A small two-axis stabilization control system for a cruise missile seeker

Abstract

The application discloses a small two-axis stabilizing control system for a cruise missile seeker, which comprises a frame, a main control module, a gyro module, a motor driving module and a power module, wherein the main control module, the gyro module and the power module are all installed on the frame, the frame comprises an azimuth axis and a pitching axis, the motor driving module comprises an azimuth axis driving module and a pitching axis driving module, and the azimuth axis driving module and the pitching axis driving module are respectively installed on the azimuth axis and the pitching axis of the frame. The control system adopts a CAN networking communication mode, distinguishes azimuth and pitching information through an ID frame number, collects and analyzes data of the gyro module through the main control module, and issues instructions to the motor driving module; the control system has the advantages of fast servo response speed, high control precision, small gyro drift and the like, and can also have the characteristics of small size and light weight, and the modular design in the control system is convenient for system transplantation and expansion.

Description

Technical Field

[0001] This invention relates to photoelectric stabilization systems, and more specifically to a small two-axis stabilization control system based on a loitering munition seeker. Background Technology

[0002] The loitering munition's seeker combines the features of a traditional seeker with an optoelectronic pod, integrating optoelectronic equipment from fields such as optics, precision mechanics, image acquisition and processing, and servo control. It possesses capabilities for target reconnaissance, target search, fire indication, and image guidance. The stabilization control system is a key component of the loitering munition's seeker. As the mounting device for the optical system, it isolates the munition from disturbances caused by the airframe and external environment, maintaining visual axis stability and ensuring clear imaging of the optical components.

[0003] In addition to the servo accuracy requirements, loitering munition seekers are also limited by physical factors such as size and weight, thus placing high demands on the design of their stable control systems. For example, while ensuring servo accuracy, it is impossible to simultaneously meet the requirements for size and weight; some control systems abandon position or current sensors, which, although small in size and low in cost, leads to low servo control accuracy, unstable control, and severe gyroscope drift; others are designed with the servo drive separated from the motor, resulting in excessive cables, excessively long motor signal transmission lines, and greater signal interference and cable resistance torque, thereby affecting the servo control performance. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a small two-axis stabilization control system for the guidance head of a loitering munition. This system has advantages such as fast servo response speed, high control accuracy, and small gyroscope drift, while also being small in size and light in weight. Furthermore, its modular design facilitates system portability and expansion.

[0005] The technical solution adopted in this invention is as follows: A small two-axis stabilization control system for a loitering munition seeker includes a frame, a main control module, a gyroscope module, a motor drive module, and a power supply module. The main control module, gyroscope module, and power supply module are all mounted on the frame. The frame includes an azimuth axis and a pitch axis. The motor drive module includes an azimuth axis drive module and a pitch axis drive module. The azimuth axis drive module and the pitch axis drive module are respectively mounted on the azimuth axis and the pitch axis of the frame. The control system adopts CAN networking communication, and distinguishes azimuth and pitch information by ID frame number. The main control module collects and parses the data from the gyroscope module and issues commands to the motor drive module. The gyroscope module adopts an IMU inertial sensor and is composed of an IMU inertial sensor and an interface board. It is used to detect, calculate and feedback the attitude angle, angular velocity and acceleration information of the photoelectric payload platform.

[0006] Furthermore, the main control module serves as an information interaction and computing hub, connecting the photoelectric payload, image processing module, and gyroscope module. The photoelectric payload and image processing module are both mounted on the frame, and the main control module communicates and controls with the host computer, photoelectric payload, and image processing module.

[0007] Furthermore, the azimuth axis drive module includes an azimuth motor, a hollow magnet, and an azimuth servo board. The azimuth motor is a split-type permanent magnet brushless DC torque motor. The hollow magnet is fixed in the inner shaft of the azimuth motor by a threaded pressure ring, and a gasket is installed between the hollow magnet and the azimuth motor. The azimuth servo board is installed inside the azimuth motor shaft and connected to the azimuth motor through a spring pin connector. The azimuth servo board includes a servo control chip, a drive chip, and a magnetic encoder chip. The magnetic encoder chip detects the real-time position information of the motor rotor. The servo control chip continuously reads the position data of the azimuth motor magnetic encoder and performs analysis and calculation according to the instructions issued by the main control module. It outputs a PWM wave to drive the brushless DC torque motor through the SimpleFOC vector control algorithm.

[0008] Furthermore, the pitch axis drive module includes a pitch motor, a hollow magnet, and a pitch servo board. The pitch motor is a split permanent magnet brushless DC torque motor. The hollow magnet is fixed in the inner shaft of the pitch motor by a threaded clamping ring, and a shim is installed between the hollow magnet and the pitch motor. The pitch servo board is installed inside the pitch motor shaft and connected to the pitch motor through a spring pin connector. The pitch servo board includes a servo control chip, a drive chip, and a magnetic encoder chip. The magnetic encoder chip detects the real-time position information of the motor rotor. The servo control chip continuously reads the position data of the pitch motor magnetic encoder and performs analysis and calculation according to the instructions issued by the main control module. It outputs a PWM wave to drive the brushless DC torque motor through the SimpleFOC vector control algorithm.

[0009] Furthermore, the motor torque control of the motor drive module adopts a sensorless voltage control method. In position mode, it uses a voltage open loop as the inner loop and a composite control method of outer loop position closed loop + middle loop speed closed loop + inner loop voltage open loop. The magnetic encoder frame angle serves as the outer loop feedback, and the speed calculated by the magnetic encoder position is used as the middle loop. When the azimuth and pitch servo boards receive the target position and turning commands from the main control module, they calculate the target speed through the PI position controller based on the current frame angle and the target position angle. Then, based on the real-time speed, they calculate the target voltage U through the PI speed controller. q ; In stable mode, a composite control method is adopted, using voltage open-loop as the inner loop, outer loop spatial attitude angle closed-loop + middle loop dual-speed closed-loop + inner loop voltage open-loop. The gyro attitude angle serves as the outer loop feedback, while the gyro angular velocity and the encoding speed calculated from the magnetic encoder position serve as the middle loop feedback. During servo system initialization, the gyro attitude angle is calibrated once based on the frame angle zero position to ensure that the zero positions of the two are basically consistent. When the azimuth and pitch servo boards receive the stabilization command from the main control module, they calculate the target angular velocity based on the spatial attitude angle fed back by the gyro, using a PI position controller. Then, the stable speed error is calculated based on the real-time gyro angular velocity. After passing through the image stabilization speed controller, the error between this error and the encoding speed is used by the speed controller to calculate the target voltage U. q .

[0010] Furthermore, the algorithm of the PI position controller includes a position error limiting algorithm, a controller output speed limiting algorithm, and a dead-zone cycle control algorithm.

[0011] Furthermore, the position error limiting algorithm is as follows: If the position error err(k) > A, then the position error err(k) = A; if the position error err(k) < -A, then the position error err(k) = -A. In other words, if the current position error is greater than the maximum amplitude, then the position error takes the maximum amplitude; if the current position error is less than the minimum amplitude, then the position error takes the minimum amplitude. The value of parameter A should not be too small, otherwise the speed of step response will be affected. At the same time, according to the mechanical limit of the system, the value of parameter A should be less than the limit value. Generally, parameter A is selected to be slightly smaller than the limit value and determined through debugging.

[0012] Furthermore, the controller output speed limiting algorithm is as follows: The maximum and minimum values ​​of the controller output are determined based on the error variation, using the following formula: If the controller outputs S out (k)>S out If _max, then the bit controller outputs S. out (k)=S out _max; if the controller outputs S out (k) out If _min, then the controller outputs S out (k)=S out _min; In other words, the maximum and minimum values ​​of the controller output are determined based on the error changes, and the controller output is limited. If the controller output is greater than the current maximum value, the controller output takes the maximum value; if the controller output is less than the current minimum value, the controller output takes the minimum value. Wherein: S​out _max is the maximum output value of the controller; S out _min is the minimum output value of the controller; v is the speed value. The value of parameter v should not be too small, otherwise it will affect the speed. If the value of parameter v is too large, it will affect the smoothness and stability. The value of parameter v can be selected as the speed limit value of the control system.

[0013] Furthermore, the dead-time cycle control algorithm is as follows: If the target position remains unchanged within a certain period and the absolute value of the position error remains within the threshold, the controller outputs S. out (k) is 0, meaning that when the target position does not change within a certain period and the absolute value of the position error remains within the threshold, the controller output is 0. The threshold value is determined according to the system control requirements. If it is too small, there will be no control effect and the position stability will be poor; if it is too large, the control accuracy will be poor. Generally, the threshold value is set to be less than the position control accuracy index.

[0014] Furthermore, the main control module is equipped with multiple communication interfaces, including UART, UARST, and CAN; the servo board control chip is equipped with a CAN interface and an SPI interface.

[0015] Compared with the prior art, the advantages of the present invention are as follows: 1) The motor drive module adopts a modular design, and the selection of azimuth and pitch motor components and servo boards, PCB boards, interface definitions, etc. are kept consistent. They are distinguished by macro definitions in the servo control program. At the same time, the servo board and motor components are in contact through spring pin connectors to realize the modular installation of the drive module, which makes the drive module replaceable and small in size and light in weight. 2) A sensorless servo control method is adopted. The brushless DC torque motor is controlled by the SimpleFOC vector control algorithm, which simplifies the motor control method and reduces the size of the hardware circuit board. At the same time, the controller PI algorithm is improved, and position error limiting, controller output speed limiting and dead-zone cycle control algorithms are proposed. By improving the control method and control algorithm, the position control accuracy and dynamic response speed are improved, and the gyroscope drift problem is suppressed. 3) Existing technical manuals typically use solid magnets to match magnetic encoders because hollow magnets have lower magnetic flux density than solid magnets, leading to insufficient data stability and abnormal data during frame movement. This invention achieves compatibility between the magnetic encoder and hollow magnets through hollow magnets and optimized mechanical structure, improving the stability of magnetic encoder data. Specifically, by increasing the thickness of the hollow magnets and adding adjustable shims at the hollow magnet mounting points, and securing them with threaded pressure rings, the spacing between the hollow magnets and the magnetic encoder chips is optimized, achieving compatibility between the magnetic encoder and hollow magnets, thereby improving the stability of magnetic encoder data and ensuring data normality and stability during movement. 4) The gyroscope module uses an IMU inertial sensor and employs attitude angles to suppress gyroscope drift through an attitude-dual-speed closed-loop control method. The motor uses a permanent magnet brushless DC torque motor. Due to the absence of brush commutation, the motor operates smoothly, has low noise, and a long lifespan. 5) To ensure sufficient margin for the optoelectronic payload and image processing board in the optoelectronic payload platform, the size and weight of the stable control system should be as small and lightweight as possible. First, to meet the requirements for size, weight, and servo performance, a small, split-type torque motor is selected based on the size and installation location of the optoelectronic payload, while meeting the torque requirements. Second, the servo board in the motor drive module eliminates the current sensor and analog-to-digital related circuits. The servo board uses an SWD interface, and during program simulation and programming, it connects to the ARM downloader via an external SWD-to-JTAG interface board, reducing interface pins and size, thus minimizing the PCB board size. To reduce wiring, a CAN network communication method is used, distinguishing azimuth and pitch information by ID frame number. The main control module acts as the master, while the azimuth and pitch servo boards act as slaves, with no communication between slaves. To reduce wiring, impedance, and signal loss, the servo board and motor assembly are in close contact via spring-loaded connectors, enabling modular installation of the servo board and motor assembly. The servo control chip is selected with minimal specifications, maximizing the utilization of peripheral resources while meeting requirements. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the control system of the present invention; Figure 2 This is a cross-sectional view of the azimuth axis driving module of the present invention; Figure 3 This is a cross-sectional view of the pitch axis drive module of the present invention; Figure 4 This is an electrical schematic diagram of the control system of the present invention; Figure 5 This is the control circuit diagram of the servo board MCU of the present invention; Figure 6 This is a magnetic encoder circuit diagram of the servo board of the present invention; Figure 7 This is a circuit diagram of the motor drive circuit of the servo board of the present invention; Figure 8 This is a block diagram of the servo control system of the present invention; Figure 9 This is a flowchart illustrating the operation of the control system of the present invention. In the diagram: 1. Frame, 2. Azimuth motor, 3. Azimuth servo board, 4. Pitch motor, 5. Pitch servo board, 6. Hollow magnet, 7. Gasket, 8. Photoelectric load, 9. Image processing module, 10. Gyroscope module, 11. Power supply module, 12. Main control module, 13. Azimuth axis drive module, 14. Pitch axis drive module, 15. Threaded pressure ring, 16. Spring pin connector, 17. Magnetic braided chip. Detailed Implementation

[0017] The technical solutions in 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] like Figure 1 As shown, a small two-axis stabilization control system based on a loitering munition seeker in this embodiment includes a frame 1, a main control module 12, a gyroscope module 10, a motor drive module, and a power supply module 11. The main control module 12, the gyroscope module 10, and the power supply module 11 are all mounted on the frame 1. The frame 1 includes an azimuth axis and a pitch axis. The motor drive module includes an azimuth axis drive module 13 and a pitch axis drive module 14. The azimuth axis drive module 13 and the pitch axis drive module 14 are respectively mounted on the azimuth axis and the pitch axis of the frame 1. like Figure 2 As shown, the azimuth axis drive module 13 includes an azimuth motor 2, a hollow magnet 6, and an azimuth servo board 3. The azimuth motor 2 is a split permanent magnet brushless DC torque motor. The hollow magnet 6 is installed and fixed in the inner shaft of the azimuth motor 2 by a threaded pressure ring 15. A gasket 7 is installed between the hollow magnet 6 and the azimuth motor 2. The azimuth servo board 3 is installed on the inner side of the shaft of the azimuth motor 2 and is connected to the azimuth motor 2 by a spring pin connector 16. The azimuth servo board 3 includes a servo control chip, a drive chip, and a magnetic encoder chip 17. The magnetic encoder chip 17 detects the real-time position information of the motor rotor. The servo control chip continuously reads the position data of the magnetic encoder of the azimuth motor and performs analysis and calculation according to the instructions issued by the main control module 12. The SimpleFOC vector control algorithm is used to output a PWM wave to drive the brushless DC torque motor to move. like Figure 3As shown, the pitch axis drive module 14 includes a pitch motor 4, a hollow magnet 6, and a pitch servo board 5. The pitch motor 4 is a split permanent magnet brushless DC torque motor. The hollow magnet 6 is installed and fixed in the inner shaft of the pitch motor 4 by a threaded pressure ring 15. A shim 7 is installed between the hollow magnet 6 and the pitch motor 4. The pitch servo board 5 is installed on the inner side of the shaft of the pitch motor 4 and is connected to the pitch motor 4 by a spring pin connector 16. The pitch servo board 5 includes a servo control chip, a drive chip, and a magnetic encoder chip 17. The magnetic encoder chip 17 detects the real-time position information of the motor rotor. The servo control chip continuously reads the position data of the pitch motor magnetic encoder and performs analysis and calculation according to the instructions issued by the main control module 12. The SimpleFOC vector control algorithm is used to output a PWM wave to drive the brushless DC torque motor to move. The azimuth servo board 3 and pitch servo board 5 are both mounted inside the shafts of the azimuth motor 2 and the pitch motor 4, respectively, and are tightly connected to the azimuth motor 2 and the pitch motor 4 via spring pin connectors 16. Motor drive and control are concentrated on the azimuth servo board 3 and the pitch servo board 5. This design improves drive integration, shortens the distance between the motor and the drive, reduces external signal interference, optimizes drive control circuitry, reduces cable resistance torque, and also reduces electrical wiring, thereby reducing the overall size and weight of the pod. The magnetic encoder chip 17 in the servo board is located below the hollow magnet 6. The hollow magnet 6 uses optional shims 7 to adjust the distance between the hollow magnet 6 and the magnetic encoder chip 17, achieving compatibility between the hollow magnet 6 and the magnetic encoder and ensuring stable and reliable magnetic encoder data.

[0019] In this embodiment, the control system adopts CAN networking communication, distinguishing azimuth and pitch information by ID frame number. The main control module 12 serves as the information interaction and calculation hub, connecting the photoelectric payload 8, image processing module 9, and gyroscope module 10. Both the photoelectric payload 8 and image processing module 9 are mounted on frame 1. The main control module 12 communicates and controls with the host computer, the photoelectric payload 8, and the image processing module 10. The gyroscope module 10 uses an IMU inertial sensor, consisting of an IMU inertial sensor and an interface board, and is used to detect, calculate, and feedback the attitude angle, angular velocity, and acceleration information of the photoelectric payload platform. The main control module 12 collects and parses the data from the gyroscope module 10, decouples the IMU inertial sensor data, and issues commands to the motor drive module to achieve azimuth, pitch, and image stabilization control.

[0020] like Figure 4As shown, the IMU inertial sensor is used to acquire and report attitude data. The servo board mainly integrates a servo chip, a magnetic encoder, and a driver chip to control the motor and report its status. The main control module 12 communicates with an external host computer via a serial port to issue commands and report information from the slave device. Simultaneously, the main control module 12 communicates with the motor drive module via CAN to control azimuth and pitch according to instructions, achieving status feedback.

[0021] like Figure 5 , Figure 6 , Figure 7 As shown, the MCU in the motor drive module servo board uses the STM32F103TUB7 control chip. This chip has fewer peripheral resources and a smaller package size. The control chip program uses the SWD interface. When program simulation and burning are required, it is connected to the ARM programmer through an external SWD-to-JTAG interface board. At the same time, a UART serial port interface is reserved for the initial debugging of the servo. The driver chip uses the HTD8325, which is directly powered by the power module at 12V. The three-phase input pins IN1, IN2, and IN3 are connected to the PWM output pins PA1, PA2, and PA3 of the STM32F103TUB, respectively. The chip output pins OUT1, OUT2, and OUT3 are connected to the three-phase UVW of the motor, respectively. The chip EN1, EN2, and EN3 pins are the chip PWM enable outputs. In the above design, these three pins are connected together and then connected to PB1 of the STM32F103TUB. The high and low levels of the IO output are controlled by the program to enable and disable the motor drive. The magnetic encoder uses the MT6835GT-STD, which has high angular resolution (21-bit), fast signal processing capabilities, and short latency and update rate. It communicates with the control chip via SPI.

[0022] like Figure 8 As shown, in this embodiment, the motor torque control of the motor drive module adopts a voltage control method without current sensors. The specific operation is as follows: In position mode, a control method is adopted consisting of an outer loop position closed loop, a middle loop speed closed loop, and an inner loop voltage open loop. The magnetic encoder frame angle serves as the outer loop feedback, and the speed calculated from the magnetic encoder position serves as the middle loop. When the servo board receives the target position and turning command from the main control module, it calculates the target speed using a PI position controller based on the current frame angle and the target position angle. Then, based on the real-time speed, it calculates the target voltage U using a PI speed controller. qIn stable mode, a control method is adopted, consisting of an outer-loop spatial attitude angle closed loop, a middle-loop dual-speed closed loop, and an inner-loop voltage open loop. The gyro attitude angle serves as the outer loop feedback, while the gyro angular velocity and the encoding speed calculated from the magnetic encoder position serve as the middle loop feedback. During servo system initialization, the gyro attitude angle is calibrated once using the frame angle zero position as a reference to ensure that the zero positions of the two are basically consistent. When the servo board receives the stabilization command from the main control module, it calculates the target angular velocity based on the spatial attitude angle fed back by the gyro, using the position controller. Then, it calculates the stabilization speed error based on the real-time gyro angular velocity. After passing through the image stabilization speed controller, the error between this error and the encoding speed is used by the speed controller to calculate the target voltage U. q By controlling the spatial attitude angle, the influence of gyroscope drift is effectively reduced. In the voltage control method, U is directly set. d The value is 0, the motor angle is obtained based on the magnetic encoder, and the target U is also determined. q The voltage value is used to drive the motor motion through the SVPWM commutation method using the SimpleFOC vector control algorithm.

[0023] The controller employs a PI control algorithm and has undergone the following optimizations and improvements: 1) To address the issues of overshoot, large overshoot, and even loss of control during large-angle position adjustments, a position error limiting algorithm was designed based on the limiting algorithm. This algorithm can reduce the impact of large step signals on position control. The algorithm is as follows: if the position error err(k) > A, then the position error err(k) = A; if the position error err(k) < -A, then the position error err(k) = -A. The value of parameter A should not be too small, otherwise the speed of step response will be affected. At the same time, according to the mechanical limit of the system, the value of parameter A should be less than the limit value. Generally, parameter A is selected to be slightly smaller than the limit value and determined through debugging. 2) To address the issue that a fixed output limiter cannot flexibly adapt to real-time changes during motion, a variable speed and amplitude limiting algorithm for the controller output is designed by combining the speed-changing algorithm with the amplitude-limiting algorithm. The algorithm is as follows: The maximum and minimum values ​​of the controller output are determined based on the error changes, and the formula is: If the controller outputs S out (k)>S out If _max, then the bit controller outputs S. out (k)=S out _max; if the controller outputs S out (k) out If _min, then the controller outputs S out (k)=S out _min; Wherein: S out _max is the maximum output value of the controller; S out ​_min is the minimum output value of the controller; v is the speed value. The value of parameter v should not be too small, otherwise it will affect the speed. If the value of parameter v is too large, it will affect the smoothness and stability. The value of parameter v can be selected as the speed limit value of the control system. 3) To balance position control accuracy and stability, a dead-zone periodic control algorithm was designed based on the dead-zone control algorithm. The algorithm is as follows: when the target position remains unchanged within a certain period and the absolute value of the position error remains within the threshold, the controller outputs S. out (k) is 0. The threshold value is determined according to the system control requirements. If it is too small, there will be no control effect and poor position stability. If it is too large, the control accuracy will be poor. Generally, the threshold value is less than the position control accuracy index.

[0024] like Figure 9 As shown, the two-axis stabilization control system in this embodiment is affected by mechanical limits. The zero position of the frame angle is determined in the initial stage and will not change. Therefore, when the servo system starts working, the servo program initializes, including the motor electrical angle and mechanical angle. The main control module 12 sends the decoupled attitude angle and gyroscope speed of the gyroscope through CAN at regular intervals, and puts the servo system into position mode. Using the zero position of the frame angle as a reference, the gyroscope attitude angle is calibrated once to make the zero position of the gyroscope attitude angle basically consistent with the zero position of the frame angle. The attitude angle subsequently sent by the main control module is based on this zero position. After calibration, it waits for the main control module to send a command to switch to stable mode. Within the servo cycle of 1ms, each loop control is performed to drive the motor movement through SVPWM.

[0025] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A small two-axis stabilization control system for a loitering munition seeker, characterized in that, The system includes a frame (1), a main control module (12), a gyroscope module (10), a motor drive module, and a power supply module (11). The main control module (12), the gyroscope module (10), and the power supply module (11) are all mounted on the frame (1). The frame (1) includes an azimuth axis and a pitch axis. The motor drive module includes an azimuth axis drive module (13) and a pitch axis drive module (14). The azimuth axis drive module (13) and the pitch axis drive module (14) are respectively mounted on the azimuth axis and the pitch axis of the frame (1). The control system adopts CAN networking communication mode, and distinguishes azimuth and pitch information by ID frame number. The main control module (12) collects and analyzes the data of the gyroscope module (10) and issues commands to the motor drive module. The gyroscope module (10) adopts an IMU inertial sensor, which is composed of an IMU inertial sensor and an interface board, and is used to detect, calculate and feedback the attitude angle, angular velocity and acceleration information of the photoelectric load platform.

2. A small two-axis stabilization control system for a loitering munition seeker as described in claim 1, characterized in that, The main control module (12) serves as an information interaction and computing hub, connecting the photoelectric load (8), the image processing module (9), and the gyroscope module (10). The photoelectric load (8) and the image processing module (9) are both mounted on the frame (1). The main control module (12) communicates and controls with the host computer, the photoelectric load (8), and the image processing module (9).

3. A small two-axis stabilization control system for a loitering munition seeker as described in claim 2, characterized in that, The azimuth axis drive module (13) includes an azimuth motor (2), a hollow magnet (6), and an azimuth servo board (3). The azimuth motor (2) is a split permanent magnet brushless DC torque motor. The hollow magnet (6) is fixed in the inner shaft of the azimuth motor (2) by a threaded pressure ring (15). A gasket (7) is installed between the hollow magnet (6) and the azimuth motor (2). The azimuth servo board (3) is installed on the inner side of the shaft of the azimuth motor (2) and is connected to the azimuth motor (2) by a spring pin connector (16). The azimuth servo board (3) includes a servo control chip, a drive chip, and a magnetic encoder chip (17). The magnetic encoder chip (17) detects the real-time position information of the motor rotor. The servo control chip continuously reads the position data of the magnetic encoder of the azimuth motor and performs analysis and calculation according to the instructions issued by the main control module (12). The PWM wave is output through the SimpleFOC vector control algorithm to drive the brushless DC torque motor to move.

4. A small two-axis stabilization control system for a loitering munition seeker as described in claim 3, characterized in that, The pitch axis drive module (14) includes a pitch motor (4), a hollow magnet (6), and a pitch servo board (5). The pitch motor (4) is a split permanent magnet brushless DC torque motor. The hollow magnet (6) is fixed in the inner shaft of the pitch motor (4) by a threaded pressure ring (15). A gasket (7) is installed between the hollow magnet (6) and the pitch motor (4). The pitch servo board (5) is installed on the inner side of the shaft of the pitch motor (4) and is connected to the pitch motor (4) by a spring pin connector (16). The pitch servo board (5) includes a servo control chip, a drive chip, and a magnetic encoder chip (17). The magnetic encoder chip (17) detects the real-time position information of the motor rotor. The servo control chip continuously reads the position data of the pitch motor magnetic encoder and performs analysis and calculation according to the instructions issued by the main control module (12). The SimpleFOC vector control algorithm outputs a PWM wave to drive the brushless DC torque motor to move.

5. A small two-axis stabilization control system for a loitering munition seeker as described in claim 4, characterized in that, The motor torque control of the motor drive module adopts a sensorless voltage control method. In position mode, it uses a voltage open-loop control as the inner loop, and employs a composite control method of outer loop position closed-loop + middle loop speed closed-loop + inner loop voltage open-loop. The magnetic encoder frame angle serves as the outer loop feedback, and the speed calculated from the magnetic encoder position serves as the middle loop. When the azimuth servo board and pitch servo board receive the target position and turning commands from the main control module, they calculate the target speed using a PI position controller based on the current frame angle and the target position angle. Then, based on the real-time speed, they calculate the target voltage U using a PI speed controller. q ; In stable mode, a composite control method is adopted, using voltage open-loop as the inner loop, outer loop spatial attitude angle closed-loop + middle loop dual-speed closed-loop + inner loop voltage open-loop. The gyro attitude angle serves as the outer loop feedback, while the gyro angular velocity and the encoding speed calculated from the magnetic encoder position serve as the middle loop feedback. During servo system initialization, the gyro attitude angle is calibrated once based on the frame angle zero position to ensure that the zero positions of the two are basically consistent. When the azimuth and pitch servo boards receive the stabilization command from the main control module, they calculate the target angular velocity based on the spatial attitude angle fed back by the gyro, using a PI position controller. Then, the stable speed error is calculated based on the real-time gyro angular velocity. After passing through the image stabilization speed controller, the error between this error and the encoding speed is used by the speed controller to calculate the target voltage U. q .

6. A small two-axis stabilization control system for a loitering munition seeker as described in claim 5, characterized in that, The PI position controller algorithm includes a position error limiting algorithm, a controller output speed limiting algorithm, and a dead-zone cycle control algorithm.

7. A small two-axis stabilization control system for a loitering munition seeker as described in claim 6, characterized in that, The position error limiting algorithm is as follows: If the position error err(k) > A, then the position error err(k) = A; if the position error err(k) < -A, then the position error err(k) = -A; where the value of parameter A is less than the limit value.

8. A small two-axis stabilization control system for a loitering munition seeker as described in claim 6, characterized in that, The controller output speed limiting algorithm is as follows: The maximum and minimum values ​​of the controller output are determined based on the error variation, using the following formula: If the controller outputs S out (k)>S out If _max, then the bit controller outputs S. out (k)=S out _max; if the controller outputs S out (k) out If _min, then the controller outputs S out (k)=S out _min;​ Among them, S out _max is the maximum output value of the controller; S out _min is the minimum output value of the controller; v is the speed value, and the parameter v takes the speed limit value of the control system.

9. A small two-axis stabilization control system for a loitering munition seeker as described in claim 6, characterized in that, The dead-time cycle control algorithm is as follows: If the target position remains unchanged within a certain period and the absolute value of the position error remains within the threshold, the controller outputs S. out (k) is 0; where the threshold value is less than the position control accuracy index.

10. A small two-axis stabilization control system for a loitering munition seeker as described in claim 1, characterized in that, The main control module (12) is equipped with multiple communication interfaces UART, UARST and CAN; the servo board control chip is equipped with CAN interface and SPI interface.

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