Ultrasonic polarization and synchronous trigger control system and method

Abstract

The invention relates to an ultrasonic polarization and synchronous trigger control system and method.The system comprises an ultrasonic motor module, an imaging detector, an MCU and an upper computer, the ultrasonic motor module comprises an ultrasonic motor and a polaroid, the ultrasonic motor is of a hollow shaft structure design, the polaroid is arranged on a hollow shaft, and the imaging detector is arranged on the upper computer; the MCU comprises a PWM signal generator, the upper computer is used for sending out a control instruction, the MCU is used for receiving and analyzing the control instruction sent out by the upper computer, the analyzed control instruction is converted into a PWM control pulse through the PWM signal generator, and the angle of the polaroid is adjusted by modulating the PWM control pulse. And when the polaroid rotates to a preset angle, the MCU outputs a synchronous trigger signal to control the imaging detector to carry out image acquisition. Compared with the prior art, the requirements of the fields of polarization imaging, polarization measurement and the like on accurate control of the angle of the polaroid and synchronization with image acquisition are effectively met.

Description

Technical Field

[0001] The present invention relates to the technical field of polarization imaging, and in particular to an ultrasonic polarization and synchronous triggering control system and method. Background Art

[0002] Traditional polarization measurement systems mainly use manual or stepper motor drive to adjust the angle of the polarizer. The manual adjustment method is cumbersome and has low precision, making it difficult to ensure the repeatability and reliability of the measurement; while the stepper motor drive solution achieves the automation of angle adjustment, it has the following obvious shortcomings: First, the step angle of conventional stepper motors is large (usually 1.8°), and it is difficult to obtain the ideal angle resolution even with subdivision drive; second, stepper motors often need to drive polarizers through mechanical transmission structures such as gear sets, which inevitably introduces mechanical gaps and backlash errors, reducing the accuracy of angle control; finally, the multi-stage transmission structure makes the system bulky and complicated, which is not conducive to the miniaturization and integration of the entire system.

[0003] In recent years, as polarization imaging technology has developed towards high precision and real-time, higher requirements have been placed on the angle control accuracy and synchronization of polarization modulation. For example, in polarization stress measurement, a small error in the angle of the polarizer may lead to a large deviation in the stress calculation results. In polarization imaging of biological tissues, due to the dynamic characteristics of biological samples, the image acquisition process is required to have good real-time and synchronization. These application requirements are difficult to meet with traditional polarization modulation schemes.

[0004] On the other hand, current polarization imaging systems generally have the problem of low automation. Most systems require operators to manually set acquisition parameters, adjust polarizer angles, trigger camera acquisition, etc., which not only reduces work efficiency but also easily introduces human errors. Although some systems have introduced simple automatic control functions, they are often limited to fixed acquisition schemes and lack sufficient flexibility to adapt to different application requirements. At the same time, the coordination between the various parts of the system is not perfect, especially in the synchronization of polarization modulation and image acquisition. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide an ultrasonic polarization and synchronous triggering control system and method, so as to realize the precise control of the polarizer angle and the synchronous acquisition of the image.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] An ultrasonic polarization and synchronous trigger control system comprises an ultrasonic motor module, an imaging detector, an MCU and a host computer, wherein the ultrasonic motor module comprises an ultrasonic motor and a polarizer, the ultrasonic motor adopts a hollow shaft structure design, the polarizer is arranged on the hollow shaft, the MCU comprises a PWM signal generator, the host computer is used to issue control instructions, the MCU is used to receive and parse the control instructions issued by the host computer, the PWM signal generator converts the parsed control instructions into PWM control pulses, the PWM control pulses are modulated to adjust the angle of the polarizer, and when the polarizer rotates to a preset angle, the MCU outputs a synchronous trigger signal to control the imaging detector to collect images.

[0008] Furthermore, the ultrasonic motor module is fixed to the optical light-transmitting part at the front end of the imaging detector through a precision optomechanical coupling mechanism, the optical axis of the ultrasonic motor module remains coaxial with the optical axis of the imaging detector, and the rotor of the ultrasonic motor is coaxially fixed with the polarizer.

[0009] Furthermore, the host computer is configured with a standard serial port driver, and reliably communicates with the MCU through the standard serial port driver to transmit the control instruction, wherein the control parameters of the control instruction include multiple polarization channel numbers and single rotation angles, and the relationship between the polarization channel numbers and the single rotation angles is:

[0010]

[0011] Where n is the number of polarization channels and degree is the single rotation angle.

[0012] Furthermore, the MCU has an external interrupt function, which responds to and counts each PWM control pulse in real time, and obtains the number of PWM control pulses corresponding to a single rotation in combination with the step angle of the ultrasonic motor, and converts the number of PWM control pulses into the rotation angle of the polarizer. The number of PWM control pulses is:

[0013]

[0014] Where pwm_num is the number of PWM control pulses, and step is the step angle parameter.

[0015] Furthermore, the MCU is equipped with a USART serial communication interface and a general input / output interface.

[0016] Furthermore, the USART interface is connected to the host computer through a USB-TTL conversion module to build a stable and reliable two-way communication link, and a synchronous trigger signal is output through the universal input / output interface.

[0017] Furthermore, the configurable PWM output port of the MCU is connected to the pulse input port of the ultrasonic motor, and the rotation speed and angle of the ultrasonic motor are precisely controlled by modulating the signal parameters of the PWM control pulse, and the signal parameters include duty cycle, frequency and quantity.

[0018] Furthermore, the imaging detector is equipped with a standard external trigger interface and a high-speed digital image transmission interface, and provides adjustable imaging parameter configuration. The synchronous trigger signal issued by the MCU is received through the standard external trigger interface, and the collected image is transmitted to the host computer in real time through the high-speed digital image transmission interface.

[0019] Furthermore, the imaging parameters include multiple ones of resolution, frame rate, signal-to-noise ratio and dynamic range.

[0020] According to another aspect of the present invention, there is provided an ultrasonic polarization and synchronization trigger control method, comprising the following steps:

[0021] The host computer issues a control instruction, and the MCU receives and analyzes the control instruction issued by the host computer;

[0022] The analyzed control instruction is converted into a PWM control pulse by a PWM signal generator, and the angle of the polarizer is adjusted by modulating the PWM control pulse;

[0023] When the polarizer rotates to a preset angle, the MCU outputs a synchronous trigger signal to control the imaging detector to collect images.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention realizes high-precision and automatic adjustment of the polarizer angle by controlling the PWM driving pulse of the motor in real time through the MCU, outputs a synchronous trigger signal at a preset angle, and controls the imaging detector to collect images, thereby realizing precise synchronization of the polarization angle and image collection, and effectively solving the needs of polarization imaging, polarization measurement and other fields for precise control of the polarizer angle and its synchronization with image collection.

[0026] 2. The present invention uses MCU to accurately record the number of PWM pulses sent, introduces a real-time pulse counting mechanism, and accurately records the actual rotation amount of the ultrasonic motor to ensure the angle accuracy of polarization modulation. At the same time, the interrupt function of the hardware timer is used to strictly synchronize the acquisition process of the imaging detector to obtain a high-quality polarization image sequence.

[0027] 3. The present invention fixes the ultrasonic motor rotor and the polarizer coaxially, and directly drives the ultrasonic motor through the MCU, which simplifies the control system, improves the response speed and synchronization, and avoids the mechanical clearance and backlash errors that may be introduced by multi-stage transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of the ultrasonic polarization and synchronous triggering control system proposed by the present invention;

[0029] Figure 2 This is a hardware connection diagram of the ultrasonic polarization and synchronous trigger control system proposed in the present invention;

[0030] Figure 3 This is a schematic diagram of the control flow of the MCU.

[0031] Legend: 1. Host computer; 2. MCU; 3. Imaging detector; 4. Ultrasonic motor module; 5. Polarizer. DETAILED DESCRIPTION

[0032] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0033] Abbreviations involved:

[0034] Microcontroller Unit: Microcontroller Unit, MCU

[0035] Pulse Width Modulation: Pulse Width Modulation, PWM

[0036] Universal Synchronous / Asynchronous Receiver / Transmitter, USART

[0037] USB to TLL communication interface converter: Universal Serial Bus to Transistor-TransistorLogic, USB-TLL

[0038] Example 1

[0039] This embodiment provides an ultrasonic polarization and synchronization trigger control system, such as Figure 1As shown, it includes: an ultrasonic motor module 1, an imaging detector 2, an MCU3 and a host computer 4, wherein the ultrasonic motor module 1 includes an ultrasonic motor and a polarizer 5, the ultrasonic motor adopts a hollow shaft structure design, the polarizer 5 is arranged on the hollow shaft, the MCU3 includes a PWM signal generator, the host computer 4 is used to issue a control instruction, the MCU3 is used to receive and parse the control instruction issued by the host computer 4, and convert the parsed control instruction into a PWM control pulse through the PWM signal generator, and adjust the angle of the polarizer 5 by modulating the PWM control pulse. When the polarizer 5 rotates to a preset angle, the MCU3 outputs a synchronous trigger signal to control the imaging detector 2 to collect images.

[0040] The ultrasonic motor module 1 is fixed to the optical light-transmitting part of the front end of the imaging detector 2 by an elastic hinge design. The optical axis of the ultrasonic motor module 1 is coaxial with the optical axis of the imaging detector 2. The rotor of the ultrasonic motor and the polarizer 5 are coaxially fixed, avoiding the gap and backlash errors that may be introduced by multi-stage transmission. The smaller the step angle of the ultrasonic motor, the higher the accuracy of the angle control. An ultrasonic motor with a step angle of 0.05° can be used to achieve sub-resolution polarization modulation.

[0041] The imaging detector 2 is used to collect images at different polarization angles and transmit the image data to the host computer 4. The imaging detector 2 is equipped with a standard external trigger interface and a high-speed digital image transmission interface, such as USB3.0, GigE Vision or Camera Link, to ensure the real-time transmission of image data; and provides adjustable imaging parameter configuration, and receives the synchronization trigger signal issued by MCU3 through the standard external trigger interface. Imaging parameters include resolution, frame rate, signal-to-noise ratio and dynamic range. In specific implementation, an industrial camera with an external trigger interface can be selected, such as a black and white CCD camera with a GigE interface, with a resolution of more than 2 million pixels, which meets the needs of most polarization imaging. At the same time, the maximum frame rate of the camera is also a factor that needs to be considered. Too low a frame rate will affect the acquisition efficiency of the entire system. A camera with a maximum frame rate of 80fps can be selected to maximize the data acquisition speed while ensuring the imaging quality.

[0042] MCU3, as the core of the whole system, is responsible for coordinating the work of each module, controlling the rotation of the ultrasonic motor, and triggering the imaging detector 2 to collect images at a preset angle. MCU3 needs to have sufficient computing power, storage space and peripheral interfaces to meet the needs of real-time control. MCU3 is equipped with a USART serial communication interface and a general input / output interface. The configurable PWM output port of MCU3 is connected to the pulse input port of the ultrasonic motor. The speed of the ultrasonic motor and the rotation angle of the polarizer 5 are precisely controlled by modulating the signal parameters of the PWM control pulse. The signal parameters include duty cycle, frequency and quantity. The USART interface is connected to the host computer 4 through a USB-TTL conversion module to build a stable and reliable two-way communication link, and output a synchronous trigger signal through a general input / output interface. The STM32F1 series of microcontrollers can be used, with a main frequency of up to 72MHz, integrated with a rich communication interface (SPI, USART, I2C, etc.), and supports multi-channel PWM output, which can easily realize the synchronous control of the ultrasonic motor and the imaging detector 2.

[0043] As a user interaction interface, it is responsible for sending control instructions to MCU3, receiving and storing image data collected by the imaging detector 2, and performing subsequent image processing and analysis. The host computer 4 is usually a PC or an industrial computer, equipped with rich software resources. In the specific implementation, the necessary programming environment (such as LabVIEW, MATLAB, Python, etc.) and image processing library (such as OpenCV, Halcon, etc.) can be pre-installed in the host computer according to application requirements for secondary development. At the same time, the host computer 4 is configured with a standard serial port driver, and communicates reliably with MCU3 through a standard serial port driver (such as CH340, FT232, etc.) to transmit control instructions. The control parameters of the control instructions include multiple types of polarization channels and single rotation angles. The relationship between the number of polarization channels and the single rotation angle is:

[0044]

[0045] Where n is the number of polarization channels and degree is the single rotation angle.

[0046] MCU3 has an external interrupt function, which responds and counts each PWM control pulse in real time. Combined with the step angle of the ultrasonic motor, the number of PWM control pulses corresponding to a single rotation is obtained, and the number of PWM control pulses is converted into the rotation angle of the polarizer 5. The number of PWM control pulses is:

[0047]

[0048] Where pwm_num is the number of PWM control pulses, and step is the step angle parameter.

[0049] The hardware connection of the control system is as follows: Figure 2 As shown. Among them, the PWM pin of MCU3 is connected to the control end of the ultrasonic motor through the driving circuit to provide a PWM driving signal. The external trigger end of the imaging detector 2 is connected to the GPIO pin of MCU3 to receive a synchronous trigger signal. The host computer 4 and MCU3 use serial communication, and use a USB to TTL module (such as CH340) for level conversion. The host computer 4 and the imaging detector 2 generally use a Gigabit Ethernet direct connection to transmit image data. Isolation measures need to be considered for the power supply of the entire system to avoid mutual interference. The ultrasonic motor is powered separately, and its control end can be selectively left floating.

[0050] The control flow of MCU3 is as follows Figure 3 As shown, the following steps are included:

[0051] After the system is powered on, MCU3 is initialized first, including the configuration of peripherals such as GPIO, timer, and serial port:

[0052] (1) GPIO initialization: configure one GPIO (such as PA7) to PWM output mode to drive the ultrasonic motor; configure another GPIO (such as PA8) to push-pull output mode to generate a synchronous trigger signal; configure the TX and RX pins of USART (such as PA9 and PA10) to multiplexed function mode. The speed of all GPIOs is configured to 50MHz to improve the response speed.

[0053] (2) Timer initialization: Select a timer (such as TIM3) to generate PWM waves. By configuring the prescaler and auto-reload register, set the PWM frequency to the rated operating frequency of the ultrasonic motor (typical value is 20kHz to 80kHz), and the initial duty cycle is set to 50%. At the same time, configure the update interrupt of the timer, enter the interrupt service routine at the end of each PWM cycle, and add 1 to the global variable SUM_NUM to record the number of PWM pulses sent. Finally, enable the timer, start outputting PWM waveforms, and the ultrasonic motor starts to rotate.

[0054] (3) Serial port initialization: Configure the USART communication parameters, including baud rate (such as 115200), data bits (8 bits), stop bits (1 bit), parity bit (none), etc., and enable the receive interrupt and send functions to establish a communication connection with the host computer.

[0055] After initialization, MCU3 enters the main loop and continuously detects the control instructions sent by the host computer 4. Once a legal instruction is received, MCU3 performs the following processing:

[0056] (1) Command parsing: Extract the key parameters of this acquisition from the received data frame, including the number of polarization channels n and the single rotation angle degree.

[0057] (2) Parameter calculation: Combined with the actual step angle parameter step of the ultrasonic motor, the number of PWM pulses PWM_NUM corresponding to a single rotation is calculated as the basis for determining the timer interrupt.

[0058] (3) Angle judgment: The value of SUM_NUM is continuously read. When the increment of SUM_NUM is equal to PWM_NUM, it is considered that the polarizer 5 has been rotated to the preset angle.

[0059] (4) Trigger acquisition: pull up and delay for a short period of time, then pull down the synchronous IO port (such as PA8) to generate a synchronous pulse, triggering the imaging detector 2 to acquire the image. The imaging detector 2 sends the image data to the host computer through the GigE port.

[0060] (5) Loop control: Repeat steps (3) and (4) until the image acquisition of all n polarization channels is completed. After the acquisition is completed, MCU3 sends a completion mark to the host computer 4 through the serial port and waits for the next instruction to arrive.

[0061] The above process can ensure the precise synchronization of the rotation of the ultrasonic motor and the imaging detector 2, avoiding the accumulation of angle errors. At the same time, the host computer 4 can receive and store the collected polarization image sequence in real time, and perform subsequent processing and analysis, such as polarization denoising, anti-salt and pepper noise, decoupling, etc., to finally obtain a high-quality polarization image.

[0062] Example 2

[0063] This embodiment provides an ultrasonic polarization and synchronization trigger control method, comprising the following steps:

[0064] The host computer 4 issues control instructions, and the MCU 3 receives and analyzes the control instructions issued by the host computer 4;

[0065] The analyzed control instruction is converted into a PWM control pulse by a PWM signal generator, and the angle of the polarizer 5 is adjusted by modulating the PWM control pulse;

[0066] When the polarizer 5 rotates to a preset angle, the MCU 3 outputs a synchronous trigger signal to control the imaging detector 2 to collect images.

[0067] The rest is the same as in Example 1.

[0068] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. An ultrasonic polarization and synchronous trigger control system, characterized in that: The invention comprises an ultrasonic motor module (1), an imaging detector (2), an MCU (3) and a host computer (4); the ultrasonic motor module (1) comprises an ultrasonic motor and a polarizing plate (5); the ultrasonic motor adopts a hollow shaft structure design; the polarizing plate (5) is arranged on the hollow shaft; the MCU (3) comprises a PWM signal generator; the host computer (4) is used to issue a control instruction; the MCU (3) is used to receive and analyze the control instruction issued by the host computer (4); the analyzed control instruction is converted into a PWM control pulse by the PWM signal generator; the angle of the polarizing plate (5) is adjusted by modulating the PWM control pulse; when the polarizing plate (5) rotates to a preset angle, the MCU (3) outputs a synchronous trigger signal to control the imaging detector (2) to collect images.

2. The ultrasonic polarization and synchronous trigger control system according to claim 1, characterized in that: The ultrasonic motor module (1) is fixed to the optical light-transmitting portion at the front end of the imaging detector (2) through a precision optical-mechanical coupling mechanism, the optical axis of the ultrasonic motor module (1) remains coaxial with the optical axis of the imaging detector (2), and the rotor of the ultrasonic motor and the polarizing plate (5) are coaxially fixed.

3. The ultrasonic polarization and synchronous triggering control system according to claim 1, characterized in that: The host computer (4) is configured with a standard serial port driver, communicates with the MCU (3) through the standard serial port driver, and transmits the control instruction, wherein the control parameters of the control instruction include multiple polarization channel numbers and single rotation angles, and the relationship between the polarization channel numbers and the single rotation angles is: Where n is the number of polarization channels and degree is the single rotation angle.

4. The ultrasonic polarization and synchronous trigger control system according to claim 3, characterized in that: The MCU (3) responds to and counts each PWM control pulse in real time, and obtains the number of PWM control pulses corresponding to a single rotation in combination with the step angle of the ultrasonic motor, and converts the number of PWM control pulses into the rotation angle of the polarizer (5). The number of PWM control pulses is: Where pwm_num is the number of PWM control pulses, and step is the step angle parameter.

5. The ultrasonic polarization and synchronous trigger control system according to claim 1, characterized in that: The MCU (3) is equipped with a USART serial communication interface and a general input / output interface.

6. The ultrasonic polarization and synchronous trigger control system according to claim 5, characterized in that: The USART interface is connected to the host computer through a USB-TTL conversion module to build a stable and reliable two-way communication link, and a synchronous trigger signal is output through the universal input / output interface.

7. The ultrasonic polarization and synchronous trigger control system according to claim 1, characterized in that: The configurable PWM output port of the MCU (3) is connected to the pulse input port of the ultrasonic motor, and the rotation speed and angle of the ultrasonic motor are precisely controlled by modulating the signal parameters of the PWM control pulse, wherein the signal parameters include duty cycle, frequency and quantity.

8. The ultrasonic polarization and synchronous trigger control system according to claim 1, characterized in that: The imaging detector (2) is equipped with a standard external trigger interface and a high-speed digital image transmission interface, and provides adjustable imaging parameter configuration, receives a synchronous trigger signal sent by the MCU (3) through the standard external trigger interface, and transmits the collected image to the host computer (4) in real time through the high-speed digital image transmission interface.

9. The ultrasonic polarization and synchronous trigger control system according to claim 8, characterized in that: The imaging parameters include various ones of resolution, frame rate, signal-to-noise ratio and dynamic range.

10. An ultrasonic polarization and synchronous trigger control method, characterized in that: The following steps are involved: The host computer (4) issues a control instruction, and the MCU (3) receives and analyzes the control instruction issued by the host computer (4); The analyzed control instruction is converted into a PWM control pulse by a PWM signal generator in the MCU (3), and the angle of the polarizer (5) in the ultrasonic motor module (1) is adjusted by modulating the PWM control pulse; When the polarizing plate (5) rotates to a preset angle, the MCU (3) outputs a synchronous trigger signal to control the imaging detector (2) to collect images.

Images