A method for photoelectric tracking of weapon follow-up elevation axis

Abstract

The application discloses a weapon follow-up pitching axis photoelectric tracking method, which takes servo control and target prediction as independent parts, a target prediction unit combines photoelectric error data and an actual pitching angle, is responsible for target angle prediction, extrapolation and interpolation processing and target angular velocity prediction processing, and provides accurate target angle information and angular velocity information for a servo control system. The servo control takes the target prediction angle information output by the target prediction unit as the input of an angle control loop, combines the actual pitching angle of a current tracking support to calculate a pitching error value, adopts PID to correct and output a pitching shaft speed given value, simultaneously superimposes the target prediction angular velocity information output by the target prediction unit to form a compound control system, and improves the tracking performance of the photoelectric tracking system. According to the fixed nonlinear function relationship between the pitching shaft angular velocity and the electric cylinder linear speed of the structure model, an electric cylinder speed processing algorithm is adopted to realize accurate control of the pitching shaft angular velocity.

Description

Technical Field

[0001] This invention relates to the field of photoelectric tracking technology, and in particular to a method for photoelectric tracking of a weapon's pitch axis. Background Technology

[0002] In existing technologies, photoelectric tracking and weapon servoing are based on different rotating platforms. The photoelectric tracking turntable is mounted on the weapon servoing platform, and the command and control system coordinates the photoelectric system and the weapon system. With the development of electromagnetic weapon technology, higher requirements are placed on the integration of the system, necessitating the research of a weapon servo tracking technology that integrates photoelectric devices.

[0003] In existing technologies, photoelectric tracking systems operate independently, with turntables mostly based on a π-frame structure and employing a torque motor direct drive scheme; weapon servo systems, also based on a π-frame structure, use a servo motor drive scheme; and photoelectric deployment and retraction often employ an electric inverting mechanism, which is driven by a servo motor. This mechanism converts the motor's rotational motion into the linear motion of the electric cylinder via a reducer and an electric cylinder, thus achieving the photoelectric deployment and retraction function. Due to the special characteristics of the new weapon platform, the π-frame structure used for the pitch axis of this tracking system suffers from numerous defects, such as exceeding dimensional limits and weight limits, which cannot be resolved by existing servo tracking methods.

[0004] Therefore, a weapon-following pitch axis photoelectric tracking method was developed to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to design a weapon follow-up pitch axis photoelectric tracking method to solve the above problems.

[0006] The present invention achieves the above objectives through the following technical solutions:

[0007] A weapon-following pitch axis photoelectric tracking method includes the following steps:

[0008] S1. Target prediction is achieved based on a servo controller. The servo controller uses an α-β filter to predict the target angle and angular velocity based on the photoelectric error values ​​periodically sent by the command and control system and the current pitch angle position information of the tracking support. The smoothing estimation recursive equation for the α-β filter is:

[0009]

[0010] The prediction and estimation recursive equation is:

[0011]

[0012] In the formula, E represents pitch, the subscript s represents smoothing, p represents prediction, and m represents measurement;

[0013] S2. According to equation (1), a residual accumulation method is used to calculate the values ​​of α and β; a sliding window of length 6 is set up to continuously update. That is, the root mean square error of the prediction; This is due to inherent errors in optoelectronic equipment;

[0014]

[0015]

[0016]

[0017] Substituting equations (4) and (5) into equation (1) yields the predicted angle and angular velocity of the target.

[0018] S3. Data Extrapolation Method: When the target pitch angle changes at a constant speed, the controller represents the predicted angle value of the target using a first-order polynomial, i.e.

[0019] E(a,t)=a0+a1t

[0020] Solving for the coefficients using least squares yields the extrapolated expression for the m-th update period T.

[0021]

[0022] Using a three-point acceleration extrapolation method (n=3), then

[0023]

[0024] S4. Data interpolation adopts the parabolic interpolation method: Take the three points closest to the interpolation point: t1 = kT + T, t2 = kT + 2T, t3 = kT + 3T. The quadratic interpolation formula is:

[0025]

[0026] The pitch angle setpoint E(t) for any control cycle can be obtained from the above formula;

[0027] S5. Based on the pitch angle setpoint E(t) and the pitch angle position of the tracking support, the controller can obtain the pitch angle error value, and output the pitch axis velocity setpoint ω through the position loop correction. p The target feedforward angular velocity ω is predicted according to Equation 2. q Then the total velocity setpoint of the pitch axis

[0028]

[0029] S6. The electric cylinder speed processing algorithm is based on the structural model, which states that the pitch axis angular velocity and the electric cylinder linear velocity have a fixed nonlinear functional relationship.

[0030]

[0031] Where a and b are the lengths of the two fixed sides, θ is the pitch angle, and L is the length of the electric cylinder. Set the total velocity of the pitch axis;

[0032] The linear velocity of the electric cylinder is directly proportional to the angular velocity of the motor; therefore, the controller outputs the given motor speed as follows:

[0033]

[0034] Where n is the reduction ratio, e is the lead of the electric cylinder, and the motor speed is in revolutions per minute;

[0035] S7. Pitch motor speed control method;

[0036] The servo controller sends the given angular velocity and drive enable signal of the pitch motor to the servo driver via the CAN bus. The servo driver is used to implement closed-loop control of the motor speed.

[0037] The beneficial effects of this invention are as follows:

[0038] Based on the coaxial tracking concept, servo control and target prediction are treated as independent components. The target prediction unit, combining photoelectric error data and the actual pitch angle, is responsible for target angle prediction, extrapolation and interpolation processing, and target angular velocity prediction processing, providing accurate target angle and angular velocity information to the servo control system. The servo control uses the target prediction angle information output by the target prediction unit as the input to the angle control loop, calculates the pitch error value based on the actual pitch angle of the current tracking bracket, and uses PID correction to output the pitch axis velocity setpoint. Simultaneously, the target prediction angular velocity information output by the target prediction unit is superimposed to form a composite control system, improving the tracking performance of the photoelectric tracking system. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the rear structure of the pitch mechanism of the servo system;

[0040] Figure 2 This is a side view of the pitch mechanism of the servo system;

[0041] Figure 3 for Figure 2 AA section view in the middle;

[0042] Figure 4 This is a schematic diagram showing the installation position of the pitch mechanism in the servo system's pitch mechanism.

[0043] Figure 5 This is a schematic diagram of the crank and right-angle reducer in the pitch mechanism of the servo system.

[0044] Figure 6 This is a schematic diagram illustrating the tracking control principle of this application;

[0045] Figure 7 This is a schematic diagram of the pitch axis structure model;

[0046] In the diagram: 1. Electric cylinder, 2. Balancing device, 3. Buffer device, 4. Pitch support, 5. Pitch motor, 6. Pitch rotary transformer, 7. Pitch shaft, 8. Cylindrical roller bearing, 9. Antenna back frame, 10. Piston rod, 11. Antenna, 12. Azimuth turntable, 13. Crank handle, 14. Right angle reducer. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0049] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0050] In the description of this invention, it should be understood that the terms "upper," "lower," "inner," "outer," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0051] Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0052] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, terms such as "set" and "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0054] The structure of the pitch mechanism of the servo system corresponding to this invention is shown below:

[0055] like Figures 1-5 As shown, the pitch mechanism of the servo system includes:

[0056] The pitch motor 5 is connected to two electric cylinders 1 via a drive shaft. The fixed end of the electric cylinder 1 is rotatably connected to the pitch support 4, and the end of the piston rod 10 of the electric cylinder 1 is rotatably connected to the antenna back frame 9.

[0057] The crank handle 13 is connected to the drive shaft 7 via a right-angle reducer 14, thereby achieving a transmission connection with the electric cylinder 1 to enable the antenna to be manually tilted when the power is off.

[0058] The pitch rotary transformer 6 is installed between the pitch support 4 and the antenna backplate 9. The rotary transformer is used to obtain the absolute angle of the pitch axis 7;

[0059] The two ends of the spring balancing device 2 are connected to the antenna back frame 9 and the elevation support 4 respectively, in order to balance the gravitational torque of the antenna;

[0060] The buffer device 3 is installed on the upper part of the elevation support 4 to buffer the impact force of the antenna back frame 9 on the elevation support 4.

[0061] Under normal control conditions, the pitch motor 5 operates, transmitting power to the two electric cylinders 1 via the drive shaft, thereby controlling the pitch angle of the antenna back frame 9. In the event of a power outage, the right-angle reducer 14 is manually driven by turning the crank handle 13 to achieve manual pitch adjustment of the antenna back frame 9.

[0062] The first end of the antenna back frame 9 is connected to the first end of the elevation support 4 via an elevation shaft 7, which is connected to two tapered roller bearings 8. The tapered roller bearings 8 are fixed on the elevation support 4, and the elevation shaft 7 is fitted onto the tapered roller bearings 8. The antenna back frame 9 is fixedly connected to the elevation shaft 7.

[0063] Driven by the pitch motor 5, the two sets of electric cylinders 1 enable the antenna back frame 9 to move synchronously with the two electric cylinders, thus avoiding pitch error caused by mechanical asynchrony.

[0064] Figure 7 In the diagram, 'a' represents the distance between the fixed rotation point of the electric cylinder 1 and the pitch axis 7; 'b' represents the distance between the pitch axis 7 and the hinge point of the piston rod 10; 'L' represents the distance between the fixed rotation point of the electric cylinder 1 and the hinge point of the piston rod 10; and 'θ' represents the pitch angle.

[0065] Example

[0066] The servo controller communicates with the command and control system via a network. The command and control system sends data frames at a frequency of 50Hz, and the servo controller updates the received control command information and photoelectric error information every 20ms. To match the data communication frame rate, the servo controller performs synthesis, filtering, and extrapolation of the target pitch angle every 20ms. Let the photoelectric pitch error be denoted as Error, and the current pitch angle measurement value of the weapon tracking bracket be Current_position, then the target pitch angle is...

[0067] E m (kT) = Current_position + Error

[0068] The predicted angle of the target can be obtained by filtering according to Equation 1-5. The predicted angular velocity can be obtained by performing differential filtering on the predicted target angle. Take the three most recent extrapolated angle values ​​as follows: According to Equation 6, the extrapolated value can be obtained.

[0069]

[0070] Where E(kT-T), E(kT), E(kT+T), and E(kT+2T) are known sampled values, and the extrapolated values ​​from historical perspectives are respectively... Current angular velocity prediction value

[0071] The servo controller control cycle is 1ms. Let kT = 1.0s, t1 = kT + T = 1.02s, t2 = kT + 2T = 1.04s, t3 = kT + 3T = 1.06s, and t = 1.05s. Then, according to the quadratic interpolation formula (Equation 7), the target pitch setpoint when the servo control cycle t = 1.05s can be obtained as follows:

[0072]

[0073] Since t1, t2, t3, and t in the system are constantly changing, the extrapolated angle values ​​corresponding to the three most recent values ​​are... It also changes constantly. The target pitch setpoint E(t) for each control cycle can be obtained by using the quadratic interpolation formula (Equation 7) for data interpolation.

[0074] The coaxial tracking principle of this application is as follows: Figure 6 As shown, the system is based on a servo controller, which uses the GigaDevice GD32F407VET6 control chip as its processor. The servo controller receives photoelectric error information from the command and control system via a network port. The data fusion module uses an adaptive parameter α-β filter algorithm to filter the pitch target angle. Parameter adaptation is based on the residual accumulation method, using a sliding window of length 6. According to Equation 3, the root mean square error of the prediction error can be calculated in real time. Inherent errors obtained from the inspection of optoelectronic equipment The values ​​of the filtering parameters α and β can be obtained from equations 4 and 5. The data fusion module extrapolates and interpolates the filtered pitch target angle information to obtain the pitch angle setpoint information for each control cycle; simultaneously, it performs differential filtering based on the extrapolated pitch angle value to obtain the predicted angular velocity value.

[0075] The pitch spindle angle feedback uses a dual-channel resolver transmitter with a coarse-to-fine ratio of 1:64. The four signals output from the coarse-finishing stage of the resolver are connected to the four input terminals S1, S2, S3, and S4 of the coarse-finishing stage of the dual-speed R / D converter. The four signals output from the fine-finishing stage of the resolver are connected to the four input terminals S5, S6, S7, and S8 of the fine-finishing stage of the dual-speed R / D converter. The dual-speed R / D converter outputs a set of 18-bit binary signals, which are the binary angle digital signals output by the axis angle encoder board.

[0076] The servo control angle controller can obtain the current angle error e(k) = E(t) - Current_position and the angle error change value Δe(k) = e(k) - e(k-1) based on the pitch angle E(t) given by the data fusion module and the current pitch angle Current_position output by the axis angle encoder.

[0077] The angle controller is based on PID control and incorporates adaptive control principles to form a multimodal PID controller. That is, it uses a PID controller as its basic structure, and the controller's structure and the coefficients of P, I, and D adjust themselves according to factors such as error and the rate of change of error, thus forming a complete controller. In other words, the angle controller output...

[0078] ω2=k p ·(e(k),Δe(k))·e(k)+k i ·(e(k),Δe(k))·∑e(k)+k d ·(e(k),Δe(k))·(e(k)-e(k-1))

[0079] The proportional, integral, and derivative coefficients are adjusted online based on the error and its changes. Simultaneously, considering system performance requirements, the controller structure can be adjusted. When |e(k)| > E0 (a certain constant), the integral parameter is set to 0 to avoid the lag effect caused by the integral. Conversely, when |e(k)| < E1 (a certain constant), the derivative parameter is set to 0 to avoid control fluctuations caused by the derivative action and improve the smoothness of the system response.

[0080] A weapon-guided pitch axis photoelectric tracking method is implemented based on an electrically operated inverting mechanism. A schematic diagram of the pitch axis transmission mechanism is shown below. Figure 2 As shown. The speed setpoint output by the servo controller angle controller and the target angular velocity prediction output by data fusion are ω1 and ω2, respectively. Therefore, the pitch spindle angular velocity setpoint is...

[0081]

[0082] The linear velocity of the electric cylinder and the angular velocity of the pitch axis have a fixed nonlinear functional relationship. Figure 7 ),Right now

[0083]

[0084] Where a and b are the lengths of the two fixed sides, θ is the pitch angle, and L is the length of electric cylinder 1. A given angular velocity is given for target tracking. Further explanation, considering the structure of the servo system's pitch mechanism, is as follows: a is the shortest distance between the first and second rotation center lines, where the first rotation center line is the rotation center line at the rotatable connection between the fixed end of the electric cylinder 1 and the pitch support 4, and the second rotation center line is the axis of the pitch axis; b is the shortest distance between the second and third rotation center lines, where the third rotation center line is the rotation axis line at the rotatable connection between the piston rod 10 end of the electric cylinder 1 and the antenna backplate 9; θ is the angle between a and b.

[0085] The linear velocity of the electric cylinder is directly proportional to the angular velocity of the motor; therefore, the controller outputs the given motor speed as follows:

[0086]

[0087] Where n is the reduction ratio, e is the electric cylinder lead, and the motor speed is in revolutions per minute (rpm).

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A weapon servo pitch axis photoelectric tracking method, characterized in that, Includes the following steps: S1. Target prediction is implemented based on a servo controller. The servo controller predicts the target angle and angular velocity using an α-β filter based on the photoelectric error value sent periodically by the command and control system and the current pitch angle position information of the tracking bracket. The smoothing estimation recursive equation of the α-β filter is: （1） The prediction and estimation recursive equation is: （2） In the formula, E represents pitch, the subscript s represents smoothing, p represents prediction, and m represents measurement; S2. According to equation (1), a residual accumulation method is used to calculate the values ​​of α and β; a sliding window of length 6 is set up to continuously update. , That is, the root mean square error of the prediction; This is due to inherent errors in optoelectronic equipment; （3） （4） （5） Substituting equations (4) and (5) into equation (1) yields the predicted angle and angular velocity of the target. S3. Data Extrapolation Method: When the target pitch angle changes at a constant speed, the servo controller represents the predicted angle value of the target using a first-order polynomial, i.e. Solving for the coefficients using least squares yields the extrapolated expression for the m-th update period T. Using a three-point accelerated extrapolation method (n=3), then （6） S4. Data interpolation adopts the parabolic interpolation method: Take the three points closest to the interpolation point: t1=kT+T, t2=kT+2T, t3=kT+3T. The quadratic interpolation formula is: .......（7） The pitch angle setpoint E(t) for any control cycle can be obtained from the above formula; S5. Based on the pitch angle setpoint E(t) and the pitch angle position of the tracking support, the servo controller can obtain the pitch angle error value, and output the pitch axis velocity setpoint ω through position loop correction. p The target feedforward angular velocity ω is predicted according to equation (2). q Then the total velocity setpoint of the pitch axis S6. Electric Cylinder Speed ​​Processing Algorithm: Based on the structural model, there is a fixed nonlinear functional relationship between the pitch axis angular velocity and the electric cylinder linear velocity, i.e. Where a and b are the lengths of the two fixed sides, a is the shortest distance between the first rotation center line and the second rotation center line, the first rotation center line is the rotation center line at the rotatable connection between the fixed end of the electric cylinder and the pitch support, and the second rotation center line is the axis of the pitch axis; b is the shortest distance between the second rotation center line and the third rotation center line, the third rotation center line is the axis of rotation at the rotatable connection between the piston rod end of the electric cylinder and the antenna back frame; θ is the pitch angle, and L is the length of the electric cylinder. Set the total velocity of the pitch axis; The linear velocity of the electric cylinder is directly proportional to the angular velocity of the motor; therefore, the servo controller outputs the given motor speed as follows: （8） Where n is the reduction ratio, e is the lead of the electric cylinder, and the motor speed is in revolutions per minute; S7. Pitch motor speed control method; The servo controller sends the given angular velocity and drive enable signal of the pitch motor to the servo driver via the CAN bus. The servo driver is used to implement closed-loop control of the motor speed.

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