CN110231845B - Control method and composite control system for seeker stabilization platform - Google Patents

Abstract

The invention discloses a control method and a composite control system for a seeker stabilizing platform. The control method adopts three-loop control for the seeker stabilizing platform, namely a current loop, a speed loop and a position loop; It is realized by the PWM power drive chip of the brushed motor. The speed loop is realized by a composite control strategy. The composite control strategy includes a Butterworth filter, a disturbance observer, a notch filter, and an incomplete differential PID; the position loop adopts Small integral PI or proportional controller to achieve. The composite control system of the seeker stabilization platform of the present invention adopts the above-mentioned control method for the seeker stabilization platform to realize the control of the seeker stabilization platform. The control method of the present invention can effectively improve the noise immunity and rapidity of the system, and is easy to implement. In addition, the composite control system of the seeker stabilizing platform has the advantages of simple structure and easy implementation.

Description

A kind of control method and composite control system of seeker stabilizing platform

technical field

The invention relates to the field of automatic control, in particular to a control method and a composite control system for a seeker stabilizing platform.

Background technique

With the increasing demand of the current guidance system for precise strike targets, higher requirements are also put forward for the performance of the seeker photoelectric stabilization platform. The seeker system is a device that integrates optical, mechanical and electrical technologies. Usually consists of indexer and electronic components. The positioner is located at the front end of the seeker, and is composed of an optoelectronic stabilization platform and a detection system. It is the core component to realize target detection, optical axis stabilization, follow-up and tracking of the guidance system. The main function of the photoelectric stabilization platform is to use the space stabilization function of the inertial sensor to isolate the disturbance of the missile and stabilize the optical axis of the photoelectric detector. The ability of the stable platform to isolate disturbances depends on the control accuracy of the platform servo system, and the maneuverability of the stable platform depends on the rapidity of the platform servo system.

At present, the commonly used method in seeker stabilization platform is PID control. This method is simple and effective in design, but when faced with disturbances in complex environments, the anti-disturbance capability of PID is limited. In order to meet the increasingly advanced tactical technical indicators, it is necessary to design corresponding controllers to improve the rapidity and anti-disturbance of the system. .

Therefore, it is necessary to design a control method and a composite control system for the stabilizer platform of the seeker, which have the advantages of simple structure, easy implementation, rapidity and noise immunity.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, and to provide a control method for the seeker stabilizing platform, which adopts effective three-loop control of current loop, speed loop and position loop for the seeker stabilizing platform. , in order to solve the problem of limited anti-interference ability of PID in the prior art.

The technical scheme of the present invention is: a control method for a seeker stabilizing platform, the control method adopts three-loop control for the seeker stabilizing platform, and the three loops are: a current loop, a speed loop and a position loop; the current loop The loop is realized by using a brushed motor PWM power drive chip, the speed loop is realized by a composite control strategy, which includes a Butterworth filter, disturbance observer, notch filter, incomplete differential PID, the position The loop adopts small integral PI or proportional controller; the speed loop and position loop are controlled by the following steps:

The first step is to use the Butterworth filter to filter the gyroscope;

The second step is to identify the open-loop system;

The third step is to design the interference observer;

The fourth step is to test the system frequency characteristics after adding the interference observer;

The fifth step is to design the notch filter; according to the result of the frequency characteristic test of the system in the fourth step, the notch filter is designed;

The sixth step is to test the system frequency characteristics after adding the notch filter;

The seventh step is to design an incomplete differential PID controller; the frequency characteristic curve obtained in the sixth step is analyzed, and an incomplete differential PID controller is designed according to the analysis results;

The eighth step is to test the frequency characteristics of the speed closed-loop system after adding the incomplete differential PID controller;

The ninth step, design a position loop controller; the position loop adopts a small integral PI controller or a proportional controller, and adjusts the controller parameters to obtain a system that meets the performance index.

Further, in the first step, the Butterworth filter is designed according to the steady-state error index of the speed output of the stabilized platform of the seeker, and the Butterworth filter adopts a second-order Butterworth The filtering is analyzed and the final cutoff frequency is determined.

Further, in the second step, the filtered open-loop system is identified, the frequency sweep method or random noise method is used to obtain the input and output data of the system, and the input and output data are processed to obtain the frequency characteristic curve of the system. The first-order linear transfer function model is used to identify the system by the least square method, and the open-loop system model is obtained.

Further, in the third step, designing the interference observer is realized by the following steps:

Step 1, comprehensively consider noise and immunity, and obtain a low-pass filter in the interference observer that meets the requirements through repeated debugging;

Step 2, secondly, obtain the nominal model of the system according to the open-loop system model identified in the second step;

Step 3: Combine the nominal model of the system to finally obtain a disturbance observer that meets the requirements.

Further, in the described 4th step, 6th step and 8th step, the system after adding the observer, the system after adding the notch filter and the closed-loop system of the speed after adding the incomplete differential PID controller respectively carry out the frequency characteristic test. , adopt frequency sweep method or random noise method to obtain input and output data, and process the input and output data to obtain the frequency characteristic curve of the system.

Further, in the fifth step, referring to the system mechanical resonance suppression method, a wave trap is designed to suppress the convex hull region introduced by the system frequency characteristic after adding the interference observer.

Further, the specific parameters of the wave notch filter determine the center frequency according to the highest point of the convex hull region.

Further, the current loop is realized by hardware, and the coefficient is configured according to the characteristics of the hardware chip to realize the current closed loop.

The present invention also provides a composite control system for a seeker stabilizing platform. The above-mentioned control method for a seeker stabilizing platform realizes the control of the seeker stabilizing platform. The seeker stabilizing platform adopts a pitch and yaw double frame. Structure; a detection system, a gyroscope and an angle sensor are installed on the stabilizer platform of the seeker.

Further, the detection system is installed on the seeker stable platform as a load, and the gyroscope is installed on the seeker stable platform to measure the angular velocity of the pitch and yaw, and the angle sensor is respectively installed on the pitch and yaw axis to measure the angle. displacement.

Beneficial effects of the present invention: The present invention provides a control method for a seeker stabilizing platform, which adopts effective three-loop control of a current loop, a speed loop and a position loop for the seeker stabilizing platform, which can effectively improve the system's performance. Noise immunity and speed, and easy to implement. In addition, a composite control system of a seeker stabilizing platform is also provided, which has the advantages of simple structure and easy realization.

Description of drawings

1 is a schematic diagram of a semi-active laser seeker system according to an embodiment of the present invention;

Fig. 2 is the controller block diagram of Embodiment 1 of the present invention;

Fig. 3 is the controller block diagram of Embodiment 2 of the present invention;

4 is a flowchart of a control method according to an embodiment of the present invention;

Fig. 5 is the Butterworth filtering comparison of the embodiment of the present invention;

6 is an open-loop system identification curve according to an embodiment of the present invention;

7 is an equivalent transformation of an interference observer according to an embodiment of the present invention;

8 is a system frequency characteristic after adding an interference observer according to an embodiment of the present invention;

9 is a system frequency characteristic after adding a notch filter according to an embodiment of the present invention;

Fig. 10 is the speed loop step response of the embodiment of the present invention;

Fig. 11 is the speed closed-loop frequency characteristic of the embodiment of the present invention;

12 is a position closed-loop step response of an embodiment of the present invention;

13 is a composition diagram of an isolation test platform according to an embodiment of the present invention;

FIG. 14 is an isolation test output according to an embodiment of the present invention.

In the figure, 10—optical system, 20—laser detector, 30—stabilized platform, 40—yaw motor, 50—angle sensor, 60—gyroscope, 70—speed loop, 80—incomplete integral PID controller, 90— Notch, 100-second-order Butterworth filter, 110-proportional controller, 120-potentiometer, 130-small integral PI controller.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

The schematic diagram of the semi-active laser seeker system is shown in FIG. 1 , which includes an optical system 10 , a laser detector 20 , a stable platform 30 , a yaw motor 40 , and the like. Among them, the performance of the pitch frame in the photoelectric stabilization platform 30 is verified by using the composite control system and control method proposed in this paper. The main indicators of the system are as follows: the maximum steady-state error of the system speed is less than 0.2°; the isolation degree of the system is less than or equal to 5% under the disturbance input of 7°1Hz; the bandwidth of the system speed loop 70 is not less than 15Hz.

The seeker stabilization platform 30 adopts a pitch and yaw double-frame structure, and a detection system, a gyro 60 and an angle sensor 50 are installed on the seeker stabilization platform 30 . The detection system is installed on the seeker stabilization platform 30 as a load, the gyro 60 is installed on the seeker stabilization platform 30 to measure the angular velocity of pitch and yaw, and the angle sensor 50 is respectively installed on the pitch and yaw axis to measure the angular displacement. . Specifically, the gyro 60 adopts a MEMS gyro 60, and the angle sensor 50 adopts a potentiometer.

Specifically, the system is divided into three loops for debugging, namely the current loop, the speed loop 70 and the position loop. Among them, the current loop adopts the brushed motor PWM power driver chip MSK4253 to realize the current closed loop, and the current loop adopts the hardware to realize the current closed loop. After the system is assembled and hardware connected, the driver chip is configured to achieve a current loop bandwidth of more than 1000Hz.

Specifically, the designed bandwidth of the current loop reaches 1300 Hz.

As shown in Figure 2, the velocity loop 70 adopts a compound control strategy, which includes a Butterworth filter, a disturbance observer, a notch filter 90, and an incomplete differential PID, and the position loop adopts a proportional controller 110 (black dotted line with arrows in the figure) part, which shows the unique tracking mode of the seeker. If it is in the command tracking mode, it uses the potentiometer output and the command difference to generate the control input of the position controller; if it is in the target tracking mode, it is through the laser detector 20 and data processing. The off-target amount obtained directly after is used as the input of the position controller. In fact, two modes are used here. In the ninth step below, the position step response is the command tracking mode, and the potentiometer feedback is used; during the isolation test Detector processing mode is used, no potentiometer feedback is used). After completing the assembly work and hardware connection work of the system, the control method of this embodiment is carried out according to the flow chart shown in FIG. Discrete method, sampling period, speed loop 70 is 1ms, position loop is 20ms).

The speed loop 70 and the position loop are implemented by the following steps:

The first step is to use the Butterworth filter to filter the gyro 60; design the Butterworth filter according to the steady-state error index of the speed output of the seeker stabilization platform 30, and use the second-order Butterworth filter 100 to filter the gyro 60. The filtering is analyzed and the final cutoff frequency is determined.

Specifically, a second-order Butterworth filter 100 is used, which is implemented by software. The Butterworth filter is as follows:

where ω _c is the cutoff frequency.

The cut-off frequency is selected as 100Hz, and the steady-state output of the system before and after filtering is finally obtained, as shown in Figure 5, which meets the requirement that the steady-state maximum error is less than 0.2°/s.

The second step is open-loop system identification; to identify the filtered open-loop system, the input and output data of the system can be obtained by the frequency sweep method or the random noise method, and the frequency characteristic curve of the system can be obtained by processing the input and output data. Based on the second-order linear transfer function model, the system is identified by the least square method, and the open-loop system model is obtained.

Specifically, using the random noise method, the system inputs random noise with an amplitude of 0.3°/s for 10s, collects the output value of the gyroscope 60 after passing through the filter, and processes the input and output to obtain the Bode plot of the system as shown in Figure 6 As shown in the curve (measured), the second-order linear system and the least squares method are used to identify the system. The identification curve is shown in the curve (fitting) in Figure 6. The obtained nominal model of the system is

The third step is to design the disturbance observer; the design of the disturbance observer is achieved through the following steps:

Step 1, comprehensively consider noise and immunity, and obtain a low-pass filter in the interference observer that meets the requirements through repeated debugging;

Step 2, secondly, obtain the nominal model of the system according to the open-loop system model identified in the second step;

Step 3: Combine the nominal model of the system to finally obtain a disturbance observer that meets the requirements.

Specifically, the basic idea of the interference observer proposed by C.J.Kempf et al. is adopted, and the equivalent block diagram of the interference observer is used to design the interference observer, as shown in Figure 6. The design of the low-pass filter in the interference observer adopts a second-order linear model:

Considering the ability to suppress disturbance and the sensitivity to noise, τ=0.005 in the low-pass filter is finally determined.

Since the disturbance observer can observe disturbances, but is sensitive to noise, it needs to be comprehensively considered in the design.

The fourth step is to test the frequency characteristics of the system after adding the interference observer; to test the frequency characteristics of the system after adding the observer, the input and output data can be obtained by the frequency sweep method or the random noise method, and the frequency of the system can be obtained by processing the input and output data. Characteristic curve, the analysis of the curve is used to design the notch filter 90.

Specifically, the model of the system has also changed after the interference observer is added. The random noise method is used to test the frequency characteristics of the system. The method follows the second step to obtain the frequency characteristic response curve of the system as shown in Figure 8. It can be seen that the system is in the There is a raised area near the frequency point of 211.7rad/s.

The fifth step is to design the notch filter 90; the fourth step is used to analyze the frequency characteristics of the system. It can be seen that due to the addition of the interference observer in the third step, the system frequency characteristic introduces a convex hull region, and the system needs to suppress this point, Referring to the system mechanical resonance suppression method, a wave trap 90 is designed to suppress this region, and the specific parameters of the wave trap 90 determine the center frequency according to the highest point of the convex hull region.

In order to reduce the influence of the raised area on the system in the third step, referring to the mechanical resonance suppression method, the method of the wave trap 90 is used to suppress the raised area. The notch filter 90 adopts the double-T network notch filter 90:

The center frequency point of the double-T network notch filter 90 is at ω _n =211.7rad/s, and A _vf =1.

The use of the notch filter 90 effectively suppresses the system convex hull introduced by the interference observer, reduces the system overshoot, and increases the system bandwidth.

The sixth step is to test the frequency characteristics of the system after adding the notch filter 90; to test the frequency characteristics of the system after adding the interference observer and the notch filter 90, the input and output data can be obtained by the sweep frequency method or the random noise method, and the input and output data can be obtained. The data is processed to obtain the frequency characteristic curve of the system, and the curve is analyzed to design the incomplete differential PID controller.

Specifically, the random noise method is used to test the frequency characteristics of the system. The method follows the second step, and the frequency characteristic response curve of the system is obtained as shown in Figure 9. It can be seen that after the notch filter 90 is added to the system near the frequency point of 211.7rad/s, the bulge of the system does not exist, which is better for system control.

The seventh step is to design an incomplete differential PID controller; analyze the frequency characteristic curve obtained in the sixth step, and design an incomplete differential PID controller according to the analysis results; in order to improve the rapidity of the system, it is necessary to increase the P value in the PID , but the P value increases, the overshoot of the system increases, and the differential can effectively reduce the overshoot of the system and improve the dynamic performance of the system, so the incomplete differential PID is added.

Specifically, in order to improve the bandwidth of the system, an incomplete differential PID controller is used. The transfer function of the incomplete differential PID controller is as follows:

The controller parameters are proportional coefficients of k _p =0.062, k _i =0.5, k _d =0.0002, and N=500, respectively. The step response of the system is shown in Figure 10, the rise time of the system is 24ms, and the overshoot is 3%, which meets the requirements.

The eighth step is to test the frequency characteristics of the speed closed-loop system after adding the incomplete differential PID controller; to test the frequency characteristics of the speed closed-loop system, the frequency sweep method or random noise method can be used to obtain the input and output data, and the input and output data can be processed to obtain the system. The frequency characteristic curve is analyzed, and the curve is used to evaluate the characteristics of the speed loop 70 of the system.

Specifically, the random noise method is used to test the frequency characteristics of the system. The method follows the second step, and the frequency characteristic response curve of the system is obtained as shown in Figure 11. It can be seen that the system bandwidth is 24Hz to meet the requirements.

The ninth step is to design a position loop controller; the position loop adopts a proportional controller 110, and adjusts the parameters of the controller to obtain a system that satisfies the performance index. Since the current loop and the speed loop 70 have been used, in order to avoid controlling two loops with cascaded parts, the proportional controller 110 can be used for the position loop to achieve system position loop stabilization.

ω_out＝1.1为俯仰轴陀螺60输出角速度，ω_b＝7×1×2π＝43.98弹体扰动角速度，角速度单位为°/s。给定幅值为7°频率为1Hz的弹体扰动时导引头输出角速度对比系统的隔离度输出如图13所示。隔离度为测试为2.5％，满足系统要求。Specifically, the position loop adopts the proportional controller 110, and the proportional coefficient is 6.3. The step output of the system is shown in Figure 12. It can be seen that the output overshoot of the position loop is small, and the steady-state error is less than 0.05°. In order to verify the noise immunity of the seeker, a performance test experiment of the seeker was carried out on a five-axis turntable. The principle block diagram of the seeker experimental device is shown in Figure 13. The seeker is installed on the three-axis turntable, and the target signal is generated by the laser simulator installed on the two-axis turntable. The three-axis simulation turntable applies disturbances of different amplitudes and frequencies to simulate the disturbance of the missile. Define the isolation degree to describe the immunity of the system, and the isolation degree J is defined as:

ω _out =1.1 is the output angular velocity of the pitch-axis gyro 60 , ω _b =7×1×2π=43.98 projectile disturbance angular velocity, and the unit of angular velocity is °/s. The isolation output of the seeker output angular velocity contrast system is shown in Figure 13 for a given projectile disturbance with an amplitude of 7° and a frequency of 1Hz. The isolation is tested to be 2.5%, which meets the system requirements.

Example 2

The schematic diagram of the semi-active laser seeker system is shown in FIG. 1 , which includes an optical system 10 , a laser detector 20 , a stable platform 30 , a yaw motor 40 , and the like. Among them, the performance of the pitch frame in the photoelectric stabilization platform 30 is verified by using the composite control system and control method proposed in this paper. The main indicators of the system are as follows: the maximum steady-state error of the system speed is less than 0.2°; the isolation degree of the system is less than or equal to 5% under the disturbance input of 7°1Hz; the bandwidth of the system speed loop 70 is not less than 15Hz.

The seeker stabilization platform 30 adopts a pitch and yaw double-frame structure, and a detection system, a gyro 60 and an angle sensor 50 are installed on the seeker stabilization platform 30 . The detection system is installed on the seeker stabilization platform 30 as a load, the gyro 60 is installed on the seeker stabilization platform 30 to measure the angular velocity of pitch and yaw, and the angle sensor 50 is respectively installed on the pitch and yaw axis to measure the angular displacement. . Specifically, the gyro 60 adopts a MEMS gyro 60, and the angle sensor 50 adopts a potentiometer.

Specifically, the system is divided into three loops for debugging, namely the current loop, the speed loop 70 and the position loop. Among them, the current loop adopts the brushed motor PWM power driver chip MSK4253 to realize the current closed loop, and the current loop adopts the hardware to realize the current closed loop. After the system is assembled and hardware connected, the driver chip is configured to achieve a current loop bandwidth of more than 1000Hz.

Specifically, the designed bandwidth of the current loop reaches 1300 Hz.

As shown in FIG. 3 , the velocity loop 70 adopts a composite control strategy, which includes a Butterworth filter, a disturbance observer, a notch filter 90, and an incomplete differential PID, and the position loop adopts a small-integral PI controller 130 (black dotted line in the figure). The part with arrows indicates the unique tracking mode of the seeker. If it is in the command tracking mode, the potentiometer output and the command difference are used to generate the control input of the position controller; if it is in the target tracking mode, it is through the laser detector 20 and The off-target amount directly obtained after data processing is used as the input of the position controller. In fact, two modes are used here. In the ninth step below, the position step response is the command tracking mode, and the potentiometer feedback is used; Detector processing mode is used for testing, no potentiometer feedback is used). After completing the assembly work and hardware connection work of the system, the control method of this embodiment is carried out according to the flow chart shown in FIG. Discrete method, sampling period, speed loop 70 is 1ms, position loop is 20ms).

The rest of the embodiment 2 is the same as that of the embodiment 1, and the difference from the embodiment 1 is: in the ninth step, the small integral PI controller 130 is used in the design of the position loop.

The ninth step, design the position loop controller; the position loop adopts the small integral PI controller 130, and adjusts the controller parameters to obtain a system that meets the performance index. Since the current loop and the speed loop 70 have been used, in order to avoid controlling two loops with cascaded parts, the position loop adopts the small integral PI controller 130 to realize the system position loop stabilization.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their technical equivalents, the present invention is also intended to include such modifications and variations.

Claims (10)

1. a control method for seeker stabilization platform, is characterized in that: described control method adopts three-loop control to seeker stabilization platform, and described three-loop is: current loop, speed loop and position loop; The loop is realized by using a brushed motor PWM power drive chip, and the speed loop is realized by a composite control strategy, which includes Butterworth filter, disturbance observer, notch filter, incomplete differential PID controller, so The above-mentioned position loop adopts a small integral PI controller or a proportional controller; the speed loop and the position loop adopt the following steps to realize control: The first step is to use the Butterworth filter to filter the gyroscope; The second step is to identify the open-loop system; The third step is to design the interference observer; The fourth step is to test the frequency characteristics of the speed open-loop system after adding the interference observer; The fifth step is to design a notch filter; the notch filter is designed according to the result of the frequency characteristic test of the open-loop system in the fourth step; The sixth step is to test the frequency characteristics of the speed open-loop system after adding the notch filter; The seventh step is to design an incomplete differential PID controller; the frequency characteristic curve obtained in the sixth step is analyzed, and an incomplete differential PID controller is designed according to the analysis results; The eighth step is to test the frequency characteristics of the speed closed-loop system after adding the incomplete differential PID controller; The ninth step, design a position loop controller; the position loop adopts a small integral PI controller or a proportional controller, and adjusts the controller parameters to obtain a system that meets the performance index. 2. the control method of seeker stabilization platform as claimed in claim 1 is characterized in that: in the described first step, Butterworth filter is to design according to the speed output steady-state error index of seeker stabilization platform Yes, the Butterworth filter uses a second-order Butterworth filter to analyze the gyro filter and determine the final cutoff frequency. 3. The control method of the seeker stabilization platform as claimed in claim 1, it is characterized in that: in the described second step, the open-loop system after filtering is identified, and the system input is obtained by a frequency sweep method or a random noise method Output data, process the input and output data to obtain the frequency characteristic curve of the system, and use the least squares method to identify the system based on the second-order linear transfer function model to obtain an open-loop system model. 4. The control method of seeker stabilization platform as claimed in claim 3, is characterized in that: in the described 3rd step, the design disturbance observer is realized by the following steps: Step 1, comprehensively consider noise and immunity, and obtain a low-pass filter in the interference observer that meets the requirements through repeated debugging; Step 2, obtain the nominal model of the system according to the open-loop system model identified in the second step; Step 3: Combine the nominal model of the system to finally obtain a disturbance observer that meets the requirements. 5. The control method of seeker stabilization platform as claimed in claim 1, is characterized in that: in the described 4th step, 6th step and 8th step, the speed open-loop system after adding observer, adding The frequency characteristics of the speed open-loop system after the notch filter and the speed closed-loop system after adding the incomplete differential PID controller are tested. The frequency sweep method or random noise method is used to obtain the input and output data, and the frequency characteristics of the system are obtained by processing the input and output data. curve. 6. The control method for a seeker stabilizing platform according to any one of claims 1 to 5, wherein in the fifth step, referring to the system mechanical resonance suppression method, a wave trap is designed to add a disturbance observer The convex hull area introduced by the frequency characteristics of the rear system is suppressed. 7 . The control method of the seeker stabilizing platform according to claim 6 , wherein the specific parameters of the wave notch filter determine the center frequency according to the highest point of the convex hull region. 8 . 8 . The method for controlling the stabilizer platform of the seeker according to claim 1 , wherein the current loop is realized by hardware, and the current closed loop is realized by configuring the coefficient according to the characteristics of the hardware chip. 9 . 9. A composite control system for a seeker stabilization platform, which realizes the control of the seeker stabilization platform through the control method of the seeker stabilization platform according to any one of claims 1 to 8, characterized in that: the The seeker stabilization platform adopts a pitch and yaw double-frame structure; a detection system, a gyroscope and an angle sensor are installed on the seeker stabilization platform. 10. The composite control system of the seeker stable platform according to claim 9, wherein the detection system is installed on the seeker stable platform as a load, and the gyro is installed on the seeker stable platform for measuring The pitch and yaw angular velocity and angle sensors are respectively installed on the pitch and yaw axis to measure the angular displacement.

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