CN105547286B - A kind of compound three visual fields star sensor star map simulation method - Google Patents

Abstract

The invention discloses a method for simulating a star map of a composite three-field star sensor, which includes the following steps: Step 1. According to the limit magnitude of the star sensor, select an observation star that meets the requirements, and extract the star number, magnitude, and The data of right ascension and declination are stored as the observation star database; step 2, count the observation stars in the field of view of the three optical systems of the composite three-field star sensor, and calculate the X, Y of the observation star in the coordinate system of the subsystem to which it belongs The angle of incidence in the direction; step 3, according to the total number of pseudostars, randomly generate the magnitude and field of view position data of pseudostars; step 4, through ray tracing, simulate the imaging of the observed stars and pseudostars in their respective fields of view by the optical system, Calculate the image plane information; step 5, calculate the brightness of each pixel in the digital star map, and output the digital star map. This method is easy to operate, does not depend on the hardware system of processing and molding, and has low cost. It can provide abundant simulated star map data for other technical researches of the composite three-field star sensor.

Description

A star map simulation method for a composite three-field star sensor

technical field

The invention belongs to the technical field of celestial navigation, and relates to a technology for obtaining a simulated star map by using a computer to simulate the imaging process of a composite three-field star sensor.

Background technique

Effective attitude control is a necessary guarantee for the smooth flight of satellites and other spacecraft, and attitude measurement is the premise of attitude control. The star sensor takes stars as the working object, takes pictures of them and recognizes them, and then measures the attitude information, which is the current accuracy. One of the tallest attitude measuring instruments. At present, single-view star sensors are mainly used. These star sensors usually have a large field of view, are easily affected by stray light such as sunlight, and have low reliability. At the same time, the attitude measurement accuracy of the roll angle is lower than that of the pitch and yaw angles. Spacecraft often need to install two or more such star sensors to ensure high reliability and measurement accuracy.

The multi-field star sensor combines multiple optical systems according to a certain spatial distribution into a whole. Each optical system images the starry sky in their field of view to their respective image sensors, and their output star maps are combined to develop Star map recognition, calculation and output pose. Compared with the single-field star sensor, the field of view of each optical system of the multi-field star sensor is small, and it is easy to obtain higher attitude measurement accuracy.

At present, the star map simulation method of the composite three-field star sensor is to use three single-field star sensors to take pictures of the star simulator and output the star map. Since the optical systems of the three fields of view of the compound three-field star sensor satisfy a certain spatial geometric relationship, and their imaging should be kept in sync, this simulation method requires that the simulated starry sky output by each multi-star simulator be compared with the composite The starry sky observed by the three fields of view of the three-field star sensor is consistent and can be changed synchronously. The system structure of this simulation method is complex and the operation is cumbersome.

"A Star Map Recognition Method for a Multi-field Star Sensor" (public number: CN 103363987A) is actually a double field of view star map recognition method. Convert to the image space coordinates of the first field of view, and then use the star map recognition method of the dual field of view star sensor to identify. The focus of this method is to realize the real-time performance of star map recognition, which has high requirements on the device and cannot realize star map simulation.

Contents of the invention

Aiming at the problems existing in the prior art, the object of the present invention is: provide a kind of compound three field of view star sensor star map simulation method, for the study of compound three field of view star sensor star image extraction, navigation star optimization, star Image recognition and other technologies provide rich star map data and provide technical support for testing the imaging quality of optical lenses in the design stage of the composite three-field star sensor optical system.

A kind of composite three field of view star sensor star map simulation method proposed by the present invention comprises the following steps:

(1) First, according to the limit magnitude of the star sensor, select a single star with a magnitude not greater than the limit magnitude, a double star with an equivalent magnitude not greater than the limit magnitude, and a star with the highest magnitude not greater than the limit magnitude from the original star catalog. magnification variable stars, extract their asterisk, magnitude, right ascension, declination and other data, and establish an observation star database.

(2) Then, determine the observed stars in the field of view of the three optical systems of the compound three-field star sensor, and calculate their incident angles in the X and Y directions in the coordinate system of the subsystem to which they belong.

(3) Next, according to the total number of pseudostars, generate random data to simulate the magnitude and field of view position of pseudostars.

(4) Through ray tracing, simulate the imaging of each optical system to the observed stars and pseudo-stars in their respective fields of view, and calculate the image plane information. The optical surface of the optical system can be spherical or aspheric. Let the coordinates of any point on the jth optical surface be (x _j , y _j , z _j ), j range from 1 to η, and η is the total number of optical surfaces. The coordinate points satisfy

Where R _j is the radius of curvature of the vertex of the jth optical surface, K _j is the quadratic surface coefficient, A _j,i is the aspheric coefficient, N _j is the highest order number of the aspheric coefficient, is the distance from the coordinate point to the axis. This formula determines the shape of the optical surface, called the surface function of the optical surface. When K _j =0 and A _j,i are both 0, the optical surface is spherical.

The specific process of this step includes:

Step 1. Calculate the direction cosine vector (l ₁ , m ₁ , p ₁ ) of the light incident on the first optical surface according to the incident angle and incident position of the incident light. According to the position of the ray on the entrance pupil, the distance from the entrance pupil to the first optical surface, and the surface function of the first optical surface, calculate the position of the incident point of the ray on the first optical surface (x ₁ , y ₁ , z ₁ ). The j corresponding to this step is equal to 1.

Step 2, calculate the direction cosine vector of the light exiting the jth optical surface, that is, the direction cosine vector (l _j+1 , m _j+1 , p _j+1 ) when the light is incident on the j+1th optical surface .

Step 3, if j<η, then use the approximation algorithm to calculate the incident point position (x _j+1 , y _j+1 , z _j+1 ) of the ray on the j+1th optical surface, and then increase j by 1, Repeat step 2. Otherwise, go to step 4.

Step 4, calculate the position (x _image , y _image , z _image ) where the light reaches the image plane.

(5) Calculate the brightness of each pixel in the digital star map, and output the digital star map.

Compared with prior art, the present invention has following characteristics:

(1) When the relative positions of the three optical systems of the composite three-field star sensor change, the star field imaging simulation can be carried out only by modifying the parameters, which is easy to operate.

(2) The present invention does not require a starry sky simulator and a processed star sensor optical system, and the star map simulation is realized by a computer program, which has no requirement for hardware equipment and is low in cost.

(3) The output star map data can reflect the imaging quality of the optical system. The present invention provides support for foreseeing and avoiding the design errors of the composite three-field star sensor optical system, and improves the design quality of the composite three-field star sensor optical system. for reference.

Description of drawings

Fig. 1 is a flow chart of star map simulation in the embodiment of the present invention.

Figure 2 is a schematic diagram of the imaging of stars in the coordinate system of the first subsystem.

Figure 3 is a diagram of the relationship between the body coordinate system and the subsystem coordinate system.

Fig. 4 is a schematic diagram of light propagating between two adjacent optical surfaces of the optical system.

Figure 5 shows a schematic diagram of the optical system in the embodiment.

Fig. 6 shows a schematic diagram of the simulated star map output by the first subsystem in the embodiment.

Fig. 7 shows a schematic diagram of the simulated star map output by the second subsystem in the embodiment.

Fig. 8 shows a schematic diagram of the simulated star map output by the third subsystem in the embodiment.

FIG. 9 shows a schematic diagram of a star map output by Sky chart software corresponding to the first subsystem in the embodiment.

Fig. 10 shows a schematic diagram of a star map corresponding to the second subsystem in the embodiment output by the Sky chart software.

Fig. 11 shows a schematic diagram of a star map corresponding to the third subsystem in the embodiment output by the Sky chart software.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

The principle of this embodiment is: to carry out the star field imaging simulation of the composite three-field star sensor, it is necessary to establish an inertial coordinate system and a body coordinate system, which are respectively set to O _i -X _i Y _i Z _i and O _b -X _b Y _b Z _b . It is also necessary to establish a coordinate system fixedly connected with each optical system of the compound three-field star sensor, which is called the subsystem coordinate system, and it is set as O _k -X _k Y _k Z _k , where k is 1, 2 or 3, for each optical system.

First, establish the subsystem coordinate system. The optical system is equivalent to an ideal imaging system, H _k and H _k ′ are the principal points of the object and image space respectively, f is the focal length of the optical system, and the origin O _k of the subsystem coordinate system is taken at the principal point of the image space of the optical system H _k '. The three axes X _k , Y _k , and Z _k form a right-handed coordinate system, wherein the X _k axis and the Y _k axis are in the main plane of the image side, and are respectively parallel to the row and column of the focal plane of the detector. The Z _k -axis is along the optical axis, and the positive direction points to the object plane, as shown in Figure 2.

If the ideal imaging of the observed star S is S′, and the coordinates of S′ in the coordinate system of the first subsystem are (x _s , y _s , -f), then the direction cosine of the observed star S in the coordinate system of the subsystem The vector is

Then its field angle in the direction of X _k and Y _k is

Next, establish the body coordinate system. In order to facilitate the manufacture and assembly of the star sensor, the optical axes of the three optical systems are selected in a symmetrical form, and the angles between them are equal. For this reason, this embodiment regards the coordinate system O _b -X _b Y _b Z _b weight as shown in FIG. 3 as the body coordinate system. Among them, the origin O _b is taken as the intersection of the three axes Z ₁ , Z ₂ , and Z ₃ , and the Z _b axis has the same included angle as Z ₁ , Z ₂ , and Z ₃ , and the included angle is set as The angle between X ₁ O ₁ Z ₁ plane and X _b O _b Z _b plane is τ. In the body coordinate system O _b -X _b Y _b Z _b , the azimuth interval of the optical axis of the subsystem coordinate system is 120°, and the elevation angle is It can be seen from Figure 3 that the angle Or the elevation angle determines the positional relationship between the three optical systems.

If it is known that the orientation of the body coordinate system Z _b in the inertial coordinate system is (α _c , δ _c ), and the structural parameters have been given and τ, then the inertial coordinate system OX _i Y _i Z _i can coincide with the body coordinate system O _b -X _b Y _b Z _b by rotating 3 times. The inertial coordinate system first rotates α _c around the Z _i axis from the +X _i axis to the +Y _i axis to obtain the X'Y'Z' coordinate system, and the new coordinate system then circles the Y' axis from the +Z' axis to the +X' axis Rotate 90°-δ _c to obtain the X"Y"Z" coordinate system, which is rotated around the Z" axis by θ, and the obtained coordinate system coincides with the body coordinate system. Where θ is determined by the actual orientation of the X _b axis and the Y _b axis of the body coordinate system. Similarly, the body coordinate system O _b -X _b Y _b Z _b can coincide with the subsystem coordinate system O _k -X _k Y _k Z _k by rotating twice. The body coordinate system first rotates τ+(k-1)*120° around the Z _b axis from the +X _b axis +Y _b axis to obtain the X _k 'Y _k 'Z _k ' coordinate system, and then the new coordinate system revolves around Y _k 'Axis rotated by +Z _k ' to +X _k ' axis The obtained coordinate system coincides with the subsystem coordinate system O _k -X _k Y _k Z _k .

According to the above relationship, if the coordinates of a star S in the inertial coordinate system are (α, δ), then its direction cosine vector in the subsystem coordinate system O _k -X _k Y _k Z _k is

Conversely, if a vector is {V _k1 , V _k2 , V _k3 } in the direction cosine vector in the subsystem coordinate system O _k -X _k Y _k Z _k , then its vector in the inertial coordinate system is

As shown in Figure 1, the star map simulation process of the composite three-field star sensor is as follows:

1. Establish observation star database. According to the limit magnitude of the star sensor, process the original star catalog, and select single stars whose magnitude is not greater than the limit magnitude, double stars whose equivalent magnitude is not greater than the limit magnitude, and variable stars whose highest magnitude is not greater than the limit magnitude, Extract their asterisks, magnitudes, right ascension, declination and other data, and store them as the observed star database. In this database, the observed star data are arranged in descending order of declination.

2. The orientation of the Z _b axis in the known body coordinate system (α _c , δ _c ), and the angle that characterizes the structure of the three-field system Under the conditions of and τ, determine the observed stars in the three optical system fields of view of the compound three-field star sensor, and calculate their incident angles XFLD and YFLD in the X and Y directions of the respective optical system field of view.

First, the direction vector of the Z _k axis of the subsystem coordinate system O _k -X _k Y _k Z _k in this coordinate system is {V _k1 , V _k2 , V _k3 }={0 01}, then calculate according to formula (4) Its orientation in the inertial coordinate system {V ₁ , V ₂ , V ₃ }, corresponding to right ascension and declination (α _zk ,δ _zk ) is

Only coordinates (α, δ) satisfy

|δ-δ _zk |≤w _m (6)

The observed star may appear in the field of view of the k optical system, where w _m represents the field angle corresponding to the diagonal of the image plane detector of the optical system.

Then, according to the formula (3), the position of the selected observation star is converted from the inertial coordinate system to the subsystem coordinate system.

Finally, according to formula (2), the incident angle of the observed star in the subsystem coordinate system O _k -X _k Y _k Z _k is calculated. If the maximum viewing angle of the optical system in the direction of X _k and Y _k is w _A and w _B , only if the

The stars can be observed by the kth optical system, so as to determine whether they appear in the field of view of the optical system. According to the above method, the observed stars in the field of view of each optical system are statistically obtained, and their incident angles XFLD and YFLD are also obtained.

3. According to the total number of pseudo-stars, the magnitude, position and other data of pseudo-stars are randomly generated. When the pseudostar appears in the field of view of the kth optical system, its field angle in the direction of X _k , Y _k is

Where r and χ are a random number in the interval [0, 1].

4. Through ray tracing, simulate the imaging of each optical system to the observed stars and pseudo-stars in their respective field of view, and calculate the image plane information.

(1) Select the ray for tracing. Each light represents a share of energy, and the light should be evenly distributed. For the kth optical system, the entrance pupil of the optical system is divided into square grids, and the light emitted by the observation star in the field of view of the kth optical system and passed through the center of the entrance pupil and the grid points in the entrance pupil is selected for the light Tracking and simulated imaging.

Considering the brightness of the observed star and the spectral response characteristics of the detector, the weights W _m and W _w of the light are set, where W _m is proportional to the brightness of the star, and W _w is proportional to the spectral response of the detector. Assume that the total number of rays that fill the entrance pupil from each observation star is n _ray , and the initial energy of each ray is W _m W _w /n _ray .

(2) Perform ray tracing for each optical surface, and calculate the position and energy of the light rays reaching the image surface. In this embodiment, a coordinate system is established for each optical surface. For the jth optical surface, the origin O _j of the coordinate system O _j -X _j Y _j Z _j is located at the vertex of the optical surface, and the Z _j axis points to the image plane along the optical axis. As shown in FIG. 4 , the distance from the vertex of the jth optical surface to the vertex of the j+1th optical surface is d _j . Let the coordinates of any point on the jth optical surface be (x _j , y _j , z _j ), j ranges from 1 to η, η is the total number of optical surfaces, and the coordinate points satisfy

Where R _j is the radius of curvature of the vertex of the jth optical surface, K _j is the quadratic surface coefficient, A _j,i is the aspheric coefficient, N _j is the highest order number of the aspheric coefficient, is the distance from the coordinate point to the axis. When K _j =0 and A _j,i are both 0, the optical surface is spherical. Along the forward direction of the light, the refractive indices of the front and rear of the optical surface are n _j and n _j+1 respectively, and the axial distance from it to the j+1th optical surface is d _j .

Step 1. Calculate the direction cosine vector (l ₁ , m ₁ , p ₁ ) of the light incident on the first optical surface according to the incident angle and incident position of the incident light. Then according to the position of the light on the entrance pupil, the distance from the entrance pupil to the first optical surface, and the surface function of the first optical surface, the position of the incident point of the light on the first optical surface (x ₁ , y ₁ , z ₁ ). The j corresponding to this step is equal to 1.

For light rays with incident angles of XFLD and YFLD, the direction cosine vector when it reaches the first optical surface is

Taking the first optical surface coordinate system as a reference, assuming that the coordinates of the light on the entrance pupil plane are (x _ρ , y _ρ , d _ρ ), where d _ρ is the distance from the entrance pupil to the first optical surface, then

By combining formulas (9) and (11), the coordinates (x ₁ , y ₁ , z ₁ ) of the incident point can be obtained.

Step 2, calculate the direction cosine vector of the light exiting the jth optical surface, that is, the direction cosine vector (l _j+1 , m _j+1 , p _j+1 ) when the light is incident on the j+1th optical surface . If its incident point on the jth optical surface is (x _j ,y _j ,z _j ), then the normal direction (ζ _j ,ξ _j ,γ _j ) at this point on the optical surface is

Then the outgoing direction of the light is (l _'j+1 ,m _j+1 ,p _j+1 ), and the calculation is

where μ is the angle between the incident direction and the normal,

Step 3, if j<η, then use the approximation algorithm to calculate the incident point position (x _j+1 , y _j+1 , z _j+1 ) of the ray on the j+1th optical surface, and then increase j by 1, Repeat step 2. Otherwise, go to step 4.

Using the approximation algorithm, set the initial coordinate values (x _j+1,0 , y _j+1,0 , z _j+1,0 ), which are respectively

x _j+1,0 =x _j ,y _j+1,0 =y _j and z _j+1,0 =z _j -d _j (14)

Use the formula (14) to calculate the new coordinate value until the difference between the calculated z _j+1,t+1 and z _j+1,t is very small, and the final x _j+1,t+1 and y _{j+ 1,t+1} , z _j+1,t+1 are the incident point position (x _j+1 , y _j+1 , z _j+1 ) of the light on the j+1th optical surface.

Step 4, calculate the position (x _image , y _image , z _image ) where the light reaches the image plane. The exit point of light on the last optical surface is (x _η , y _η , z _η ), the direction cosine vector is (l _η , m _η , p _η ), and the distance from the optical surface to the image plane is d _η . So

According to the intersection points of the light on each optical surface, the propagation distance of the light in the same medium can be obtained, and then the light energy attenuation coefficient of the medium can be used to obtain the energy of the light reaching the image plane. If a ray reaches the image plane, the energy attenuates by σ times, and the energy when it reaches the image plane is σW _m W _w /n _ray . For each observed star in the field of view of the kth optical system, do ray tracing in the spectral range to obtain their images formed by the optical system.

5. Calculate the brightness of each pixel in the digital star map and output the digital star map. The star sensor uses a CCD or APS detector to receive star images, and the detector takes a pixel as the basic unit. According to the position (x _image , y _image ) and energy of each ray reaching the image plane, calculate the pixel where they are located, and accumulate the energy of the ray reaching the same pixel position to obtain the light intensity on the pixel in the star map. It is stipulated that the gray value of the brightest pixel is 255, and the brightness of the remaining pixels is proportionally scaled to obtain the corresponding gray value. The position of each pixel and its grayscale are saved in a digital image format, and the digital star map can be output.

Example:

The field of view of the optical system of the three-field star sensor is 10°×10°, the aperture is 27.3mm, and the focal length is 43.89mm. The optical system is shown in Figure 5, including 5 lenses, and the optical surface parameters are shown in Table 1. , where the first and seventh optical surfaces are aspherical. The aspheric coefficients of the first optical surface are K ₁ =-0.41, A _1,8 =3.12×10 ^-12 , and the others are 0. The aspherical coefficient of the seventh optical surface is K ₁ = -0.61, A _1,4 = 4.85×10 ^-5 , A _1,6 = 3.80×10 ^-7 , A _1,8 = 1.26×10 ^-9 , and the rest is 0. The limit star magnitude is selected as 5.2, and the number of detector pixels is 1024×1024.

Table 1 Optical system parameters (unit: mm)

Face number radius thickness Material 1 19.44 6.00 Silica 2 219.08 9.00 3 16.90 6.00 K9 4 -40.89 1.00 ZF1 5 9.24 9.00 6 18.87 5.59 K9 7 22.07 3.96 8 -92.60 6.00 ZF1 9 -16.40 7.32 10 Infinity 10.94

Create a star observation database. When the right ascension and declination pointed by the Z _b axis of the body coordinate system are selected as (36°, 30°), the angle between the Z ₁ axis and the Z _b axis When the angle between the X ₁ O ₁ Z ₁ plane and the X _b O _b Z _b plane is τ=0, the Z _k -axis of the subsystem coordinate system points to (341.43°, 41.28°), (36 °, -15°), (90.57°, 41.28°). Figures 6, 7, and 8 show the star maps obtained by imaging the observed stars through the optical system of each subsystem, and 5, 5, and 6 stars were observed in the three fields of view, respectively. Figures 9, 10, and 11 show the star maps corresponding to the three fields of view output by using the Sky chart software. Compared with Figures 6, 7, and 8, it can be seen that the star maps output by the star map simulation method of this embodiment are consistent with the Sky chart software .

Table 2 shows the star image position when the observed star is ideally imaged, and the star image position obtained by using the star image extraction algorithm to process Figures 6, 7, and 8. For convenience, they are respectively referred to as the ideal position and the measured position. It can be seen from the data in the table that the position error obtained by the star map simulation is less than 0.4 pixels, and the star map simulation method of the composite three-field star sensor is correct.

Table 2 Simulated star image data

The invention can provide abundant simulated star map data for studying technologies such as star image extraction, navigation star optimization, star map recognition and the like of a composite three-field star sensor. It has been disclosed as above with preferred embodiments, but they are not used to limit the present invention, and any person skilled in the art can make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be defined by the scope of protection of the claims of this application.

Claims (2)

1. A composite three-field of view star sensor star map simulation method, is characterized in that, comprises the steps: Step 1. Establish the observed star database; according to the limit magnitude of the star sensor, select a single star whose magnitude is not greater than the limit magnitude, a double star whose equivalent magnitude is not greater than the limit magnitude, and the highest magnitude less than For variable stars greater than the limit magnitude, extract the asterisk, magnitude, right ascension, and declination data of the observed star, and store them as the observed star database; Step 2, counting the observed stars in the three optical system fields of view of the composite three-field star sensor, and calculating the incident angles of the observed stars in the X and Y directions in the coordinate system of the subsystem to which they belong; Step 3. According to the total number of pseudostars, the magnitude and field of view position data of the pseudostars are randomly generated; Step 4, by ray tracing, simulating the imaging of the observed star and the pseudo star in the respective field of view by the optical system, and calculating the image plane information; Step 5, calculate the brightness of each pixel of the digital star map, and output the digital star map; In the observed star database, the observed star data are arranged in ascending order of declination; The optical axes of the three optical systems are selected in a symmetrical form, and the included angles between them are equal; firstly, the subsystem coordinate system is established, and then the body coordinate system is established; the body coordinate system is O _b -X _b Y _b Z _b , where the origin O _b is taken as the intersection point of the three axes of Z ₁ , Z ₂ , and Z ₃ , and the Z _b axis has the same included angle as Z ₁ , Z ₂ , and Z ₃ , and the included angle is set as The included angle between X ₁ O ₁ Z ₁ plane and X _b O _b Z _b plane is τ; the inertial coordinate system first rotates α _c around Z _i axis from +X _i axis to +Y _i axis to obtain X'Y'Z' Coordinate system, the new coordinate system rotates 90°-δ _c around the Y' axis from the +Z' axis to the +X' axis to obtain the X"Y"Z" coordinate system, and the coordinate system rotates θ around the Z" axis to obtain The coordinate system coincides with the body coordinate system; After step 2 further include: Knowing the orientation of the Z _b axis of the body coordinate system (α _c , δ _c ), and the included angle of the compound three-field system structure, step 21, the Z _k axis of the subsystem coordinate system O _k -X _k Y _k Z _k is at The direction vector of this coordinate system is {V _k1 , V _k2 , V _k3 }={0,0,1}, according to: Calculate its orientation {V ₁ , V ₂ , V ₃ } in the inertial coordinate system, and the corresponding right ascension and declination (α _zk ,δ _zk ) are: δ _zk = sin ^-1 (V ₃ ), Only coordinates (α, δ) satisfy |δ-δ _zk |≤w _m (3) The observed star may appear in the field of view of the kth optical system, where w _m represents the angle of view corresponding to the diagonal line of the image plane detector of the optical system; Step 22, according to: transforming the position of the observation star from an inertial coordinate system to a subsystem coordinate system; Step 23, according to: <mrow><mi>X</mi><mi>F</mi><mi>L</mi><mi>D</mi><mo>=</mo><mo>-</mo><msup><mi>tg</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup><mrow><mo>(</mo><mfrac><msub><mi>V</mi><mrow><mi>s</mi><mi>k</mi><mn>1</mn></mrow></msub><msub><mi>V</mi><mrow><mi>s</mi><mi>k</mi><mn>3</mn></mrow></msub></mfrac><mo>)</mo></mrow><mo>,</mo><mi>Y</mi><mi>F</mi><mi>L</mi><mi>D</mi><mo>=</mo><mo>-</mo><msup><mi>tg</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup><mrow><mo>(</mo><mfrac><msub><mi>V</mi><mrow><mi>s</mi><mi>k</mi><mn>2</mn></mrow></msub><msub><mi>V</mi><mrow><mi>s</mi><mi>k</mi><mn>3</mn></mrow></msub></mfrac><mo>)</mo></mrow><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>5</mn><mo>)</mo></mrow></mrow> Calculate the incident angle of the observed star in the subsystem coordinate system O _k -X _k Y _k Z _k ; if the maximum viewing angle of the optical system in the direction of X _k and Y _k is w _A and w _B , only if the <mrow><mo>|</mo><mi>X</mi><mi>F</mi><mi>L</mi><mi>D</mi><mo>|</mo><mo>&amp;le;</mo><mfrac><msub><mi>w</mi><mi>A</mi></msub><mn>2</mn></mfrac><mi>h</mi><mo>|</mo><mi>Y</mi><mi>F</mi><mi>L</mi><mi>D</mi><mo>|</mo><mo>&amp;le;</mo><mfrac><msub><mi>w</mi><mi>B</mi></msub><mn>2</mn></mfrac><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>6</mn><mo>)</mo></mrow></mrow> The stars can only be observed by the kth optical system. 2. composite three-field of view star sensor star map simulation method according to claim 1, is characterized in that: the optical surface of described optical system adopts spherical surface or aspheric surface, suppose the coordinate of any point on the j optical surface is ( x _j , y _j , z _j ), j takes 1 to η, η is the total number of optical surfaces, and the coordinate points satisfy: <mrow><msub><mi>z</mi><mi>j</mi></msub><mo>=</mo><msub><mi>f</mi><mi>j</mi></msub><mrow><mo>(</mo><msub><mi>x</mi><mi>j</mi></msub><mo>,</mo><msub><mi>y</mi><mi>j</mi></msub><mo>)</mo></mrow><mo>=</mo><mfrac><msubsup><mi>r</mi><mi>j</mi><mn>2</mn></msubsup><mrow><msub><mi>R</mi><mi>j</mi></msub><mo>+</mo><msqrt><mrow><msubsup><mi>R</mi><mi>j</mi><mn>2</mn></msubsup><mo>-</mo><mrow><mo>(</mo><mn>1</mn><mo>+</mo><msub><mi>K</mi><mi>j</mi></msub><mo>)</mo></mrow><msubsup><mi>r</mi><mi>j</mi><mn>2</mn></msubsup></mrow></msqrt></mrow></mfrac><mo>+</mo><munderover><mo>&amp;Sigma;</mo><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><msub><mi>N</mi><mi>j</mi></msub></munderover><msub><mi>A</mi><mi>j</mi></msub><mo>,</mo><msubsup><mi>r</mi><mi>j</mi><mi>i</mi></msubsup><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>7</mn><mo>)</mo></mrow></mrow> Where R _j is the radius of curvature of the vertex of the jth optical surface, K _j is the quadratic surface coefficient, A _j,i is the aspheric coefficient, N _j is the highest order number of the aspheric coefficient, is the distance from the coordinate point to the axis; when K _j =0, A _{j, i} are both 0, the optical surface is spherical; After step 4, further include: Step 41, according to the incident angle and incident position of the incident light, calculate the direction cosine vector (l ₁ , m ₁ , p ₁ ) of the light incident on the first optical surface; according to the position of the light on the entrance pupil, the entrance pupil to The distance of the first optical surface, and the surface function of the first optical surface, calculate the position (x ₁ , y ₁ , z ₁ ) of the incident point of the light on the first optical surface, at this time j=1; Step 42, calculate the direction cosine vector of the light exiting the jth optical surface, that is, the direction cosine vector (l _j+1 , m _j+1 , p _j+1 ) when the light is incident on the j+1th optical surface ; Step 43, if j<η, then use the approximation algorithm to calculate the incident point position (x _j+1 , y _j+1 , z _j+1 ) of the ray on the j+1th optical surface, then increase j by 1, Repeat step 42; if j≥n, execute step 44; Step 44, calculate the position (x _image , y _image , z _image ) where the light rays reach the image plane.