Shipborne sea fog monitoring laser radar and monitoring method

Abstract

The invention relates to a laser radar, in particular to a shipborne sea fog monitoring laser radar and a monitoring method. The radar comprises a laser radar host which comprises a photoelectric detector, and an optical receiving system, a laser emission system and a data processing system which are connected with the photoelectric detector; the main control module is connected with the laser radar host; an optical visibility meter; an attitude adjustment system; an inertial navigation system; wherein the main control module is also respectively connected with the optical visibility meter, the attitude adjusting system and the inertial navigation system; and the main control module is used for combining data correction of the inertial navigation system and the optical visibility meter to obtain sea fog concentration and sea fog moving state information with high accuracy. The wind field change and the sea fog concentration can be measured at the same time, and the sea fog distribution and moving process can be accurately observed.

Description

Technical Field

[0001] The invention relates to a laser radar, in particular to a shipborne sea fog monitoring laser radar and a monitoring method. Background Art

[0002] Sea fog affects aviation traffic, maritime wind power and climate environment in coastal areas. Inaccurate monitoring of the movement and generation and disappearance of sea fog can easily lead to adverse phenomena such as flight delays, ship collisions, decreased fishery production, decreased temperature and increased humidity. The wind field has an important influence on the formation and distribution of sea fog. Changes in the wind field will cause the diffusion and aggregation of water vapor on the ocean surface, which in turn affects the formation and dissipation of sea fog. In view of the frequent occurrence of sea fog, irregular movement state, and extremely low visibility, sea fog can cause various maritime traffic accidents. A ship-borne laser radar that effectively monitors the movement process of sea fog can effectively reduce the probability of ship collisions and reef runs, and correctly guide marine operations, sea surface aircraft takeoffs and other work.

[0003] Existing sea fog monitoring methods mainly include manual observation, remote sensing monitoring and meteorological sensor monitoring, and the data has problems of one-sidedness and accuracy. Based on detection equipment such as visibility meters, remote sensing satellites and millimeter wave radars, the detection accuracy is easily affected by complex climate, resulting in poor results, and it is impossible to detect wind field changes, thus unable to deeply analyze the movement process of sea fog and its impact on human activities. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a shipborne sea fog monitoring laser radar, and the specific technical solution is as follows: A ship-borne sea fog monitoring laser radar comprises: a laser radar host including a photoelectric detector, an optical receiving system connected to the photoelectric detector, a laser emission system and a data processing system, which is used to monitor the movement of sea fog in coastal areas or deep seas; a main control module connected to the laser radar host; an optical visibility meter, which is used to generate a near-field visibility signal and calibrate the near-field visibility data of the laser radar; an attitude adjustment system, which is used to correct the beam pointing deviation of the laser radar caused by the hull turbulence; an inertial navigation system, which is used to provide the attitude information of the laser radar for correcting the pitch and roll angles of the attitude adjustment laser emission system and providing the speed and north direction information for correcting the wind field error of the laser radar; wherein the main control module is also connected to the optical visibility meter, the attitude adjustment system and the inertial navigation system respectively; the main control module is used to obtain high-accuracy sea fog concentration and sea fog movement status information by combining the data correction of the inertial navigation system and the optical visibility meter.

[0005] Preferably, the laser radar host also includes a fiber optic combiner, and the fiber optic combiner is connected to the photoelectric detector and the optical receiving system respectively.

[0006] A monitoring method for a shipborne sea fog monitoring laser radar is used for a shipborne sea fog monitoring laser radar. The method corrects the direction of the radar beam in real time and quickly through high-frequency feedback of two-axis angles and attitude adjustment of an inertial navigation system and an attitude adjustment system, thereby ensuring the stability of the detection angle; calibrates the error of Doppler information through the speed information of the inertial navigation system, thereby ensuring the measurement accuracy of wind speed and direction; obtains near-field visibility information through an optical visibility meter to calibrate visibility data measured by the laser radar, thereby ensuring the measurement accuracy of changes in sea fog concentration.

[0007] Compared with the prior art, the present invention has the following beneficial effects: The ship-borne sea fog monitoring laser radar provided by the present invention can correct the radar beam pointing in real time and quickly through the two-axis angle high-frequency feedback and attitude adjustment of the inertial navigation system and the attitude adjustment system to ensure the stability of the detection angle; the error of the Doppler information can be calibrated through the speed information of the inertial navigation system to ensure the measurement accuracy of the wind speed and direction; combined with the optical visibility meter, the visibility data measured by the laser radar is calibrated by obtaining the near-field visibility information to ensure the measurement accuracy of the sea fog concentration change. The laser radar has the characteristics of wide detection range, fast response, high precision, and no interference from complex climate environment. It can observe the movement and generation and disappearance process of sea fog and group fog in real time, and provide early warning and forecasting data support for shipping and transportation, maritime wind power and climate and environmental changes in coastal areas; it can simultaneously measure wind field changes and sea fog concentrations, accurately observe the distribution and movement process of sea fog, and reduce the probability of encountering risks in low-visibility situations of marine vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is the framework diagram of this application; Figure 2 It is a schematic diagram of the structure of the laser radar host; Figure 3 It is a data processing flow chart. DETAILED DESCRIPTION

[0009] The present invention will be further described with reference to the accompanying drawings.

[0010] At present, the monitoring methods of sea fog include using coastal observation stations and shore visibility meters, which are one-sided and cannot effectively guide marine operations; using remote sensing satellites for remote sensing detection, but the detection accuracy is easily affected by clouds, rain, snow and other climate factors; using millimeter wave radar and near-infrared laser radar, but they cannot detect wind field changes and thus cannot effectively analyze the dynamic changes of sea fog. In short, the existing methods have some shortcomings in terms of response speed, accuracy and in-depth analysis of the sea fog change process.

[0011] The present application can correct the direction of the radar beam in real time and quickly through the high-frequency feedback and attitude adjustment of the two-axis angles of the inertial navigation system and the attitude adjustment system to ensure the stability of the detection angle; the error of the Doppler information can be calibrated through the speed information of the inertial navigation system to ensure the measurement accuracy of the wind speed and direction; combined with the optical visibility meter, the visibility data measured by the lidar is calibrated by obtaining the near-field visibility information to ensure the measurement accuracy of the changes in sea fog concentration.

[0012] like Figures 1 to 3 As shown, a ship-borne sea fog monitoring laser radar includes a laser radar host including a photoelectric detector, an optical receiving system connected to the photoelectric detector, a laser emission system and a data processing system, which is used to monitor the movement of sea fog along the coast or in the deep sea; a main control module, connected to the laser radar host; an optical visibility meter, used to generate a near-field visibility signal and calibrate the near-field visibility data of the laser radar; an attitude adjustment system, used to correct the beam pointing deviation of the laser radar caused by the hull turbulence; an inertial navigation system, used to provide the attitude information of the laser radar for correcting the pitch and roll angles of the attitude adjustment laser emission system and providing the speed and north direction information for correcting the wind field error of the laser radar; wherein the main control module is also connected to the optical visibility meter, the attitude adjustment system and the inertial navigation system respectively; the main control module is used to obtain high-accuracy sea fog concentration and sea fog movement status information in combination with the data correction of the inertial navigation system and the optical visibility meter.

[0013] The laser radar host also includes a fiber optic combiner, which is connected to the photoelectric detector and the optical receiving system respectively.

[0014] The laser radar host is a coherent Doppler laser radar host for synchronous measurement of wind field and visibility.

[0015] The laser radar host 1 emits a laser beam with a wavelength of 1550nm through the laser emission system 11, which interacts with atmospheric components, collects Doppler motion information and material characteristic information carried by aerosols through the optical receiving system 12, converts the optical signal into an electrical signal through the photoelectric detector 13, and then undergoes high-speed collection counting and noise filtering amplification. Through the data processing system 14, combined with the data correction of the inertial navigation system 2 and the optical visibility meter 4, high-accuracy sea fog concentration and sea fog movement status information are obtained, thereby achieving the purpose of monitoring sea fog movement and providing important reference value for guiding marine operations.

[0016] The attitude adjustment system 5 makes real-time and rapid adjustments according to the radar attitude angle information transmitted by the inertial navigation system 2 to ensure the stable pointing of the laser radar detection beam; the optical visibility meter 4 provides visibility data of the laser radar installation location for comparing and calibrating the visibility product of the laser radar host.

[0017] The functions of various parts of a shipborne sea fog monitoring lidar are as follows: 1. Coherent Doppler LiDAR host for synchronous measurement of wind field and visibility: It detects the wind field and visibility information of the area to be measured by emitting a laser light source with a specific beam, and collects and processes echo signals carrying specific substances and Doppler information, which is used to monitor the movement of sea fog along the coast or in the deep sea. The LiDAR host mainly includes: laser emission system, optical receiving system, photoelectric detector and data processing system, etc. The specific function is to realize the detection of wind field and visibility information within a range of 10km and above, and to achieve the pointing stability of the detection beam through the main control module and attitude adjustment system; to realize information interaction with the inertial navigation system and the optical visibility meter through the main control module, and to calibrate and ensure the accuracy of the data products.

[0018] (11) Laser emission system: emits a detection beam to interact with atmospheric components. The system can be a fiber laser or a semiconductor laser. The laser wavelength is 1550nm, the repetition frequency is not less than 10kHz, the pulse energy is not less than 100uJ, and the line width is not greater than 10kHz.

[0019] (12) Optical receiving system: used to receive optical signals carrying aerosol characteristic information. The system can be a Galileo-type transmission telescope. The optical aperture is not less than 100 mm, the focal length is not less than 400 mm, the coating band is 1550±10 nm, and the transmittance is not less than 99.5%.

[0020] (13) Photodetector: used to detect the laser radar echo signal and the laser intrinsic signal, and perform beat frequency processing. It can be an InGaAs balanced detector. The bandwidth is not less than 200 MHz and the responsivity is not less than 0.95 A / W.

[0021] (14) Data processing system: It has a high-speed acquisition network port to quickly process echo signals to generate wind field and visibility data. The specific function is to collect echo signals, filter and reduce noise, divide the range gate, fill zero and refine, FFT transform and spectrum recognition to obtain wind field information. At the same time, the signal energy is calculated using the spectrum signal, that is, the echo signal power at each distance position, through the laser radar equation: (1) Where Pt is the average power of the laser pulse, k is the system receiving efficiency of the laser radar, is the atmospheric aerosol extinction backscattering ratio, and its value is generally between 0 and 90. is the ratio of air analysis extinction backscattering. The extinction coefficient is calculated , and then according to Koschmieder theory: (2) K represents the contrast threshold, which is the minimum value for an observer to distinguish an object from the background. Calculate the standard visibility.

[0022] Inertial navigation system: Provides attitude information of the laser radar to correct the pitch and roll angles of the attitude adjustment system, and provides speed and north direction information to correct the wind field error of the laser radar. The system can be MEMS micro-inertial navigation or strapdown inertial navigation, using high-precision inertial measurement units and high-precision master-slave antenna GNSS modules to measure the position, speed, and attitude information of the laser radar equipment. The heading accuracy is not less than 0.1°, the speed accuracy is not less than 0.1m / s, the attitude accuracy is not less than 0.1°, the data upload speed exceeds 20Hz, and the protection level is above IP66.

[0023] Main control module: controls the working status of the laser radar and the accuracy correction of the product. It has an Ethernet port for transmitting to the laser radar host to receive wind field and visibility information, an RS485 interface for transmitting to the optical visibility meter to calibrate the visibility data of the laser radar, an RS232 interface for transmitting to the inertial navigation system to calibrate the Doppler error information, and an RS422 interface for transmitting to the attitude adjustment system to adjust the detection beam direction. Accurate wind field data is obtained through the formula: (3) Where Vtrue represents the wind speed vector in the earth reference coordinate system, Vlaser represents the wind speed vector in the lidar reference coordinate system, and Vcor ​​represents the velocity vector in the inertial navigation system reference coordinate system. The accurate visibility data is obtained by calibrating the visibility value of the lidar host obtained by formulas (1) and (2) with the visibility value generated by the optical visibility meter.

[0024] Optical visibility meter: generates near-field visibility signals, calibrates the near-field visibility data of the lidar, and ensures the accuracy of sea fog concentration monitoring. It can be a forward scattering visibility meter, which is based on the forward scattering principle and obtains the scattering coefficient based on formula (4).

[0025] (4) Where P(θ) represents the phase function in the aerosol mode, which is related to the forward scattering angle. Is represents the scattered light intensity, and I0 represents the incident light intensity. Without considering the absorption of air particles, the scattering coefficient is assumed to be approximately equal to the extinction coefficient, and the visibility value output is obtained according to formula (2).

[0026] Attitude adjustment system: corrects the laser radar beam pointing deviation caused by the hull turbulence. The system can be a two-degree-of-freedom leveling platform with fast action feedback and high resolution. The positioning accuracy is not less than 0.02°, the steady-state accuracy is not less than 0.3°, the response frequency exceeds 20Hz, and the protection level is above IP66.

[0027] The composition and cascade relationship of each part are as follows: The laser radar's laser emission system emits a 1550nm beam to illuminate the area to be measured. The material information and Doppler information of the aerosol in the area are collected by the optical receiving system, and then the photoelectric detector responds and converts. Finally, the data processing system analyzes and processes the signal to obtain the required wind speed and direction changes and visibility profile data. The inertial navigation system detects the position, attitude and speed information of the laser radar. The attitude adjustment system uses the attitude information of the inertial navigation system to adjust the two-dimensional attitude angle to ensure the stability of the laser radar beam pointing and thus ensure the accuracy of the data product. The main control module uses the north guidance information and speed information of the inertial navigation system to correct the wind field data of the laser radar host. The main control module uses the near-field visibility data of the optical visibility meter to calibrate the visibility data detected by the laser radar.

[0028] The ship-borne laser radar has the advantages of fast response speed, high accuracy and strong environmental adaptability. Through the attitude adjustment system, it can help the laser radar to conduct real-time monitoring of the movement of sea fog within a horizontal range of 10km in various complex marine environments, providing useful information value for marine operations, exploration, navigation and meteorological changes.

[0029] A monitoring method for a shipborne sea fog monitoring laser radar is used for a shipborne sea fog monitoring laser radar. The method corrects the direction of the radar beam in real time and quickly through high-frequency feedback of two-axis angles and attitude adjustment of an inertial navigation system and an attitude adjustment system, thereby ensuring the stability of the detection angle; calibrates the error of Doppler information through the speed information of the inertial navigation system, thereby ensuring the measurement accuracy of wind speed and direction; obtains near-field visibility information through an optical visibility meter to calibrate visibility data measured by the laser radar, thereby ensuring the measurement accuracy of changes in sea fog concentration.

[0030] The ship-borne sea fog monitoring lidar monitors the dynamic process of sea fog with high accuracy. The accuracy of the data product is calibrated and corrected by the inertial navigation system and optical visibility meter, and the lidar speed measurement accuracy is better than 0.3m / s, the wind direction accuracy is better than 3°, and the visibility deviation is less than 10%. It can truly accurately analyze the movement and concentration change process of sea fog.

[0031] The ship-borne sea fog monitoring laser radar has strong environmental adaptability. It is not restricted by environmental conditions and is equipped with a posture adjustment system with fast frequency and high precision, which can overcome the influence of waves on the laser radar pointing when working at sea. In addition, the protection level of each module reaches IP66, with anti-corrosion and wind resistance, and can be competent for sea fog monitoring in complex climate environments.

[0032] The ship-borne sea fog monitoring laser radar has fast response, high accuracy and can simultaneously measure wind field changes and sea fog concentration. It can overcome the influence of wave turbulence on the accuracy of the equipment, the error influence of speed on Doppler information measurement, and the deviation influence of laser radar on sea fog concentration measurement through regular calibration of visibility meter.

[0033] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the protection scope of the claims of the present invention.

Claims

1. A shipborne sea fog monitoring laser radar, characterized in that: include: A laser radar host, including a photoelectric detector, an optical receiving system, a laser emission system and a data processing system all connected to the photoelectric detector, for monitoring the movement of sea fog along the coast or in the deep sea; A main control module connected to the laser radar host; Optical visibility meter, used to generate near-field visibility signal and calibrate near-field visibility data of LiDAR; Attitude adjustment system, used to correct the laser radar beam pointing deviation caused by the hull turbulence; The inertial navigation system is used to provide the attitude information of the laser radar for attitude correction and adjustment of the pitch and roll angles of the laser launch system, as well as to provide speed and north pointing information for correcting the wind field error of the laser radar; Wherein, the main control module is also connected to the optical visibility meter, the attitude adjustment system and the inertial navigation system respectively; The main control module is used to obtain high-accuracy sea fog concentration and sea fog movement status information by combining the data correction of the inertial navigation system and the optical visibility meter.

2. A shipborne sea fog monitoring laser radar according to claim 1, characterized in that: The laser radar host also includes a fiber optic combiner, which is connected to the photoelectric detector and the optical receiving system respectively.

3. A monitoring method of a shipborne sea fog monitoring laser radar, used for a shipborne sea fog monitoring laser radar according to claim 1, characterized in that: Through the two-axis angle high-frequency feedback and attitude adjustment of the inertial navigation system and attitude adjustment system, the radar beam pointing is corrected in real time and quickly to ensure the stability of the detection angle; The error of Doppler information is calibrated by the speed information of the inertial navigation system to ensure the measurement accuracy of wind speed and direction; The near-field visibility information is obtained through an optical visibility meter to calibrate the visibility data measured by the lidar to ensure the measurement accuracy of changes in sea fog concentration.

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