A radar servo system adaptive variable bandwidth tracking implementation method

Abstract

The present invention relates to a radar servo system adaptive variable bandwidth tracking implementation method. The difficulties in implementing adaptive variable bandwidth mainly include the setting of servo parameters and the construction of adaptive servo bandwidth switching criteria. The present invention firstly uses a type II radar servo system according to K a The maximum phase margin criterion is used to determine the controller parameters of the self-tracking loop, 5 to 6 groups of servo bandwidths are debugged, and the phase margin is used to judge their stability. Secondly, the criterion construction and switching process of radar servo adaptive bandwidth switching are introduced. Finally, simulation analysis and test verification show that this method has strong adaptability, smooth bandwidth switching process and simple engineering implementation, which fully meets the needs of equipment development and test tasks, and is the best choice for completing high dynamic tasks such as the re-entry phase of the aircraft.

Description

Technical Field

[0001] The invention belongs to the field of automation technology, and in particular relates to a design and implementation method of adaptive servo bandwidth switching of a radar servo system. Background Art

[0002] With the emergence of spacecraft re-entry and near-space spacecraft measurement missions, the characteristics are fast target flight angular velocity, low flight altitude, and large flight pipeline deviation. Especially when the target flies over the radar, that is, high-elevation angle tracking, the angular velocity and angular acceleration of the radar servo tracking are relatively large, and the dynamic lag is very large, which can easily exceed the antenna beam width and cause the target to be lost.

[0003] At present, radar servo systems generally use open-closed loop composite control system methods to reduce dynamic lag. When extracting the target feedforward angular velocity, the jitter of the target feedforward angular velocity is relatively large due to the influence of random angle measurement errors, especially the error voltage jump factor. The effect of using this signal for composite control is relatively poor, or when the error voltage cannot pass the data rationality check, angular velocity positive feedback will be automatically used to improve the servo tracking performance, but angular velocity positive feedback may affect the stability of the system. These factors have greatly limited the application of composite control systems.

[0004] The basic idea of ​​this patent is to fully tap the potential of the radar servo system, and to a The value is divided, the maximum phase margin criterion is used to determine the expected characteristic parameters, and the adaptive bandwidth switching method is used to achieve the tracking of high dynamic targets. The focus of this patent is the construction of the criterion for servo bandwidth adjustment and adaptive bandwidth switching. Through actual simulation analysis and test verification, it is shown that this method has strong adaptability, smooth bandwidth switching process, simple engineering implementation, and fully meets the needs of equipment development and test tasks.

[0005] The 32nd issue of Electronic Mechanical Engineering published in February 2016 disclosed a method for designing and implementing a high-precision speed radar servo bandwidth adaptation. This method designs a bandwidth adaptation method based on the narrow bandwidth range of the tracking radar, that is, three sets of PID parameters are preset to correspond to different servo bandwidths, and the corresponding bandwidth is switched according to the tracking angular velocity. Simulation verification shows that this method has smooth bandwidth switching, smooth angular velocity changes, and can obtain good dynamic response at high and low speeds. Compared with fixed bandwidth, it has better adaptability and control effect. The disadvantages are: ① The number of servo bandwidths is too small, and the servo tracking performance is limited; ② For the type II radar servo system, the angular velocity information cannot reflect the dynamic lag of radar tracking, and precise control cannot be performed.

[0006] The 6th issue of Volume 30 of the Sichuan Ordnance Journal published in June 2009 disclosed a fuzzy adaptive PID controller design method for a radar servo system. This method designs a fuzzy adaptive PID controller based on the complex and nonlinear characteristics of the mathematical model of the radar servo system. The controller combines the experience of the staff and uses fuzzy control theory to adjust the PID parameters online in real time. The disadvantages are: ① This method is limited to simulation analysis and has no practical application in engineering; ② The differential component of the angle measurement error is required in the implementation of this method. When the error voltage vibrates violently, the system cannot work normally. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a method for realizing adaptive variable bandwidth tracking of a radar servo system in response to the above-mentioned prior art. The method has strong adaptability, a smooth bandwidth switching process, and simple engineering implementation. It fully meets the needs of equipment development and execution of test tasks, and is the best choice for completing high-dynamic tasks such as the CE-5 return segment.

[0008] The technical solution adopted by the present invention to solve the above problem is: a radar servo system adaptive variable bandwidth tracking implementation method, the method comprising the following steps:

[0009] Step 1: Modeling of radar servo system

[0010] In order to simplify the design and calculation, the speed loop can be approximated as an inertial link when modeling the position loop of the radar servo system. In this way, the self-tracking loop of the radar servo system is a typical type II system, and its open-loop and closed-loop transfer functions are:

[0011]

[0012]

[0013] in, is the open-loop gain of the system, K s To track the directional sensitivity of the receiver, K p is the proportional gain of the self-tracking loop PI regulator, T p K is the integral time constant of the self-tracking loop PI regulator, v is the closed-loop gain of the angular velocity loop, T v is the equivalent time constant of the angular velocity loop, N is the reduction ratio, and the definition of the intermediate frequency width h is given:

[0014] h=ω2 / ω1=T p / T v

[0015] Where ω1 represents the first turning frequency (ω1 = 1 / T p), ω2 represents the second turning frequency (ω2=1 / T v ).

[0016] Step 2: Position loop servo parameter tuning of radar servo system

[0017] In the known K s , K v , T v , N, in the case of pre-determined K a When the value is K, the design of the expected characteristics of the typical type II system is transformed into K p , T p Since the radar servo system variable bandwidth tracking measurement requires 5 to 6 sets of bandwidth, it can be selected according to K a The servo gears are divided into different positions from small to large, and then h and K are calculated using the maximum phase margin criterion. p and T p Then, analyze its stability based on the phase margin, and finally calculate the K based on its closed-loop transfer function. a The servo bandwidth corresponding to the value. The following is an introduction using a radar servo system as an example:

[0018] (1) Determine the required set of K a Value, such as orientation K a =[1.5,2.5,5.0,7.5,10].

[0019] (2) Determine the intermediate frequency bandwidth h based on the maximum phase margin criterion

[0020]

[0021] (3) Determine K based on the intermediate frequency width h p , T p :

[0022] T p =hT v

[0023] (4) Analyze system stability based on phase margin. Generally, the phase margin γ(ω c ) is greater than 40°.

[0024]

[0025] (5) Calculate a certain K based on the amplitude-frequency characteristics of the closed-loop system a The servo bandwidth corresponding to the value.

[0026] (6) Convergence characteristic test and tracking performance verification using target simulator.

[0027] Step 3: Construction of the criterion for radar servo bandwidth switching

[0028] Since the radar servo system is designed as a type II system, the dynamic lag is mainly caused by the angular acceleration of the servo tracking. The azimuth cross section (the schematic diagram of the cross section and the azimuth plane is shown in Figure 2 The best method is to use the angular acceleration of the pitch as the criterion for adaptive bandwidth switching.

[0029] According to the different types of data sources that can be provided, the servo bandwidth can be switched according to the following three criteria: Criterion 1 is to directly calculate the angular acceleration values ​​of the cross section and pitch based on the real-time digital data provided by the central computer; Criterion 2 and Criterion 3 are based on the trajectory of uniform flight of equal height straight lines (such as Figure 3 Calculating the angular acceleration value or envelope value of the cross section and pitch) is an engineering approximation, but it fully meets the requirements of servo bandwidth switching.

[0030] Criterion 1: {cross-plane acceleration, pitch acceleration}

[0031] When the data contains a A 、a E ,ω A ,ω E , E time

[0032]

[0033] Criterion 2: {cross-plane acceleration, pitch acceleration}

[0034] When the data contains ω A ,ω E , E time

[0035]

[0036] Criterion 3: {Transverse acceleration envelope, pitch acceleration envelope}

[0037] When the numerical data contains v, E, R

[0038]

[0039] In the formula, a A represents the azimuthal acceleration, a E represents the pitch angular acceleration, ω A represents the azimuth velocity, ω E represents the pitch angular velocity, E represents the pitch angle, R represents the distance, v represents the target horizontal flight speed, and K represents the coefficient (generally K=0.866). The target horizontal flight speed v can be calculated by the following formula:

[0040] v=ω A0 R0cos E0

[0041] Among them, ω A0 , R0, and E0 respectively represent the azimuth velocity, radial distance, and elevation angle during the mission tracking performance table.

[0042] Considering the accuracy of servo bandwidth switching and the simplicity of engineering implementation, it is recommended to use criterion 1, criterion 2, and criterion 3 as the criterion for switching the bandwidth of the radar servo system. In addition, criterion 2 is derived based on the target flying at a constant speed and in a straight line, which will produce a large deviation at low elevation angles. In order to overcome this effect, when E < 3° is calculated in the acceleration criterion, E = 3°.

[0043] Step 4: Adaptive servo bandwidth switching process

[0044] The adaptive servo bandwidth switching process is as follows: Figure 4 shown.

[0045] Step 1: Initialization

[0046] (1) Setting the azimuth / elevation servo gear: Assume that the azimuth bandwidth of a radar servo system is divided into 5 gears, such as K a The value is 1.5s -2 , 2.5s -2 、5s -2 , 7.5s -2 , 10s -2 , corresponding to gear positions N are 1, 2, 3, 4, and 5 respectively; the pitch bandwidth is divided into 6 gears, such as K a The value is 1.5s -2 , 2.5s -2 、5s -2 , 7.5s -2 , 10s -2 , 15s -2 , corresponding to gear positions M are 1, 2, 3, 4, 5, and 6 respectively.

[0047] (2) Set the angular acceleration thresholds for the cross section and pitch, such as a A =[0.06,0.15,0.30,0.45], a E =[0.06,0.15,0.30,0.45,0.60].

[0048] (3) Initialize the radar servo tracking gear N=1, M=1; initialize the pitch comparison values ​​EtA=0, EtE=0 for azimuth and pitch bandwidth switching.

[0049] Step 2: Receive data from the central computer of the station

[0050] (1) Determine whether the servo system is in the tracking state. If "yes", go to step (2); if "no", capture the target.

[0051] (2) Determine whether the digital indexing data is received. If "yes", go to step (3); if "no", switch to the manual bandwidth switching mode.

[0052] (3) Calculate the acceleration criteria for the azimuth cross-section and elevation based on the received data from the station central computer. The preferred order of the criteria is: criterion 1 → criterion 2 → criterion 3.

[0053] Step 3: Select the servo bandwidth gear according to the angular acceleration value

[0054] If the radar servo is in the tracking state:

[0055] 1) Determine the acceleration gear (taking the azimuth branch as an example, the elevation branch is similar)

[0056] If a AS ≤ a1 or E < 7°, select servo gear #1, n = 1; if a1 ≤ a AS < a2, select servo gear #2, n = 2; if a2 ≤ a AS < a3, select servo gear #3, n = 3; if a3 ≤ a AS < a4, select servo gear #4, n = 4; if a AS ≥ a5, select servo gear #5, n = 5.

[0057] 2) Determine the timing of bandwidth switching

[0058] If n = N, do not perform bandwidth switching; if n > N and E > EtA, perform bandwidth switching and set the current E value to EtA and the n value to N; if n < N and E < EtA, perform bandwidth switching and set the current E value to EtA and the n value to N; otherwise, do not perform bandwidth switching and repeat step two until the tracking ends.

[0059] Compared with the prior art, the advantages of the present invention are as follows:

[0060] The present invention first uses the type II radar servo system, divides it according to the K a value, determines the controller parameters of the self-tracking loop using the maximum phase margin criterion, tunes out 5 - 6 groups of servo bandwidths, and judges its stability using the phase margin. Secondly, it introduces the construction of the criteria and the switching process for the radar servo adaptive bandwidth switching. Finally, through simulation analysis and test verification, it shows that this method has strong adaptability, a smooth bandwidth switching process, and simple engineering implementation, fully meeting the needs of equipment development and test mission execution, and is the best choice for completing high-dynamic tasks similar to the CE-5 return segment. Description of the Drawings

[0061] Figure 1 Block diagram of the transfer function model of the radar servo system self-tracking loop.

[0062] Figure 2 Schematic diagram of the azimuth and cross-section.

[0063] Figure 3 Tracking geometric relationships of targets flying at constant speed and at equal altitudes.

[0064] Figure 4 Radar servo bandwidth adaptive switching flow chart.

[0065] Figure 5 Angular acceleration data of criterion 1 and the timing of bandwidth switching.

[0066] Figure 6 Angular acceleration data of criterion 2 and the timing of bandwidth switching.

[0067] Figure 7 Angular acceleration data of criterion 3 and the timing of bandwidth switching.

[0068] Figure 8 Dynamic hysteresis curve of a radar when adaptive servo bandwidth is switched.

[0069] Fig. 9 Criterion 3 and bandwidth switching time diagram. DETAILED DESCRIPTION

[0070] The present invention is further described in detail below with reference to the accompanying drawings.

[0071] The embodiment of the present invention includes: an example is given of a radar servo system adaptive variable bandwidth tracking implementation method, the method comprising the following steps:

[0072] Step 1: Parameter Setting

[0073] Taking a radar servo system as an example, the parameters of the self-tracking loop PI regulator are adjusted. When designing the self-tracking loop, the angular velocity loop is approximated as an inertial link, and the closed-loop gain of the angular velocity loop K is v =1200° / V, equivalent time constant T v ≈0.08s, the quantitative sensitivity of the tracking receiver is K s =0.5V / mil, azimuth transmission ratio N A =406, pitch transmission ratio N E =659.

[0074] Position according to K a The value is divided into 5 groups of servo gears, K a The values ​​are 1.5s -2 , 2.5s -2 , 5.0s-2 , 7.5s -2 , 10s -2 , pitch according to K a The value is divided into 6 groups of servo gears, K a The values ​​are 1.5s -2 , 2.5s -2 , 5.0s -2 , 7.5s -2 , 10s -2 , 15s -2 , use the phase margin maximum adjustment method to determine the corresponding PI regulator parameter proportional gain K p and the integration time constant T p , and calculate the corresponding characteristic parameters, as listed in Table 1 and Table 2, where ω c is the open-loop cut-off frequency, γ(ω c ) is the phase margin, ω b (rad / s) and B n (Hz) is the servo bandwidth.

[0075] Table 1 Expected characteristic parameters of a radar servo system (azimuth)

[0076] Serial number <![CDATA[K a (s -2 )]]> <![CDATA[K p ]]> <![CDATA[T p (s)]]> <![CDATA[ω c (rad / s)]]> <![CDATA[γ(ω c )(°)]]> <![CDATA[ω b (rad / s)]]> <![CDATA[B n (Hz)]]> 1 1.5 0.108 1.771 2.657 66.003 3.897 0.620 2 2.5 0.128 1.260 3.150 61.714 4.847 0.771 3 5.0 0.161 0.794 3.969 54.773 6.457 1.028 4 7.5 0.184 0.606 4.543 50.055 7.567 1.204 5 10 0.203 0.500 5.000 46.397 8.423 1.341

[0077] Table 2 Expected characteristic parameters (pitch) of a radar servo system

[0078] Serial number <![CDATA[K a (s -2 )]]> <![CDATA[K p ]]> <![CDATA[T p (s)]]> <![CDATA[ω c (rad / s)]]> <![CDATA[γ(ω c )(°)]]> <![CDATA[ω b (rad / s)]]> <![CDATA[B n (Hz)]]> 1 1.5 0.175 1.771 2.657 66.003 3.897 0.620 2 2.5 0.208 1.260 3.150 61.714 4.847 0.771 3 5.0 0.262 0.794 3.969 54.773 6.457 1.028 4 7.5 0.299 0.606 4.543 50.055 7.567 1.204 5 10 0.329 0.500 5.000 46.397 8.423 1.341 6 15 0.377 0.382 5.724 40.795 9.722 1.547

[0079] Step 2: Simulation Analysis

[0080] When conducting simulation analysis, the numerical data in a certain task is used to analyze the data stability of criteria 1, 2, and 3. The target flight trajectory has an elevation angle of 43° and a maximum angular acceleration of 0.266° / s 2 The maximum angular acceleration of the cross section is 0.168° / s 2 , the maximum angular acceleration of pitch is 0.205° / s 2 , through calculation, we can get the horizontal flight speed to be 6872m / s, such as Figure 5 to Figure 7 The angular acceleration thresholds used in the simulation are [0.03, 0.15, 0.30, 0.45, 0.60].

[0081] Step 3: Test and Verify

[0082] During the dynamic tracking test, the target flight trajectory had an elevation angle of 75° and a maximum angular acceleration of 4.26° / s. 2 The maximum angular acceleration of the azimuth cross section is 0.701° / s 2, the maximum angular acceleration of pitch is 1.634° / s 2 .

[0083] In the test verification, criterion 3 was used as the criterion for switching the azimuth and pitch servo bandwidths. The advantage is that these two functions are monotonically increasing and decreasing before and after Hangjie, and the switching control is relatively simple. The disadvantage is that the servo bandwidth switching is not precise enough, and there is a certain difference in value from the actual angular acceleration, which will result in the advance or lag of the servo bandwidth switching. Figure 8 The radar uses a target simulator to track the dynamic hysteresis curve of the above trajectory. Fig. 9 It is a schematic diagram of criterion 3 and bandwidth switching time.

[0084] In the adaptive servo bandwidth switching test, the bandwidth was switched 8 times in azimuth (4 times before and after Hangjie), and 10 times in pitch (5 times before and after Hangjie). The maximum dynamic hysteresis when pitching through Hangjie was 1.8mil, which was consistent with the theoretical analysis (1.82mil); the maximum dynamic hysteresis in azimuth was about 1.2mil, which was also consistent with the theoretical analysis (1.17mil).

[0085] In addition to the above embodiments, the present invention also includes other implementation modes. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the protection scope of the claims of the present invention.

Claims

1. A radar servo system adaptive variable bandwidth tracking implementation method, characterized in that: Servo bandwidth is calculated according to K a The method is divided into two parts, and the position loop servo parameters are adjusted by the maximum phase margin adjustment method, and 5 to 6 groups of servo bandwidths are debugged. The phase margin is used to judge their stability, and then the criterion for radar servo adaptive bandwidth switching is constructed, and the switching process is optimized to ensure that the front and rear servo bandwidth switching of Hangjie increases or decreases monotonically. The method includes the following steps: Step 1: Modeling of Radar Servo System Set the open-loop and closed-loop transfer functions as follows: in, is the open-loop gain of the system, K s To track the directional sensitivity of the receiver, K p is the proportional gain of the self-tracking loop PI regulator, T p K is the integral time constant of the self-tracking loop PI regulator, v is the closed-loop gain of the angular velocity loop, T v is the equivalent time constant of the angular velocity loop, N is the reduction ratio, and the definition of the intermediate frequency width h is given: h=ω2 / ω1=T p / T v Where ω1 represents the first turning frequency, ω1=1 / T p , ω2 represents the second turning frequency, ω2=1 / T v ; Step 2: Tuning of Position Loop Servo Parameters of Radar Servo System Known K s , K v 、T v , N, predetermine K a Value, according to K a The servo gears are divided into different positions from small to large, and then h and K are calculated using the maximum phase margin criterion. p and T p Then, analyze its stability based on the phase margin, and finally calculate the K based on its closed-loop transfer function. a The servo bandwidth corresponding to the value; Step 3: Construction of Criterion for Radar Servo Bandwidth Switching Use the angular accelerations of the azimuth cross-section and elevation as the criterion for adaptive bandwidth switching. According to the different types of data sources available, the servo bandwidth is switched according to three criteria. Among them, Criterion 1 directly calculates the angular acceleration values of the cross-section and elevation based on the real-time data index provided by the central computer. Criteria 2 and 3 calculate the angular acceleration values or envelope values of the cross-section and elevation based on the orbit of uniform flight along the contour line; Step 4: Establishment of Adaptive Servo Bandwidth Switching Process First Step: Initialization (1) Set the azimuth / elevation servo gear positions. The azimuth servo gear position is set to N, and the elevation servo gear position is set to M; (2) Set the angular acceleration thresholds for the cross section and pitch. The cross section angular acceleration threshold is a AS , the pitch angle acceleration threshold is a ES ; (3) Initialize the radar servo tracking gear positions N = 1, M = 1; Initialize the elevation comparison values EtA = 0 and EtE = 0 for azimuth and elevation bandwidth switching; Second Step: Receive the data index from the central computer of the station (1) Determine whether the servo system is in the tracking state. If "yes", go to step (2); if "no", capture the target; (2) Determine whether the data index has been received. If "yes", go to step (3); if "no", switch to the manual bandwidth switching mode; (3) Calculate the acceleration criteria for the azimuth cross-section and elevation based on the received data from the central computer of the station. The order of the criteria is: Criterion 1 → Criterion 2 → Criterion 3; Third Step: Select the servo bandwidth gear according to the angular acceleration value If the radar servo is in the tracking state: 1) Determine the acceleration gear position 2) Determine the timing of bandwidth switching If n = N, no bandwidth switching is performed; if n > N and E > EtA, bandwidth switching is performed, and the current E value is placed into EtA, and the n value is placed into N; if n < N and E < EtA, bandwidth switching is performed, and the current E value is placed into EtA, and the n value is placed into N; otherwise, no bandwidth switching is performed, and repeat step two until the tracking ends.

2. The radar servo system adaptive variable bandwidth tracking implementation method according to claim 1, characterized in that: The tuning of the position loop servo parameters in the above step 2 specifically includes: (1) Determine the required set of K a value; (2) Determine the intermediate frequency width h based on the maximum phase margin criterion (3) Determine K based on the intermediate frequency width h p 、T p : T p =hT v (4) Analyze the system stability based on the phase margin, and the phase margin γ(ω c ) is greater than 40°, (5) Calculate a certain K based on the amplitude-frequency characteristics of the closed-loop system a The servo bandwidth corresponding to the value; (6) Convergence characteristic test and use of the target simulator to test and verify the tracking performance.

3. The radar servo system adaptive variable bandwidth tracking implementation method according to claim 1, characterized in that: The three judgment bases in the above step 3 are respectively: Criterion 1: Cross-section acceleration, elevation acceleration When the data contains a A 、a E ,ω A ,ω E , E time Criterion 2: Cross-section acceleration, elevation acceleration When the data contains ω A ,ω E , E time Criterion 3: Cross-section acceleration envelope, elevation acceleration envelope When the data index contains v, E, R In the formula, a A represents the azimuthal acceleration, a E represents the pitch angular acceleration, ω A represents the azimuth velocity, ω E represents the pitch angular velocity, E represents the pitch angle, R represents the distance, v represents the target horizontal flight speed, K represents the coefficient, and K=0.866 is taken. The target horizontal flight speed v can be calculated by the following formula: v=ω A0 R0cosE0 Among them, ω A0 , R0, and E0 respectively represent the azimuth velocity, radial distance, and elevation angle during the mission tracking performance table.

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