Method, system and device for controlling digital variable optical attenuator

Abstract

The invention provides a control method, system and device for a digital variable optical attenuator, and relates to the technical field of optical communication, and the control device mainly comprises a power supply management circuit, a main control circuit, a communication interface circuit, a motor drive circuit, a Hall sensor and an optical power feedback circuit. The pulse width modulation circuit is used for outputting the pulse width modulation signal to the motor driving circuit and collecting state monitoring data of the motor driving circuit; information interaction with the communication interface circuit is realized; and collecting data of the Hall sensor and the optical power feedback circuit. According to the scheme, digital control is carried out on the variable optical attenuator motor in a pulse width modulation mode; a Hall sensor can be arranged on the main shaft of the motor, so that internal closed-loop feedback is facilitated, and the control precision is improved; a photoelectric detection sensor can be arranged at the output end of the light path, so that external closed-loop feedback is realized, and the control precision is further improved; the scheme has the advantages of being small in size, good in integration, high in response speed and high in resolution.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a control method, system and device for a digital adjustable optical attenuator. Background Art

[0002] When optically interconnecting different devices or measuring laser parameters, it is often necessary to weaken the laser light intensity. The device that realizes this function is called an optical attenuator. The optical attenuator can be roughly divided into two categories: a fixed attenuator with a fixed attenuation and an adjustable optical attenuator with adjustable attenuation. Among them, the adjustable optical attenuator is widely used.

[0003] At present, the adjustable optical attenuator is one of the main passive components and has long remained at the level of mechanical adjustment. The mechanical adjustable optical attenuator mainly includes a stepper motor, a light blocking element and a fiber collimator: the motor drives the light blocking element to rotate between two fiber collimators to achieve the attenuation of optical power. Although the optical characteristics of the mechanical adjustable optical attenuator meet the requirements, and it has advantages such as mature technology and no need for temperature control, it also has disadvantages such as large size, slow response speed, poor integration and low resolution.

[0004] As all-optical communication networks place increasingly higher demands on the convenience, response speed and resolution of components, the industry is in urgent need of developing adjustable optical attenuators with small size, good integration, fast response speed and high resolution. Summary of the invention

[0005] The object of the present invention is to provide a control method, system and device for a digital adjustable optical attenuator to solve at least one of the above technical problems existing in the prior art.

[0006] In a first aspect, in order to solve the above technical problem, the present invention provides a control method of a digital adjustable optical attenuator, comprising the following steps: Step 1, receiving the required optical power value input from the outside; Step 2: Compare the required optical power value with the current optical power value: if they are the same, execute step 1; if they are different, execute step 3; Step 3: Calculate the attenuation value of the required optical power value and the current optical power value; based on the attenuation value, calculate the rotation step angle of the adjustable optical attenuator motor; based on the rotation step angle, calculate the duty cycle and frequency of the pulse width modulation (PWM) signal. The specific formula can be: Duty cycle = (motor control accuracy / rotation step angle) x 100%; Frequency = maximum motor speed x number of pulses in a single step; Inputting the pulse width modulation signal to the motor to drive the motor shaft to rotate; Step 4: Collect the actual rotation angle of the motor main shaft, and compare the rotation step angle with the actual rotation angle: if they are the same, take the required optical power value as the current optical power value, and iterate step 1 until the first iteration end condition is reached; if they are different, execute step 5; Step 5, determine whether the rotation step angle is greater than the actual rotation angle: if so, drive the motor forward by the preset compensation step angle according to the method in step 3, and execute step 4; if not, drive the motor reverse by the preset compensation step angle according to the method in step 3, and execute step 4.

[0007] Through the above method, the motor of the adjustable optical attenuator can be closed-loop controlled by pulse width modulation, so as to achieve the purpose of digitally and accurately adjusting the optical attenuation value.

[0008] In a feasible implementation manner, the motor control accuracy in step 3 may be 0.1 degrees, and of course may be set according to actual industrial control.

[0009] In a feasible implementation manner, in step 4, the actual rotation angle of the motor main shaft can be collected through the state monitoring function of the motor drive circuit.

[0010] In a feasible implementation manner, in step 4, a Hall sensor may be installed on the motor shaft to collect the actual rotation angle of the motor shaft, so as to improve the detection accuracy of the actual rotation angle.

[0011] In a feasible implementation manner, the first iteration end condition in step 4 is that the required optical power value is equal to the current optical power value.

[0012] In a feasible implementation manner, the preset compensation step angle in step 5 is one step angle.

[0013] In a feasible implementation manner, the control method further includes: Step 6: Collect the optical power signal at the output end of the optical path through a photoelectric detection sensor and other devices and convert it into a current signal; then convert the current signal into a voltage signal through Ohm's law; based on the voltage signal, calculate the actual optical power value; the specific formula can be: Current signal = optical power signal x photoelectric conversion efficiency; Voltage signal = current signal x preset resistance value; Actual optical power value = voltage signal / (photoelectric conversion efficiency x preset resistance value); Step 7: Use the actual optical power value as the current optical power value and iteratively execute step 2 until the second iteration end condition is reached.

[0014] Through the above steps, the attenuation effect of the optical attenuator can be automatically fed back, and based on the actual optical power value, the optical attenuator can be iteratively adjusted until the use requirement is met.

[0015] In a feasible implementation manner, the second iteration end condition in step 7 is that the required optical power value is equal to the current optical power value.

[0016] In the second aspect, based on the same inventive concept, the present application also provides a control system for a digital adjustable optical attenuator, including a control module and a motor drive module: The control module is used to receive the required optical power value input from the outside; calculate the attenuation value of the required optical power value and the current optical power value; based on the attenuation value, calculate the rotation step angle of the adjustable optical attenuator motor; based on the rotation step angle, calculate the duty cycle and frequency of the pulse width modulation (PWM) signal. The specific formula can be: Duty cycle = (motor control accuracy / rotation step angle) x 100%; Frequency = maximum motor speed x number of pulses in a single step; Inputting the pulse width modulation signal to the motor drive module; Receive the actual rotation angle of the motor spindle, compare the rotation step angle with the actual rotation angle and perform iterative compensation; The motor driving module drives the motor of the adjustable optical attenuator to operate based on the pulse width modulation signal, and feeds back the actual rotation angle of the motor main shaft to the control module.

[0017] In a feasible implementation manner, the control system further includes a position feedback module, which is used to collect the actual rotation angle of the motor spindle and feed it back to the control module to further improve the detection accuracy of the actual rotation angle.

[0018] In a feasible implementation manner, the control system further includes an optical power feedback module, which is used to collect the optical power signal at the output end of the optical path and convert it into a current signal; and then, according to Ohm's law, the current signal is converted into a voltage signal and fed back to the control module. The specific formula can be: Current signal = optical power signal x photoelectric conversion efficiency; Voltage signal = current signal x preset resistance value; The control module also calculates the actual optical power value according to the voltage signal and compares it with the required optical power value, and then iteratively compensates the rotation step angle. The specific formula can be: Actual optical power value = voltage signal / (photoelectric conversion efficiency x preset resistance value).

[0019] This forms a closed-loop feedback loop of optical power, which can compensate for the error in optical power caused by the mechanical structure transmission and other links of the adjustable optical attenuator, and improve the overall attenuation accuracy of the optical attenuator.

[0020] In the third aspect, based on the same inventive concept, the present application also provides a control device for a digital adjustable optical attenuator, including a power supply management circuit, a main control circuit, a communication interface circuit and a motor drive circuit: The power supply management circuit is used to supply power to the motor drive circuit, the main control circuit and the communication interface circuit respectively; The main control circuit includes a single chip microcomputer (such as STM32), which is electrically connected to the power supply management circuit, the communication interface circuit and the motor drive circuit, and is used to output a pulse width modulation signal to the motor drive circuit and collect the latter's state monitoring data through program control; and realize information interaction with the communication interface circuit; The communication interface circuit is used to interact with the outside through a standard protocol interface; The motor driving circuit comprises a stepper motor driving chip, which is used to: control the rotation angle of the stepper motor main shaft through the duty cycle of the pulse width modulation signal; and monitor the working state of the stepper motor.

[0021] Through the above structure, the working process that can be realized is as follows: receiving the required optical power value transmitted from the outside through the communication interface circuit; calculating the attenuation value of the required optical power value and the current optical power value through the main control circuit; calculating the rotation step angle of the adjustable optical attenuator motor based on the attenuation value; calculating the duty cycle and frequency of the pulse width modulation (PWM) signal based on the rotation step angle, and inputting the pulse width modulation signal to the motor driving circuit; driving the stepping motor of the adjustable optical attenuator to operate through the motor driving circuit and feeding back the working state of the stepping motor to the single chip microcomputer, wherein the working state includes the actual rotation angle of the motor main shaft.

[0022] In a feasible implementation, the power supply management circuit includes two linear voltage regulator power supply chips (LDO), which convert the +12V power supply into a +5V power supply and a +3.3V power supply respectively: the +5V power supply is used to power the motor drive circuit; the +3.3V power supply is used to power the main control circuit and the communication interface circuit; this can meet the conventional power supply configuration requirements.

[0023] In a feasible implementation manner, the communication interface circuit includes an RS232 communication circuit and / or a CAN communication circuit: The RS232 communication circuit is used to realize point-to-point control with a host computer (such as a computer) through an RS232 standard protocol interface; The CAN communication circuit is used to be connected in series with a superior device or a device of the same level through a CAN standard protocol interface; Of course, other standard protocol interface communication circuits known in the art may also be used according to actual needs.

[0024] In a feasible implementation, the control device also includes a Hall sensor, which is connected to the stepper motor spindle through a mechanical structure such as a coupling to ensure the synchronous rotation of the light blocking element, the stepper motor spindle and the Hall sensor; the Hall sensor is electrically connected to the single-chip computer to collect and feedback the actual rotation angle of the stepper motor spindle to achieve closed-loop control and further improve control accuracy; the Hall sensor is connected to the +3.3V power supply.

[0025] In a feasible implementation manner, the control device also includes an optical power feedback circuit, which is arranged at the optical path output end of the adjustable optical attenuator and is electrically connected to the +3.3V power supply and the main control circuit respectively, and is used to collect the optical power signal at the optical path output end and convert it into a current signal; then, through Ohm's law, the current signal is converted into a voltage signal and fed back to the single-chip microcomputer; the single-chip microcomputer also calculates the actual optical power value based on the voltage signal and compares it with the required optical power value, and then iteratively compensates the rotation step angle; in this way, a closed-loop feedback of optical power is formed, which can compensate for the error of the optical power caused by the mechanical structure transmission and other links of the adjustable optical attenuator, thereby improving the overall attenuation accuracy of the optical attenuator.

[0026] In a feasible implementation, the assembly principles of the control device include: high-frequency cables and low-frequency cables cannot appear in the same wiring harness; power lines and signal lines are separated; input signal lines and output signal lines are separated; signal lines are kept away from high-power devices; this can reduce electromagnetic interference and coupling problems.

[0027] By adopting the above technical solution, the present invention has the following beneficial effects: The present invention provides a control method, system and device for a digital adjustable optical attenuator, which digitally controls the motor of the adjustable optical attenuator by means of pulse width modulation; a Hall sensor can be arranged on the main shaft of the motor, which is beneficial to internal closed-loop feedback and improves control accuracy; a photoelectric detection sensor can be arranged at the output end of the optical path to achieve external closed-loop feedback and further improve control accuracy; the solution has the characteristics of small size, good integration, fast response speed and high resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1A flow chart of a control method of a digital adjustable optical attenuator provided by an embodiment of the present invention; Figure 2 A control system diagram of a digital adjustable optical attenuator provided by an embodiment of the present invention; Figure 3 A simplified diagram of the structural relationship of a control device for a digital adjustable optical attenuator provided by an embodiment of the present invention; Figure 4 A layout diagram of a power supply management circuit provided in an embodiment of the present invention; Figure 5 A main control circuit layout diagram provided for an embodiment of the present invention; Figure 6 A layout diagram of a motor drive circuit provided by an embodiment of the present invention; Figure 7 A layout diagram of an optical power feedback circuit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] Before describing each embodiment in detail, in order to facilitate understanding of each embodiment, the inventive concept of the present application is briefly described as follows: In order to solve the various problems mentioned in the background technology, the present application first considers using a single-chip microcomputer to apply the duty cycle in pulse width modulation to the control of the stepper motor of the adjustable optical attenuator, thereby realizing digital control; then considers using a Hall sensor to detect the rotation angle of the stepper motor spindle and feed it back to the single-chip microcomputer, and then the single-chip microcomputer compensates the stepper motor, thereby improving the closed-loop feedback effect; then considers using a photoelectric detection sensor to detect the optical power at the output end of the optical path and feed it back to the single-chip microcomputer, and then the single-chip microcomputer compensates the stepper motor, thereby further improving the closed-loop feedback effect.

[0034] The present invention is further explained below in conjunction with specific implementation modes.

[0035] It should also be noted that the following specific embodiments or specific implementations are a series of optimized settings listed in the present invention to further explain the specific content of the invention, and these settings can be used in combination or in association with each other.

[0036] Embodiment 1: like Figure 1 As shown, the present embodiment provides a control method for a digital adjustable optical attenuator, comprising the following steps: Step 1, receiving the required optical power value input from the outside; Step 2: Compare the required optical power value with the current optical power value: if they are the same, execute step 1; if they are different, execute step 3; Step 3: Calculate the attenuation value of the required optical power value and the current optical power value; based on the attenuation value, calculate the rotation step angle of the adjustable optical attenuator motor; based on the rotation step angle, calculate the duty cycle and frequency of the pulse width modulation (PWM) signal. The specific formula can be: Duty cycle = (motor control accuracy / rotation step angle) x 100%; Frequency = maximum motor speed x number of pulses in a single step; Inputting the pulse width modulation signal to the motor to drive the motor shaft to rotate; Step 4: Collect the actual rotation angle of the motor main shaft, and compare the rotation step angle with the actual rotation angle: if they are the same, take the required optical power value as the current optical power value, and iterate step 1 until the first iteration end condition is reached; if they are different, execute step 5; Step 5, determine whether the rotation step angle is greater than the actual rotation angle: if so, drive the motor to rotate forward by a preset compensation step angle according to the method in step 3, and execute step 4; if not, drive the motor to rotate reversely by a preset compensation step angle according to the method in step 3, and execute step 4; Step 6: Collect the optical power signal at the output end of the optical path through a photoelectric detection sensor and other devices and convert it into a current signal; then convert the current signal into a voltage signal through Ohm's law; based on the voltage signal, calculate the actual optical power value; the specific formula can be: Current signal = optical power signal x photoelectric conversion efficiency; Voltage signal = current signal x preset resistance value; Actual optical power value = voltage signal / (photoelectric conversion efficiency x preset resistance value); Step 7: Use the actual optical power value as the current optical power value and iteratively execute step 2 until the second iteration end condition is reached.

[0037] Furthermore, the motor control accuracy in step 3 may be 0.1 degrees; Furthermore, in step 4, the actual rotation angle of the motor main shaft can be collected through the state monitoring function of the motor drive circuit; Furthermore, in step 4, a Hall sensor may be installed at the motor spindle to collect the actual rotation angle of the motor spindle, so as to improve the detection accuracy of the actual rotation angle; Furthermore, the first iteration end condition in step 4 is that the required optical power value is equal to the current optical power value.

[0038] Furthermore, the compensation step angle is preset in step 5 as a step angle.

[0039] Furthermore, the second iteration end condition in step 7 is that the required optical power value is equal to the current optical power value.

[0040] Embodiment 2: like Figure 2 As shown, this embodiment provides a control system for a digital adjustable optical attenuator, including a control module, a motor drive module, a position feedback module and an optical power feedback module: The control module is used to receive the required optical power value input from the outside; calculate the attenuation value of the required optical power value and the current optical power value; based on the attenuation value, calculate the rotation step angle of the adjustable optical attenuator motor; based on the rotation step angle, calculate the duty cycle and frequency of the pulse width modulation (PWM) signal. The specific formula can be: Duty cycle = (motor control accuracy / rotation step angle) x 100%; Frequency = maximum motor speed x number of pulses in a single step; Inputting the pulse width modulation signal to the motor drive module; Receive the actual rotation angle of the motor spindle, compare the rotation step angle with the actual rotation angle and perform iterative compensation; The motor driving module drives the motor of the adjustable optical attenuator to operate based on the pulse width modulation signal, and feeds back the actual rotation angle of the motor main shaft to the control module.

[0041] The position feedback module is used to collect the actual rotation angle of the motor spindle and feed it back to the control module to further improve the detection accuracy of the actual rotation angle; The optical power feedback module is used to collect the optical power signal at the output end of the optical path and convert it into a current signal; then, according to Ohm's law, the current signal is converted into a voltage signal and fed back to the control module. The specific formula can be: Current signal = optical power signal x photoelectric conversion efficiency; Voltage signal = current signal x preset resistance value; The control module also calculates the actual optical power value according to the voltage signal and compares it with the required optical power value, and then iteratively compensates the rotation step angle. The specific formula can be: Actual optical power value = voltage signal / (photoelectric conversion efficiency x preset resistance value).

[0042] Embodiment three: like Figure 3 As shown, this embodiment provides a control device for a digital adjustable optical attenuator, including a power supply management circuit (power supply and distribution system), a main control circuit (STM32 / FPGA main control), a communication interface circuit (connecting a host computer and a host device) and a motor drive circuit: The power management circuit includes two linear voltage regulator chips (LDO), which convert +12V power into +5V power and +3.3V power respectively: The +5V power supply is used to power the motor drive circuit. Figure 4 As shown in the upper middle part, it mainly includes: LDO linear voltage-stabilized power supply chip U5 (AMS1117-5), capacitor C12 (10μF), capacitor C13 (4.7μF), capacitor C14 (4.7μF) and capacitor C15 (10μF): the input pin of the LDO linear voltage-stabilized power supply chip U5 is connected to the +12V power supply, the ground pin is grounded, the two output pins are short-circuited, and the output voltage is +5V; the capacitor C12 and the capacitor C13 are connected in parallel between the input pin and the ground pin of the LDO linear voltage-stabilized power supply chip U5, so that they can be used as input and output capacitors for energy storage filtering; the capacitor C14 and the capacitor C15 are connected in parallel between the output pin and the ground pin of the LDO linear voltage-stabilized power supply chip U5, so that the output load capacity can be further enhanced while realizing the power supply filtering function; The +3.3V power supply is used to power the main control circuit and the communication interface circuit. Figure 4As shown in the lower middle part, it mainly includes: LDO linear voltage-stabilized power supply chip U6 (AMS1117-3.3), capacitor C16 (10μF), capacitor C17 (4.7μF), capacitor C18 (4.7μF) and capacitor C19 (10μF): the input pin of the LDO linear voltage-stabilized power supply chip U6 is connected to the +12V power supply, the ground pin is grounded, the two output pins are short-circuited, and the output voltage is +3.3V; the capacitor C16 and the capacitor C17 are connected in parallel between the input pin and the ground pin of the LDO linear voltage-stabilized power supply chip U6, so that they can be used as input and output capacitors for energy storage filtering; the capacitor C18 and the capacitor C19 are connected in parallel between the output pin and the ground pin of the LDO linear voltage-stabilized power supply chip U6, so that the output load capacity can be further enhanced while realizing the power supply filtering function; The main control circuit includes a single-chip microcomputer U7 (STM32G47RET6), which is electrically connected to the power supply management circuit, the communication interface circuit and the motor drive circuit, and is used to output a pulse width modulation signal to the motor drive circuit and collect the latter's state monitoring data through a program control method; and realize information interaction with the communication interface circuit; The circuit diagram of the main control circuit is as follows: Figure 5 As shown, it mainly includes: a single-chip microcomputer U7, a capacitor C25 (100nF) and a capacitor C26 (100nF): the PB1 pin, the PB2 pin, the VSSA pin and the VREF+ pin of the single-chip microcomputer U7 are respectively electrically connected to the motor drive circuit for outputting a pulse width modulation (PWM) signal and collecting the latter's state monitoring data; the VSSA pin is grounded; the VREF+ pin is connected to a +3.3V power supply; the capacitor C25 and the capacitor C26 are connected in parallel between the VSSA pin and the VREF+ pin for filtering; the PC4 / USART1_TX pin, the PC5 / USART1_RX pin, the PA12 / CAN_TX pin and the PA11 / CAN_RX pin of the single-chip microcomputer U7 are respectively electrically connected to the communication interface circuit for realizing information interaction; The communication interface circuit includes an RS232 communication circuit and / or a CAN communication circuit: The RS232 communication circuit is used to realize point-to-point control with a host computer (such as a computer) through an RS232 standard protocol interface; The CAN communication circuit is used to be connected in series with a superior device or a device of the same level through a CAN standard protocol interface; The motor drive circuit is used to control the rotation angle of the stepper motor spindle through the duty cycle of the pulse width modulation signal; monitor the working state of the stepper motor; The circuit diagram of the motor drive circuit is as follows: Figure 6As shown, it mainly includes a stepper motor driver chip U1 (DRV8833), a resistor R1 (200MΩ), a resistor R2 (200MΩ), a resistor R3 (4.7KΩ), a capacitor C1 (2.2μF), a capacitor C2 (100nF), a capacitor C3 (4.7μF) and a polarity capacitor E1 (10μF): the ALSEN pin of the stepper motor driver chip U1 is connected to one end of the resistor R1, and the other end of the resistor R1 is grounded; the BLSEN pin of the stepper motor driver chip U1 is connected to one end of the resistor R2, and the other end of the resistor R2 is grounded , used to adjust the stepper motor drive current. Changing the resistance values ​​of resistors R1 and R2 can change the stepper motor drive current, which is convenient for controlling the maximum output current of the stepper motor driver chip U1 to be lower than the rated current of the stepper motor during the debugging process, thereby avoiding overcurrent and burning of the stepper motor; the nSLEEP pin of the stepper motor driver chip U1 is a sleep mode pin. When the device is turned on and not used for a long time, setting the pin to a high level will put the stepper motor driver chip U1 into sleep mode, thereby reducing power consumption; the AOUT1 pin of the stepper motor driver chip U1 The AOUT1 pin, AOUT2 pin, BOUT1 pin and BOUT2 pin are respectively connected to the input winding of the stepper motor to drive the stepper motor to rotate; the nFAULT pin of the stepper motor driver chip U1 is connected to one end of the resistor R3 to output the fault information of the stepper motor driver chip; the AIN1 pin, AIN2 pin, BIN1 pin and BIN2 pin of the stepper motor driver chip U1 are respectively connected to the PB1 pin, PB2 pin, VSSA pin and VREF+ pin of the single-chip computer U7 to input pulse width modulation (PWM) signals and change the pulse width modulation The duty cycle of the PWM signal adjusts the rotation angle of the stepper motor; the VINT pin of the stepper motor driver chip U1 is connected to one end of the capacitor C1, and the other end of the capacitor C1 is grounded for input power decoupling; the capacitor C2 is connected to the VM pin and the VCP pin of the stepper motor driver chip U1 for input power filtering; the capacitor C3 and the polar capacitor E1 are connected in parallel between the VM pin and the ground, and the positive electrode of the polar capacitor E1 is connected to the VM pin and connected to the +5V power supply for input power energy storage, so as to realize the function of stable operation of the stepper motor under high load conditions.

[0043] Through the above structure, the working process that can be realized is as follows: receiving the required optical power value transmitted from the outside through the communication interface circuit; calculating the attenuation value of the required optical power value and the current optical power value through the main control circuit; calculating the rotation step angle of the adjustable optical attenuator motor based on the attenuation value; calculating the duty cycle and frequency of the pulse width modulation (PWM) signal based on the rotation step angle, and inputting the pulse width modulation signal to the motor driving circuit; driving the stepping motor of the adjustable optical attenuator to operate through the motor driving circuit and feeding back the working state of the stepping motor to the single chip microcomputer, wherein the working state includes the actual rotation angle of the motor main shaft.

[0044] Furthermore, the control device also includes a Hall sensor, which is connected to the stepper motor spindle through a mechanical structure such as a coupling or a coaxial device to ensure the synchronous rotation of the light blocking element, the stepper motor spindle and the Hall sensor; the Hall sensor is electrically connected to the single-chip computer to collect and feedback the actual rotation angle of the stepper motor spindle, thereby realizing closed-loop control and further improving control accuracy; the Hall sensor is connected to the +3.3V power supply.

[0045] Furthermore, the control device also includes an optical power feedback circuit, which is arranged at the optical path output end of the adjustable optical attenuator and is electrically connected to the single-chip microcomputer and the +3.3V power supply respectively, and is used to collect the optical power signal at the optical path output end and convert it into a current signal; then, according to Ohm's law, the current signal is converted into a voltage signal and fed back to the single-chip microcomputer; the single-chip microcomputer also calculates the actual optical power value according to the voltage signal and compares it with the required optical power value, and then iteratively compensates the rotation step angle; thus, a closed-loop feedback of optical power is formed, which can compensate for the error of the optical power caused by the mechanical structure transmission and other links of the adjustable optical attenuator, and improve the overall attenuation accuracy of the optical attenuator; The optical power feedback circuit, such as Figure 7 As shown, it mainly includes operational amplifier U4 (OAP2188), resistor R12 (1KΩ), resistor R13 (1KΩ), capacitor C10 (100nF), capacitor C11 (100nF) and photoelectric probe PD: The OUTA pin, INA- pin, INA+ pin, GND pin and INB+ pin of the operational amplifier U4 are all grounded; the capacitor C11 and the resistor R13 are connected in parallel between the INB+ pin and the INB- pin of the operational amplifier U4; the INB- pin is also connected to the No. 2 pin of the photoelectric probe PD; the No. 1 pin of the photoelectric probe PD is grounded; the No. 3 pin of the photoelectric probe PD is connected to one end of the resistor R12, and the other end of the resistor R12 is connected to the VCC pin of the operational amplifier U4; the capacitor C10 is connected between the VCC pin and the ground, and is used for decoupling the input power supply of the operational amplifier U4 to prevent the operational amplifier U4 from being affected by the power supply ripple when collecting weak signals; the OUTB pin of the operational amplifier U4 is connected to the PC3 / ADC12_IN9 pin of the microcontroller U7, and is used to feed back the voltage signal to the microcontroller U7.

[0046] Furthermore, the assembly principles of the control device include: high-frequency cables and low-frequency cables cannot appear in the same wiring harness; power lines and signal lines are separated; input signal lines and output signal lines are separated; signal lines are kept away from high-power devices; this can reduce electromagnetic interference and coupling problems.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for a digital adjustable optical attenuator, characterized in that: include: Step 1, receiving the required optical power value input from the outside; Step 2: Compare the required optical power value with the current optical power value: if they are the same, execute step 1; if they are different, execute step 3; Step 3: Calculate the attenuation value of the required optical power value and the current optical power value; based on the attenuation value, calculate the rotation step angle of the adjustable optical attenuator motor; based on the rotation step angle, calculate the duty cycle and frequency of the pulse width modulation signal, the specific formula is: Duty cycle = (motor control accuracy / rotation step angle) x 100%; Frequency = maximum motor speed x number of pulses in a single step; Inputting the pulse width modulation signal to the motor to drive the motor shaft to rotate; Step 4: Collect the actual rotation angle of the motor main shaft, and compare the rotation step angle with the actual rotation angle: if they are the same, take the required optical power value as the current optical power value, and iterate step 1 until the first iteration end condition is reached; if they are different, execute step 5; Step 5, determine whether the rotation step angle is greater than the actual rotation angle: if so, drive the motor forward by the preset compensation step angle according to the method in step 3, and execute step 4; if not, drive the motor reverse by the preset compensation step angle according to the method in step 3, and execute step 4.

2. The control method according to claim 1, characterized in that: In step 4, a Hall sensor is installed on the motor shaft to collect the actual rotation angle of the motor shaft.

3. The control method according to claim 1, characterized in that: The first iteration end condition in step 4 is that the required optical power value is equal to the current optical power value.

4. The control method according to claim 1, characterized in that: In step 5, the compensation step angle is preset to be one step angle.

5. The control method according to claim 1, characterized in that: Also includes: Step 6, collecting the optical power signal at the output end of the optical path and converting it into a current signal; Then, the current signal is converted into a voltage signal by Ohm's law. Based on the voltage signal, the actual optical power value is calculated. The specific formula is: Current signal = optical power signal x photoelectric conversion efficiency; Voltage signal = current signal x preset resistance value; Actual optical power value = voltage signal / (photoelectric conversion efficiency x preset resistance value); Step 7: Use the actual optical power value as the current optical power value and iteratively execute step 2 until the second iteration end condition is reached.

6. A control system for a digital variable optical attenuator, characterized in that: Including control module and motor drive module: The control module is used to receive the required optical power value input from the outside; calculate the attenuation value of the required optical power value and the current optical power value; based on the attenuation value, calculate the rotation step angle of the adjustable optical attenuator motor; based on the rotation step angle, calculate the duty cycle and frequency of the pulse width modulation signal, and the specific formula is: Duty cycle = (motor control accuracy / rotation step angle) x 100%; Frequency = maximum motor speed x number of pulses in a single step; Inputting the pulse width modulation signal to the motor drive module; Receive the actual rotation angle of the motor spindle, compare the rotation step angle with the actual rotation angle and perform iterative compensation; The motor driving module drives the motor of the adjustable optical attenuator to operate based on the pulse width modulation signal; The actual rotation angle of the motor shaft is fed back to the control module.

7. The control system according to claim 6, characterized in that: It also includes a position feedback module, which is used to collect the actual rotation angle of the motor main shaft and feed it back to the control module.

8. The control system according to claim 7, characterized in that: It also includes an optical power feedback module, which is used to collect the optical power signal at the output end of the optical path and convert it into a current signal; then, according to Ohm's law, the current signal is converted into a voltage signal and fed back to the control module. The specific formula is: Current signal = optical power signal x photoelectric conversion efficiency; Voltage signal = current signal x preset resistance value; The control module also calculates the actual optical power value according to the voltage signal and compares it with the required optical power value, and then iteratively compensates the rotation step angle. The specific formula is: Actual optical power value = voltage signal / (photoelectric conversion efficiency x preset resistance value).

9. A control device for a digital adjustable optical attenuator, characterized in that: Including power supply management circuit, main control circuit, communication interface circuit, motor drive circuit, Hall sensor and optical power feedback circuit: The power supply management circuit is used to supply power to the motor drive circuit, the main control circuit, the communication interface circuit, the Hall sensor and the optical power feedback circuit respectively; The main control circuit includes a single chip microcomputer, which is electrically connected to the power supply management circuit, the communication interface circuit, the motor drive circuit, the Hall sensor and the optical power feedback circuit, respectively, for implementing the control method as claimed in any one of claims 1 to 5; The communication interface circuit is used to interact with the outside through a standard protocol interface; The motor drive circuit includes a stepper motor drive chip, which is used to: control the rotation angle of the stepper motor main shaft through the duty cycle of the pulse width modulation signal; and monitor the working state of the stepper motor; The Hall sensor is installed on the main shaft of the stepper motor; The optical power feedback circuit is arranged at the optical path output end of the adjustable optical attenuator, and is used to collect the optical power signal at the optical path output end and convert it into a current signal; and then, according to Ohm's law, the current signal is converted into a voltage signal and fed back to the single chip microcomputer.

10. The control device according to claim 9, characterized in that: The communication interface circuit includes an RS232 communication circuit and / or a CAN communication circuit.

Images