Star sensor, monitoring device and monitoring method

Abstract

The application discloses a star sensor, a monitoring device and a monitoring method for reference light vector change based on the star sensor. The star sensor comprises a base, a total reflection optical lens arranged on the base, a plurality of crossbeams fixedly connected to the total reflection optical lens, and two bevel mirrors arranged on adjacent crossbeams. The two bevel mirrors are both at an angle of 45 degrees with the optical axis of the total reflection optical lens. The star sensor, the monitoring device and the monitoring method measure the change of the light spot of the reference light on the photoelectric detector, and then measure and calibrate the reference light vector change caused by the track force or thermal deformation, so as to improve the correlation reference precision between the star sensor and the attitude measurement system, and then improve the ground positioning precision of the satellite.

Description

Technical Field

[0001] This invention relates to a star sensor, a monitoring device for monitoring changes in a reference light vector based on the star sensor, and a monitoring method. Background Technology

[0002] A star sensor is a photoelectric measurement instrument based on computer vision principles. The physical quantity it directly measures is the centroid of the nearly circular light spot formed on the photoelectric sensor by the optical system of a star. Through steps such as star vector calculation, star map matching, attitude calculation, and data fusion, the final result is the quaternion (including pitch, tilt angle, right ascension of the ascending node, and orbital center altitude) required by the satellite attitude and orbit control system. According to frequency, the errors of a star sensor can be divided into noise equivalent angle, low-frequency error of the field of view period, and low-frequency error of the orbital period. The low-frequency error of the orbital period corresponds to the change in the optical axis pointing of the star sensor, mainly including thermal deformation of the optomechanical structure and optical aberration. The former can be controlled to a very small range through optomechanical structure design and precise temperature control during on-orbit operation. The latter can be controlled to a very small range by injecting angular velocity into the space photoelectric sensor through the GNC (Guidance, Navigation, Control) subsystem and correcting it in real time via software.

[0003] The accuracy of payload references significantly impacts operational quality. For instance, the accuracy of the reference between the line-of-sight camera's line of sight and the attitude measurement system housing the star sensor directly affects the satellite's ground positioning accuracy. While mechanical fastening can reduce some reference transfer errors, it's difficult to ignore changes in the onboard reference light vector caused by orbital forces and thermal environment variations. When the star sensor's own optical axis changes are negligible, it's necessary to establish a reference transfer relationship between the star sensor, the satellite platform, and the payload. This allows for calibration to correct reference offsets, ultimately improving the satellite's ground positioning accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a star sensor, a monitoring device for monitoring changes in the reference light vector based on the star sensor, and a monitoring method.

[0005] To achieve the above objectives, the present invention provides a star sensor, the star sensor comprising:

[0006] Base;

[0007] A total internal reflection optical lens, wherein the total internal reflection optical lens is mounted on the base;

[0008] Multiple crossbeams are fixedly connected to the total internal reflection optical lens, and the crossbeams are perpendicular to the optical axis of the total internal reflection optical lens.

[0009] Two obliquely cut mirrors are disposed on adjacent crossbeams; both obliquely cut mirrors form a 45° angle with the optical axis of the total internal reflection optical lens.

[0010] Optionally, four crossbeams are evenly distributed along the circumference of the total reflection optical lens, and two beveled mirrors are disposed on two adjacent crossbeams, with the normals of the two beveled mirrors perpendicular to each other.

[0011] Optionally, the beveled mirror surface is formed by machining the surface of the beam.

[0012] Optionally, the crossbeam is provided with a mirror mounting surface, and two beveled prisms are respectively mounted on the mirror mounting surface on the crossbeam to form the beveled mirror.

[0013] Optionally, the star sensor further includes a light shield connected to the base, the light shield having a light-transmitting hole that is opposite to the beveled mirror surface.

[0014] Optionally, the star sensor further includes a temperature control component and a photodetector. The temperature control component and the photodetector are connected to the base. The temperature control component is used to perform precise temperature control on the star sensor to ensure that the star sensor itself has no deformation or negligible deformation.

[0015] The present invention also provides a monitoring device for the reference light vector change based on a star sensor, the monitoring device comprising:

[0016] Such as the star sensor mentioned above;

[0017] A reference light source is used to emit two beams of parallel light that are directed toward the beveled mirror surface and perpendicular to the optical axis of the total internal reflection optical lens.

[0018] Optionally, the reference light source is located on the entire star where the star sensor is located.

[0019] The present invention also provides a method for monitoring changes in on-board reference light vector based on a star sensor, the monitoring method being used in the aforementioned monitoring device for monitoring changes in reference light vector based on a star sensor, the monitoring method comprising:

[0020] S10. The reference light source emits two parallel beams that are perpendicular to each other towards the oblique mirror. The two parallel beams are reflected by the two oblique mirrors and then pass through the total internal reflection optical lens to finally form a light spot on the photodetector of the star sensor.

[0021] S20. Acquire the light spot on the photodetector, and calculate the angular displacement of the reference light vector around the star sensor along the X and Y axes based on the change in the position of the light spot.

[0022] Optionally, in step S20, the calculation formulas for calculating the angular displacement of the reference light vector around the star sensor along the X and Y axes based on the light spot are as follows:

[0023] (1)

[0024] (2)

[0025] In the formula: This represents the displacement of the light spot's centroid along the X and Y axes of the star sensor; f The focal length of a total internal reflection optical lens

[0026] In summary, compared with the prior art, the star sensor, the monitoring device for monitoring the reference light vector change based on the star sensor, and the monitoring method provided by the present invention have the following beneficial effects:

[0027] By setting oblique mirrors on the crossbeam to reflect reference light, the change of the reference light spot on the detector is measured, and the change of the reference light vector is then measured and calibrated in orbit. This improves the correlation accuracy between the star sensor and the attitude measurement system, thereby improving the satellite's ground positioning accuracy. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the star sensor of the present invention.

[0029] Figure 2 This is a top view of the star sensor of the present invention.

[0030] Figure 3 This is a schematic diagram of the reflected light from the obliquely cut mirror surface of the star sensor of the present invention.

[0031] Figure 4 A schematic diagram of the light shield of the star sensor of the present invention.

[0032] Explanation of possession markings:

[0033] Star Sensor 10

[0034] Parallel light 20

[0035] Base 100

[0036] Total reflection optical lens 110

[0037] 120 crossbeam

[0038] 130mm beveled mirror

[0039] 140mm sunshade

[0040] 150mm light-transmitting aperture Detailed Implementation

[0041] The following will be combined with the appendix in the embodiments of the present invention. Figure 1 ~Attached Figure 4 The technical solutions, structural features, objectives and effects achieved in the embodiments of the present invention will be described in detail.

[0042] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0043] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0044] like Figure 1 and Figure 2 As shown, the present invention provides a star sensor 10. The star sensor 10 includes a base 100, a total internal reflection optical lens 110, and two obliquely cut mirrors 130 mounted on adjacent crossbeams 120. The star sensor 10 is used to detect the centroid of a nearly circular light spot formed on a photodetector by the total internal reflection optical lens 110 after parallel light emitted from a reference light source passes through the total internal reflection optical lens 110. The total internal reflection optical lens 110 includes multiple lenses arranged along the optical axis. The photodetector is disposed at one end of the total internal reflection optical lens 110 and is used to convert the light signal passed through the total internal reflection optical lens 110 into an electrical signal. The total internal reflection optical lens 110 is disposed on the base 100. Multiple crossbeams 120 are fixedly connected to the total internal reflection optical lens 110, and the crossbeams 120 are arranged perpendicular to the optical axis of the total internal reflection optical lens 110. Two beveled mirrors 130 are mounted on adjacent crossbeams 120, and the mirror surfaces of both beveled mirrors 130 form a 45° angle with the optical axis of the total internal reflection optical lens 110. For example... Figure 3 As shown, the oblique mirror 130 is used to reflect incident light perpendicular to the optical axis and then incident it parallel to the optical axis onto the photodetector of the star sensor 10 to monitor the deflection of the reference light vector around the X and Y axes of the star sensor.

[0045] Continue as Figure 1 and Figure 2 As shown, in this embodiment, the beveled mirror 130 is formed by surface grinding of the crossbeam 120, that is, the beveled mirror 130 and the crossbeam 120 are integrally processed to avoid relative movement between the beveled mirror 130 and the crossbeam 120, and to ensure that the beveled mirror and the optical axis of the star sensor form a 45° angle.

[0046] In other embodiments, a mirror mounting surface may be machined on the beam 120, and then a beveled prism may be mounted on the mirror mounting surface to form a beveled mirror 130.

[0047] In this embodiment, four crossbeams 120 are evenly distributed along the circumference of the total internal reflection optical lens 110, and the included angle between two adjacent crossbeams 120 along the circumference of the total internal reflection optical lens 110 is 90°. Two beveled mirrors 130 are mounted on two adjacent crossbeams 120, and the normals of the mirrors of the two beveled mirrors 130 are perpendicular to each other, and the included angle between two adjacent crossbeams 120 is 90°. With this arrangement, the light spots that are reflected by the two beveled mirrors 130 and illuminate the photodetector can be directly calculated by extracting the centroid position of the light spots, thereby improving the monitoring efficiency.

[0048] In other embodiments, three or more crossbeams 120 may be arranged circumferentially around the total internal reflection optical lens 110. If three crossbeams 120 are arranged circumferentially around the total internal reflection optical lens 110, the included angle between adjacent crossbeams 120 is 120°. In this case, the deflection of the reference light vector around the X-axis and Y-axis of the star sensor affects the change in the position of the light spot illuminating the photodetector after reflection by the two oblique mirrors 130. It is necessary to decompose the change in the position of the light spot illuminating the photodetector after reflection by the two oblique mirrors 130 into the change in the position of the light spot caused by the deflection of the reference light vector around the X-axis and Y-axis of the star sensor, and then calculate the deflection of the reference light vector around the X-axis and Y-axis of the star sensor.

[0049] Star sensor 10 also includes Figure 4 A light shield 140 is used to protect the star sensor 10 and reduce the impact of sunlight or rays on the total internal reflection optical lens 110. The light shield 140 is connected to the base 100. A light-transmitting hole 150 is formed on the light shield 140, and the light-transmitting hole 150 is opposite to the mirror surface of the beveled mirror surface 130. Both light-transmitting holes 150 have a diameter of 8 mm. Selecting appropriate locations on the light shield 140 to create 8 mm diameter light-transmitting holes helps to release stress generated during the manufacturing process of the light shield 140.

[0050] The star sensor 10 also includes a temperature control component connected to the base 100, which is used to ensure that the star sensor itself has no deformation or negligible deformation.

[0051] The present invention also provides a monitoring device for the reference light vector change based on a star sensor. The monitoring device includes a star sensor 10 as described above and a reference light source. The reference light source is used to emit parallel light 20 perpendicular to the optical axis of the total internal reflection optical lens 110 towards the oblique mirror 130. The parallel light 20 is reflected by the oblique mirror 130 and then shines on the photodetector along the optical axis of the total internal reflection optical lens 110.

[0052] The reference light source is set on the entire satellite where the star sensor is located. When the star sensor 10 is working in orbit, it can monitor the deflection of the reference light vector around the X-axis or Y-axis of the star sensor in orbit.

[0053] The present invention also provides a method for monitoring changes in a reference light vector based on a star sensor. The monitoring method is used in the aforementioned monitoring device for monitoring changes in a reference light vector based on a star sensor. The monitoring method includes:

[0054] S10 and the reference light source respectively emit two beams of parallel light 20 towards the oblique mirror 130. After being reflected by the two oblique mirrors 130, the two beams of parallel light 20 illuminate the photodetector on the star sensor along the optical axis of the total reflection optical lens 110 and form a light spot.

[0055] S20. Collect the light spot on the photodetector, and calculate the angular displacement of the reference light vector around the X-axis and Y-axis of the star sensor based on the light spot. In this embodiment, four crossbeams 120 are provided along the circumference of the total internal reflection optical lens 110, and two obliquely cut mirrors 130 are disposed on adjacent crossbeams 120. The calculation formulas for calculating the angular displacement of the reference light vector around the X-axis and Y-axis of the star sensor based on the light spot are as follows:

[0056] (1)

[0057] (2)

[0058] In the formula: This represents the displacement of the light spot's centroid along the X and Y axes of the star sensor; f The focal length of a total internal reflection optical lens

[0059] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A star sensor, characterized in that, The star sensor includes: a base; a total internal reflection optical lens disposed on the base; multiple crossbeams fixedly connected to the total internal reflection optical lens, and the crossbeams being perpendicular to the optical axis of the total internal reflection optical lens; two obliquely cut mirrors disposed on adjacent crossbeams; both obliquely cut mirrors forming a 45° angle with the optical axis of the total internal reflection optical lens.

2. The star sensor as described in claim 1, characterized in that, Four crossbeams are evenly distributed along the circumference of the total internal reflection optical lens. Two oblique mirrors are disposed on two adjacent crossbeams, and the normals of the two oblique mirrors are perpendicular to each other.

3. The star sensor as described in claim 2, characterized in that, The beveled mirror surface is formed by machining the surface of the beam.

4. The star sensor as described in claim 2, characterized in that, The crossbeam is provided with a mirror mounting surface, and two oblique-cut prisms are respectively mounted on the mirror mounting surface on the crossbeam to form the oblique-cut mirror surface.

5. The star sensor as described in claim 1, characterized in that, The star sensor also includes a light shield connected to the base. The light shield has a light-transmitting hole, which is opposite to the beveled mirror surface.

6. The star sensor as described in claim 1, characterized in that, The star sensor also includes a temperature control component and a photodetector. The temperature control component and the photodetector are connected to the base. The temperature control component is used to perform precise temperature control on the star sensor to ensure that the star sensor itself has no deformation or negligible deformation.

7. A monitoring device for reference light vector changes based on a star sensor, characterized in that, The monitoring device includes: a star sensor as described in any one of claims 1-6; and a reference light source, the reference light source being used to emit two beams of parallel light that are directed toward the oblique mirror surface and perpendicular to the optical axis of the total internal reflection optical lens.

8. The monitoring device for reference light vector change based on a star sensor as described in claim 7, characterized in that, The reference light source is located on the entire star where the star sensor is located.

9. A method for monitoring changes in a reference light vector based on a star sensor, characterized in that, The monitoring method is used in the monitoring device for the reference light vector change based on a star sensor as described in any one of claims 7-8. The monitoring method includes: S10, the reference light source emits two mutually perpendicular parallel beams toward the oblique mirror, and the two parallel beams are reflected by the two oblique mirrors and then pass through a total internal reflection optical lens to finally form a light spot on the photodetector of the star sensor; S20, the light spot on the photodetector is collected, and the angular displacement of the reference light vector around the X-axis and Y-axis of the star sensor is calculated according to the change in the position of the light spot.

10. The method for monitoring the change of reference light vector based on a star sensor as described in claim 9, characterized in that, In step S20, the formulas for calculating the angular displacement of the reference light vector around the star sensor along the X and Y axes based on the light spot are as follows: (1) (2) In the formula: This represents the displacement of the light spot's centroid along the X and Y axes of the star sensor; f This refers to the focal length of a total internal reflection optical lens.

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