Dynamic calibration system and method for raindrop spectrometer

Abstract

The invention discloses a raindrop spectrometer dynamic calibration system and method, and belongs to the technical field of meteorological instrument metering. The automatic distance adjusting transparent turntable is connected with the rotating motor; the rotating motor, the laser transmitter and the laser receiver are respectively connected with the control unit; circular light-proof shielding objects with different sizes are adhered to the automatic distance adjusting transparent turntable along the circumferential direction; the rotating motor drives the automatic distance adjusting transparent turntable to rotate at a constant speed and penetrate through the laser detection area; and laser emitted by the laser emitter passes through the laser detection area and then is received by the laser receiver. According to the method, the limitation that two parameters cannot be coupled in a traditional method is broken through, the influence of mechanical vibration on speed simulation is reduced, and the particle size recognition precision is improved.

Description

Technical Field

[0001] This invention relates to the field of meteorological instrument metrology technology, and in particular to a dynamic calibration system and method for a raindrop spectrometer. Background Technology

[0002] A raindrop spectrometer is an instrument that samples precipitation to obtain parameters such as the shape, size, velocity, and droplet distribution of precipitation particles. Based on laser attenuation or optical imaging principles, it is an automatic precipitation observation instrument capable of observing all types of precipitation phenomena in all weather conditions. For example, under certain weather conditions, a raindrop spectrometer can observe various weather phenomena occurring in the atmosphere and on the ground, including drizzle, rain, snow, sleet, and hail. A raindrop spectrometer can be used as a standalone sensor attached to an automatic weather station or integrated observation system, or it can be equipped with a data logger for independent observation.

[0003] Current traditional raindrop spectrometer calibration methods have the following drawbacks:

[0004] Droplet generation method: relies on droplet generators to simulate precipitation, but has low particle size control accuracy (>±0.1 mm) and velocity is significantly affected by airflow disturbance.

[0005] Static calibration method: only calibrates particle size, cannot simulate dynamic falling process, and ignores the interference of velocity on optical measurement system.

[0006] International standards (such as the WMO CIMO Guide) do not specify dynamic methods for simultaneous calibration of particle size and velocity. Chinese patent CN119375987A, "Raindrop Spectrometer Calibration Method and Related Device," does not address the repeatability control problem of multi-particle-velocity combined calibration. Existing devices cannot achieve continuous automatic measurement of different particle sizes.

[0007] Therefore, a dynamic calibration system and method for raindrop spectrometers is needed to achieve synchronous dynamic calibration of particle size and velocity, overcoming the limitation of traditional methods that cannot couple the two parameters. Summary of the Invention

[0008] The purpose of this invention is to propose a dynamic calibration system and method for a raindrop spectrometer.

[0009] A dynamic calibration system for a raindrop spectrometer includes a rotating motor, an automatically adjustable transparent turntable, a circular opaque shield, a laser emitter, a laser receiver, and a control unit;

[0010] The automatic distance-adjustable transparent turntable is connected to a rotating motor, and the rotating motor, laser emitter, and laser receiver are respectively connected to a control unit. Circular opaque objects of different sizes are pasted around the circumference of the automatic distance-adjustable transparent turntable. The rotating motor drives the automatic distance-adjustable transparent turntable to rotate at a constant speed, passing through the laser detection area. The laser emitted by the laser emitter is received by the laser receiver after passing through the laser detection area.

[0011] Furthermore, the diameter of the circular opaque obstruction is the equivalent particle size of the precipitation particles.

[0012] Furthermore, the diameter of the circular opaque obstruction is 2.1mm~21mm, with a diameter error of ≤±0.06mm.

[0013] Furthermore, the rotating motor is a stepper motor with a speed control accuracy of ±0.01%.

[0014] Furthermore, the diameter of the automatic distance adjustment transparent turntable is 200 mm, the rotation speed is 0.6 m / s to 16 m / s, and the turntable linear speed error is ≤ ±0.03 m / s.

[0015] Furthermore, the diameters of the circular opaque obstructions are 2.4 mm, 4.3 mm, 9.5 mm, and 21 mm, respectively.

[0016] Furthermore, the deviation between the center trajectory of the circular opaque object and the optical path axis of the laser is ≤0.05mm.

[0017] A calibration method for a raindrop spectrometer dynamic calibration system includes the following steps:

[0018] Step S1: Select 4 particle size points of 2.4 mm, 4.3 mm, 9.5 mm and 21 mm, and 4 velocity points of 2 m / s, 3.4 m / s, 7 m / s and 12 m / s, and obtain 16 calibration points by combining each particle size point × each velocity point.

[0019] Step S2: Perform synchronous calibration of particle size and velocity, specifically including:

[0020] Step S201: Set the diameter of the circular opaque obstruction to 2.4 mm and adjust the linear speed of the rotating motor to 2 m / s;

[0021] Step S202: Start the laser emitter and laser receiver to perform laser detection and collect the particle size readings output by the raindrop spectrometer. With speed reading Repeat 10 times;

[0022] Step S203: Calculate the average particle size average speed It refers to the number of data collections.

[0023] Step S204: Calculate the particle size indication error , The standard value is 2.4 mm; speed indication error. , The standard linear velocity is 2 m / s;

[0024] Step S205: Change the velocity points to 3.4 m / s, 7 m / s, and 12 m / s, and change the corresponding particle size points to 4.3 mm, 9.5 mm, and 21 mm, and repeat steps S201 to S204.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. This invention can achieve synchronous dynamic calibration of particle size (2.1mm~21mm) and velocity (0.6m / s~16m / s), and complete the dual-parameter calibration in a single experiment. The time taken is only 40% of that of traditional step-by-step calibration, breaking through the limitation of traditional methods that cannot couple two parameters; reducing the influence of mechanical vibration on velocity simulation, and ensuring that the expanded uncertainty (particle size ≤0.26 mm, velocity ≤0.12 m / s) is better than 1 / 3 of the tolerance of the calibrated instrument;

[0027] 2. The automatic position adjustment system of the turntable of the present invention has a displacement resolution of up to 0.05μm (Z-axis), a tilt adjustment range of ±0.5°, a flatness closed-loop control accuracy of ≤0.1μm, and a response time of <100ms; it has anti-interference capabilities: turntable dynamic balance correction (vibration amplitude ≤1 μm) to reduce speed fluctuations; and a laser scattering correction algorithm for the edge of obstructions to improve particle size recognition accuracy. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the dynamic calibration system for a raindrop spectrometer.

[0029] Figure 2 A schematic diagram of the displacement control of the automatic distance adjustment transparent turntable;

[0030] Figure 3 This is a flowchart of the calibration method for the dynamic calibration system of the raindrop spectrometer. Detailed Implementation

[0031] This invention proposes a dynamic calibration system and method for a raindrop spectrometer. The invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] Figure 1This is a schematic diagram of the dynamic calibration system for a raindrop spectrometer, including a rotating motor 1, an automatic distance-adjusting transparent turntable 2, a circular opaque shield 3, a laser emitter 4, a laser receiver 5, and a control unit 6. The automatic distance-adjusting transparent turntable 2 is connected to the rotating motor 1, and the rotating motor 1, laser emitter 4, and laser receiver 5 are respectively connected to the control unit 6. Circular opaque shields 3 of different sizes are attached to the circumference of the automatic distance-adjusting transparent turntable 2. The rotating motor 1 drives the automatic distance-adjusting transparent turntable 2 to rotate at a constant speed, passing through the laser detection area. The laser emitted by the laser emitter 4 is received by the laser receiver 5 after passing through the laser detection area.

[0033] In this specific embodiment, the rotating motor 1 is a stepper motor located on the left side, driving the automatic distance-adjusting transparent turntable 2 to rotate at a uniform speed with a speed control accuracy of ±0.01%. The automatic distance-adjusting transparent turntable 2 is made of optical-grade transparent material with a diameter of 200mm, a rotation speed of 0.6m / s to 16m / s, a turntable linear velocity error ≤±0.03m / s, and a surface flatness error ≤0.05mm. Circular opaque objects 3 of different sizes are circumferentially attached to the automatic distance-adjusting transparent turntable 2. The diameter of the opaque objects 3 corresponds to the equivalent particle size of precipitation particles (2.1mm to 21mm), with a diameter error ≤±0.06mm. The width of the laser detection area is adjustable to ensure that the center trajectory of the object coincides with the optical path axis (deviation ≤0.05mm). A laser alignment device is used to ensure that the deviation between the center trajectory of the object and the optical path axis is ≤0.05mm.

[0034] The circular, opaque obstruction 3 is made of opaque material (diameter 2.1mm-21mm), with an edge sharpness of Ra≤0.2μm and uniform circumferential distribution (dynamically balanced). The laser emitter 4 has a wavelength of 650nm, a beam diameter of 1.0±0.1mm, and power stability of ±0.5%. The laser receiver 5 has a sampling rate of 10MHz and a photoelectric conversion linearity error of ±0.1%. The control unit 6 has a rotation speed control resolution of 0.001rpm, synchronously acquires particle size / velocity signals, and displays the trajectory of the obstruction as it passes through the detection area in real time.

[0035] Using a standard raindrop spectrometer setup, circular opaque objects of different sizes are attached to a uniformly rotating transparent turntable. A stepper motor drives the turntable to rotate at a constant speed, passing through the laser detection area of ​​the raindrop spectrometer being calibrated. Different sized objects simulate different sizes of precipitation particles. The linear velocity of the turntable at the center of the opaque object is the terminal velocity of the simulated particle's fall.

[0036] Figure 2This is a schematic diagram of the displacement control of an automatic distance-adjustable transparent turntable. An automatic moving device is also installed on the transparent turntable, which allows the transparent turntable to move automatically. The automatic moving device includes a micro-displacement platform 2a1 and a position sensor 2a2. The micro-displacement platform 2a1 includes a horizontal adjustment mechanism and a vertical adjustment mechanism.

[0037] By using an automatic moving device to change the relative position of the turntable center and the laser detection zone axis, automatic measurement of different particle sizes can be achieved. By automatically adjusting the rotation speed, automatic measurement of different precipitation rates can be achieved. By using data processing algorithms and program control, calibration can be automated.

[0038] The micro-displacement platform 2a1 is integrated on the turntable support shaft and is driven by a high-precision piezoelectric ceramic or micro-stepping motor, possessing micro-motion capability along the XY axis (or XYZ axis) (stroke ≥ ±1mm, resolution ≤ 0.1µm). Position sensors 2a2 are high-precision laser displacement sensors or capacitive displacement sensors (non-contact type), monitoring the turntable's position relative to a preset reference plane in real time (especially the height and parallelism of the laser beam passage area). There are ≥3 sensors, circumferentially distributed. The control unit 6 implements closed-loop control, driving the micro-displacement platform 2a1 based on feedback from the position sensors 2a2, automatically adjusting the turntable's attitude (height, tilt) to ensure that the plane of the laser beam passage area is strictly perpendicular to the laser beam axis and is at the preset optimal focal plane position.

[0039] Figure 3 The calibration method flowchart of the raindrop spectrometer dynamic calibration system is as follows: the laser emitter 4 and laser receiver 5 are started, and the control unit 6 sends a speed command to the rotating motor 1 (stepper motor). The automatic distance adjustment transparent turntable 2 drives the circular opaque object 3 to pass through the laser detection area at a constant speed. The circular opaque object 3 blocks the laser beam and generates a pulse signal. The laser receiver 5 measures and calculates the signal, and the data is transmitted to the control unit 6 for processing in real time.

[0040] In this specific embodiment, it specifically includes:

[0041] Step S1: Calibration point selection:

[0042] Particle size ranges: 2.4 mm, 4.3 mm, 9.5 mm, 21 mm (covering the lower, median, and upper limits of the measurement range).

[0043] Velocity points: 2 m / s, 3.4 m / s, 7 m / s, 12 m / s (corresponding to different precipitation intensities)

[0044] Combination method: each particle size point × each velocity point, for a total of 16 calibration points.

[0045] Step S2: Perform synchronous calibration:

[0046] Step S201: Set the diameter of the turntable obstruction (e.g., 2.4 mm), and adjust the motor speed to make the linear velocity 2 m / s.

[0047] Step S202: Start laser detection, collect the particle size reading d and velocity reading v output by the raindrop spectrometer, and repeat 10 times.

[0048] Step S203: Calculate the average value .

[0049] Step S204: Calculate the indication error:

[0050] Particle size error ( (This is a standard value, such as 2.4 mm)

[0051] speed error ( (Standard linear velocity)

[0052] Step S205: Repeat S201-S204 by changing the velocity point (3.4 m / s, 7 m / s, 12 m / s); repeat the entire process by changing the particle size point.

[0053] Example 1: Calibration with a particle size of 2.4 mm and a velocity of 2 m / s

[0054] (1) Equipment preparation:

[0055] A circular obstruction with a diameter of 2.4 mm (error ±0.06 mm) is attached at a radius of 100 mm on the turntable.

[0056] Calculate the motor speed:

[0057] (2) Data collection:

[0058] The raindrop spectrometer outputs 10 particle size readings: [2.42, 2.38, 2.45, ..., 2.41] mm

[0059] Speed ​​readings: [1.98, 2.01, 2.03, ..., 2.00] m / s

[0060] (3) Error calculation:

[0061]

[0062]

[0063] Example 2: Calibration with a particle size of 21 mm and a velocity of 12 m / s

[0064] (1) Equipment preparation:

[0065] A circular obstruction with a diameter of 21 mm (error ±0.06 mm) is attached at a radius of 100 mm on the turntable.

[0066] Calculate the motor speed:

[0067]

[0068] (2) Data collection:

[0069] Collect 10 particle size and velocity readings from the raindrop spectrometer;

[0070] (3) Error calculation results:

[0071] .

[0072] Experimental calibration was performed on the following 16 calibration points selected for this invention:

[0073] Particle size ranges: 2.4 mm, 4.3 mm, 9.5 mm, 21 mm (covering the lower, median, and upper limits of the measurement range).

[0074] Velocity points: 2 m / s, 3.4 m / s, 7 m / s, 12 m / s (corresponding to different precipitation intensities)

[0075] Combination method: each particle size point × each velocity point, for a total of 16 calibration points.

[0076] Verification conclusion: The errors of all 16 calibration points meet the requirements. .

[0077] In summary, this invention enables dynamic calibration: accurately simulating the terminal velocity of raindrops (0.6~16) m / s; dual-parameter synchronization: independent control of particle size and velocity measurement errors; anti-interference design: air-bearing bearings reduce mechanical vibration, and temperature-controlled lasers eliminate thermal drift; traceability: the diameter of the obstruction is traced to a length reference, and the rotational speed is traced to a time-frequency reference. It can achieve a particle size calibration synthesis uncertainty u. c =0.13mm (k=2), velocity calibration combined uncertainty u c=0.06 m / s (k=2), meeting the calibration requirements of ±0.4 mm and ±0.2 m / s for the maximum permissible error of the raindrop spectrometer. A transparent turntable is driven by a stepper motor to rotate circumferentially and move axially. Opaque circular obstructions of different diameters (2.1 mm~21 mm) are fixed circumferentially on the turntable to simulate precipitation particles. The rotational speed of the turntable is adjusted (0.6 m / s~16 m / s) to control the simulated particle velocity. Sixteen calibration points are formed by combining four particle size points and four velocity points, and the particle size and velocity readings are measured simultaneously, with the error calculated. This method solves the problem of traditional calibration's inability to couple dynamic particle size and velocity. The particle size calibration uncertainty reaches 0.26 mm (k=2), and the velocity reaches 0.12 m / s (k=2), improving efficiency by 60%.

Claims

1. A dynamic calibration system for a raindrop spectrometer, characterized in that: It includes a rotating motor (1), an automatic distance-adjustable transparent turntable (2), a circular opaque barrier (3), a laser emitter (4), a laser receiver (5), and a control unit (6); Among them, the automatic distance adjustment transparent turntable (2) is connected to the rotating motor (1), and the rotating motor (1), the laser emitter (4), and the laser receiver (5) are respectively connected to the control unit (6); circular opaque objects (3) of different sizes are pasted on the circumferential direction of the automatic distance adjustment transparent turntable (2); the rotating motor (1) drives the automatic distance adjustment transparent turntable (2) to rotate at a constant speed and pass through the laser detection area; the laser emitted by the laser emitter (4) is received by the laser receiver (5) after passing through the laser detection area.

2. The dynamic calibration system for a raindrop spectrometer according to claim 1, characterized in that: The diameter of the circular opaque barrier (3) is the equivalent particle size of the precipitation particles.

3. The dynamic calibration system for a raindrop spectrometer according to claim 1 or 2, characterized in that: The diameter of the circular opaque shield (3) is 2.1 mm to 21 mm, and the diameter error is ≤ ±0.06 mm.

4. The dynamic calibration system for a raindrop spectrometer according to claim 1, characterized in that: The rotating motor (1) is a stepper motor with a speed control accuracy of ±0.01%.

5. The dynamic calibration system for a raindrop spectrometer according to claim 1 or 4, characterized in that: The diameter of the automatic distance-adjusting transparent turntable (2) is 200 mm, the rotation speed is 0.6 m / s to 16 m / s, and the turntable linear speed error is ≤ ±0.03 m / s.

6. The dynamic calibration system for a raindrop spectrometer according to claim 4, characterized in that: The diameters of the circular opaque shields (3) are 2.4 mm, 4.3 mm, 9.5 mm and 21 mm, respectively.

7. The dynamic calibration system for a raindrop spectrometer according to claim 1, characterized in that: The deviation between the center trajectory of the circular opaque shield (3) and the optical path axis of the laser is ≤0.05 mm.

8. A calibration method for the dynamic calibration system of the raindrop spectrometer as described in claim 1, characterized in that: Includes the following steps: Step S1: Select 4 particle size points of 2.4 mm, 4.3 mm, 9.5 mm and 21 mm, and 4 velocity points of 2 m / s, 3.4 m / s, 7 m / s and 12 m / s, and obtain 16 calibration points according to the combination of each particle size point × each velocity point; Step S2: Perform synchronous calibration of particle size and velocity, specifically including: Step S201: Set the diameter of the circular opaque obstruction (3) to 2.4 mm and adjust the linear speed of the rotating motor (1) to 2 m / s; Step S202: Start the laser emitter (4) and laser receiver (5) to perform laser detection and collect the particle size readings output by the raindrop spectrometer. With speed reading Repeat 10 times; Step S203: Calculate the average particle size average speed It refers to the number of data collections. Step S204: Calculate the particle size indication error , The standard value is 2.4 mm; speed indication error. , The standard linear velocity is 2 m / s; Step S205: Change the velocity points to 3.4 m / s, 7 m / s, and 12 m / s, and change the corresponding particle size points to 4.3 mm, 9.5 mm, and 21 mm, and repeat steps S201 to S204.

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