Laser projection control method and distributed control device

Abstract

The invention discloses a laser projection control method and a distributed control device. The laser projection control method comprises the following steps: step 1, designing a first control board card for galvanometer control; the first control board card comprises a first main control chip for realizing real-time calculation, a static random access memory for external memory expansion, a differential driving chip for transmitting a galvanometer control signal and a chip for realizing an independent communication system; 2, designing a second control board card for laser control, focal length control and temperature monitoring; and the second control board card comprises a second main control chip for realizing real-time calculation, a motor driving chip for driving a motor to move the lens to control the focal length, a laser control circuit amplifier chip and a thermistor. According to the invention, the effect of cooperative control of the laser and the galvanometer is realized.

Description

Technical Field

[0001] This application relates to the fields of laser positioning, laser projection, and galvanometer control technology, and in particular to a laser projection control method and a distributed control device. Background Technology

[0002] The coordinated control method of galvanometers and lasers is the core technology for realizing laser tracking and laser positioning projection. Its control accuracy, speed and real-time performance directly determine the quality of laser tracking and projection. To achieve precise laser tracking and positioning and high-speed parallel projection, the laser source needs to be combined with components that can change the laser optical path (such as laser galvanometers, MEMS galvanometers, etc.) to form a laser scanning system, enabling it to perform laser scanning quickly within a certain range.

[0003] In this project, effective control of the components that alter the laser path (most commonly the laser galvanometer) is crucial. The precision and speed of this control directly impact the projection accuracy and the final projection effect. Furthermore, simultaneous galvanometer control and laser switching are necessary to enable the projection of arbitrary shapes. Therefore, galvanometer control and laser switching must be performed in parallel and with high efficiency and speed to ensure the projected image completes its loop within the human eye's visual persistence time, thus achieving the goal of laser projection augmented reality.

[0004] However, traditional single-processor-based control strategies cannot efficiently achieve coordinated control of the laser and galvanometer. Due to the limitations of a single processor, laser control and galvanometer control must be performed sequentially, and the next galvanometer position needs to be calculated in real time during projection, resulting in very low projection efficiency. Furthermore, since the distance between the projection surface and the galvanometer changes depending on the application scenario, dynamic focus adjustment is required. Moreover, as the laser projection time increases, the internal temperature of the device gradually rises; excessively high temperatures can cause significant proportional drift and zero-point drift in the galvanometer motor, reducing the device's projection accuracy. Summary of the Invention

[0005] This application proposes a laser projection control method and a distributed control device, the purpose of which is to achieve coordinated control of the laser and the galvanometer.

[0006] The specific implementation is as follows: The distributed control device consists of dual control boards based on dual processors. The first control board is mainly responsible for high-speed galvanometer control, performing linear interpolation of the galvanometer control path based on SRAM, which improves control accuracy while avoiding a decrease in projection speed due to real-time calculation. The second control board is mainly used for coordinated laser control, simultaneously performing parallel focus adjustment and real-time temperature control, effectively enhancing the stability of the equipment and maintaining projection accuracy during laser projection. In actual use, after receiving the graphic signal, the first control board calculates the interpolation points and stores them in high-speed SRAM. During galvanometer control, these points are directly obtained through a 16-bit parallel bus, greatly shortening the control cycle and improving the galvanometer control speed. After receiving the graphic signal, the second control board calculates the position where the laser needs to be switched on and off, and performs real-time calculations with the first control board, thereby completing the parallel control of the laser and galvanometer during galvanometer movement, improving control efficiency and reducing control latency. Moreover, the two processors support independent communication systems, enabling the host computer to achieve parallel control of the galvanometer, laser, and focus.

[0007] The distributed galvanometer control method and distributed multi-axis galvanometer control device based on multiprocessors and SRAM provided in this application adopt the following technical solution: A laser projection control method includes the following steps: Step 1: Design a first control board for galvanometer control; the first control board includes a first main control chip for real-time calculation, a static random access memory for external memory expansion, a differential drive chip for transmitting galvanometer control signals, and a chip for implementing an independent communication system; Step 2: Design a second control board for laser control, focal length control, and temperature monitoring; the second control board includes a second main control chip for real-time calculation, a motor drive chip for driving the motor to move the lens and control the focal length, a laser control circuit amplifier chip, and a thermistor; Step 3: Scan the projection coordinate system of the galvanometer to obtain the center position of the reflective target point; Step 4: Obtain the scanned and located graphic file; analyze and identify the inflection points of the graphic file; perform adaptive delay; Step 5: Perform linear interpolation on the graphic file; store the linear interpolation data; Step 6: Determine the laser's on / off time based on the number of graphics and the linear interpolation point data; Step 7: Adjust the focal length according to the distance to the target projection surface; Step 8: The first and second control boards work together to complete the projection task; Step 9: Monitor the internal temperature of the equipment in real time and implement temperature control.

[0008] By adopting the above technical solution, significant advantages are achieved compared to existing technologies. The first control board is primarily responsible for high-speed galvanometer control, performing linear interpolation of the galvanometer control path based on SRAM. This method improves control accuracy while avoiding a decrease in projection speed due to real-time calculation. Specifically, in actual use, after receiving the graphic signal, the first control board calculates the interpolation points and stores them in high-speed SRAM. During galvanometer control, these points are directly retrieved via a 16-bit parallel bus, greatly shortening the control cycle and increasing the galvanometer control speed. The second control board is mainly used for coordinated laser control, simultaneously performing parallel focus adjustment and real-time temperature control, effectively enhancing the stability of the equipment and maintaining projection accuracy during laser projection. When the second control board receives the graphic signal, it calculates the position where the laser needs to be switched on and off, and performs real-time calculations with the first control board, thereby completing parallel control of the laser and galvanometer during galvanometer movement, improving control efficiency and reducing control latency. Moreover, the two processors support independent communication systems, enabling the host computer to achieve parallel control of the galvanometer, laser, and focus.

[0009] Preferably, step three specifically includes the following steps: Step 3.1: Adjust the focal length of the galvanometer using the first control board so that the diameter of the light spot generated by the galvanometer focusing on the plane is less than 10μm; Step 3.2: Use the first control board to control the focal length of the galvanometer to move to the initial position of the target point given by the host computer; and use the second control board to control the laser to turn on; Step 3.3: The first control board controls the galvanometer to perform an expansion scan centered on the initial position of the target point; the laser is always on; the second control board judges the reflected light signal in real time; Step 3.4: After acquiring the reflective signal, the second control board sends the reflective signal to the first control board; the first control board calculates the center position of the target reflective point by combining the position of the galvanometer when the reflective signal occurs; and sends the center position of the target reflective point to the host computer.

[0010] Preferably, step four specifically includes the following steps: Step 4.1: The first control board obtains the graphics file from the host computer. The graphics file contains several path points. Path point Xn forms vector A with the previous point Xn-1 and forms vector B with the next point Xn+1. Calculate the angle between vector A and vector B. ; Step 4.2: If If the angle is greater than 175°, it is determined that it is not an inflection point and no delay is performed; otherwise, it is determined that it is an inflection point and an inflection point delay is performed.

[0011] Preferably, step five specifically includes the following steps: Step 5.1: The first control board calculates the distance of the interpolation point based on the currently set galvanometer moving speed; Step 5.2: Calculate the required number of interpolation points based on the calculated interpolation point distances; and calculate the relative positions of the interpolation points in the projected coordinate system. Step 5.3: Due to the large number of interpolation points, the processor's internal storage space cannot meet the requirements, while the high-speed parallel static random access memory has the fastest read and write speed among external memory. Therefore, the interpolation points are ultimately stored in the external static random access memory.

[0012] Preferably, step six specifically includes the following steps: Step 6.1: The second control board determines the laser's on / off time based on the interpolation point data; Step 6.2: Calculate the time required for laser activation and deactivation, and transmit the calculated activation and deactivation time to the first control board; the galvanometer control board will stop when it is in the corresponding position to meet the laser activation delay and deactivation delay.

[0013] Preferably, steps seven and eight specifically include the following steps: Step 7.1: Based on the projection surface distance sent by the host computer, the second control board automatically calculates the focal length of the target projection surface, and drives the motor to move the lens through the motor drive chip until the focal length reaches the target focal length. Step 8.1: The first control board reads the next interpolation point position information from the static random access memory through the FSMC bus (Flexible Static Memory Controller), outputs it to the differential driver chip through four independent signals, converts it into eight differential signals, and then transmits it to the galvanometer through the XY2-100 protocol. Step 8.2: Simultaneously, the second control board outputs a laser control signal, which is amplified and followed by TL062 before being sent to the laser module; Step 8.3: Complete the coordinated control of the laser and galvanometer.

[0014] Preferably, step nine specifically includes the following steps: Step 9.1: The second control board periodically collects the voltage value on the thermistor through the ADC, calculates the resistance value of the thermistor based on the voltage, and then calculates the current temperature. Step 9.2: By judging the current temperature, obtain the corresponding fan speed, and control the fan to reach the corresponding speed through PWM wave.

[0015] A distributed control device includes a host computer and an industrial control computer. The industrial control computer is electrically connected to the host computer. The industrial control computer includes a first control board, a second control board, and a laser energy feedback device, and the three are electrically connected to each other.

[0016] By adopting the above technical solution, this device has significant advantages compared to existing technologies. The first control board is mainly responsible for high-speed galvanometer control, performing linear interpolation of the galvanometer control path based on SRAM. This improves control accuracy and avoids a decrease in projection speed due to real-time calculation. Specifically, in actual use, after receiving the graphic signal, the first control board calculates the interpolation points and stores them in the high-speed SRAM. During galvanometer control, these points are directly obtained through a 16-bit parallel bus, greatly shortening the control cycle and increasing the galvanometer control speed. The second control board is mainly used for coordinated laser control, simultaneously performing parallel focus adjustment and real-time temperature control, effectively enhancing the stability of the device and maintaining projection accuracy during laser projection. After receiving the graphic signal, the second control board calculates the position where the laser needs to be switched on and off, and performs real-time calculations with the first control board to complete the parallel control of the laser and galvanometer during galvanometer movement, improving control efficiency and reducing control latency. This control device has advantages such as high integration, fast galvanometer control speed, high galvanometer control accuracy, parallel control of the laser galvanometer, real-time temperature control, and dynamic focusing. It can be widely used in fields such as laser positioning projection and laser tracking measurement.

[0017] In summary, this application includes at least one of the following beneficial technical effects: 1. This invention utilizes a dual-processor distributed system for collaborative control, allowing galvanometer control and laser control to be performed in parallel, which greatly improves the efficiency of laser projection and enhances projection accuracy through linear interpolation; 2. At the same time, using external SRAM to expand the processor memory allows for the storage of more interpolation points simultaneously; 3. Finally, while controlling the galvanometer, the advantages of dual processors are utilized to use a real-time temperature control system to maintain the internal temperature of the equipment, thereby improving the equipment's service life and stability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the distributed control device in this embodiment; Figure 2 This is a diagram showing the laser projection effect in Example 3. Detailed Implementation

[0019] The following is in conjunction with the appendix Figures 1-2 This application will be described in further detail.

[0020] Example 1 This application discloses a distributed control device.

[0021] Reference Figure 1 It includes a host computer and an industrial control computer. The industrial control computer is electrically connected to the host computer. The industrial control computer includes a first control board, a second control board, and a laser energy feedback device. The first control board, the second control board, and the laser energy feedback device are electrically connected. The laser energy feedback device includes a lens and a photoelectric signal sensor circuit board.

[0022] The first control board is also called the galvanometer control board; the second control board is also called the laser control board.

[0023] In this embodiment, the specific laser energy feedback device structure and host computer structure are common structures in the prior art, and will not be described in detail here. Please refer to [reference needed]. Figure 1 .

[0024] Example 2 This application discloses a laser projection control method.

[0025] Reference Figure 1 It includes the following steps: Step 1: Design a first control board for galvanometer control; the first control board includes a first main control chip, static random access memory, differential drive chip and chip; the first main control chip, static random access memory, differential drive chip and chip are electrically connected.

[0026] The primary control chip is the STM32F407ZGT6, which features a hardware acceleration unit and a high clock frequency to meet real-time computing requirements. The static random access memory (SRAM) used for external memory expansion is model IS61WV102416BLL, providing 1024MB of SRAM. A 16-bit storage unit provides memory for the processor; it also accesses the SRAM memory address through the FSMC (Flexible Static Memory Controller) 16-bit parallel bus, with a read / write time of 8ns; the AM26LS31C differential driver chip is selected to convert the output mirror control single-ended signal into a differential signal and send it to the mirror through the XY2-100 protocol; the CH340C chip is used as the USB communication to serial TTL communication chip to complete the independent communication system.

[0027] Step 2: Design a second control board for laser control, focal length control, and temperature monitoring; the second control board includes a second main control chip, a motor drive chip, a laser control circuit amplifier chip, and a thermistor, and the second main control chip, motor drive chip, laser control circuit amplifier chip, and thermistor are electrically connected.

[0028] The second main control chip is an STM32F407ZGT6, which provides computing resources for high-speed control. An L293DD is selected as the motor driver chip to drive the motor to move the lens and control the focal length. At the same time, a photoelectric switch is selected as the lens position sensor to return to the lens position for closed-loop control. A TL062 is selected as the laser control circuit amplifier chip to amplify and follow the laser control signal. An NTC thermistor is used as the temperature sensing element. The voltage value of the thermistor is collected by an ADC to calculate the current temperature, and the fan speed is adjusted by a PWM wave for real-time temperature control.

[0029] Step 3: Projection coordinate system positioning before laser projection; the positioning stage requires laser scanning and positioning of the target points, which is completed by a distributed control device. The specific steps are as follows: Step 3.1: Adjust the focal length of the galvanometer using the first control board to minimize the diameter of the light spot generated by the galvanometer focusing on the plane (the diameter can be less than 10μm). Step 3.2: Use the first control board to control the focal length of the galvanometer to move to the initial position of the target point given by the host computer; and use the second control board to control the laser to turn on; Step 3.3: Perform scanning and positioning with the initial position as the center. The laser is always on during this period. The galvanometer control board controls the galvanometer to perform an expansion scan with the initial point as the center. At the same time, the laser control board judges the reflected light signal in real time. Step 3.4: After acquiring the reflective signal, the second control board sends the reflective signal to the first control board; the first control board calculates the center position of the target reflective point by combining the position of the galvanometer when the reflective signal occurs; and sends the center position of the target reflective point to the host computer.

[0030] This scanning and positioning process is completed collaboratively by the galvanometer control board and the laser control board.

[0031] Step 4: After completing the scanning and positioning, the galvanometer control board obtains the graphic file from the host computer, automatically identifies the inflection points of the graphic file, and performs adaptive delay. The specific steps are as follows: Step 4.1: The first control board obtains the graphics file from the host computer. The graphics file contains several path points. Path point Xn forms vector A with the previous point Xn-1 and forms vector B with the next point Xn+1. Calculate the angle between vector A and vector B. ; Step 4.2: If If the angle is greater than 175°, it is determined that it is not an inflection point and no delay is performed; otherwise, it is determined that it is an inflection point and an inflection point delay is performed.

[0032] This ensures that the final projected image has sharp edges and corners, preventing the inflection points from becoming rounded due to the speed of the galvanometer.

[0033] Step 5: After completing the inflection point delay processing and obtaining the graphic file, due to the large difference and distance between graphic points, in order to ensure the speed and accuracy of galvanometer control, the galvanometer control board performs linear interpolation on the graphic file and stores the calculation results in external SRAM through the FSMC bus.

[0034] The specific steps are as follows: Step 5.1: The first control board calculates the distance of the interpolation point based on the currently set galvanometer moving speed; Step 5.2: Calculate the required number of interpolation points based on the calculated interpolation point distances; and calculate the relative positions of the interpolation points in the projected coordinate system. Step 5.3: Due to the large number of interpolation points, the processor's internal storage space cannot meet the requirements, while the high-speed parallel static random access memory has the fastest read and write speed among external memory. Therefore, the interpolation points are ultimately stored in the external static random access memory.

[0035] Step 6: After the interpolation calculation is completed, the interpolation points are transmitted to the laser control board. The laser control board determines the laser switching time based on the number of graphics and the number of interpolation points when switching graphics.

[0036] Specifically: Step 6.1: Since laser projection requires the laser switch to move in coordination with the galvanometer, determining the laser switch time requires obtaining the position information of the graphic switching, and then calculating the time points when the laser is turned on and off. That is, the second control board determines the laser's on and off time based on the interpolation point data. Step 6.2: Calculate the time required for laser activation and deactivation, and transmit the calculated activation and deactivation time to the first control board; the galvanometer control board will stop when it is in the corresponding position to meet the laser activation delay and deactivation delay.

[0037] Step 7: After the laser switching time and galvanometer interpolation are completed, the laser control board adjusts the focal length according to the distance to the target projection surface. Before projection begins, to ensure a thin laser linewidth, the laser focal length needs to be adjusted so that the laser is precisely focused on the target projection surface.

[0038] First, based on the projection distance sent by the host computer, the laser control board automatically calculates the focal length of the target projection surface, and drives the motor to move the lens through the L293DD motor driver chip until the focal length reaches the target focal length, at which point the laser linewidth is the thinnest.

[0039] Step 8: After the focus is adjusted, the laser control board and the galvanometer control board perform laser projection through the XY2-100 protocol, and use an amplifier based on TL062 to amplify and follow the laser control signal to complete the projection task.

[0040] Step 8.1: The first control board reads the next interpolation point position information from the static random access memory through the FSMC bus (Flexible Static Memory Controller), outputs it to the differential driver chip through four independent signals, converts it into eight differential signals, and then transmits it to the galvanometer through the XY2-100 protocol. Step 8.2: Simultaneously, the second control board outputs a laser control signal, which is amplified and followed by TL062 before being sent to the laser module; Step 8.3: Complete the coordinated control of the laser and galvanometer.

[0041] Step 9: After the projection starts, the laser control board monitors the internal temperature of the equipment in real time and implements temperature control to prevent the temperature from being too high and affecting the accuracy of the galvanometer motor.

[0042] Step 9.1: The second control board periodically collects the voltage value on the thermistor through the ADC, calculates the resistance value of the thermistor based on the voltage, and then calculates the current temperature. Step 9.2: By judging the current temperature, obtain the corresponding fan speed, and control the fan to reach the corresponding speed through PWM wave.

[0043] Example 3 refer to Figure 2 A laser projection calibration board was prepared, on which several reflective target points were distributed. Several contour grooves with a width of 1mm were machined on the surface of the board. The purpose of this calibration board is to verify the positioning accuracy of the distributed control device.

[0044] The distributed control device in Example 1 and the laser projection control method of this application described in Example 2 were used for verification.

[0045] First, the relative position of the calibration board in the coordinate system is located and sent to the host computer. The host computer combines the graphic file with the target position of the target point and then sends the corresponding graphic file to the distributed control device. This device interpolates the graphic file and coordinates with the laser and galvanometer to project the graphic file.

[0046] It can be observed that the file perfectly overlaps with the contour groove of the calibration plate, confirming the control accuracy of the linear interpolation points in this application. Furthermore, the sharp angles of the inflection points in the graphic indicate accurate calculation. Moreover, there is no mutual interference between the graphics during multi-graphic projection, demonstrating the consistency of the laser and galvanometer's coordinated operation.

[0047] It should be noted that the various embodiments of this application can be arbitrarily combined into new embodiments, provided that the solutions do not conflict and the technical solutions can coexist.

[0048] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A laser projection control method, characterized in that: Includes the following steps: Step 1: Design a first control board for galvanometer control; the first control board includes a first main control chip for real-time calculation, a static random access memory for external memory expansion, a differential drive chip for transmitting galvanometer control signals, and a chip for implementing an independent communication system; Step 2: Design a second control board for laser control, focal length control, and temperature monitoring; the second control board includes a second main control chip for real-time calculation, a motor drive chip for driving the motor to move the lens and control the focal length, a laser control circuit amplifier chip, and a thermistor; Step 3: Scan the projection coordinate system of the galvanometer to obtain the center position of the reflective target point; Step 4: Obtain the scanned and located graphic file; analyze and identify the inflection points of the graphic file; perform adaptive delay; Step 5: Perform linear interpolation on the graphic file; store the linear interpolation data. Step 6: Determine the laser's on / off time based on the number of graphics and the linear interpolation point data; Step 7: Adjust the focal length according to the distance to the target projection surface; Step 8: The first and second control boards work together to complete the projection task; Step 9: Monitor the internal temperature of the equipment in real time and implement temperature control.

2. The laser projection control method according to claim 1, characterized in that: Step three specifically includes the following steps: Step 3.1: Adjust the focal length of the galvanometer using the first control board so that the diameter of the light spot generated by the galvanometer focusing on the plane is less than 10μm; Step 3.2: Use the first control board to control the focal length of the galvanometer to move to the initial position of the target point given by the host computer; and use the second control board to control the laser to turn on; Step 3.3: The first control board controls the galvanometer to perform an expansion scan centered on the initial position of the target point; the laser is always on; the second control board judges the reflected light signal in real time; Step 3.4: After acquiring the reflective signal, the second control board sends the reflective signal to the first control board; the first control board calculates the center position of the target reflective point by combining the position of the galvanometer when the reflective signal occurs; and sends the center position of the target reflective point to the host computer.

3. The laser projection control method according to claim 1, characterized in that: Step four specifically includes the following steps: Step 4.1: The first control board obtains the graphics file from the host computer. The graphics file contains several path points. Path point Xn forms vector A with the previous point Xn-1 and forms vector B with the next point Xn+1. Calculate the angle between vector A and vector B. ; Step 4.2: If If the angle is greater than 175°, it is determined that it is not an inflection point and no delay is performed; otherwise, it is determined that it is an inflection point and an inflection point delay is performed.

4. The laser projection control method according to claim 1, characterized in that: Step five specifically includes the following steps: Step 5.1: The first control board calculates the distance of the interpolation point based on the currently set galvanometer moving speed; Step 5.2: Calculate the required number of interpolation points based on the calculated interpolation point distances; and calculate the relative positions of the interpolation points in the projected coordinate system. Step 5.3: Due to the large number of interpolation points, the processor's internal storage space cannot meet the requirements, while the high-speed parallel static random access memory has the fastest read and write speed among external memory. Therefore, the interpolation points are ultimately stored in the external static random access memory.

5. The laser projection control method according to claim 1, characterized in that: Step six specifically includes the following steps: Step 6.1: The second control board determines the laser's on / off time based on the interpolation point data; Step 6.2: Calculate the time required for laser activation and deactivation, and transmit the calculated activation and deactivation time to the first control board; the galvanometer control board will stop when it is in the corresponding position to meet the laser activation delay and deactivation delay.

6. The laser projection control method according to claim 1, characterized in that: Steps seven and eight specifically include the following steps: Step 7.1: Based on the projection surface distance sent by the host computer, the second control board automatically calculates the focal length of the target projection surface, and drives the motor to move the lens through the motor drive chip until the focal length reaches the target focal length. Step 8.1: The first control board reads the next interpolation point position information from the static random access memory through the FSMC bus, outputs it to the differential driver chip through four independent signals, converts it into eight differential signals, and then transmits it to the galvanometer through the XY2-100 protocol. Step 8.2: Simultaneously, the second control board outputs a laser control signal, which is amplified and followed by TL062 before being sent to the laser module; Step 8.3: Complete the coordinated control of the laser and galvanometer.

7. The laser projection control method according to claim 1, characterized in that: Step nine specifically includes the following steps: Step 9.1: The second control board periodically collects the voltage value on the thermistor through the ADC, calculates the resistance value of the thermistor based on the voltage, and then calculates the current temperature. Step 9.2: By judging the current temperature, obtain the corresponding fan speed, and control the fan to reach the corresponding speed through PWM wave.

8. A distributed control device, characterized in that: It includes a host computer and an industrial control computer, the industrial control computer being electrically connected to the host computer, the industrial control computer including a first control board, a second control board and a laser energy feedback device, the first control board, the second control board and the laser energy feedback device being electrically connected.

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