moment of correction t _k the filter gain K _k is calculated:

and then the state vector and its covariance matrix are refined:

Where - refined state vector δX _k , - refined covariance matrix P _k .

Correction of navigation parameters (coordinates, speed and angles) is carried out according to the formulas

Claims (2)

1. A device for determining the coordinates of objects, placed on a standard flight-lifting vehicle (FLS) and containing a transmitting module, a video surveillance unit, a sequentially connected navigation unit and a storage device, the second group of information inputs of which is connected to a group of information outputs of the video surveillance unit, characterized in that that on the LPS an information processing and display device, a control unit, a reference rotary device and an inertial measurement module are additionally placed, and the video surveillance unit and the inertial measurement module are placed together on a reference rotary device, the group of control outputs of which is the input bus of the device for determining the coordinates of objects, a group of information the outputs of the inertial measurement module are connected to the third group of information inputs of the storage device, the group of information outputs of which is connected to the group of information inputs of the control unit and the first group of information inputs of the information processing and display device, the second group of information inputs of which is connected to the group of information outputs of the control unit, and the group information outputs are connected to a group of information inputs of the transmitting module, and at the preparatory stage and in the “correction” device operating mode, a group of information inputs of the inertial measurement module is connected to a group of information outputs of the navigation block. 2. A device for determining the coordinates of objects according to claim 1, characterized in that controlled aircraft and helicopters of various modifications are used as LPS.

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