A method for cooperative control of brushless outer rotor motor in micro server

Abstract

This invention relates to the field of motor drive technology, specifically to a collaborative control method for brushless external rotor motors in a micro servo system. The method includes the following steps: First, a precise mathematical model is established for each brushless external rotor motor in the micro servo system. One motor acts as the "master shaft," receiving commands from a high-performance controller. The other motors act as "slave shafts," acquiring the master shaft's position, speed, or torque commands in real time via a communication bus and performing closed-loop tracking. The mechanical coupling relationship between the multiple motors is also analyzed. This invention deeply understands system coupling by establishing multibody dynamics equations and comprehensively utilizes master-slave tracking, cross-coupling compensators, and deterministic synchronous communication to construct a multi-synchronization mechanism of "model feedforward + error feedback + real-time restraint." This mechanism can suppress the synchronization error between multiple motors to an extremely low level, meeting the stringent requirements of micro-precision systems.

Description

Technical Field

[0001] This invention relates to the field of motor drive technology, and more specifically, to a collaborative control method for a brushless external rotor motor in a micro servo. Background Technology

[0002] With the development of cutting-edge technologies such as precision manufacturing, biomedicine, and semiconductors, unprecedented requirements have been placed on the motion performance of micro servos: not only do individual motors need to have extremely high positioning accuracy and fast dynamic response, but multiple motors also need to move as precisely and synchronously as "a whole" when working together. Brushless external rotor motors are widely used in such micro servos due to their advantages such as compact structure, high torque density, and good dynamic response.

[0003] However, in micro servo systems driven by multiple brushless external rotor motors, the following technical challenges urgently need to be addressed:

[0004] 1. Mechanical Coupling and Interference Issues: Multiple motors are typically connected by rigid or flexible mechanical structures (such as linkages or platforms) to form a multibody dynamics system. The motion of one motor can directly affect the state of other motors through mechanical coupling. Traditional independent control methods ignore this coupling, leading to asynchrony, vibration, or even instability among the motors when the system is in dynamic motion or under external disturbances, severely restricting overall performance.

[0005] 2. Communication Asynchrony Issue: In a distributed multi-motor control system, if a non-deterministic communication method is used when the host computer sends commands to the lower-level drivers and collects feedback status, the communication delay and asynchrony will introduce additional control deviations. These deviations will be amplified in high-speed, high-precision coordinated motion and become a bottleneck in system performance.

[0006] 3. Disturbance Suppression and Consistency Challenges: Micro servo systems are extremely sensitive to disturbances such as load changes, frictional nonlinearity, and external interference. Due to subtle differences in installation location and load characteristics, the disturbance characteristics of each motor are not entirely the same. If these disturbances cannot be estimated and compensated for in real time and accurately, it will lead to inconsistent dynamic responses of the motors, compromising the accuracy of coordinated motion.

[0007] 4. Limitations of the control architecture: Purely centralized control has a large computational load and poor real-time performance; while completely decentralized control is difficult to handle strong coupling and global coordination optimization. A collaborative control method for brushless external rotor motors in a micro servo is needed to solve this problem. Summary of the Invention

[0008] The purpose of this invention is to provide a collaborative control method for a brushless external rotor motor in a micro servo, so as to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a collaborative control method for a brushless external rotor motor in a micro servo, comprising a motor body, the motor body being composed of a lower execution area and an upper coordination area, the upper coordination area being respectively provided with a high-precision reducer, a compensator and a load torque observer, a connecting line being connected to one side of the motor body, a main shaft being provided at the output end of the motor body, and an opening being provided at the upper end of the upper coordination area, the diameter of which is larger than the size of the main shaft.

[0010] As a preferred technical solution of the present invention, the following steps are included:

[0011] S1. First, establish an accurate mathematical model for each brushless external rotor motor in the micro servo. One motor acts as the "master shaft" and receives instructions from the high-performance controller. The other motors act as "slave shafts" and obtain the position, speed, or torque instructions of the master shaft in real time through the communication bus. They also perform closed-loop tracking and analyze the mechanical coupling relationship between multiple motors. The multibody dynamics equations of the entire servo system are established, and the mutual influence and constraints between the motions of each motor are clarified.

[0012] S2. Connect the adaptive controllers designed for each of the above motors in parallel and then connect them through a cross-coupling compensator;

[0013] S3. It adopts a two-layer architecture of "upper-level coordination area + lower-level execution area" to achieve a balance between decoupling and centralized control;

[0014] S4. Use CAN bus and time-based industrial Ethernet to ensure that the upper coordination area can simultaneously and deterministically send commands and collect status data from all lower drives, and eliminate control deviations caused by communication delays and asynchrony through strict time synchronization.

[0015] S5. Design a load torque observer for each motor to estimate the disturbances caused by load changes, friction nonlinearity, and external interference in real time. Feed the obtained disturbance values ​​forward to compensate the current command, which significantly improves the anti-interference capability of the system and the consistency between motors.

[0016] S6. Finally, through system integration and debugging, we verify whether the coordinated control of the brushless external rotor motor in the micro servo meets the extreme requirements of high-end micro servo applications for precision, dynamics and coordination.

[0017] As a preferred technical solution of the present invention, the mathematical model in step S1 needs to include the electrical and mechanical parameters of the motor, and obtain the actual parameters of the motor and load through offline or online identification technology, so as to lay the foundation for the design of high-performance controller.

[0018] As a preferred embodiment of the present invention, the core matrix formula of the multibody dynamics equations in step S1 is as follows:

[0019] M(q)q+C(q,q)q+G(q)+Ffric(q)=τ

[0020] Where q is the generalized coordinate vector composed of the rotation angles of each motor, M(q) is the inertia matrix (including coupled inertia) that varies with position, C(q,q) represents the coupling term of Coriolis force and centripetal force, G(q) is the gravity term, Ffric is the friction term, and τ is the output torque vector of each motor. This equation fully describes the dynamic coupling relationship between motors and between motors and load, and is the theoretical basis for designing feedforward compensation and decoupling cooperative control algorithms.

[0021] As a preferred embodiment of the present invention, the compensator in step S2 dynamically generates an additional compensation signal based on the synchronization error between the motors, and injects it into the control input of each motor. This ensures that any speed fluctuation in one motor will immediately affect the control of the other motors, forming a tight "restraint" effect. The compensation signal formula is as follows:

[0022]

[0023] This compensator generates an additional compensation signal in real time based on the synchronization error. This signal is injected into the control input of each motor. Its main function is to achieve a "restraint" effect: any speed or position fluctuation of any motor will immediately affect the control commands of other motors through the compensation signal, thereby actively suppressing synchronization deviation. This cross-coupling mechanism significantly improves the synchronization accuracy and coordination between multiple motors. Especially under dynamic load changes or external interference, it can effectively reduce following errors and ensure that all motors maintain a high degree of consistent coordinated movement in high-speed and high-precision applications.

[0024] As a preferred technical solution of the present invention, each motor in the lower-level coordination area in step S3 is independently equipped with a high-performance dual-closed-loop servo driver, which adopts field-oriented control (FOC) to achieve fast and accurate decoupling control of d-axis current and q-axis current. According to the instruction, PID control and adaptive control are used to generate q-axis current instructions. This loop ensures that a single motor can quickly and smoothly track its own given instructions.

[0025] As a preferred technical solution of the present invention, the upper-level coordination area in step S3 is the core of the collaborative control, responsible for generating and adjusting the instructions issued to each lower-level execution area. A motor is designated as the "master motor", whose motion trajectory is generated by the overall task planning, while the instructions of the "slave motor" are based on the actual instruction state of the master motor. In the control loop of the slave motor, the synchronization error between the master and slave motors is introduced as an additional feedback quantity. Through a cross-coupled controller, this synchronization error is converted into a correction of the slave motor instructions, thereby actively suppressing the synchronization deviation.

[0026] As a preferred technical solution of the present invention, in step S4, after calculating the target of the next cycle for all motors in each control cycle, the coordination zone simultaneously triggers all drivers to update their instruction values ​​through a synchronization frame. Similarly, the real-time feedback of all motors also needs to be collected and uploaded to the coordination zone at strictly aligned time points for global state estimation and synchronization error calculation.

[0027] As a preferred technical solution of the present invention, the parameters of the micro servo system in step S5 may change slowly with the operating conditions, and the load characteristics of each motor are slightly different. An adaptive control algorithm can be used to fine-tune the parameters of the PID controllers of each motor online to keep the dynamic performance of all loops matched. In the micro precision system in step S5, the resonant frequency of the mechanical structure falls within the control bandwidth. Therefore, a notch filter needs to be added to the control algorithm to prevent the coordinated motion from exciting structural resonance, which would affect accuracy and stability. The notch filter formula is as follows:

[0028]

[0029] In micro servo systems, the resonant frequency of mechanical structures (such as transmission components) may fall within the control bandwidth. If left unaddressed, this can easily lead to resonance, causing system oscillation, decreased accuracy, or even instability. Adding a notch filter can mitigate this by addressing the resonant frequency. It produces deep attenuation, significantly suppressing vibration energy near the frequency and thus avoiding resonance excitation. At the same time, the filter has little impact on other frequency signals, ensuring the phase and gain margin of the control system and improving system stability and motion smoothness.

[0030] As a preferred technical solution of the present invention, before the physical construction in step S6, a complete system simulation model including a motor model, control algorithm and mechanical coupling is constructed using MATLAB tools to verify the effectiveness of the cooperative control strategy.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) This invention is a collaborative control method for a brushless external rotor motor in a micro servo. This invention deeply understands the system coupling by establishing multibody dynamic equations and comprehensively utilizes master-slave tracking, cross-coupling compensators and deterministic synchronous communication to construct a multi-synchronization mechanism of "model feedforward + error feedback + real-time restraint". It can suppress the synchronization error between multiple motors to an extremely low level, meet the stringent requirements of micro precision systems, and use a load torque observer combined with feedforward compensation to almost real-time cancel various disturbances, greatly improving the dynamic stiffness and robustness of the system.

[0033] (2) This invention is a collaborative control method for brushless external rotor motors in micro servos. The hierarchical control architecture of this invention separates complex global coordination tasks from high-speed local execution tasks, reducing system complexity and dependence on the performance of a single processor, and improving reliability. Starting from system analysis based on physical models, to control architecture design, algorithm implementation, and then to MATLAB simulation verification and physical debugging, a complete and scientific development process has been formed. This method systematically solves the core problem of collaborative control of brushless external rotor motors in micro servos. Its technical ideas and specific means can be widely applied to the high-end equipment manufacturing field with high requirements for multi-axis synchronization performance, and has important promotion value. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of a brushless external rotor motor in a micro servo according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the internal structure of the upper coordination area of ​​a brushless external rotor motor in a micro servo according to an embodiment of the present invention.

[0037] Figure label:

[0038] 1. Motor body; 2. Spindle; 3. Connecting wires; 4. Lower-level execution area; 5. Upper-level coordination area; 6. Opening; 7. High-precision reducer; 8. Compensator; 9. Load torque observer. Detailed Implementation

[0039] The invention will now be further described with reference to the accompanying drawings and specific embodiments:

[0040] Example 1

[0041] refer to Figure 1 and Figure 2 Example 1 describes a motor body 1, which consists of a lower execution area 4 and an upper coordination area 5. The upper coordination area 5 is equipped with a high-precision reducer 7, a compensator 8, and a load torque observer 9. A connecting line 3 is connected to one side of the motor body 1. A main shaft 2 is provided at the output end of the motor body 1. An opening 6 is provided at the upper end of the upper coordination area 5, and the diameter of the opening 6 is larger than the size of the main shaft 2.

[0042] Example 2

[0043] refer to Figure 1 and Figure 2 Example 2 is described below. This embodiment further illustrates Example 1 and includes the following steps:

[0044] S1. First, establish an accurate mathematical model for each brushless external rotor motor in the micro servo. One motor acts as "spindle 2" and receives instructions from the high-performance controller. The other motors act as "slave axes" and obtain the position, speed or torque instructions of spindle 2 in real time through the communication bus. Perform closed-loop tracking and analyze the mechanical coupling relationship between multiple motors. Establish the multibody dynamics equations of the entire servo system and clarify the mutual influence and constraints between the motions of each motor.

[0045] In this embodiment, the mathematical model in step S1 needs to include the electrical and mechanical parameters of the motor, and the actual parameters of the motor and load are obtained through offline or online identification technology, laying the foundation for the design of a high-performance controller.

[0046] In this embodiment, the core matrix formula of the multibody dynamics equations in step S1 is:

[0047] M(q)q+C(q,q)q+G(q)+Ffric(q)=τ

[0048] Where q is the generalized coordinate vector composed of the rotation angles of each motor, M(q) is the inertia matrix (including coupled inertia) that varies with position, C(q,q) represents the coupling term of Coriolis force and centripetal force, G(q) is the gravity term, Ffric is the friction term, and τ is the output torque vector of each motor. This equation fully describes the dynamic coupling relationship between motors and between motors and load, and is the theoretical basis for designing feedforward compensation and decoupling cooperative control algorithms.

[0049] S2. Connect the adaptive controllers designed for each motor in parallel and then connect them through the cross-coupling compensator 8.

[0050] In this embodiment, the compensator 8 in step S2 dynamically generates an additional compensation signal based on the synchronization error between the motors, and injects it into the control input of each motor. This ensures that any speed fluctuation in one motor will immediately affect the control of the other motors, forming a tight "restraint" effect. The compensation signal formula is as follows:

[0051]

[0052] This compensator generates an additional compensation signal in real time based on the synchronization error. This signal is injected into the control input of each motor. Its main function is to achieve a "restraint" effect: any speed or position fluctuation of any motor will immediately affect the control commands of other motors through the compensation signal, thereby actively suppressing synchronization deviation. This cross-coupling mechanism significantly improves the synchronization accuracy and coordination between multiple motors. Especially under dynamic load changes or external interference, it can effectively reduce following errors and ensure that all motors maintain a high degree of consistent coordinated movement in high-speed and high-precision applications.

[0053] S3. It adopts a two-layer architecture of "upper-level coordination area + lower-level execution area" to achieve a balance between decoupling and centralized control;

[0054] In this embodiment, each motor in the lower coordination area 4 in step S3 is independently equipped with a high-performance dual closed-loop servo driver, which adopts field-oriented control (FOC) to achieve fast and accurate decoupling control of d-axis current and q-axis current. According to the command, PID control and adaptive control are used to generate q-axis current command. This loop ensures that a single motor can quickly and smoothly track its own given command.

[0055] In this embodiment, the upper coordination area 5 in step S3 is the core of the collaborative control. It is responsible for generating and adjusting the instructions issued to each lower execution area. A motor is designated as the "master motor" and its motion trajectory is generated by the overall task planning. The instructions of the "slave motor" are based on the actual instruction state of the master motor. In the control loop of the slave motor, the synchronization error between the master and slave motors is introduced as an additional feedback quantity. Through a cross-coupled controller, this synchronization error is converted into a correction of the slave motor instructions, thereby actively suppressing the synchronization deviation.

[0056] S4. Use CAN bus and time-based industrial Ethernet to ensure that the upper coordination area 5 can simultaneously and deterministically send commands and collect status data from all lower-level drivers, and eliminate control deviations caused by communication delays and asynchrony through strict time synchronization.

[0057] In this embodiment, in step S4, after calculating the target of the next cycle for all motors in each control cycle, the coordination area simultaneously triggers all drivers to update their command values ​​through a synchronization frame. Similarly, the real-time feedback of all motors also needs to be collected and uploaded to the coordination area at strictly aligned time points for global state estimation and synchronization error calculation.

[0058] S5. Design a load torque observer 9 for each motor to estimate the disturbance caused by load changes, friction nonlinearity and external interference in real time. Feed the obtained disturbance value forward to the current command to significantly improve the anti-interference capability of the system and the consistency between motors.

[0059] In this embodiment, the parameters of the micro servo system in step S5 may change slowly with the working conditions, and the load characteristics of each motor are slightly different. An adaptive control algorithm can be used to fine-tune the parameters of the PID controller of each motor online so that the dynamic performance of all loops remains matched.

[0060] In this embodiment, in the micro-precision system of step S5, the resonant frequency of the mechanical structure falls within the control bandwidth. Therefore, a notch filter needs to be added to the control algorithm to prevent cooperative motion from exciting structural resonance, which would affect accuracy and stability. The notch filter formula is as follows:

[0061]

[0062] In micro servo systems, the resonant frequency of mechanical structures (such as transmission components) may fall within the control bandwidth. If left unaddressed, this can easily lead to resonance, causing system oscillation, decreased accuracy, or even instability. Adding a notch filter can mitigate this by addressing the resonant frequency. It produces deep attenuation, significantly suppressing vibration energy near the frequency and thus avoiding resonance excitation. At the same time, the filter has little impact on other frequency signals, ensuring the phase and gain margin of the control system and improving system stability and motion smoothness.

[0063] S6. Finally, through system integration and debugging, we verify whether the coordinated control of the brushless external rotor motor in the micro servo meets the extreme requirements of high-end micro servo applications for precision, dynamics and coordination.

[0064] In this embodiment, before the physical construction in step S6, a complete system simulation model including a motor model, control algorithm, and mechanical coupling is constructed using MATLAB tools to verify the effectiveness of the cooperative control strategy.

[0065] In the description of this invention, it should be noted that the terms "top," "bottom," "one side," "the other side," "front," "rear," "middle part," "inner," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0066] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A brushless external rotor motor for a micro servo, characterized in that, The motor body (1) consists of a lower execution area (4) and an upper coordination area (5). The upper coordination area (5) is equipped with a high-precision reducer (7), a compensator (8) and a load torque observer (9). A connecting line (3) is connected to one side of the motor body (1). A main shaft (2) is provided at the output end of the motor body (1). An opening (6) is provided at the upper end of the upper coordination area (5), and the diameter of the opening (6) is larger than the size of the main shaft (2).

2. The collaborative control method for a brushless external rotor motor in a micro servo unit according to claim 1, characterized in that, Includes the following steps: S1. First, establish an accurate mathematical model for each brushless external rotor motor in the micro servo. One motor is the "main shaft (2)" and receives instructions from the high-performance controller. The other motors are the "slave shafts" and obtain the position, speed or torque instructions of the main shaft (2) in real time through the communication bus. They also perform closed-loop tracking and analyze the mechanical coupling relationship between multiple motors. Establish the multibody dynamics equation of the entire servo system and clarify the mutual influence and constraint conditions between the motions of each motor. S2. Connect the adaptive controllers designed for each of the above motors in parallel and then connect them through a cross-coupling compensator (8); S3. A two-layer architecture of "upper-level coordination area (5) + lower-level execution area (4)" is adopted to achieve a balance between decoupling and centralized control; S4. Use CAN bus and time-based industrial Ethernet to ensure that the upper coordination area (5) can simultaneously and deterministically send instructions and collect status to all lower-level drivers, and eliminate control deviations caused by communication delays and asynchrony through strict time synchronization. S5. Design a load torque observer (9) for each motor to estimate the disturbance caused by load changes, friction nonlinearity and external interference in real time. Feed the obtained disturbance value forward to the current command to significantly improve the anti-interference capability of the system and the consistency between motors. S6. Finally, through system integration and debugging, we verify whether the coordinated control of the brushless external rotor motor in the micro servo meets the extreme requirements of high-end micro servo applications for precision, dynamics and coordination.

3. The collaborative control method for a brushless external rotor motor in a micro servo unit according to claim 2, characterized in that, The mathematical model in step S1 needs to include the electrical and mechanical parameters of the motor, and obtain the actual parameters of the motor and load through offline or online identification technology, laying the foundation for the design of a high-performance controller.

4. The collaborative control method for a brushless external rotor motor in a micro servo unit according to claim 3, characterized in that, The core matrix formula for the multibody dynamics equations in step S1 is: M(q)q+C(q,q)q+G(q)+Ffric(q)=τ Where q is the generalized coordinate vector composed of the rotation angles of each motor, M(q) is the inertia matrix (including coupled inertia) that varies with position, C(q,q) represents the coupling term of Coriolis force and centripetal force, G(q) is the gravity term, Ffric is the friction term, and τ is the output torque vector of each motor. This equation fully describes the dynamic coupling relationship between motors and between motors and load, and is the theoretical basis for designing feedforward compensation and decoupling cooperative control algorithms.

5. The collaborative control method for a brushless external rotor motor in a micro servo unit according to claim 2, characterized in that, In step S2, the compensator (8) dynamically generates an additional compensation signal based on the synchronization error between the motors, and injects it into the control input of each motor. This ensures that any speed fluctuation in one motor will immediately affect the control of other motors, forming a tight "restraint" effect. The compensation signal formula is as follows: This compensator generates an additional compensation signal in real time based on the synchronization error. This signal is injected into the control input of each motor. Its main function is to achieve a "restraint" effect: any speed or position fluctuation of any motor will immediately affect the control commands of other motors through the compensation signal, thereby actively suppressing synchronization deviation. This cross-coupling mechanism significantly improves the synchronization accuracy and coordination between multiple motors. Especially under dynamic load changes or external interference, it can effectively reduce following errors and ensure that all motors maintain a high degree of consistent coordinated movement in high-speed and high-precision applications.

6. The collaborative control method for a brushless external rotor motor in a micro servo unit according to claim 2, characterized in that, In step S3, each motor in the lower-level coordination area is independently equipped with a high-performance dual-closed-loop servo driver, which uses field-oriented control (FOC) to achieve fast and accurate decoupling control of d-axis current and q-axis current. According to the command, PID control and adaptive control are used to generate q-axis current command. This loop ensures that a single motor can quickly and smoothly track its given command.

7. The collaborative control method for a brushless external rotor motor in a micro servo according to claim 2, characterized in that, The upper coordination area (5) in step S3 is the core of the collaborative control. It is responsible for generating and regulating the instructions issued to each lower execution area (4). A motor is designated as the "master motor". Its motion trajectory is generated by the overall task planning. The instructions of the "slave motor" are based on the actual instruction state of the master motor. In the control loop of the slave motor, the synchronization error between the master and slave motors is introduced as an additional feedback quantity. Through a cross-coupled controller, this synchronization error is converted into a correction of the slave motor instructions, thereby actively suppressing the synchronization deviation.

8. The collaborative control method for a brushless external rotor motor in a micro servo according to claim 2, characterized in that, In step S4, after calculating the target for the next cycle of all motors in each control cycle, the coordination zone simultaneously triggers all drivers to update their command values ​​through a synchronization frame. Similarly, the real-time feedback of all motors also needs to be collected and uploaded to the coordination zone at strictly aligned time points for global state estimation and synchronization error calculation.

9. The collaborative control method for a brushless external rotor motor in a micro servo according to claim 2, characterized in that, The parameters of the micro servo system in step S5 may change slowly with the operating conditions, and the load characteristics of each motor are slightly different. An adaptive control algorithm can be used to fine-tune the parameters of the PID controllers of each motor online to keep the dynamic performance of all loops matched. In the micro precision system in step S5, the resonant frequency of the mechanical structure falls within the control bandwidth. Therefore, a notch filter needs to be added to the control algorithm to prevent the coordinated motion from exciting structural resonance, which would affect accuracy and stability. The notch filter formula is as follows: In micro servo systems, the resonant frequency of mechanical structures (such as transmission components) may fall within the control bandwidth. If left unaddressed, this can easily lead to resonance, causing system oscillation, decreased accuracy, or even instability. Adding a notch filter can mitigate this by addressing the resonant frequency. It produces deep attenuation, significantly suppressing vibration energy near the frequency and thus avoiding resonance excitation. At the same time, the filter has little impact on other frequency signals, ensuring the phase and gain margin of the control system and improving system stability and motion smoothness.

10. The collaborative control method for a brushless external rotor motor in a micro servo according to claim 2, characterized in that, Before the physical construction in step S6, a complete system simulation model including a motor model, control algorithm, and mechanical coupling is built using MATLAB tools to verify the effectiveness of the cooperative control strategy.

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