A method for optoelectronic target tracking and speed measurement of a helicopter

Abstract

The application belongs to the technical field of avionics, and discloses a kind of helicopter photoelectric target tracking speed measurement method, obtains longitude, latitude, height of helicopter, target relative distance, azimuth, pitch angle of helicopter;Solve the longitude, latitude and height of target;Calculate the average change of longitude, latitude and height of target in m period;Judge whether target displacement offset exceeds preset threshold;Calculate the correlation coefficient of northeast direction of target in n period;Determine whether the target is a stationary target, a ground moving target or an air moving target;If the target is a stationary target, set the target motion speed to zero, if the target is a ground moving target or an air moving target, use Kalman filter to calculate the corresponding speed of the target, which can stably track and accurately measure the speed of the target.

Description

Technical Field

[0001] This invention belongs to the field of avionics technology, and in particular relates to a method for tracking and measuring the speed of helicopter photoelectric targets. Background Technology

[0002] Helicopter optoelectronic equipment for target tracking and speed measurement mainly relies on the first frame image comparison method. For speed measurement of moving targets, especially in non-uniform motion states, the difference between the current frame image and the first frame image has a large uncertainty as the target position changes, resulting in problems such as large jumps in the calculated target speed value, inaccurate prediction values, and large prediction lag. Summary of the Invention

[0003] The technical problem solved by this invention is that traditional target tracking and velocity measurement methods result in large jumps in target velocity values, inaccurate prediction values, and prediction lag. This invention can prevent the problem of jumps in the calculated target velocity values ​​and has the advantages of accurate prediction values ​​and low lag.

[0004] To overcome the shortcomings of the prior art, this invention provides a helicopter electro-optical target tracking and speed measurement algorithm. By substituting the longitude, latitude, and altitude of the helicopter, as well as the azimuth, pitch, and distance values ​​of the target relative to the helicopter's electro-optical system, the algorithm calculates the target's longitude, latitude, and altitude. Within a specified period, it determines that the target's displacement deviation does not exceed a threshold. Within 10 consecutive periods, it calculates the target's correlation in the northeast, sky, and three directions, classifying the target's state as stationary, ground-moving, or airborne. For moving targets, Kalman filtering is used to calculate two-axis and three-axis velocities, and the target's position in the next period is predicted based on these velocities. This algorithm can track targets stably and measure their speed accurately.

[0005] The technical solution of this invention:

[0006] A method for tracking and measuring the velocity of a helicopter electro-optical target, the method comprising:

[0007] S1, obtain the helicopter's longitude, latitude, altitude, heading angle, pitch angle, and roll angle output by the helicopter's inertial navigation system; and obtain the target's distance, azimuth angle, and pitch angle relative to the helicopter output by the helicopter's electro-optical turret.

[0008] S2, based on the information in S1, calculates the longitude, latitude, and altitude of the target;

[0009] S3, within m cycles of the photoelectric turret, calculate the longitude, latitude and altitude of the target respectively, and calculate the average change in longitude, average change in latitude and average change in altitude of the target within m cycles;

[0010] S4. Based on the average change in longitude, average change in latitude, and average change in altitude, determine whether the target displacement exceeds a preset threshold.

[0011] If the target displacement offset is greater than a preset threshold, return to S1 to recalculate the target's longitude, latitude, and altitude;

[0012] If the target displacement offset is less than or equal to a preset threshold, the target displacement offset is determined to be reasonable, and S5 is executed again.

[0013] S5 records the longitude, latitude, and altitude of the target over n periods, converts them to northeast-sky coordinates in the geographic coordinate system, and calculates the correlation coefficient of the target in the northeast-sky direction over n periods.

[0014] S6. Based on the correlation coefficient of the northeast direction, determine whether the target is a stationary target, a ground moving target, or an air moving target;

[0015] S7. If the target is stationary, the target's velocity is set to zero. If the target is a ground-based moving target, the Kalman filter is used to calculate the target's eastward and northward velocities. If the target is an airborne moving target, the Kalman filter is used to calculate the target's eastward, northward, and skyward velocities.

[0016] Furthermore, S2 specifically refers to:

[0017] S21, Calculate the coordinates of the target in the body coordinate system;

[0018] S22, calculate the rotation matrix from the body coordinate system to the geographic coordinate system, and then obtain the target's coordinates in the geographic coordinate system;

[0019] S23: Calculate the target's coordinates in the latitude and longitude coordinate system based on the target's coordinates in the geographic coordinate system, and obtain the target's longitude, latitude, and altitude.

[0020] Furthermore, S21 specifically refers to: the target's coordinates in the body coordinate system ( , , ) is calculated using the following formula:

[0021]

[0022] Where L is the distance between the target and the helicopter, The azimuth angle of the target relative to the helicopter, The pitch angle of the target relative to the helicopter.

[0023] Furthermore, S22 calculates the rotation matrix from the body coordinate system to the geographic coordinate system, specifically:

[0024] Calculate the roll matrix from the body coordinate system to the geographic coordinate system. :

[0025]

[0026] Calculate the pitch matrix from the body coordinate system to the geographic coordinate system. :

[0027]

[0028] Calculate the heading matrix from the body coordinate system to the geographic coordinate system. :

[0029]

[0030] Calculate the rotation matrix T from the body coordinate system to the geographic coordinate system:

[0031]

[0032] The coordinates of the target in the body coordinate system ( , , Convert to coordinates in a geographic coordinate system. , , ): .

[0033] Furthermore, in step S23, the target's coordinates in the latitude and longitude coordinate system are calculated based on its coordinates in the geographic coordinate system, thus obtaining the target's longitude. ,latitude and height Specifically:

[0034]

[0035] in, For the longitude of the helicopter, The latitude of the helicopter. The altitude of the helicopter. It is the radius of curvature of the circle. It is the radius of curvature of the meridian.

[0036] Furthermore, S3 calculates the average change in longitude of the target over m periods. latitudinal average change and average change in height Specifically:

[0037]

[0038] in, For photoelectric ranging period, , , These represent the longitude, latitude, and altitude of the target in the m-th cycle. , , These are the longitude, latitude, and altitude of the target for the first cycle.

[0039] Furthermore, S4 specifically refers to:

[0040] like or or If any one of the conditions is met, it is determined that the target position offset is greater than the preset threshold, and the helicopter inertial navigation data is reacquired to track and measure the speed of the target.

[0041] like and and If all three conditions are met, the target displacement is deemed reasonable.

[0042] in, The target maximum speed threshold. One degree of latitude and longitude on Earth represents the actual distance.

[0043] Furthermore, a threshold is set for the data correlation coefficient. ;

[0044] like and and If so, the target is determined to be a stationary target;

[0045] like and and If so, the target is determined to be a moving ground target;

[0046] like and and If so, the target is determined to be a moving aerial target;

[0047] in, The correlation coefficients for the target direction in the east and north directions. The correlation coefficients for the target direction eastward and upward. The correlation coefficients for the target direction (northward and celestial).

[0048] This invention provides a helicopter photoelectric target tracking and velocity measurement method. By substituting the longitude, latitude, and altitude of the helicopter, as well as the azimuth, pitch, and distance values ​​of the target relative to the helicopter's photoelectric system, the longitude, latitude, and altitude of the target are calculated. Within a specified period, the target displacement is determined to be within a threshold value. The correlation of the target in the three directions (northeast, sky, and north) is calculated over m consecutive periods, which can classify the target state as stationary, ground-moving, or air-moving. For moving targets, Kalman filtering is used to calculate the two-axis and three-axis velocities respectively, and the position of the target in the next period is predicted based on the velocities. This algorithm can track targets stably and measure their velocities accurately. Attached Figure Description

[0049] Figure 1 This is a flowchart illustrating a helicopter photoelectric target tracking and speed measurement method provided in an embodiment of the present invention. Detailed Implementation

[0050] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0051] This invention provides a helicopter photoelectric target tracking and speed measurement method, such as... Figure 1 As shown, the method includes:

[0052] S1 acquires the helicopter's longitude, latitude, altitude, heading angle, pitch angle, and roll angle from the helicopter's inertial navigation system output; and acquires the target's distance, azimuth angle, and pitch angle from the helicopter's electro-optical turret output.

[0053] Longitude output periodically by helicopter A inertial navigation system ,latitude Height value Heading angle Pitch angle and roll angle And the data value is valid, that is, the valid position of the data value is 1;

[0054] The helicopter's electro-optical turret can output the target's distance L and azimuth relative to the helicopter in real time. (0° is due north, increasing clockwise), pitch angle (Horizontal plane is 0°, upward is positive), and the data value is valid, that is, the valid data value position is 1.

[0055] S2, calculate the latitude, longitude, and altitude information of target B:

[0056] ① Calculate the coordinate system from the target to the helicopter body:

[0057] In the body coordinate system, the coordinates of target B are ( , , It can be calculated using the following formula.

[0058]

[0059] ② Calculate the coordinate system from the body coordinate system to the geographic coordinate system:

[0060] Considering the helicopter's attitude (heading angle) Pitch angle and roll angle Define the rotation matrix:

[0061] Roll Matrix :

[0062]

[0063] Pitch matrix :

[0064]

[0065] Heading Matrix :

[0066]

[0067] The total rotation matrix T is:

[0068] Then, the coordinates of target B in the body coordinate system ( , , Convert to coordinates in a geographic coordinate system. , , ):

[0069]

[0070] ③ Calculate the conversion from the geographic coordinate system to the latitude and longitude coordinate system:

[0071] Calculate the longitude of target B ,latitude Height value :

[0072]

[0073] in It is the radius of curvature of the circle. It is the radius of curvature of the meridian;

[0074]

[0075]

[0076] Here, a is the Earth's semi-major axis, and e is the Earth's first eccentricity.

[0077] Among them, a = 6,378,137 meters;

[0078]

[0079] f is the Earth's oblateness, with a value of f = 1 / 298.257223563.

[0080] To rule out the possibility that the distance L of target B measured by the laser of the optoelectronic equipment of helicopter A may be due to a few frames of data jumps, or human error caused by changes in the azimuth and pitch of the optoelectronic equipment by human operation, resulting in jumps in the distance of target B;

[0081] S3, within m cycles of the photoelectric turret, calculate the longitude, latitude and altitude of the target respectively, and calculate the average change in longitude, average change in latitude and average change in altitude of the target within m cycles.

[0082] The specified number of cycles, m, is selected as m=3. The photoelectric ranging cycle time is Δt=0.2s. The maximum target velocity threshold is set to... The average changes in longitude, latitude, and altitude of the target over m periods are calculated as follows:

[0083]

[0084] in, , These are the longitude values ​​of the targets for the first and third cycles, respectively. , These are the target latitude values ​​for the first and third cycles, respectively. , These are the target height values ​​for the first and third cycles, respectively.

[0085] Let ρ represent 1 degree of Earth's latitude and longitude. The solution is ρ = 111319 meters.

[0086] S4: Based on the average changes in longitude, latitude, and altitude, determine whether the target displacement exceeds a preset threshold. If the target displacement exceeds the preset threshold, return to S1 to recalculate the target's longitude, latitude, and altitude. If the target displacement is less than or equal to the preset threshold, determine that the target displacement is reasonable and continue executing S5.

[0087] like or or If any one of the conditions is met, it is determined that the target position offset is too large, and the helicopter inertial navigation data is reacquired to track and measure the target speed.

[0088] like and and If all three conditions are met, the target position offset is determined to be reasonable, and there is no systematic error or error caused by human operation.

[0089] Data storage logic after determining that there are no systematic errors or errors caused by human operation:

[0090] ① After determining that there are no systematic errors or errors caused by human operation, the target B longitude, latitude and altitude data are continuously and cyclically overwritten and stored for 10 cycles, and a data list is formed. The data values ​​in the list are valid, the valid data position is 1, and the photoelectric ranging cycle time is △t=0.2s;

[0091] ② After determining that there is a systematic error or an error caused by human operation, clear the list of target B longitude, latitude, and altitude data for the current 10 cycles. The list data values ​​are invalid, the valid data position is 0, and the photoelectric ranging cycle time is △t=0.2s.

[0092] S5 records the longitude, latitude, and altitude of the target over n periods, converts them to northeast-sky coordinates in the geographic coordinate system, and calculates the correlation coefficient of the target's northeast-sky direction over n periods.

[0093] Determining the relevance coefficient r of target B in East (X), North (Y), and Sky (Z):

[0094] Solve the longitude, latitude, and altitude data stored for target B, and calculate the correlation coefficient r of target B in East (X), North (Y), and Sky (Z) over 10 (electro-optical ranging) cycles; including the following calculations:

[0095] ① Convert the longitude, latitude, and altitude data stored in target B into coordinates in a geographic coordinate system:

[0096] The three variables, East (X), North (Y), and Sky (Z), each have n (n=10) observations, denoted as... , and ;

[0097] ② Calculate the mean

[0098] Mean value in the east (X) direction The mean of North (Y) The mean of days (Z) ;

[0099] ③ Calculate covariance

[0100] Calculate the covariance of X and Y ;

[0101] Calculate the covariance of X and Z ;

[0102] Calculate the covariance of Y and Z ;

[0103] ④ Calculate the standard deviation

[0104] Standard deviation in the east (X) direction ;

[0105] Standard deviation in the north (Y) direction ;

[0106] Standard deviation in the Z direction ;

[0107] ⑤ Calculate the correlation coefficient r

[0108] Correlation coefficient between X and Y

[0109] Correlation coefficient between X and Z

[0110] Correlation coefficient between Y and Z

[0111] S6, based on the correlation coefficient of the northeast direction, determines whether the target is a stationary target, a ground moving target, or an air moving target.

[0112] Classify and determine the type of motion of the target:

[0113] Set the threshold for the data correlation coefficient The photoelectric ranging cycle time is Δt = 0.2s.

[0114] Correlation coefficient determination, if and and If so, the target is determined to be a stationary target;

[0115] Correlation coefficient determination, if and and If so, the target is determined to be a moving ground target;

[0116] Correlation coefficient determination, if and and If so, the target is determined to be a moving aerial target;

[0117] S7. If the target is stationary, the target's velocity is set to zero. If the target is a ground-based moving target, the Kalman filter is used to calculate the target's eastward and northward velocities. If the target is an airborne moving target, the Kalman filter is used to calculate the target's eastward, northward, and skyward velocities.

[0118] Method for calculating the biaxial velocity of a target using a Kalman filter:

[0119] If the target is determined to be a ground moving target, a Kalman filter is used to calculate the target's two-axis velocity, namely the eastward and northward velocities.

[0120] The true state vector of target B in the Kalman filter Includes the target's position (x, y) and velocity (v_B) x , v_B y Information, namely

[0121] Wherein, the true state vector The initial value is: , x 9. x 10 , y 9. y 10 It can be calculated according to requirements;

[0122] The state transition matrix F in a Kalman filter is defined as:

[0123] ;

[0124] The photoelectric ranging cycle time is Δt = 0.2s;

[0125] The process noise covariance matrix in a Kalman filter is Q: ;

[0126] In a Kalman filter, the measurement matrix H is defined as: H = [1 0 0 0; 0 1 0 0];

[0127] The measurement noise covariance matrix in a Kalman filter is : ;

[0128] in , These are a 4th-order identity matrix and a 2nd-order identity matrix, respectively.

[0129] Method for calculating the triaxial velocity of a target using a Kalman filter:

[0130] If the target is determined to be an aerial moving target, a Kalman filter is used to calculate the target's three-axis velocity, namely the eastward, northward, and skyward velocities.

[0131] The true state vector of target B in the Kalman filter Includes the target's position (x, y, z) and velocity (v_B) x ,v_B y , v_B z Information, namely ;

[0132] Wherein, the true state vector The initial value is: ,

[0133] x9、x 10 y9, y 10 z9 z 10 It can be calculated according to requirements;

[0134] The state transition matrix F is defined as follows:

[0135]

[0136] The photoelectric ranging cycle time is Δt = 0.2s;

[0137] The process noise covariance matrix in a Kalman filter is Q: ;

[0138] In a Kalman filter, the measurement matrix is ​​defined as H: H = [1 0 0 0 0 0; 0 1 0 0 0 0; 0 0 1 00 0];

[0139] The measurement noise covariance matrix in a Kalman filter is : ;

[0140] in , These are a 6th-order identity matrix and a 3rd-order identity matrix, respectively.

[0141] The present invention provides a helicopter photoelectric target tracking and speed measurement method that can effectively distinguish target states, including stationary ground targets, moving ground targets, and moving air targets. By applying different Kalman filtering strategies for different target types, it can stably track targets and accurately measure their speed.

Claims

1. A method of optoelectronic target tracking for speed measurement of a helicopter, characterized in that, The method comprises: S1, obtaining the longitude, latitude and height of the helicopter output by the helicopter inertial navigation system, and the heading angle, pitch angle and roll angle of the helicopter, and obtaining the distance, azimuth angle and pitch angle of the target relative to the helicopter output by the optical-electric conversion turret of the helicopter; S2, calculating the longitude, latitude and height of the target according to the information in S1; S3, calculating the longitude, latitude and height of the target in m cycles of the optical-electric conversion turret respectively, and calculating the average change amount of the longitude, latitude and height of the target in m cycles; S4, judging whether the target displacement offset amount exceeds a preset threshold according to the average change amount of the longitude, latitude and height; If the target displacement offset amount is greater than the preset threshold, returning to S1 to recalculate the longitude, latitude and height of the target; If the target displacement offset amount is less than or equal to the preset threshold, determining that the target displacement offset amount is reasonable, and continuing to execute S5; S5, recording the longitude, latitude and height of the target in n cycles, converting them into the east-north-sky coordinates in the geographic coordinate system, and calculating the correlation coefficient of the target in the east-north-sky direction in n cycles; S6, determining whether the target is a stationary target, a ground moving target or an air moving target according to the correlation coefficient of the east-north-sky direction; S7, if the target is a stationary target, setting the target motion speed to zero, if the target is a ground moving target, calculating the eastward and northward speeds of the target by using a Kalman filter, and if the target is an air moving target, calculating the eastward, northward and skyward speeds of the target by using a Kalman filter.

2. A method of optoelectronic target tracking and speed measurement for a helicopter according to claim 1, characterized in that, S2 specifically comprises: S21, calculating the coordinates of the target in the body coordinate system; S22, calculating the rotation matrix from the body coordinate system to the geographic coordinate system, and then obtaining the coordinates of the target in the geographic coordinate system; S23, calculating the coordinates of the target in the longitude and latitude coordinate system according to the coordinates of the target in the geographic coordinate system, and obtaining the longitude, latitude and height of the target.

3. A method of optoelectronic target tracking and speed measurement for a helicopter as claimed in claim 2, characterised in that, S21 specifically refers to: the target's coordinates in the body coordinate system ( , , ) is calculated using the following formula: where L is the distance of the target relative to the helicopter, is the azimuth angle of the target relative to the helicopter, is the elevation angle of the target relative to the helicopter.

4. A method of optoelectronic target tracking and speed measurement for a helicopter as claimed in claim 3, characterised in that, S22 specifically comprises: calculating the rotation matrix from the body coordinate system to the geographic coordinate system, which specifically comprises: Computing a roll matrix from a body coordinate system to a geographical coordinate system : ; Computing a pitch matrix from a body coordinate system to a geographical coordinate system : ; Computing a heading matrix from a body coordinate system to a geographical coordinate system : ; The rotation matrix T from the body coordinate system to the geographical coordinate system is calculated: ; The coordinates of the target in the body coordinate system ( , , Convert to coordinates in a geographic coordinate system. , , ): .

5. A method of optoelectronic target tracking and speed measurement for a helicopter as claimed in claim 4, characterised in that, S23, calculating the coordinates of the target in the latitude-longitude coordinate system according to the coordinates of the target in the geographic coordinate system, to obtain the longitude of the target , the latitude and the height , specifically: wherein, is the longitude of the helicopter, is the latitude of the helicopter, is the altitude of the helicopter, is the radius of the meridian of right ascension, is the radius of the meridian of longitude.

6. A method of optoelectronic target tracking and speed measurement for a helicopter as claimed in claim 5, characterised in that, S3, calculating the average change of longitude of the target in m periods , the average change of latitude , and the average change of altitude , specifically: wherein, is the photoelectric ranging period, , , longitude, latitude and altitude of the target in the mth period, respectively, , , longitude, latitude and altitude of the target in the 1st period, respectively.

7. A method of optoelectronic target tracking and speed measurement for a helicopter as claimed in claim 6, characterised in that, S4 specifically comprises: If or or If any one of the conditions is met, it is determined that the target position offset is greater than a preset threshold, and the helicopter inertial navigation data is re-acquired to track and measure the speed of the target. If and and If the three conditions are met simultaneously, it is determined that the target displacement offset is reasonable. wherein, is a target maximum motion speed threshold value, is a 1 degree representative actual distance under the earth longitude and latitude.

8. A method of optoelectronic target tracking and speed measurement for a helicopter according to claim 7, characterized in that, S6 specifically comprises: Setting a threshold for a data correlation coefficient ; If and and then it is determined that the target is a stationary target; If and and then it is determined that the target is a ground moving target; If and and then the target is determined to be an aerial moving target; wherein, is a correlation coefficient of the target east and north directions, is a correlation coefficient of the target east and sky directions, is a correlation coefficient of the target north and sky directions.

Images