A method for identifying roll angle of a projectile guided by velocity integral based on launching coordinate system

Abstract

The application discloses a launch coordinate system guidance shell roll angle identification method based on speed integration. In the case of meeting the air identification precision of the guidance shell, in order to improve the reliability and anti-interference of identification, the speed differential equation of the launch coordinate system is deduced, the lateral / normal overload is applied to the static stable shell body, the roll angle is identified by using the speed measurement value, and the influence of the speed measurement value noise is reduced in the mode of speed integration, so that the roll angle identification precision is improved.

Description

Technical Field

[0001] This invention relates to the field of guided projectile aerial alignment, and specifically to a method for identifying the roll angle of a guided projectile based on a launch coordinate system using velocity integral. Background Technology

[0002] During launch, guided projectiles endure high overload and high rotational speed within the barrel, requiring power-on after launch and in-flight alignment. Due to the high-speed rotation of the projectile during launch, roll angle is difficult to determine. Current research addresses roll angle identification: some guided projectiles utilize inertial devices such as gyroscopes and accelerometers to identify roll angle based on ballistic characteristics, but their accuracy is limited by the precision of these devices; others use solar sensors, infrared sensors, and geomagnetic sensors, relying on natural beacons such as solar, infrared, and geomagnetic information for identification, but their accuracy is affected by the external environment. Therefore, to improve the reliability and anti-interference capabilities of in-flight identification while maintaining the required accuracy, this invention proposes a roll angle identification method for guided projectiles in a launch coordinate system based on velocity integration. The method is derived from the velocity differential equation of the launch coordinate system. By applying lateral / normal overloads to the statically stable projectile, the roll angle is identified using velocity measurements. Furthermore, velocity integration reduces the influence of noise in the velocity measurements, thereby improving the accuracy of roll angle identification. Summary of the Invention

[0003] To address the aforementioned shortcomings in the prior art, this invention provides a method for identifying the roll angle of guided projectiles in a launch coordinate system based on velocity integral.

[0004] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0005] A method for identifying the roll angle of a guided projectile based on a launch coordinate system using velocity integral includes the following steps:

[0006] S1. After the guided projectile is launched and lifted into the air, the projectile body despins and maintains a stable roll angle. After the satellite receiver stabilizes, an overload maneuver command is applied. The transformation matrix from the geocentric coordinate system to the launch coordinate system is calculated using the geographical latitude, longitude and launch azimuth of the launch point.

[0007] S2. After receiving the maneuver command, the guided projectile begins to maneuver. Using the initial velocity of the guided projectile in the geocentric coordinate system received at the start of the maneuver and the transformation matrix obtained in step S1, the initial velocity of the guided projectile in the launch coordinate system is calculated. Then, the trajectory inclination angle of the guided projectile at that moment is calculated using the initial velocity in the launch coordinate system, and the transformation matrix from the launch coordinate system to the pseudo launch coordinate system is calculated based on the trajectory inclination angle.

[0008] S3. After the guided projectile begins its maneuver, each time data is received, the velocity in the launch coordinate system at the corresponding moment is calculated based on the velocity in the geocentric coordinate system and the transformation matrix in step S1.

[0009] S4. Using the calculated transformation matrix, the initial velocity in the launch coordinate system in step S2, the velocity in the launch coordinate system when each data is received in step S3, and the gravitational acceleration are transformed to the pseudo-launch coordinate system to obtain the initial velocity in the pseudo-launch coordinate system, the velocity in the pseudo-launch coordinate system when each data is received, and the gravitational acceleration in the pseudo-launch coordinate system.

[0010] S5. Perform an integral operation based on the initial velocity in the pseudo-emission coordinate system in step S4 and the velocity in the pseudo-emission coordinate system when receiving data each time. Calculate the velocity integral based on the result of the integral operation, the initial velocity in the pseudo-emission coordinate system, and the gravitational acceleration in the pseudo-emission coordinate system.

[0011] S6. Substitute the obtained velocity integral into the roll angle calculation formula to calculate the roll angle and complete the attitude identification.

[0012] Furthermore, the transformation matrix from the geocentric Earth-fixed coordinate system to the launch coordinate system in S1 is expressed as:

[0013]

[0014] in, λ is the transformation matrix from the geocentric coordinate system to the launch coordinate system, B0 is the geographical latitude of the launch point, λ0 is the geographical longitude of the launch point, and A0 is the launch azimuth of the launch point.

[0015] Furthermore, the initial velocity in the launch coordinate system at the start of the maneuver in S2 is calculated as follows:

[0016]

[0017] in, The initial velocity in the launch coordinate system, This is the transformation matrix from the geocentric Earth-fixed coordinate system to the launch coordinate system. The initial velocity of the guided projectile in the geocentric coordinate system received at the moment of the start of its maneuver.

[0018] Furthermore, the calculation method for the trajectory inclination angle of the guided projectile in S2 is as follows:

[0019]

[0020] in, The trajectory angle for guiding artillery shells, The initial velocity has three-axis components in the launch coordinate system.

[0021] Furthermore, in S4

[0022] The initial velocity in the pseudo-launch coordinate system is calculated as follows:

[0023]

[0024] in, Initial velocity in the pseudo-launch coordinate system at the moment the maneuver begins This is the transformation matrix from the launch coordinate system to the pseudo-launch coordinate system. Initial velocity in the launch coordinate system at the moment the maneuver begins;

[0025] The velocity calculation method in the pseudo-transmission coordinate system for each received data is as follows:

[0026]

[0027] in, The velocity in the pseudo-transmission coordinate system at each data reception time. The velocity in the transmission coordinate system at each time data is received;

[0028] The calculation method for gravitational acceleration in the pseudo-launch coordinate system is as follows:

[0029]

[0030] Among them, g w Let g be the gravitational acceleration in the pseudo-launch coordinate system. g This represents the gravitational acceleration in the launch coordinate system.

[0031] Furthermore, the integration operation in S5 is represented as follows:

[0032]

[0033] in, The velocity in the pseudo-launch coordinate system, Let be the velocity in the pseudo-launch coordinate system when the data is received for the i-th time, Δt be the time interval for receiving data, and t be the projectile alignment time.

[0034] Furthermore, the velocity integral in S5 is expressed as:

[0035]

[0036] in, The velocity integral in the pseudo-launch coordinate system. Its three-axis components; The three-axis components of the initial velocity measurement of the guided projectile in the pseudo-launch coordinate system at the moment of maneuver initiation. These are the three-axis components of gravitational acceleration in the pseudo-launch coordinate system.

[0037] Furthermore, the specific calculation method for the roll angle in S6 is as follows:

[0038] If the maneuver is only performed in the positive direction on the y-axis, the roll angle is expressed as:

[0039]

[0040] If the maneuver is performed only in the negative direction on the y-axis, the roll angle is expressed as:

[0041]

[0042] If the maneuver is only performed in the positive direction along the z-axis, the roll angle is expressed as:

[0043]

[0044] If the maneuver is performed only in the negative direction along the z-axis, the roll angle is expressed as:

[0045]

[0046] Where γ is the roll angle, These are the three-axis components of the velocity measurement values ​​in the pseudo-launch coordinate system.

[0047] The present invention has the following beneficial effects:

[0048] The roll angle identification method proposed in this invention is unaffected by the accelerometer measurement accuracy; the roll angle identification accuracy depends only on the velocity measurement accuracy. By integrating the velocity, random noise affecting the velocity measurement is weakened, thus improving the roll angle identification accuracy. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the process for identifying the roll angle of a guided projectile based on a velocity integral launch coordinate system according to the present invention.

[0050] Figure 2 This is a schematic diagram of the launch coordinate system according to an embodiment of the present invention.

[0051] Figure 3 This is a schematic diagram illustrating the relationship between the launch coordinate system and the pseudo-launch coordinate system in an embodiment of the present invention.

[0052] Figure 4 This is a schematic diagram illustrating the relationship between the pseudo-launch coordinate system and the projectile coordinate system in an embodiment of the present invention. Detailed Implementation

[0053] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0054] This invention uses the following coordinate systems and coordinate system transformations.

[0055] (1) Geocentric and Earth-fixed coordinate system

[0056] The geocentric coordinate system (e-frame) has its origin at the Earth's center O. e x e The axis lies in the equatorial plane and points towards the prime meridian, z e The axis is the Earth's axis of rotation and points towards the North Pole, y e The axis lies in the equatorial plane and is perpendicular to the x-axis. e axis, z e The axes form a right-handed rectangular coordinate system.

[0057] (2) Launch coordinate system

[0058] Launch coordinate system (g system), origin O g x is the launch point. g The axis lies in the horizontal plane of the launch point and points in the aiming direction. g The axis is perpendicular to the horizontal plane of the launch point and points upwards, z g axis and x g axis, y g The axes form a right-handed rectangular coordinate system, and the launch coordinate system is fixed to the Earth. The geographical latitude B0, longitude λ0, altitude h0, and launch azimuth A0 of the launch point determine the relationship between the launch coordinate system and the Earth, such as... Figure 2 As shown.

[0059] (3) Projectile coordinate system

[0060] Projectile coordinate system (b-frame), origin O b For the center of mass of the projectile, x b The axis points directly forward along the longitudinal axis of the projectile. b The axis points upwards on the projectile within the plane of its principal axis of symmetry. b axis and x b axis, y b The axes form a right-handed rectangular coordinate system pointing to the right of the projectile.

[0061] (4) Pseudo-launch coordinate system

[0062] At the moment the guided projectile begins its aerial alignment, a pseudo-launch coordinate system (W-frame) is established. The relationship between the launch coordinate system and the pseudo-launch coordinate system is as follows: Figure 3 As shown. The origin O of the pseudo-launch coordinate system is the center of mass of the guided projectile. w x w The axis points in the direction of the guided projectile's velocity at the start of the maneuver, within the x-axis of the launch coordinate system. g O g y g In the plane, relative to the x-axis of the launch coordinate system g The difference angle is the trajectory inclination angle. With x w O w y w perpendicular to x in the plane w The axis is upward y w Positive direction of the axis, z w The positive direction of the axis conforms to the right-hand rule.

[0063] A method for identifying the roll angle of guided projectiles based on velocity integral in a launch coordinate system, such as... Figure 1 As shown, it includes the following steps:

[0064] S1. After the guided projectile is launched and lifted into the air, the projectile body despins and maintains a stable roll angle. After the satellite receiver stabilizes, an overload maneuver command is applied. The transformation matrix from the geocentric coordinate system to the launch coordinate system is calculated using the geographical latitude, longitude and launch azimuth of the launch point.

[0065] The transformation matrix from the Earth-centered Earth-fixed coordinate system to the launch coordinate system is: The geographical latitude B0, longitude λ0, and launch azimuth A0 of the launch point are involved, and the description of each rotation is shown in Equation (1):

[0066]

[0067] S2. After receiving the maneuver command, the guided projectile begins to maneuver. Using the initial velocity of the guided projectile in the geocentric coordinate system received at the start of the maneuver and the transformation matrix obtained in step S1, the initial velocity of the guided projectile in the launch coordinate system is calculated. Then, the trajectory inclination angle of the guided projectile at that moment is calculated using the initial velocity in the launch coordinate system, and the transformation matrix from the launch coordinate system to the pseudo launch coordinate system is calculated based on the trajectory inclination angle.

[0068] The transformation matrix from the launch coordinate system to the pseudo-launch coordinate system is: The attitude angle of the pseudo-launch coordinate system relative to the launch coordinate system is the trajectory inclination angle at the start of the maneuver. Transformation matrix from launch coordinate system to pseudo-launch coordinate system As shown in equation (2).

[0069]

[0070] Transformation matrix from pseudo-launch coordinate system to launch coordinate system

[0071] The satellite receiver can output velocity in the geocentric-fixed coordinate system. according to The velocity in the launch coordinate system can be obtained. for

[0072]

[0073] The initial velocity in the geocentric-fixed coordinate system at the moment the maneuver begins Substituting into equation (3), we obtain the initial velocity of the launch coordinate system at the moment the maneuver begins. The ballistic inclination angle of the guided projectile for

[0074]

[0075] The transformation matrix from the launch coordinate system to the projectile coordinate system is: The attitude angle of a guided projectile in the launch coordinate system relative to the projectile's body coordinate system is determined by the elevation angle. Yaw angle ψ g and roll angle γ g The three Euler angles describe the pitch angles, first by rotating about the z-axis. Then rotate around the y-axis by the y-angle ψ g , Roll angle γ around the x-axis g The 3-2-1 rotation sequence yields... As shown in equation (5).

[0076]

[0077] The transformation matrix from the projectile coordinate system to the launch coordinate system is:

[0078] The transformation matrix from the pseudo-launch coordinate system to the projectile coordinate system is: The attitude angle of a guided projectile in the pseudo-launch coordinate system relative to the projectile's body coordinate system is determined by the elevation angle. Yaw angle ψ w and roll angle γ w The three Euler angles describe the pitch angles, first by rotating about the z-axis. Then rotate around the y-axis by the y-angle ψ w , Roll angle γ around the x-axis w The 3-2-1 rotation sequence yields... As shown in equation (6).

[0079]

[0080] Transformation matrix from projectile coordinate system to pseudo-launch coordinate system

[0081] In the pseudo-launch coordinate system and ψ w All are small values, so equation (6) can be simplified to the form shown in equation (7). The relationship between the pseudo-launch coordinate system and the projectile coordinate system is as follows: Figure 4 As shown. From the definitions of the pseudo-emission coordinate system and the emission coordinate system, we know that γ g and γ w These are different descriptions of the same roll angle, γ w The roll angle that needs to be identified.

[0082]

[0083] S3. After the guided projectile begins its maneuver, each time data is received, the velocity in the launch coordinate system at the corresponding moment is calculated based on the velocity in the geocentric coordinate system and the transformation matrix in step S1.

[0084] After the maneuver begins, data is received every Δt seconds, and the guided projectile receives n data frames. Let the velocity in the Earth-centered, Earth-fixed coordinate system of the i-th (i=1,…,n) frame be denoted as . Combined with the results obtained in step S1 Calculate the velocity in the launch coordinate system for the i-th (i = 1, ..., n) frame.

[0085] S4. Using the calculated transformation matrix, the initial velocity in the launch coordinate system in step S2, the velocity in the launch coordinate system when each data is received in step S3, and the gravitational acceleration are transformed to the pseudo-launch coordinate system to obtain the initial velocity in the pseudo-launch coordinate system, the velocity in the pseudo-launch coordinate system when each data is received, and the gravitational acceleration in the pseudo-launch coordinate system.

[0086] Use the transformation matrix obtained in step S2 In step S2 In step S3 and gravitational acceleration g g Transform to the pseudo-launch coordinate system, i.e.

[0087] S5. Perform an integral operation based on the initial velocity in the pseudo-emission coordinate system in step S4 and the velocity in the pseudo-emission coordinate system when receiving data each time. Calculate the velocity integral based on the result of the integral operation, the initial velocity in the pseudo-emission coordinate system, and the gravitational acceleration in the pseudo-emission coordinate system.

[0088] The velocity differential equation in the launch coordinate system is shown in equation (8).

[0089]

[0090] In equation (8), Let be the rate of change of velocity in the launch coordinate system. The error term caused by the Earth's rotation is small and can be ignored in the identification of the roll angle of guided projectiles. The value is the accelerometer measurement. is the gravity vector of the projectile in the launch coordinate system.

[0091] Equation (8) multiplied by the transformation matrix on the left have to

[0092]

[0093] remember The velocity change rate in the pseudo-launch coordinate system. Let be the gravity vector in the pseudo-launch coordinate system. From equation (9), the velocity differential equation in the pseudo-launch coordinate system can be obtained:

[0094]

[0095] Rearranging and expanding equation (10), we get

[0096]

[0097] During aerial alignment, control the roll angle γ w Unchanged, γ w It is a constant value. (Note: The last part is a typo and can be left as is.) This represents the initial velocity measurement of the guided projectile in the pseudo-launch coordinate system at the moment of maneuver commencement. Let be the velocity measurement value in the pseudo-launch coordinate system of the guided projectile. Integrating equation (11), we get:

[0098]

[0099] In equation (12), This is the integral of the rate of change of velocity in the pseudo-launch coordinate system, i.e., the velocity change. In equation (12), only... As time t changes, and other variables remain constant, integrating equation (12) yields:

[0100]

[0101] In equation (13), This is the integral of the velocity measurement of the guided projectile in the pseudo-launch coordinate system.

[0102] remember Let the velocity integral be denoted as...

[0103] For the integral of the accelerometer measurement, the last two lines of equation (13) can be expressed as:

[0104]

[0105] S6. Substitute the obtained velocity integral into the roll angle calculation formula to calculate the roll angle and complete the attitude identification.

[0106] From equation (14), we can obtain the following regarding the roll angle γ. w The expression is

[0107]

[0108] From equation (15), the formula for calculating the roll angle is:

[0109]

[0110] If the projectile only maneuvers along the y-axis or only along the z-axis, equation (16) can be simplified to the following different cases:

[0111] (1) Perform positive maneuvers only on the y-axis but The numerical values ​​vary greatly, and Equation (16) can be transformed into

[0112]

[0113] (2) Perform negative maneuvers only on the y-axis but The numerical values ​​vary greatly, and Equation (16) can be transformed into

[0114]

[0115] (3) Perform positive maneuvers only on the z-axis but The numerical values ​​vary greatly, and Equation (16) can be transformed into

[0116]

[0117] (4) Perform negative maneuvers only on the z-axis but The numerical values ​​vary greatly, and Equation (16) can be transformed into

[0118]

[0119] As can be seen from equations (17) to (20), the roll angle identification method proposed in this invention is unaffected by the accelerometer measurement accuracy, and the roll angle identification accuracy depends only on the accuracy of the velocity measurement value. By integrating the velocity, the random noise affecting the velocity measurement value is weakened, thereby improving the roll angle identification accuracy.

[0120] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0121] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A velocity integral based method for roll angle identification of a launch coordinate system guided projectile, characterized in that, Includes the following steps: S1. After the guided projectile is launched and lifted into the air, the projectile body despins and maintains a stable roll angle. After the satellite receiver stabilizes, an overload maneuver command is applied. The transformation matrix from the geocentric coordinate system to the launch coordinate system is calculated using the geographical latitude, longitude and launch azimuth of the launch point. S2. After receiving the maneuver command, the guided projectile begins to maneuver. Using the initial velocity of the guided projectile in the geocentric coordinate system received at the start of the maneuver and the transformation matrix obtained in step S1, the initial velocity of the guided projectile in the launch coordinate system is calculated. Then, the trajectory inclination angle of the guided projectile at that moment is calculated using the initial velocity in the launch coordinate system, and the transformation matrix from the launch coordinate system to the pseudo launch coordinate system is calculated based on the trajectory inclination angle. S3. After the guided projectile begins its maneuver, each time data is received, the velocity in the launch coordinate system at the corresponding moment is calculated based on the velocity in the geocentric coordinate system and the transformation matrix in step S1. S4. Using the calculated transformation matrix, the initial velocity in the launch coordinate system in step S2, the velocity in the launch coordinate system when each data is received in step S3, and the gravitational acceleration are transformed to the pseudo-launch coordinate system to obtain the initial velocity in the pseudo-launch coordinate system, the velocity in the pseudo-launch coordinate system when each data is received, and the gravitational acceleration in the pseudo-launch coordinate system. S5. Perform an integral operation based on the initial velocity in the pseudo-emission coordinate system in step S4 and the velocity in the pseudo-emission coordinate system when receiving data each time. Calculate the velocity integral based on the result of the integral operation, the initial velocity in the pseudo-emission coordinate system, and the gravitational acceleration in the pseudo-emission coordinate system. S6. Substitute the obtained velocity integral into the roll angle calculation formula to calculate the roll angle and complete the attitude identification.

2. The method for identifying the roll angle of a guided projectile based on a velocity integral launch coordinate system according to claim 1, characterized in that, The transformation matrix from the geocentric Earth-fixed coordinate system to the launch coordinate system in S1 is expressed as follows: in, λ is the transformation matrix from the geocentric coordinate system to the launch coordinate system, B0 is the geographical latitude of the launch point, λ0 is the geographical longitude of the launch point, and A0 is the launch azimuth of the launch point.

3. The method for identifying the roll angle of a guided projectile based on velocity integral in a launch coordinate system according to claim 1, characterized in that, The initial velocity in the launch coordinate system at the start of the maneuver in S2 is calculated as follows: in, The initial velocity in the launch coordinate system, This is the transformation matrix from the geocentric Earth-fixed coordinate system to the launch coordinate system. The initial velocity of the guided projectile in the geocentric coordinate system received at the moment of the start of its maneuver.

4. The method for identifying the roll angle of a guided projectile based on velocity integral in a launch coordinate system according to claim 1, characterized in that, The method for calculating the trajectory inclination angle of the guided projectile in S2 is as follows: in, The trajectory angle for guiding artillery shells, The initial velocity has three-axis components in the launch coordinate system.

5. The method for identifying the roll angle of a guided projectile based on velocity integral in a launch coordinate system according to claim 1, characterized in that, In S4 The initial velocity in the pseudo-launch coordinate system is calculated as follows: in, Initial velocity in the pseudo-launch coordinate system at the moment the maneuver begins This is the transformation matrix from the launch coordinate system to the pseudo-launch coordinate system. Initial velocity in the launch coordinate system at the moment the maneuver begins; The velocity calculation method in the pseudo-transmission coordinate system for each received data is as follows: in, The velocity in the pseudo-transmission coordinate system at each data reception time. The velocity in the transmission coordinate system at each time data is received; The calculation method for gravitational acceleration in the pseudo-launch coordinate system is as follows: where g w is the gravitational acceleration in the pseudo launch coordinate system, g g is the gravitational acceleration in the launch coordinate system.

6. The method for identifying the roll angle of a guided projectile based on a velocity integral launch coordinate system according to claim 1, characterized in that, The integral operation in S5 is represented as follows: in, The velocity in the pseudo-launch coordinate system, Let be the velocity in the pseudo-launch coordinate system when the data is received for the i-th time, Δt be the time interval for receiving data, and t be the projectile alignment time.

7. The method for identifying the roll angle of a guided projectile based on velocity integral in a launch coordinate system according to claim 1, characterized in that, The velocity integral in S5 is expressed as follows: in, The velocity integral in the pseudo-launch coordinate system. Its three-axis components; The three-axis components of the initial velocity measurement of the guided projectile in the pseudo-launch coordinate system at the moment of maneuver initiation. These are the three-axis components of gravitational acceleration in the pseudo-launch coordinate system.

8. The method for identifying the roll angle of a guided projectile based on velocity integral in a launch coordinate system according to claim 1, characterized in that, The specific calculation method for the roll angle in S6 is as follows: If the maneuver is only performed in the positive direction on the y-axis, the roll angle is expressed as: If the maneuver is performed only in the negative direction on the y-axis, the roll angle is expressed as: If the maneuver is only performed in the positive direction along the z-axis, the roll angle is expressed as: If the maneuver is performed only in the negative direction along the z-axis, the roll angle is expressed as: Where γ is the roll angle, These are the three-axis components of the velocity measurement values ​​in the pseudo-launch coordinate system.

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