Fault-tolerant control-based scanning galvanometer device and control method

Abstract

The invention discloses a scanning galvanometer device based on fault-tolerant control and a control method, relates to the technical field of scanning galvanometer control, and solves the problems that the control precision is seriously reduced or a system is unstable when part of components of a scanning galvanometer have serious faults due to the fact that the scanning galvanometer device cannot be monitored through comprehensive hardware redundancy in the prior art. And shutdown maintenance has to be carried out. In the device, a mechanical structure unit comprises a shell, a limiting block and a bearing gland which are mounted at the upper end of the shell, and an eddy current sensor mounting seat mounted at the bottom of the shell, a corner motor is mounted in the shell through a rotating shaft, a reflector is mounted at the upper end of the rotating shaft, and a positioning plate is mounted at the lower end of the rotating shaft; the main eddy current sensor group and the standby eddy current sensor group are installed in the eddy current sensor installation seat and located at the front end of the positioning plate. A temperature sensor is mounted in the corner motor; the invention further discloses a control method, rapid normal switching of the scanning galvanometer under the fault condition is achieved, and the system precision and basic functions of the scanning galvanometer are guaranteed to be achieved.

Description

Technical Field

[0001] This invention relates to the field of scanning galvanometer control technology, specifically to a scanning galvanometer device and control method based on fault-tolerant control. Background Technology

[0002] A scanning galvanometer, or simply galvanometer, is a device that enables high-speed, precise scanning of a laser beam within a one-dimensional plane by controlling the rapid deflection of a mirror. It features fast response, high scanning accuracy, and good positioning repeatability, and is currently widely used in important fields such as laser processing, medical aesthetics, lidar, and national defense.

[0003] With the widespread application of scanning galvanometers in many important fields, higher requirements have been placed on their reliability. However, due to the influence of complex and harsh environments such as high temperature and humidity, electromagnetic interference, and vibration, scanning galvanometers are prone to failure during long-term operation. As a core component of complex systems, the failure of the scanning galvanometer can lead to the loss of partial functionality of the entire complex system.

[0004] Most existing scanning galvanometer devices, both domestically and internationally, rely on control algorithms to identify and control faults, or only rely on partial hardware redundancy and control algorithms for fault-tolerant control. They cannot achieve full redundancy to monitor the scanning galvanometer device. This results in a significant reduction in control accuracy or system instability when some components of the scanning galvanometer experience serious failures, necessitating shutdown for maintenance.

[0005] An existing invention patent, patent number 202211430413.4, entitled "An Adaptive Fault-Tolerant Control System and Method for Fast-Controlling Reflectors," discloses an adaptive fault-tolerant control system for fast-controlling reflectors, comprising a mechanical part and an electrical control part. The mechanical part includes a base, a reflector, an eddy current sensor, and a flexible hinge, as well as six voice coil motors composed of voice coil motor coils and voice coil motor magnets, evenly arranged on the circumference of the reflector's back surface in the XY plane. The patent also discloses its control method. This method employs a voice coil motor fast-reflector mechanical design with a six-point parallel drive structure, and an adaptive fault-tolerant control based on compensation and switching in a dual-mode configuration, achieving stable aiming and precise tracking of the fast-reflector under fault conditions. While this patent achieves fault-tolerant control of fast-reflectors through mechanical structure design and control algorithms, its drawback is that the method only controls the fast-reflector through motor switching and does not achieve comprehensive hardware redundancy to enable dynamic monitoring of the system and comprehensive fault-tolerant control.

[0006] An existing invention patent, patent number 202311486543.4, entitled "A Fault-Tolerant Control Method for a Fast Reflecting Mirror Control System," discloses a fault-tolerant control method for a fast reflecting mirror control system. First, a dynamic model of the fast reflecting mirror is established to obtain the state equation of the control system. Then, a fault model of the voice coil motor is established to obtain a rewritten state equation of the control system. A monitoring function based on a performance constraint function is constructed for the first group of voice coil motors. An affine relationship is established between the tracking error and the monitoring function, and an adaptive control law is designed. Finally, adaptive fault-tolerant control is applied to the second group of voice coil motors to ensure good transient performance of the system during reconstruction after a fault. This technology is based on a dual-mode adaptive fault-tolerant control of compensation and switching, achieving stable aiming and precise tracking of the fast reflecting mirror under fault conditions. It achieves fault-tolerant control of the fast reflecting mirror from the perspective of control algorithm. However, its drawback is that this method only controls the fast reflecting mirror through motor switching and PPC control algorithms, without considering other redundant control methods to achieve fault-tolerant control of the system or methods for normal machine operation when the eddy current sensor fails.

[0007] In summary, this invention achieves fault-tolerant control through three parts: mechanical structure design, control software design, and circuit design. In terms of mechanical structure design, fault-tolerant control is implemented through the switching modes of the eddy current sensor master backup and the angle motor master backup. Regarding the control software, methods for eddy current sensor fault diagnosis, motor fault diagnosis, and the basic function implementation method of the scanning galvanometer when both eddy current groups fail are designed, ensuring normal system operation even with the failure of any component. In terms of circuit design, a switching circuit between the motor and the eddy current sensor is designed. The combination of these three elements realizes the design of a scanning galvanometer device based on fault-tolerant control. Summary of the Invention

[0008] This invention addresses the problem that existing technologies cannot achieve full hardware redundancy for monitoring scanning galvanometer devices, leading to a significant reduction in control accuracy or system instability when some components of the scanning galvanometer malfunction, necessitating shutdown for maintenance. It provides a fault-tolerant scanning galvanometer device and control method, which achieves fault-tolerant control of the scanning galvanometer through full hardware and algorithm redundancy.

[0009] A fault-tolerant control-based scanning galvanometer device includes a mechanical unit and a circuit control unit. The mechanical unit includes a housing, within which a rotary motor is mounted via a rotating shaft. A reflector and a positioning plate are respectively mounted at both ends of the rotating shaft. An eddy current sensor mounting base is mounted at the lower end of the housing. An eddy current sensor array is mounted on the eddy current sensor mounting base and located at the front end of the positioning plate. A temperature sensor is mounted on the rotary motor. The upper end of the housing is closed by a bearing cap, and a limiting block is provided on the bearing cap to limit the swing angle of the reflector.

[0010] The circuit control unit is used to send control commands to drive the corner motor to rotate, thereby causing the reflector to complete a specified angle deflection. The eddy current sensor group collects the deflection state of the positioning plate and obtains the deflection angle data corresponding to the deflection angle of the reflector. At the same time, the temperature sensor collects the operating temperature data of the corner motor in real time. Based on the feedback deflection angle data and temperature data, the circuit control unit performs closed-loop control to correct the driving parameters of the corner motor.

[0011] This invention also provides a scanning galvanometer control method based on fault-tolerant control, which is implemented by the following steps:

[0012] Step 1: Power on and initialize the system; set the observer to output the desired angle value; set the motor switching count m=0 and the eddy current sensor group switching count n=0; send instructions from the host computer to the main control chip.

[0013] Step 2: Set the motor cooling cycle k=0; perform position calibration based on the positional relationship between the motor input and output;

[0014] Step 3: The main control chip controls the main motor to run and monitors the output values ​​of the temperature sensor and the main electric eddy current sensor group in real time; that is, steps 4 and 7 are executed simultaneously.

[0015] Step 4: When the temperature sensor detects the temperature... If the brakes are applied for cooling for five minutes, the cycle count is k=k+1; proceed to step five; otherwise, return to step two; where, This is the highest temperature;

[0016] Step 5: Determine if the loop count k is greater than or equal to 3. If yes, proceed to Step 6; otherwise, return to Step 4.

[0017] Step Six: The main control chip controls the relay switch to switch to the backup motor, the main motor enters the stop state, and uploads the data to the host computer, m=m+1; when m≥2, proceed to Step Ten; otherwise, return to Step Two.

[0018] Step 7. When hour, The expected angle value output by the observer. The deflection angle detected by the main eddy current sensor group. If the deviation peak value is reached, proceed to step eight; otherwise, return to step two.

[0019] Step 8: Switch to the backup sensor group, n=n+1; if n≥2, proceed to step 9; otherwise, return to step 2.

[0020] Step 9: The scanning galvanometer enters open-loop scanning mode and runs according to the scanning angle and speed input from the host computer combined with the calibration data to meet the basic scanning functions, so that the scanning galvanometer does not stop.

[0021] Step 10: The host computer alarms, and the machine is shut down for maintenance.

[0022] The beneficial effects of this invention are:

[0023] 1. The scanning galvanometer device of the present invention is equipped with comprehensive hardware redundancy, including a main motor, a backup motor, a main eddy current sensor group, and a backup eddy current sensor group, to ensure the normal operation of the galvanometer.

[0024] 2. The control method described in this invention achieves comprehensive hardware, software, and algorithm redundancy. Even after multiple heat dissipation cycles, the measured temperature of the motor coil still exceeds [a certain threshold]. The generator set will switch over time, and the error between the observer's angle prediction and the eddy current sensor's detection result exceeds [a certain threshold]. The eddy current sensor group is switched over to enable rapid switching of the scanning galvanometer in case of failure, thus ensuring system accuracy.

[0025] 3. The method described in this invention ensures the basic scanning function even when both sets of eddy current sensors fail. When both sets of eddy current sensors of the motor fail, the system performs an open-loop scan based on the calibrated relationship curve between the motor input and output, ensuring the basic function of the scanning galvanometer is realized. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a scanning galvanometer device based on fault-tolerant control according to the present invention.

[0027] Figure 2 This is a schematic diagram of the structure of the scanning galvanometer device based on fault-tolerant control according to the present invention, in which the rotary motor, bearing assembly, reflector assembly and positioning plate assembly cooperate.

[0028] Figure 3 This is a cross-sectional view of the internal structure of a scanning galvanometer device based on fault-tolerant control according to the present invention.

[0029] Figure 4 This is a schematic diagram of an eddy current sensor for a scanning galvanometer device based on fault-tolerant control, as described in this invention.

[0030] Figure 5 This is a hardware schematic diagram of a scanning galvanometer device based on fault-tolerant control according to the present invention.

[0031] Figure 6 This is a control flowchart of a scanning galvanometer device based on fault-tolerant control according to the present invention.

[0032] The markings in the diagram are as follows: 1. Housing; 2. Reflector; 3. Rotary motor; 4. Eddy current sensor mounting base; 5. Main eddy current sensor group; 6. Backup eddy current sensor group; 7. Bearing; 8. Bearing cover; 9. Limit block; 10. Positioning plate; 11. Temperature sensor; 12. Rotating shaft; 13. Reflector mounting base. Detailed Implementation

[0033] Specific Implementation Method 1: Combination Figures 1 to 5 This embodiment describes a scanning galvanometer device based on fault-tolerant control, which includes a mechanical structure unit and a circuit control unit.

[0034] like Figures 1 to 4 As shown, the mechanical structure unit includes a housing 1, a bearing cover 8 mounted on the upper end of the housing 1, a limit block 9 provided on the bearing cover 8 to limit the swing angle of the reflector; an eddy current sensor mounting base 4 mounted on the bottom of the housing 1; a rotary motor 3 mounted inside the housing via a rotating shaft; a reflector 2 mounted on the upper end of the rotating shaft 12 via a reflector mounting base 13; a positioning plate 10 mounted on the lower end of the rotating shaft; the rotating shaft 12 is connected to the housing 1 via a bearing 7; a main eddy current sensor group 5 and a backup eddy current sensor group 6 are both mounted in the eddy current sensor mounting base 4 and located at the front end of the positioning plate; a temperature sensor 11 is installed inside the rotary motor 3.

[0035] The circuit control unit includes an analog switch, a D / A conversion circuit, an A / D conversion circuit, a main control chip, a power drive circuit, and a relay switch;

[0036] like Figure 5As shown, after the scanning galvanometer is powered on, the host computer sends digital control commands. These commands are transmitted to the main control chip (DSP or FPGA) via a communication interface circuit (level conversion / protocol parsing). The main control chip outputs digital control signals, which are converted into analog voltage signals by a D / A conversion circuit. These signals then drive the angle motor to rotate via a power drive circuit, thereby causing the reflector 2 to deflect at a specified angle. The positioning plate connected to the reflector 2 deflects synchronously with the reflector. An eddy current sensor detects the deflection state of the positioning plate 10 and outputs an analog signal corresponding to the deflection angle of the reflector 2. Simultaneously, the temperature sensor 11 built into the angle motor 3 collects the operating temperature of the angle motor in real time and outputs an analog temperature signal. The analog signals of the reflector deflection angle and temperature are converted into digital signals by an A / D conversion circuit and sent back to the main control chip for processing. The main control chip combines the feedback deflection angle and temperature data to execute a closed-loop control algorithm to correct the drive parameters of the angle motor, ensuring the deflection accuracy of reflector 2. Simultaneously, it controls an analog switch and a relay switch via two control signals. The analog switch switches between the main and backup eddy current sensor groups; the relay switch switches between the main and backup motors. The final deflection angle, angle motor temperature, and other information are transmitted back to the host computer via the communication interface circuit and then fed back to the user.

[0037] In this embodiment, the corner motor 3 has two sets of coils: a main double-winding motor coil and a backup double-winding motor coil. Each set of coils functions independently, equivalent to one motor functioning independently. The two sets of coils are equivalent to two independent corner motors, namely, serving as the main motor and the backup motor, respectively. There are four eddy current sensors, arranged in pairs as the main eddy current sensor group 5 and the backup eddy current sensor group 6, as follows: Figure 4 As shown, the sensors are labeled A, B, C, and D in sequence, and the main eddy current sensor groups B and C and the backup eddy current sensor groups A and D are set. They are all installed on the front side of the positioning plate 10. There are two temperature sensors 11, both of which are distributed inside the rotary motor.

[0038] Specific Implementation Method Two: Combination Figure 6 This embodiment describes the control method of the scanning galvanometer device based on fault-tolerant control as described in Specific Embodiment 1. In this method, the deflection of the reflector is completed by one of the angle motors 3; the deflection angle information of the reflector is measured by the main eddy current sensor group 5; that is, the two eddy current sensors B and C simultaneously measure the deflection angle information, and the angular velocity information is obtained through differential calculation; when the main motor fails, it switches to the backup motor; when the main eddy current sensor group fails, it switches to the backup eddy current sensor group; this is specifically achieved by the following steps:

[0039] Step S1. After the scanning galvanometer is powered on, it performs a self-test. If the self-test is normal, it will work normally and enter the periodic self-test mode. This mode is controlled by the user. If a fault is found, the machine will be stopped for maintenance.

[0040] Perform system initialization; set up an observer for predicting angle information to predict the deflection angle of the reflector based on the system input; set the motor switching count m=0 and the eddy current sensor switching count n=0.

[0041] Step S2. Set the motor cooling cycles k=0; automatically calibrate the scanning galvanometer to determine the correspondence between the motor input control quantity and the motor output position, obtain a set of calibration data, and input this set of data into the program system;

[0042] Step S3. The host computer sends a control command to the main control chip, which controls the main motor to run. At the same time, it detects the output values ​​of the temperature sensor and the main eddy current sensor group in parallel and in real time; that is, steps S4 and S7 are executed simultaneously.

[0043] Step S4. When the temperature sensor detects the temperature Rise to temperature ,Right now If this occurs, brake cooling will be performed for five minutes, with the cycle count k = k + 1; then proceed to step S5; where, The maximum temperature at which the motor can operate normally, such as 105℃-125℃; otherwise, return to step S2.

[0044] Step S5. Determine if the number of iterations k is greater than or equal to 3. If yes, proceed to step S6; otherwise, return to step S4.

[0045] Step S6. After three heat dissipation cycles, the temperature drops to... Under these conditions, the motor begins to operate normally; if the temperature remains above [a certain level]... The motor automatically switches to the standby motor, the main motor enters the stop state, and the data is uploaded to the host computer. The parameter m = m + 1. When m ≥ 2, step S10 is executed; otherwise, step S2 is returned.

[0046] Step S7. Compare the output angle information of the observer with the deflection angle information of the reflector measured by the main eddy current sensor group. When the deviation between the two is greater than the peak deviation, the result is considered complete. At that time, that is ; Proceed to step S8; otherwise, return to step S2;

[0047] Step S8. Switch to the backup sensor group, n=n+1; if n≥2, proceed to step S9; otherwise, return to step S2;

[0048] Step S9. The scanning galvanometer enters the open-loop scanning mode and runs according to the calibration data obtained by combining the scanning angle and speed input by the host computer, which satisfies the basic scanning function and ensures that the scanning galvanometer does not stop.

[0049] Step S10. The host computer alarms and shuts down for maintenance.

[0050] In this embodiment, the determination criterion for step S7 is: the period of the input signal is... The maximum angular velocity is set to The peak deviation is Set the expected angle output of the observer to be [value]. The angle detected by the main eddy current sensor group is The analog switch switches to the backup eddy current sensor group, the main eddy current sensor group exits the working mode, and the backup eddy current sensor group enters the working mode; and the data is uploaded to the host computer.

[0051] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A scanning galvanometer device based on fault-tolerant control, the device comprising a mechanical unit and a circuit control unit; characterized in that: The mechanical unit includes a housing, within which a rotary motor is mounted via a rotating shaft. A reflector and a positioning plate are respectively mounted at both ends of the rotating shaft. An eddy current sensor mounting base is mounted at the lower end of the housing. An eddy current sensor assembly is mounted on the eddy current sensor mounting base and located at the front end of the positioning plate. A temperature sensor is mounted on the rotary motor. The upper end of the housing is closed by a bearing cover, and a limiting block is provided on the bearing cover to limit the swing angle of the reflector. The circuit control unit is used to send control commands to drive the corner motor to rotate, thereby causing the reflector to complete a specified angle deflection. The eddy current sensor group collects the deflection state of the positioning plate and obtains the deflection angle data corresponding to the deflection angle of the reflector. At the same time, the temperature sensor collects the operating temperature data of the corner motor in real time. Based on the feedback deflection angle data and temperature data, the circuit control unit performs closed-loop control to correct the driving parameters of the corner motor.

2. The scanning galvanometer device based on fault-tolerant control according to claim 1, characterized in that: The eddy current sensor group includes a main eddy current sensor group and a backup eddy current sensor group; the rotary motor has two sets of coils, namely a main double-winding motor coil and a backup double-winding motor coil, each set of coils functions independently, that is, as the main motor and the backup motor respectively; both the main motor and the backup motor are equipped with temperature sensors.

3. The scanning galvanometer device based on fault-tolerant control according to claim 2, characterized in that: The circuit control unit includes an analog switch, an A / D conversion circuit, a D / A conversion circuit, a main control chip, a power drive circuit, and a relay switch; After the scanning galvanometer is powered on, the host computer sends digital control commands to the main control chip. The main control chip outputs digital control signals, which are converted into analog voltage signals by a D / A converter circuit. These signals are then amplified by a power amplifier circuit to drive the corner motor to rotate, causing the reflector to deflect at a specified angle. At this time, the eddy current sensor group detects the deflection state of the positioning plate and outputs an analog signal corresponding to the deflection angle of the reflector. Simultaneously, the temperature sensor collects the operating temperature of the corner motor in real time and outputs an analog temperature signal. The analog signals of the reflector deflection angle and temperature are converted into digital signals by an A / D converter circuit and sent back to the main control chip. The main control chip corrects the corner motor drive parameters based on the feedback deflection angle and temperature data and sends the final deflection angle and temperature data back to the host computer for feedback to the user.

4. The scanning galvanometer device based on fault-tolerant control according to claim 3, characterized in that: The main control chip is also used to send two control signals to control the analog switch and the relay switch respectively; to switch the main eddy current sensor group and the backup eddy current sensor group through the analog switch; and to switch the main motor and the backup motor through the relay switch.

5. A scanning galvanometer device based on fault-tolerant control according to claim 4, characterized in that: The main eddy current sensor group and the backup eddy current sensor group are sequentially labeled A, B, C, and D, with the main eddy current sensor group being B and C, and the backup eddy current sensor group being A and D; both are installed at the front end of the positioning plate.

6. A control method for a scanning galvanometer device based on fault-tolerant control, characterized in that: This method is used to control the galvanometer device as described in claims 1 to 5; specifically, it is implemented by the following steps: Step 1: Power on and initialize the system; set the observer to output the desired angle value; set the motor switching count m=0 and the eddy current sensor group switching count n=0; send instructions from the host computer to the main control chip. Step 2: Set the motor cooling cycle k=0; perform position calibration based on the positional relationship between the motor input and output; Step 3: The main control chip controls the operation of the main motor and monitors the output values ​​of the temperature sensor and the main electric eddy current sensor group in real time. That is: execute steps four and seven simultaneously; Step 4: When the temperature sensor detects the temperature... If this happens, brake cooling will be applied for five minutes, with the number of cycles k = k + 1; then proceed to step five. Otherwise, return to step two; where, This is the highest temperature; Step 5: Determine if the loop count k is greater than or equal to 3. If yes, proceed to Step 6; otherwise, return to Step 4. Step Six: The main control chip controls the relay switch to switch to the backup motor, the main motor enters the stop state, and uploads the data to the host computer, m=m+1; when m≥2, proceed to Step Ten; otherwise, return to Step Two. Step 7, when hour, The expected angle value output by the observer. The deflection angle detected by the main eddy current sensor group. If the deviation peak value is reached, proceed to step eight; otherwise, return to step two. Step 8: Switch to the backup sensor group, n=n+1; if n≥2, proceed to step 9; otherwise, return to step 2. Step 9: The scanning galvanometer enters open-loop scanning mode and runs according to the scanning angle and speed input from the host computer combined with the calibration data to meet the basic scanning functions, so that the scanning galvanometer does not stop. Step 10: The host computer alarms, and the machine is shut down for maintenance.

7. The control method according to claim 6, characterized in that: The criterion for step seven is: the period of the input signal is... The maximum angular velocity is set to The peak deviation is The analog switch switches the backup eddy current sensor group, the main eddy current sensor group exits the working mode, and the backup eddy current sensor group enters the working mode; and the data is uploaded to the host computer.

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