A design method of antenna servo system controller based on PI+notch filter

Abstract

The application discloses a kind of PI+ wave trap based antenna servo system controller design method, belong to antenna servo system control technical field.The application utilizes pseudo-random sequence as model identification signal in the controller design process of antenna servo line system, obtains the frequency domain model of antenna servo system, and designs the band-stop wave trap corresponding to resonance peak based on the frequency domain model, for inhibiting the high-frequency resonance of system, can effectively improve control system gain.The application can accurately obtain the analytical model of antenna servo system, and utilize band-stop wave trap to inhibit the high-frequency resonance characteristics of system, greatly improve the dynamic control performance of antenna servo system.

Description

Technical Field

[0001] This invention relates to the field of antenna servo systems, and in particular to a design method for an antenna servo system controller based on a PI+notch filter. Background Technology

[0002] As the primary control system for antenna operation, the performance of the antenna's servo system largely determines the antenna's tracking accuracy and overall performance. With the development of communication technology, higher demands are being placed on the servo performance of antennas. To improve the dynamic performance of antenna servo systems, various high-performance controller design methods are being applied in practical engineering applications. To design a high-performance controller, we first need to obtain the analytical model of the antenna servo system, then analyze the amplitude-frequency and box-frequency characteristics of the analytical model, and design a corresponding controller to adjust the servo system characteristics, thereby optimizing the servo system's control performance.

[0003] System identification methods are based on certain prior knowledge and select specific input signals to excite the target system according to the operating characteristics of the object being identified. By analyzing the potential relationships between the system's input and output data, an accurate mathematical model of the target system is ultimately established. Pseudo-random signals are a type of identification signal widely used in system modeling. Their spectrum is uniformly distributed in the frequency domain. By utilizing the system's pseudo-random response, the system's unit impulse response can be obtained, thereby completing accurate modeling. This method can be used for model identification of various servo systems.

[0004] Antenna mounts are typically not very rigid due to limitations in the main structure, and the flexibility of the antenna reflector and transmission chain also increases. This leads to high-frequency resonance characteristics in the antenna servo system, which severely reduces the system's stability margin, exacerbates system oscillations, and can even cause instability. In such cases, the dynamic response speed of the antenna servo system must be sacrificed to suppress high-frequency resonance, thus significantly limiting the control performance of classic PI controllers. Summary of the Invention

[0005] In view of the operating characteristics of antenna servo systems, this invention provides a design method for an antenna servo system controller based on a PI+notch filter. This method can accurately obtain the analytical model of the antenna servo system and use a band-stop notch filter to suppress the high-frequency resonance characteristics of the system, thereby significantly improving the dynamic control performance of the antenna servo system.

[0006] The technical solution adopted in this invention is as follows: A design method for an antenna servo system controller based on a PI+notch filter includes the following steps: Step 1: Based on the structural characteristics and servo parameters of the antenna servo system speed loop, select the parameters of the pseudo-random signal sequence, including clock period, signal amplitude, signal bit depth and repetition period, to generate the model identification signal sequence of the antenna servo system speed loop; Step 2: Use the model identification signal sequence as the input signal of the antenna servo system velocity loop, record the output signal of the antenna servo system velocity loop, and perform correlation processing based on the input and output signals to obtain the system's impulse response sequence. Construct the system's Hankel matrix based on the impulse response sequence and decompose it to obtain the system's velocity loop analytical model. Step 3: Based on the velocity loop analytical model obtained in Step 2, design a band-stop notch filter with a notch center angular frequency, notch bandwidth, and notch depth that correspond to the frequency center point, amplitude gain, and overall bandwidth characteristics of its first-order resonant peak. Step 4: Design a PI controller for the velocity loop analytical model, and connect the PI controller in series with a band-stop notch filter to obtain the antenna servo system controller.

[0007] Furthermore, the specific process of step 2 is as follows: The model identification signal sequence is used as the input signal of the antenna servo system velocity loop. The output signal of the antenna servo system velocity loop is recorded. Based on the input and output signals, the autocorrelation function and cross-correlation function are calculated to obtain the system impulse response sequence. Based on the impulse response sequence, a Hankel matrix is ​​constructed, and matrix decomposition is performed on the Hankel matrix to obtain the coefficient matrix of the system state space equation. The singular values ​​of each mode of the system state space equation are calculated. The order of the system state space equation is reduced according to the magnitude of the singular values ​​to obtain the analytical model of the antenna servo system velocity loop in the frequency domain.

[0008] The beneficial effects of this invention are: 1. This invention uses pseudo-random signal sequences for model identification and utilizes the Hankel matrix and system singular values ​​to obtain the velocity loop analytical model, which can ensure the accuracy of the identified model.

[0009] 2. This invention designs a band-stop notch filter whose cardioid frequency, notch bandwidth, and notch depth can all be adjusted independently. This band-stop notch filter is applicable to various antenna servo systems and effectively suppresses the high-frequency resonance characteristics of the system.

[0010] 3. This invention connects a classic PI controller and a band-stop notch filter in series to form an antenna servo system controller, which can effectively improve the gain of the PI controller and enhance the dynamic servo response performance of the antenna servo system. Attached Figure Description

[0011] Figure 1 This is a diagram illustrating the pseudo-random identification signal of the present invention.

[0012] Figure 2 This is a diagram of an antenna velocity loop model obtained by model identification in this invention.

[0013] Figure 3 This is a diagram of a band-stop filter designed for a certain antenna velocity loop model according to the present invention.

[0014] Figure 4 This is a schematic diagram of the controller for a certain antenna velocity loop model based on a PI+ notch filter according to the present invention.

[0015] Figure 5 This is a comparison of the control effects of a certain antenna of the present invention. Detailed Implementation

[0016] The present invention will now be further described with reference to the accompanying drawings and corresponding embodiments.

[0017] This invention provides a design method for an antenna servo system controller based on a PI+notch filter. The specific steps of this invention are as follows: Step 1: Based on the structural characteristics and servo parameters of the antenna servo system speed loop, select parameters such as clock period, signal amplitude, signal bit depth, and repetition period of the pseudo-random signal sequence to generate the model identification signal sequence of the antenna servo system speed loop.

[0018] Step 2: Use the model identification signal sequence as the input signal of the antenna servo system velocity loop, record the output signal of the antenna servo system velocity loop, and perform correlation processing based on the input and output signals to obtain the system's impulse response sequence. Construct the system's Hankel matrix based on the impulse response sequence and decompose it to obtain the analytical model of the system's velocity loop.

[0019] Step 3: Based on the obtained velocity loop analytical model, and considering the characteristics of its first-order resonant peak, such as the frequency center point, amplitude gain, and overall bandwidth, design a band-stop notch filter whose center angular frequency, bandwidth, and depth all correspond to the notch filter.

[0020] Step 4: Design a PI controller based on the velocity loop analytical model, and connect the PI controller in series with a band-stop notch filter to obtain the antenna servo system controller. A high-performance PLC can be used as the antenna servo controller.

[0021] This method uses pseudo-random signal sequences for model identification, obtains the velocity loop analytical model using the Hankel matrix and system singular values, and designs a band-stop notch filter whose center angular frequency, bandwidth, and depth can be adjusted independently to effectively suppress the high-frequency resonance characteristics of the system. The classic PI controller and the band-stop notch filter are connected in series to form a servo controller, which can effectively improve the dynamic servo response performance of the antenna servo system.

[0022] Here is a more specific example: A design method for an antenna servo system controller based on a PI filter and a notch filter, the specific steps of which are as follows: Step 1: Design of signal sequence for model identification.

[0023] The main parameters for model-identified signal sequences include clock period, signal bit depth, signal amplitude, and repetition period. These parameters are estimated primarily through extensive engineering experiments and adjustments. Empirical values ​​for some of the main parameters are given below.

[0024] The clock period is the minimum level change interval of the signal. Based on engineering testing experience, the clock frequency is usually selected as 10 to 20 times the estimated cutoff frequency of the system, and can be adjusted according to the actual test results.

[0025] The number of signal bits determines the power spectral line intensity and spacing of the pseudo-random signal. Based on engineering testing experience, if the system settling time is... Then the number of signal bits The possible values ​​are as follows: Adjustments can be made based on actual test results, among which Sampling time.

[0026] The signal amplitude determines the intensity of the power spectrum lines of the signal to be identified. Based on engineering testing experience, it is usually taken as 5% to 10% of the maximum value of the input signal of the antenna servo system, which can be adjusted according to the actual test results.

[0027] The repetition period represents the number of times the model identifies the signal sequence as being repeatedly and continuously input into the antenna servo system. Based on engineering testing experience, it is usually taken as an integer between 1 and 3, and can be adjusted according to the actual test results.

[0028] Step 2: Obtain the velocity loop analytical model.

[0029] First, the designed model identification signal sequence is used as the excitation signal, directly serving as the reference signal for the antenna servo system's velocity loop. This input signal is then fed into the antenna servo system's velocity loop, and the output is the actual rotational speed of the antenna. For a specific antenna servo system, the input and output signals of the model identification are as follows: Figure 1 As shown; Then, by performing correlation processing on the model-identified signal sequence, the impulse response sequence of the system is obtained. Based on this sequence, a Hankel matrix is ​​constructed. After matrix decomposition of the obtained Hankel matrix, the coefficient matrix of the system state-space equation can be obtained. Finally, the singular values ​​of each mode in the system's state-space equation are calculated. Based on the magnitude of the singular values, the order of the system's state-space equation is reduced, thus obtaining the analytical velocity loop model of the antenna servo system in the frequency domain. For a specific antenna servo system, the obtained analytical velocity loop model is as follows: Figure 2As shown; Based on engineering testing experience, the order of the servo system speed loop analytical model is usually set to 3-6, which can be adjusted according to the actual test and control effect.

[0030] Step 3: Design the parameters of the band-stop notch filter.

[0031] Analyzing the velocity loop analytical model obtained in the second step reveals that the frequency of the first-order resonant peak is around 1.5Hz, the gain at the resonant peak is around 16dB, and the width of the resonant peak is around 0.3Hz. This first-order resonant peak has a significant impact on the antenna servo performance and will limit the gain of the controller.

[0032] The transfer function of the band-stop notch filter is shown below:

[0033] In the above formula, The center angular frequency of the notch filter; This refers to the notch bandwidth of the notch filter; The notch depth of the notch filter. This is the transfer function operator for a band-stop notch filter.

[0034] against Figure 2 Bandstop notch filters designed with the first-order resonance peak, such as Figure 3 As shown.

[0035] Step 4: Design a PI controller and connect it in series with a band-stop notch filter.

[0036] Considering the control characteristics of the antenna servo system, the system's response speed and anti-interference performance can be improved by appropriately adjusting the proportional and integral coefficients of the PI controller. In discrete systems, PI The general form of a controller is as follows:

[0037] In the above formula, This is the proportionality coefficient; The integral time constant; For system sampling time, for PI Controller transfer function operator.

[0038] Among them, with the proportionality coefficient As the integral time constant increases, in the frequency domain, the system's open-loop gain increases, the cutoff frequency increases, and the gain margin decreases; in the time domain, the system's response to a step signal has a faster rise time and an increased overshoot. As the frequency decreases, the low-frequency band in the system shifts upward, the cutoff frequency increases, the dynamic performance of the system improves, and the step response begins to overshoot, reducing the system's stability margin.

[0039] Therefore, the PI controller parameters can be designed according to the actual antenna servo system, and then the band-stop notch filter designed in step three can be connected in series with the PI controller to obtain a satisfactory control effect. For Figure 2 The analytical model of the medium-speed loop, the design of the PI controller and the notch filter with stop, such as Figure 4 As shown, the corresponding control effects are as follows: Figure 5 As shown.

[0040] In summary, this invention fully considers the operating characteristics of the antenna servo system. Using a pseudo-random signal as the input signal, a band-stop notch filter with individually adjustable cardioid frequency, notch bandwidth, and notch depth is designed and connected in series with a classic PI controller to form a servo controller, thereby improving the dynamic servo response performance of the antenna servo system.

Claims

1. A design method for an antenna servo system controller based on a PI+notch filter, characterized in that, Includes the following steps: Step 1: Based on the structural characteristics and servo parameters of the antenna servo system speed loop, select the parameters of the pseudo-random signal sequence, including clock period, signal amplitude, signal bit depth and repetition period, to generate the model identification signal sequence of the antenna servo system speed loop; Step 2: Use the model identification signal sequence as the input signal of the antenna servo system velocity loop, record the output signal of the antenna servo system velocity loop, and perform correlation processing based on the input and output signals to obtain the system's impulse response sequence. Construct the system's Hankel matrix based on the impulse response sequence and decompose it to obtain the system's velocity loop analytical model. Step 3: Based on the velocity loop analytical model obtained in Step 2, design a band-stop notch filter with a notch center angular frequency, notch bandwidth, and notch depth that correspond to the frequency center point, amplitude gain, and overall bandwidth characteristics of its first-order resonant peak. Step 4: Design a PI controller for the velocity loop analytical model, and connect the PI controller in series with a band-stop notch filter to obtain the antenna servo system controller.

2. The design method for an antenna servo system controller based on a PI+notch filter according to claim 1, characterized in that, Step 2 is as follows: The model identification signal sequence is used as the input signal of the antenna servo system velocity loop. The output signal of the antenna servo system velocity loop is recorded. Based on the input and output signals, the autocorrelation function and cross-correlation function are calculated to obtain the system impulse response sequence. Based on the impulse response sequence, a Hankel matrix is ​​constructed, and matrix decomposition is performed on the Hankel matrix to obtain the coefficient matrix of the system state space equation. The singular values ​​of each mode of the system state space equation are calculated. The order of the system state space equation is reduced according to the magnitude of the singular values ​​to obtain the analytical model of the antenna servo system velocity loop in the frequency domain.

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