Electronic digital sextant device, satellite measurement method and angle measurement optical calibration method

Abstract

The invention discloses an electronic digital sextant device. The electronic digital sextant device comprises a sextant body and an information processing and display unit arranged at a rotating shaft of a movable mirror on the sextant body, the information processing and display unit comprises an angle measurement module, an information processing module, an information display module and a power supply module; the angle measurement module is used for measuring elevation angle information of a star and sending the elevation angle information to the information processing module; the information processing module receives data transmitted by the angle measurement module, completes calculation of a ship position under the assistance of ephemeris data and world time information, and displays the data through the information display module; the information display module is used for displaying data transmitted by the information processing module and receiving a user operation instruction; the power supply module supplies power to the angle measurement module, the information processing module and the information display module. The invention further provides a satellite measurement method and an angle measurement optical calibration method. The device is easy to operate and fast in positioning.

Description

Technical Field

[0001] The invention belongs to the field of surveying, and in particular relates to an electronic digital sextant device, a star measurement method and an angle measurement optical calibration method. Background Art

[0002] A sextant is an optical instrument that can measure the angle between two distant objects. The most common use is to measure the angle between a celestial body and the sea (or land) horizon or between celestial bodies. By measuring the angle, the latitude of the observer can be determined. However, existing sextants have the disadvantages of being cumbersome to operate and slow to locate. Therefore, we urgently need a new sextant device. Summary of the invention

[0003] The main purpose of the present invention is to provide an electronic digital sextant device, a star measurement method and an angle measurement optical calibration method which are simple to operate and fast in positioning.

[0004] The technical solution adopted by the present invention is:

[0005] An electronic digital sextant device comprises a sextant body and an information processing and display unit arranged at a rotating shaft of a moving mirror on the sextant body;

[0006] The information processing and display unit includes an angle measurement module, an information processing module, an information display module, and a power supply module;

[0007] The angle measuring module is used to measure the altitude angle information of the star and send the altitude angle information to the information processing module;

[0008] The information processing module receives the data transmitted by the angle measuring module, calculates the ship's position with the help of the ephemeris data and the world time information, and displays it through the information display module;

[0009] The information display module is used to display the data transmitted by the information processing module and receive user operation instructions;

[0010] The power supply module supplies power to the angle measuring module, the information processing module and the information display module.

[0011] A further solution is that the information processing module includes a processor, a power conversion module, and a 485 level conversion module;

[0012] The processor is respectively connected with the power conversion module, the 485 level conversion module, and the information display module;

[0013] The power conversion module is connected to the power module;

[0014] The 485 level conversion module is connected to the angle measurement module.

[0015] A further solution is that the processor chooses STMicroelectronics' STM32F103VET6 chip; the power conversion module uses the AMS1117 chip, and the 485 level conversion module uses the SP3485 chip.

[0016] A further solution is that the information processing module is connected to the angle measuring module, the information display module and the power supply module through a pin header.

[0017] A further solution is that the angle measurement module selects the UEFA072A angle encoder; the information display module uses a TFT display screen; the power module has charging and discharging functions and has endurance, the charging port is a micro USB port, and the output port is a Type-A port.

[0018] A further solution is that the information processing module includes astronomical ship position automatic calculation software and astronomical information display software;

[0019] The astronomical position automatic calculation software includes an angle measurement information acquisition module, a dawn and dusk forecast module, a universal time synchronization and timekeeping module, an ephemeris calculation module, an astronomical positioning calculation module, and an information interaction module; the angle measurement information acquisition module receives data from the angle measurement module; the angle measurement information acquisition module, the universal time synchronization and timekeeping module, and the dawn and dusk forecast module are connected to the ephemeris calculation module, and the ephemeris calculation module and the information interaction module are respectively connected to the astronomical positioning calculation module;

[0020] The astronomical information display software includes an astronomical information display module and a user control module; the astronomical information display module and the user control module are respectively connected to the information interaction module, and the astronomical information display module and the user control module are connected to the information display module.

[0021] A further solution is that the ephemeris data includes the celestial spherical distribution of 56 easily identifiable bright visible light stars in the sky.

[0022] The present invention also provides a method for measuring stars using the electronic digital sextant device, which comprises the following steps:

[0023] Send a time synchronization command;

[0024] When the time synchronization is successful, input the ship's dead reckoning position;

[0025] Conduct astronomical star selection;

[0026] Visually observe the selected stars;

[0027] When the selected star is observed, a star measurement confirmation command is sent to obtain the altitude angle information of the measured star;

[0028] Obtain astronomical ship position data through the altitude angle information of stars;

[0029] Output astronomical position data.

[0030] The present invention also provides a method for optical calibration of angle measurement using an electronic digital sextant device, which comprises the following steps:

[0031] 1) Establish a satellite altitude angle measurement model

[0032] The measurement zero position of the sextant device is when the moving mirror is parallel to the fixed mirror, and the measured altitude angle of the star is equal to twice the rotation angle of the moving mirror from the zero position;

[0033] When the rotation axis of the moving mirror surface does not coincide with the mechanical axis of the angle measuring module installed at the rotating shaft of the moving mirror, the angle between the rotation axis of the moving mirror surface and the mechanical rotation axis of the angle measuring module is σ;

[0034] Assuming that the output of the angle measurement module is θ, the star altitude angle measurement model of the electronic digital sextant is as follows:

[0035]

[0036] Where: K represents the scale factor of the angle measurement module, η represents the zero bias of the angle measurement module, El represents the theoretical altitude angle of the target point, σ represents the angle between the mirror rotation axis of the moving mirror and the mechanical rotation axis of the angle measurement module, θ represents the output angle measurement value of the angle measurement module, and θ0 represents the initial zero bias value of the angle measurement module.

[0037] 2) Angle measurement calibration

[0038] The Leica theodolite is used to calibrate the parameters of the electronic digital sextant device before leaving the factory, specifically:

[0039] An electronic digital sextant device is placed vertically on a tripod and leveled, a Leica theodolite is placed in front of the moving mirror and the fixed mirror of the electronic digital sextant device respectively, the Leica theodolite in front of the fixed mirror is kept horizontal and motionless, the angle of incident light of the Leica theodolite in front of the fixed mirror is adjusted, and the moving mirror is rotated at the same time so that the crosshairs of the Leica theodolite in front of the moving mirror can be seen in the theodolite in front of the fixed mirror, and a calibration equation of an angle measurement module is constructed; multiple calibration parameter equations can be obtained through different angles of incidence, and the calibration parameters of the angle measurement module are solved by the least squares method.

[0040] The beneficial effects produced by the present invention are:

[0041] An information processing and display unit is installed at the rotating shaft of the moving mirror of the existing sextant, which has a simple structure and is easy to use, and can automatically calculate the astronomical position of the ship, thus solving the problems of cumbersome operation and slow positioning of the existing sextant.

[0042] The information processing and display unit is installed on the existing sextant without changing the existing sextant structure, and the installation and disassembly are very convenient;

[0043] The information processing and display unit is integrated into the existing sextant, making it easy to carry and use;

[0044] The UEFA072A angle encoder is used to ensure astronomical positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 It is a schematic diagram of the structure of an existing sextant;

[0047] Figure 2 It is a schematic diagram of the structure of an electronic digital sextant device;

[0048] Figure 3 It is a schematic diagram of the main structure of the electronic digital sextant device;

[0049] Figure 4 is a schematic diagram of the side view of the structure of an electronic digital sextant device;

[0050] Figure 5 It is a schematic diagram of the rear view structure of the electronic digital sextant device;

[0051] Figure 6 It is a schematic diagram of the structure of the information processing and display unit;

[0052] Figure 7 It is a connection diagram of the information processing and display unit;

[0053] Figure 8 It is the composition principle and block diagram of the information processing module;

[0054] Fig. 9 It is a schematic diagram of the external interface of the information processing module;

[0055] Fig.10 This is a diagram showing the distribution of 56 digital navigation stars on the celestial sphere;

[0056] Fig.11 It is a schematic diagram of the operation process of the electronic digital sextant device;

[0057] Fig.12 It is a flow chart of the star measurement method;

[0058] Fig.13 It is a schematic diagram of the star-measuring optical geometry of the electronic digital sextant device;

[0059] Fig.14 It is a schematic diagram of the optical calibration of angle measurement;

[0060] Fig.15 is the optical calibration result;

[0061] Fig.16 This is the implementation principle of TFT display;

[0062] Fig.17 It is a block diagram of the astronomical ship position automatic calculation software and the astronomical information display software;

[0063] Among them: 1. Sextant body, 1.1. Moving mirror, 1.2. Fixed mirror, 1.3. Moving mirror rotation axis, 2. Information processing and display unit, 2.1. Angle measurement module, 2.2. Information processing module, 2.3. Information display module, 2.4. Power supply module. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0065] See also Figure 1 The existing sextant includes a moving mirror 1.1, a fixed mirror 1.2, a moving mirror rotation axis 1.3, etc. The present invention is obtained by improving the existing sextant. The existing sextant is the sextant body 1 of the present application.

[0066] Example 1

[0067] See also Figure 2-Figure 7 An electronic digital sextant device comprises a sextant body 1 and an information processing and display unit 2 mounted at a moving mirror rotation axis 1.3 on the sextant body 1, with an overall size of 253mm*181mm*255mm and an overall weight of about 1.9kg.

[0068] See also Figure 7 The information processing and display unit 2 includes an angle measuring module 2.1, an information processing module 2.2, an information display module 2.3, and a power supply module 2.4. The angle measuring module 2.1 is used to measure the altitude angle information of the star body and send the altitude angle information to the information processing module 2.2. The information processing module 2.2 receives the data transmitted by the angle measuring module 2.1, and with the assistance of the ephemeris data and the world time information, performs astronomical positioning solution, completes the calculation of the ship's position, and displays it through the information display module 2.3. The information display module 2.3 is used to display the data transmitted by the information processing module 2.2 and receive user operation instructions. The power supply module 2.4 supplies power to the angle measuring module 2.1, the information processing module 2.2, and the information display module 2.3.

[0069] The angle measurement module selects the UEFA072A angle encoder, which is used to sensitively measure the inclination of the star measuring lens (moving mirror) and output digital angle signals.

[0070] The performance indicators and usage requirements of the angle measurement module are as follows: working power supply: 5.0V DC±10%; output form: RS422; output accuracy: ±20"; size: outer diameter 72.4mm; working temperature: -40℃~85℃.

[0071] Mechanical interface and electrical interface of angle measurement module: The time grating encoder is composed of a rotor and a stator. The time grating stator is a ring with a diameter of 72.4mm. There is a mounting hole every 90° on the ring, and there are 4 φ1.7 threaded holes.

[0072] The UEFA072A angle encoder uses a 6-core shielded cable, which includes power and signal lines. The signal is output via RS422 level (no input), and the receiving end receives it via the 485 port. The 6-core cable is directly connected to the receiving end without going through a connector. The cable definition is shown in Table 1:

[0073] Table 1 Definition of time-grid encoder cable

[0074] color red white Brown black yellow Ash definition 5V GND RX+ RX- TX+ TX- .

[0075] The information display module is used to display the satellite data, position calculation, and device status, and receive user operation instructions, and send the touch screen information to the information processing module to control the device. The main functions are as follows: display ephemeris information, satellite data, calculation results, and operation options; input operation content.

[0076] Performance indicators and usage requirements of the information display module: working power supply: 3.3V; power consumption: ≤2W; interface level: TTL; screen size: 2.4 inches.

[0077] Mechanical interface and electrical interface of the information display module: The information display module is fixed to the information processing module through rows of pinholes and two through holes. Among them, the mounting hole is a hole with a diameter of φ3, and the pin spacing is 2.5mm.

[0078] The electrical interface of the information display module is a double row of pin holes.

[0079] Working principle of information display module:

[0080] The information display module uses a TFT display screen (information interactive display screen), which can assist users in operating the electronic digital sextant for astronomical star measurement. The control of the TFT display screen is divided into two parts, one is display and the other is touch input. The display function is realized by a 2.4-inch TFT display screen plus the ILI9341 driver, and the touch function is realized by the resistive touch function integrated in the display screen plus the XPT2406 chip.

[0081] The information processing module can control the ILIA9341 driver through 16 parallel ports and chip selection, synchronization (actually GPIO port) and other signals, and the ILIA9341 driver then outputs signals to drive the display output image.

[0082] The TFT display screen forms a measurement point at the touched position, which divides the resistance into two parts in the X direction and the Y direction. Through the SPI bus, different configurations of XN, XP, YN, and YP access measurement are implemented according to the first 3 bits of the address. For example, when measuring the position of the touch point in the Y direction, a loop is formed between YN and XN, and AD sampling is performed on XN or XP. The ratio of the measured voltage value to the total drive voltage is the ratio of the Y coordinate of the touch point to the total length in the Y direction. The coordinate of the X position can be determined in a similar way. By continuous scanning, the touch input can be determined. The implementation principle of the TFT display screen is as follows: Fig.16 shown.

[0083] The power module 2.4 provides a stable voltage source for the entire electrical part, and its specific functions are as follows: power supply voltage stabilization; output current; rechargeable.

[0084] Performance indicators and usage requirements of the power module: output voltage: +5.0V; maximum output current: 2.0A; input voltage: +5.0V; input current: 2.0A; capacity: 20000mAh; module size: 86mm×86mm×18mm;

[0085] Mechanical and electrical interfaces of the power module: The power module is a square structure with no direct mounting holes on it and is placed in the mounting box. The power module has charging and discharging functions to meet the battery life for a certain period of time. The charging port is a micro USB port and the output port is a Type-A port.

[0086] The information processing module is used to read the altitude angle signal of the angle measurement module 2.1, calculate the coordinate information according to the pre-stored ephemeris data, and output the collected and calculated information to the TFT display screen of the information display module 2.3 (the TFT display screen displays the astronomical positioning results and the star measurement information), and control the whole process according to the user's touch operation (receiving the user's operation instructions through the TFT display screen); the memory of the information processing module stores the navigation star library, and has a clock timekeeping function inside, and retains the time synchronization interface outside to perform the initial world time synchronization operation. The main functions are as follows: RS485 serial port circuit, read the altitude angle signal; SD access function, save and check the ephemeris data; calculate the coordinate position according to the altitude angle signal and ephemeris information; SPI and parallel port control to realize the control of the touch screen.

[0087] Performance indicators and usage requirements of the information processing module: Working power supply: +5.0V, +3.3V;

[0088] Power consumption: ≤1W; Interface level: RS485; RS485 serial communication baud rate: 115200b / s; Circuit board size: 72.4mm×48.7mm; Operating temperature: -30℃~+65℃; Storage temperature: -40℃~+85℃.

[0089] Mechanical interface and electrical interface of the information processing module: The information processing module is a single 72.4mm×48.7mm circuit board, which integrates a 5.0V to 3.3V power conversion module, an RS485 conversion module, and a processor; the processor is connected to the power conversion module, the 485 level conversion module, and the information display module; the power conversion module is connected to the power module; the 485 level conversion module is connected to the angle measurement module. The information processing module has an SD card function. There are mounting holes at the four corners of the circuit board, with a hole diameter of 3.0mm and a hole spacing of 66.0mm×42.6mm.

[0090] The information processing module is connected to other modules mainly through pin headers. The electrical signal definitions are shown in Table 2:

[0091] Table 2 Information processing module connection pin signal definition

[0092]

[0093]

[0094] Figure 8 The composition principle and block diagram of the information processing module.

[0095] 5.0V to 3.3V power conversion module:

[0096] The 3.3V power supply is obtained by the LDO chip. The LDO chip is AMS1117. The input voltage is 5.0V. The LDO chip has the characteristics of large current flow and low power consumption.

[0097] processor:

[0098] The processor uses the STMicroelectronics STM32F103VET6 chip. The F103 series processor is a low-cost microcontroller launched by STMicroelectronics. The core uses the ARM architecture Cortex-M3 core, with rich peripheral resources and high cost performance.

[0099] The STM32F103VET6 chip contains an SPI controller unit, which can realize the control of the information display module 2.3. SPI uses TTL level and does not require an additional level conversion module. The parallel port data output with the TFT display is realized through GPIO. The STM32F103VET6 contains 5 channels and a total of 80 GPIO ports available. The chip also has an SDIO controller, which can be used to control the SD access to ephemeris data.

[0100] 485 level conversion module:

[0101] The 485 level conversion module uses the SP3485 chip. SP3485 is a 3.3V low-power half-duplex transceiver that meets the RS485 and RS422 serial protocol requirements and electrical specifications, and the data transmission rate can be as high as 10Mbps.

[0102] In this embodiment, the processor internally stores ephemeris data (electronic ephemeris), which includes the celestial distribution of 56 easily identifiable visible light bright stars in the sky, see Fig.10 The electronic ephemeris is shown in Table 3.

[0103] Table 3 Ephemeris

[0104]

[0105]

[0106] The processor contains an electronic digital sextant software program, which includes astronomical position automatic calculation software and astronomical information display software. The two parts of the software are called in the form of function interfaces. Fig.17The astronomical position automatic calculation software includes an angle measurement information acquisition module, a dawn and dusk forecast module, a world time synchronization and timekeeping module, an ephemeris calculation module, an astronomical positioning calculation module, and an information interaction module; the angle measurement information acquisition module receives data from the angle measurement module; the angle measurement information acquisition module, the world time synchronization and timekeeping module, and the dawn and dusk forecast module are connected to the ephemeris calculation module, and the ephemeris calculation module and the information interaction module are respectively connected to the astronomical positioning calculation module. The astronomical information display software includes an astronomical information display module and a user control module; the astronomical information display module and the user control module are respectively connected to the information interaction module, and the astronomical information display module and the user control module are connected to the information display module.

[0107] The functional requirements of each software module are as follows:

[0108] Angle measurement information acquisition module: angle measurement information acquisition; angle measurement data filtering;

[0109] Morning and dusk forecast module: civil morning and dusk forecast; navigation morning and dusk forecast; astronomical morning and dusk forecast;

[0110] World time synchronization and timekeeping module: world time synchronization; world time punctuality;

[0111] Ephemeris calculation module: calculation of solar altitude and azimuth; calculation of solar apparent radius; calculation of navigation star altitude and azimuth; calculation of celestial body sidereal time; intelligent star selection calculation;

[0112] Astronomical positioning calculation module: altitude difference astronomical position calculation;

[0113] Information interaction module: astronomical ship position information output; astronomical star measurement information output; user operation command analysis;

[0114] Astronomical information display module: astronomical star measurement information display; astronomical star selection result display; astronomical measurement ship position result display; universal time display;

[0115] User command operation module: star altitude measurement confirmation command; astronomical star selection command; astronomical dawn and dusk forecast command.

[0116] Performance requirements of the software program: Astronomical information display refresh rate: ≤1Hz; Astronomical ship position solution accuracy: ≤2nmlie.

[0117] Fig. 9 This is a schematic diagram of the external interface of the information processing module. There are 4 external interfaces in total, as shown in Table 4:

[0118] Table 4 External interfaces of information processing module

[0119]

[0120] See also Fig.11 After the information processing and display unit is turned on, the user uses the external time system device to complete the time synchronization command for the device, and the device enters the world time keeping state; and after astronomical star selection is performed on the basis of the calculated ship position, the user observes the navigation star through the handheld electronic digital sextant device, and measures the water antenna and the star through the optical system on the mechanical frame of the sextant body 1. After collecting the measured altitude angle of the star, the angle measurement module outputs the altitude angle of the star and sends it to the information processing module. The information processing module calculates the astronomical ship position based on the height difference principle and outputs it to the display screen.

[0121] Example 2

[0122] See also Fig.12 A method for measuring stars using the electronic digital sextant device in Example 1 comprises the following steps:

[0123] Send a time synchronization command;

[0124] When the time synchronization is successful, input the ship's dead reckoning position;

[0125] Conduct astronomical star selection;

[0126] Visually observe the selected stars;

[0127] When the selected star is observed, a star measurement confirmation command is sent to obtain the altitude angle information of the measured star;

[0128] Obtain astronomical ship position data through the altitude angle information of stars;

[0129] Output astronomical position data.

[0130] Example 3

[0131] The angle measurement module directly measures the altitude angle of the celestial body, and the astronomical position is calculated based on the measured altitude angle. Therefore, the accuracy of the angle measurement module is directly related to the accuracy of the astronomical position output by the final calculation. Based on the above reasons, it is necessary to establish a model for the angle measurement module and calibrate the deterministic error before leaving the factory to meet the positioning accuracy requirements.

[0132] See also Figure 13-14 A method for optical calibration of angle measurement using the electronic digital sextant device in Example 1 comprises the following steps:

[0133] 1) Establish a satellite altitude angle measurement model

[0134] According to the principle of sextant star measurement, the measurement zero position of the sextant device is when the moving mirror is parallel to the fixed mirror, and the measured altitude angle of the star is equal to twice the angle between the moving mirror and the fixed mirror, that is, the measured altitude angle of the star is equal to twice the rotation angle of the moving mirror from the zero position;

[0135] When the rotation axis of the moving mirror surface does not coincide with the mechanical axis of the angle measuring module installed at the rotating shaft of the moving mirror, the angle between the rotation axis of the moving mirror surface and the mechanical rotation axis of the angle measuring module is σ;

[0136] Assuming that the output of the angle measurement module is θ, the star altitude angle measurement model of the electronic digital sextant is as follows:

[0137]

[0138] Where: K represents the scale factor of the angle measurement module, η represents the zero bias of the angle measurement module, El represents the theoretical altitude angle of the target point, σ represents the angle between the mirror rotation axis of the moving mirror and the mechanical rotation axis of the angle measurement module, θ represents the output angle measurement value of the angle measurement module, and θ0 represents the initial zero bias value of the angle measurement module.

[0139] 2) Angle measurement calibration

[0140] According to the above-mentioned electronic digital sextant star altitude angle measurement model, the Leica theodolite is used to calibrate the parameters of the electronic digital sextant device before leaving the factory, specifically:

[0141] An electronic digital sextant device is placed vertically on a tripod and leveled, a Leica theodolite is placed in front of the moving mirror and the fixed mirror of the electronic digital sextant device respectively, the Leica theodolite in front of the fixed mirror is kept horizontal and motionless, the angle of incident light of the Leica theodolite in front of the fixed mirror is adjusted, and the moving mirror is rotated at the same time so that the crosshairs of the Leica theodolite in front of the moving mirror can be seen in the theodolite in front of the fixed mirror, and a calibration equation of an angle measurement module is constructed; multiple calibration parameter equations can be obtained through different angles of incidence, and the calibration parameters of the angle measurement module are solved by the least squares method.

[0142] The optical calibration results are as follows: Fig.15 The variance of the fitting residual is (1σ)25.2″, which is consistent with the nominal accuracy of the angle measurement module.

[0143] After the electronic digital sextant device completed the angle measurement optical calibration, the star (sun) astronomical positioning test was carried out, and the error statistics of the astronomical positioning test results of the electronic digital sextant device were performed, as shown in Table 5. It can be seen from the positioning results that the automated digital sextant can complete the astronomical positioning function, and the positioning error is within 7nmile.

[0144] Table 5 Astronomical positioning results of electronic digital sextant

[0145]

[0146] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0147] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. An electronic digital sextant device, characterized in that: It includes a sextant body and an information processing and display unit arranged at a rotating shaft of a moving mirror on the sextant body; The information processing and display unit includes an angle measurement module, an information processing module, an information display module, and a power supply module; The angle measuring module is used to measure the altitude angle information of the star and send the altitude angle information to the information processing module; The information processing module receives the data transmitted by the angle measuring module, calculates the ship's position with the help of the ephemeris data and the world time information, and displays it through the information display module; The information display module is used to display the data transmitted by the information processing module and receive user operation instructions; The power supply module supplies power to the angle measuring module, the information processing module and the information display module.

2. The electronic digital sextant device according to claim 1, characterized in that: The information processing module includes a processor, a power conversion module, and a 485 level conversion module; The processor is respectively connected with the power conversion module, the 485 level conversion module, and the information display module; The power conversion module is connected to the power module; The 485 level conversion module is connected to the angle measurement module.

3. The electronic digital sextant device according to claim 2, characterized in that: The processor uses STMicroelectronics' STM32F103VET6 chip; the power conversion module uses the AMS1117 chip, and the 485 level conversion module uses the SP3485 chip.

4. The electronic digital sextant device according to claim 1, characterized in that: The information processing module is connected with the angle measuring module, the information display module and the power supply module through the pin header.

5. The electronic digital sextant device according to claim 1, characterized in that: The angle measurement module selects the UEFA072A angle encoder; the information display module uses a TFT display screen; the power module has charging and discharging functions and has endurance, the charging port is a micro USB port, and the output port is a Type-A port.

6. The electronic digital sextant device according to claim 1, characterized in that: The information processing module includes astronomical ship position automatic calculation software and astronomical information display software; The astronomical position automatic calculation software includes an angle measurement information acquisition module, a dawn and dusk forecast module, a universal time synchronization and timekeeping module, an ephemeris calculation module, an astronomical positioning calculation module, and an information interaction module; the angle measurement information acquisition module receives data from the angle measurement module; the angle measurement information acquisition module, the universal time synchronization and timekeeping module, and the dawn and dusk forecast module are connected to the ephemeris calculation module, and the ephemeris calculation module and the information interaction module are respectively connected to the astronomical positioning calculation module; The astronomical information display software includes an astronomical information display module and a user control module; the astronomical information display module and the user control module are respectively connected to the information interaction module, and the astronomical information display module and the user control module are connected to the information display module.

7. The electronic digital sextant device according to claim 1, characterized in that: The ephemeris data include the celestial spherical distribution of 56 easily identifiable bright visible light stars in the sky.

8. The electronic digital sextant device according to claim 7, characterized in that: The 56 visible stars that are easy to identify in the sky are: Alpha Orionis, Alpha Scorpii, Alpha Hercules, Gamma Crux, Beta Grus, Alpha Boötes, Alpha Taurus, Beta Pegasus, TYC Centauri, Beta Andromeda, Rho Perseids, μ Gemini, ο Ceti, Alpha Auriga, ε Carinae, η Gemini, λ Vela, Alpha Canis Major, η Sagittarius, Alpha Carinae, Beta Ursa Minor, σ Libra, Gamma Draconis, δ Ophiuchus, δ Virgo, Alpha Hydra, Ursa Major μ, gamma Hydra, beta Gemini, gamma Leo, TYC Andromeda, π Puppis, gamma Eridanus, alpha Aries, alpha Ursa Major, ε Pegasus, ι Aurigae, alpha Canis Minor, alpha Lynx, gamma Aquila, zeta Ara, TYC Vela, gamma Phoenix, beta Ara, ε Scorpius, beta Ceti, alpha Cassiopeia, theta Centaur, alpha Tucanae, σ Puppis, δ Sagittarius, π Hercules, alpha Phoenix, ε Lepus, φ1 Lupus, and alpha Lyrae.

9. A method for measuring stars using the electronic digital sextant device according to any one of claims 1 to 8, characterized in that The steps include: Send a time synchronization command; When the time synchronization is successful, input the ship's dead reckoning position; Conduct astronomical star selection; Visually observe the selected stars; When the selected star is observed, a star measurement confirmation command is sent to obtain the altitude angle information of the measured star; Obtain astronomical ship position data through the altitude angle information of stars; Output astronomical position data.

10. A method for optical calibration of angle measurement using the electronic digital sextant device according to any one of claims 1 to 8, characterized in that The steps include: 1) Establish a satellite altitude angle measurement model The measurement zero position of the sextant device is when the moving mirror is parallel to the fixed mirror, and the measured altitude angle of the star is equal to twice the rotation angle of the moving mirror from the zero position; When the rotation axis of the moving mirror surface does not coincide with the mechanical axis of the angle measuring module installed at the rotating shaft of the moving mirror, the angle between the rotation axis of the moving mirror surface and the mechanical rotation axis of the angle measuring module is σ; Assuming that the output of the angle measurement module is θ, the star altitude angle measurement model of the electronic digital sextant is as follows: Where: K represents the scale factor of the angle measurement module, η represents the zero bias of the angle measurement module, El represents the theoretical altitude angle of the target point, σ represents the angle between the mirror rotation axis of the moving mirror and the mechanical rotation axis of the angle measurement module, θ represents the output angle measurement value of the angle measurement module, and θ0 represents the initial zero bias value of the angle measurement module. 2) Angle measurement calibration The Leica theodolite is used to calibrate the parameters of the electronic digital sextant device before leaving the factory, specifically: An electronic digital sextant device is placed vertically on a tripod and leveled, a Leica theodolite is placed in front of the moving mirror and the fixed mirror of the electronic digital sextant device respectively, the Leica theodolite in front of the fixed mirror is kept horizontal and motionless, the angle of incident light of the Leica theodolite in front of the fixed mirror is adjusted, and the moving mirror is rotated at the same time so that the crosshairs of the Leica theodolite in front of the moving mirror can be seen in the theodolite in front of the fixed mirror, and a calibration equation of an angle measurement module is constructed; multiple calibration parameter equations can be obtained through different angles of incidence, and the calibration parameters of the angle measurement module are solved by the least squares method.

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