A Small Satellite Digital Sun Sensor Polarity Automatic Testing System and Method

Abstract

This paper presents a small satellite digital sun sensor polarity automatic test system and method for the polarity test of small satellite digital sun sensors during the overall satellite test phase. This test device consists of an optical system, a support and rotation mechanism, and ground test equipment, creating a digital sun sensor polarity test mode that integrates functions such as simulating the sun light source, controllable irradiation angle, instruction execution, and corner data broadcasting. The optical system generates a simulated sun light source, and the ground test equipment receives test instructions, drives the two-degree-of-freedom rotation mechanism fixed on the support structure to change the irradiation angle, adjusts the relative position relationship between the optical system and the digital sun sensor, and broadcasts the corner data to the test network. The test personnel compare the corner data of the rotation mechanism received by the test network with the telemetry data of the digital sun sensor to determine the correctness of the polarity of the digital sun sensor, realizing the automatic test of the polarity of the small satellite digital sun sensor.

Description

Technical Field

[0001] This application relates to the field of testing, and in particular to a digital sun sensor polarity testing system and method in a small satellite attitude control system. Background Art

[0002] Automated, intelligent, and batch testing is an effective technical approach to improve the production and testing efficiency of small satellites. With the large increase in the number of small satellite models, the model testing tasks are becoming increasingly heavy, and the traditional testing mode that requires a large number of personnel to participate should be replaced as much as possible. To reduce the number of testers, reduce the on-site testing implementation operations during the testing process, and improve the testing efficiency, the development, popularization, and use of an integrated automated testing system for small satellites should be accelerated, so as to ensure the high-efficiency and high-quality completion of the manufacturing and launching tasks of a large number of small satellites.

[0003] Digital sun sensors are responsible for functions such as satellite sun capture, sun orientation, and attitude determination. The correctness of the digital sun polarity is directly related to the attitude determination and energy security of the entire satellite. The existing polarity testing methods for small satellite digital sun sensors mainly rely on the operator holding an analog sun light source to irradiate the digital sun sensor, slowly irradiating from outside the positive angle field of view of the digital sun sensor to the negative angle direction. The tester in the electrical measurement room reports the current angle telemetry of the digital sun sensor to the operator, and the operator determines the correctness of the digital sun sensor polarity by comparing the consistency between the incident angle of the analog sun light source and the angle telemetry data of the digital sun sensor. The existing polarity testing methods are inefficient. Due to the compact structure layout of small satellites, the operation space left for testers is limited, and it is often difficult to find a suitable testing position and irradiation angle. Moreover, during the testing process, the operator needs to hold the analog sun light source for a large-angle rotation of more than 120°, and possible collisions may pose a safety hazard to the satellite. To complete the automated testing of the digital sun sensor polarity in the control subsystem during the entire satellite testing stage, it is necessary to develop a set of automated testing systems and methods for small satellite digital sun sensor polarity to achieve the automated testing of small satellite digital sun sensor polarity. Summary of the Invention

[0004] The technical problem solved by the present invention is: overcoming the deficiencies of the prior art, and proposing a digital sun sensor polarity testing system and method that integrates functions such as an analog sun light source, controllable irradiation angle, instruction execution, and rotation angle data broadcasting.

[0005] The technical solution of the present invention is to provide a small satellite digital sun sensor polarity automatic test system, including an optical system, a support structure, a two-degree-of-freedom rotation mechanism, ground test equipment, a digital sun sensor, and a test network. The optical system is used to generate an analog sun light source; the support structure is used to support the whole composed of the optical system and the two-degree-of-freedom rotation mechanism, and the two-degree-of-freedom rotation mechanism realizes the automatic adjustment of the irradiation angle of the optical system; the ground test equipment receives test instructions from the test network, drives the two-degree-of-freedom rotation mechanism fixed on the support structure to change the irradiation angle of the optical system, adjusts the relative position relationship between the optical system and the digital sun sensor, and broadcasts the working time and rotation angle data of the two-degree-of-freedom rotation mechanism to the test network; the test network obtains the telemetry data of the digital sun sensor through satellite downlink telemetry, and the test network compares the received rotation angle data of the two-degree-of-freedom rotation mechanism with the telemetry data of the digital sun sensor to determine the correctness of the digital sun sensor polarity.

[0006] Further, the optical system is composed of a base, an LED array light source, and a collimating lens. The LED array light source is composed of 36 single-spectrum LED surface source chips with a beam divergence angle of -60° to 60° and a size of 1mm × 1mm. The wavelength band of the LED array light source is white light in the 415nm to 765nm band. The LED surface source chips are arranged in a 6×6 matrix on the base, and the grid spacing is 15mm; the front surface of the collimating lens is a quadratic surface, and the back surface is fixed directly above the LED array light source in the same arrangement as the LED surface source chips. The material of the collimating lens is selected through LightTools software, the initial surface radius and surface coefficient are set, and the surface radius and surface coefficient are adjusted according to whether the divergence angle of the light distribution curve meets the requirements, so that the divergence angle of the light beam from the LED surface source chips is compressed to within -5° to 5° after passing through the collimating lens.

[0007] Further, when the digital sun sensor leaves the factory, it has a fixed digital sun sensor body coordinate system. The digital sun sensor has a first slit and a second slit. The positive direction of the first slit is the positive direction of the Y axis, and the positive direction of the second slit is the positive direction of the X axis. The Z-axis direction of the digital sun sensor body coordinate system is parallel to the normal of the digital sun sensor.

[0008] Further, the two-degree-of-freedom rotation mechanism includes an inner frame, an outer frame, an inner-frame motor, and an outer-frame motor; both the inner frame and the outer frame are rigid frames for providing two rotational degrees of freedom. The inner frame is installed around the base of the optical system. The outer frame holds the optical system and the inner frame and is connected to the midpoints of two parallel sides of the inner frame. The axis of rotation of the outer frame is parallel to the Z-axis of the body coordinate system of the digital sun sensor, and the axis of rotation of the inner frame passes through the two connection points between the outer frame and the inner frame and is perpendicular to the axis of rotation of the outer frame. The inner-frame motor is installed at any one of the two connection points between the inner and outer frames, and the outer-frame motor is installed on the outer frame directly above the center of the optical system. The inner-frame motor and the outer-frame motor respectively drive the inner and outer frames to rotate around two degrees-of-freedom directions.

[0009] Further, the ground test equipment consists of a power supply module, a motor drive module, and a data processing unit.

[0010] Further, the power supply module uses a PXI power board to supply power to the optical system and the two-degree-of-freedom rotation mechanism.

[0011] Further, the motor drive module uses a DC motor drive module to drive the inner-frame motor to rotate uniformly forward or reversely around the axis of rotation of the inner frame, and drive the outer-frame motor to rotate uniformly forward or reversely around the axis of rotation of the outer frame. The rotational angular velocity range is 0° / s to 20° / s, and the rotational angle range is -90° to 90°.

[0012] Further, the data processing unit includes an instruction receiving module, a data broadcasting module, a data storage module, and a parameter configuration module;

[0013] The instruction receiving module receives various instructions sent by the test network according to the TCP protocol, including enabling and disabling instructions for testing, starting and closing instructions for the optical system, rotational speed setting instructions for the two-degree-of-freedom rotation mechanism, and rotational control instructions for the two-degree-of-freedom rotation mechanism, and executes the instruction content and responds to the response information on the execution status of the instructions;

[0014] The data broadcasting module has the function of broadcasting the angular position data of the two-degree-of-freedom rotation mechanism to the test network in UDP mode, and collects and forwards the angular position of the two-degree-of-freedom rotation mechanism;

[0015] The data storage module has a data storage function, records the start time and end time of the test, the instruction receiving time, the working time of the two-degree-of-freedom rotation mechanism, and the angular position data;

[0016] The parameter configuration module configures the IP address and port number of the test network.

[0017] Further, a method for automatically testing the polarity of a small satellite digital sun sensor based on the system of the present invention includes the following steps:

[0018] S1. Install the optical system on the inner frame of the two-degree-of-freedom rotating mechanism, then fix the two-degree-of-freedom rotating mechanism to the support structure, and adjust the support structure so that the initial position relationship between the two-degree-of-freedom rotating mechanism and the digital sun sensor meets the following requirements: The digital sun sensor is placed at a position 10 cm to 15 cm directly in front of the axis of the collimating lens and is parallel to the optical system. The axis of the inner frame rotation is parallel to the Y-axis of the body coordinate system of the digital sun sensor, and the preparation work for the polarity test is completed.

[0019] S2. Start the ground test equipment, configure the IP address and port number of the test network, and connect the ground test equipment to the test network.

[0020] S3. The data storage module of the ground test equipment records the start time of the test and the instruction reception time in real time.

[0021] S4. The test network sends a power supply instruction to the ground test equipment according to the TCP protocol. After the instruction receiving module of the ground test equipment receives and parses the instruction, it sends a power supply instruction to the power supply module, and the power supply module supplies power to the optical system and the two-degree-of-freedom rotating mechanism.

[0022] S5. The test network sends a motor drive instruction to the ground test equipment according to the TCP protocol. After the instruction receiving module of the ground test equipment receives and parses the instruction, it sends a drive instruction to the motor drive module, and the motor drive module drives the two-degree-of-freedom rotating mechanism to rotate according to the instruction.

[0023] S6. The two-degree-of-freedom rotating mechanism sends the working time and rotation angle data to the data broadcast module and the data storage module in real time. The data broadcast module broadcasts the working time and rotation angle data of the two-degree-of-freedom rotating mechanism to the test network according to the UDP protocol, and the data storage module stores the working time and rotation angle data of the rotating mechanism in the local database.

[0024] S7. The tester compares the rotation angle data of the two-degree-of-freedom rotating mechanism received by the test network with the telemetry data of the digital sun sensor to determine the correctness of the polarity of the digital sun sensor.

[0025] Further, the method for judging the correctness of the polarity of the digital sun sensor is as follows:

[0026] Under the initial position of the two-degree-of-freedom rotation mechanism, according to the right-hand rule, with the negative direction of the Y-axis of the digital sun sensor body coordinate system as the thumb direction, the rotation direction of the inner frame is the direction in which the four fingers are held to drive the motor to rotate. During the test, the digital sun sensor remains stationary, and the output angle of the first slit of the digital sun sensor changes in the positive polarity direction; when the positive direction of the Y-axis of the digital sun sensor body coordinate system is the thumb direction and the inner frame rotates in the reverse direction, the output angle of the first slit of the digital sun sensor changes in the negative polarity direction, indicating that the polarity of the first slit of the digital sun sensor is correct.

[0027] Under the initial position of the two-degree-of-freedom rotation mechanism, according to the right-hand rule, first rotate the outer frame 90° with the negative direction of the Z-axis as the thumb direction to make the rotation axis of the inner frame parallel to the X-axis of the digital sun sensor body coordinate system. With the negative direction of the X-axis of the digital sun sensor body coordinate system as the thumb direction, the rotation direction of the inner frame is the direction in which the four fingers are held to drive the motor to rotate. During the test, the digital sun sensor remains stationary, and the output angle of the second slit of the digital sun sensor changes in the positive polarity direction; when the positive direction of the X-axis of the digital sun sensor body coordinate system is the thumb direction and the inner frame rotates in the reverse direction, the output angle of the second slit of the digital sun sensor changes in the negative polarity.

[0028] The beneficial effects of the present invention compared with the prior art are as follows:

[0029] (1) The present invention selects an LED surface source chip to generate an analog sun light source, making the optical system design small and light. The size of a single LED surface source chip is only 1mm×1mm. In the scenario where the small satellite structure has a compact layout and limited operating space, compared with the prior art method of using xenon lamps / halogen lamps, it is more suitable as the analog sun light source input for the polarity test of the small satellite digital sun sensor.

[0030] (2) The present invention designs a two-degree-of-freedom rotation mechanism and develops the corresponding motor drive module and data processing unit. By driving the inner frame motor and the outer frame motor, the polarity judgment of the two slits is realized, making the irradiation angle and irradiation speed of the analog sun light source controllable, and improving the test efficiency and test safety. Description of the Drawings

[0031] Figure 1 It is a schematic diagram of the composition of the optical system according to the embodiment of the present invention

[0032] Figure 2 It is a schematic diagram of the composition and working principle of the two-degree-of-freedom rotation mechanism according to the embodiment of the present invention

[0033] Figure 3 It is a schematic diagram of the composition and information flow of the ground test equipment according to the embodiment of the present invention Detailed Embodiments

[0034] The present invention will be further described below in conjunction with the embodiments.

[0035] As shown in Figure 1 FIG. Figure 1 , which is a schematic diagram of the composition of an optical system. The optical system of the present invention is composed of a base, an LED surface array light source, and a collimating lens. The LED surface source chips are arranged in a grid pattern on the base, arranged according to 6×6 = 36 LEDs to form an LED surface array light source. Each LED surface source chip has a divergence angle of ±60° and a size of 1 mm×1 mm. Considering the heat dissipation conditions of the LEDs, the grid spacing is taken as 15 mm, and the size of the LED surface array light source is 90×90 mm; the front surface of the collimating lens is a quadratic surface, and the back surface is fixed directly above the LED surface array light source in the same arrangement as the LED surface source chips, corresponding one by one to the LED surface source chips. The normal line of the surface source chip is parallel to the axis of the collimating lens, and the center point of the surface source chip is located on the extension line of the axis of the collimating lens. The LED surface array light source, the collimating lens, and the base together form an optical system to generate a simulated solar light source.

[0036] The material of the collimating lens is selected through LightTools software, the initial surface radius and surface coefficient are set, and the surface radius and surface coefficient are adjusted according to whether the divergence angle of the light distribution curve meets the requirements, so that the divergence angle of the light beam of the LED surface source chip is compressed to within -5° to 5° after passing through the collimating lens.

[0037] White LED surface source chips in the wavelength band of 415 - 765 nm are selected to form an LED surface array light source. Each single LED surface source chip is calculated according to a supply current of 350 mA and a light power of 300 mW. The divergence angle of the surface array light source after passing through the collimating lens is taken as 5 - 10°. Through calculation, a digital sun sensor is placed 10 - 15 cm directly in front of the axis of the collimating lens. The irradiation area of the optical system is 9800 mm 2 ~13400 mm 2 , and the average irradiation intensity of the optical system on the irradiation area is 0.54 solar constants to 0.74 solar constants (1.367 mW / mm 2 ), which can meet the requirement of the irradiation intensity of the simulated solar light source for the polarity test of the digital sun sensor in the range of 0.1 - 1 solar constant.

[0038] As shown in Figure 2 FIG. Figure 2 , which is a schematic diagram of the composition and working principle of a two-degree-of-freedom rotation mechanism.

[0039] The two-degree-of-freedom rotation mechanism includes an inner frame, an outer frame, an inner-frame motor, and an outer-frame motor. Both the inner frame and the outer frame are rigid frames, which are used to provide two rotational degrees of freedom. The inner frame is installed around the base of the optical system, and the normal direction of the optical system is parallel to the normal direction of the inner frame. The outer frame holds the optical system and the inner frame and is connected to the midpoints of two parallel sides of the inner frame. The axis of rotation of the outer frame is parallel to the Z-axis of the body coordinate system of the digital sun sensor, and the axis of rotation of the inner frame passes through the two connection points between the outer frame and the inner frame and is perpendicular to the axis of rotation of the outer frame. The inner-frame motor is installed at any one of the two connection points between the inner and outer frames, and the outer-frame motor is installed on the outer frame directly above the center of the optical system. The inner-frame motor and the outer-frame motor respectively drive the inner and outer frames to rotate around the two degrees-of-freedom directions.

[0040] In this embodiment, a triangular bracket is selected as the support structure, and its height can be adjusted within the range of 40 cm to 200 cm. The support structure is fixed to the outer frame and supports the optical system and the two-degree-of-freedom rotation mechanism.

[0041] Taking the body coordinate system OXYZ of the digital sun sensor as the reference coordinate system, the initial working position state is as follows: the axis of rotation of the outer frame of the two-degree-of-freedom rotation mechanism is parallel to the Z-axis, the axis of rotation of the inner frame is parallel to OY, the normal direction of the optical system is parallel to OZ, the digital sun sensor is parallel to the optical system, and the distance between the plane of the optical system and the upper surface of the digital sun sensor is 10 cm.

[0042] Figure 2 In, the first slit of the digital sun sensor is denoted as slit 01, the second slit of the digital sun sensor is denoted as slit 02. The positive direction of slit 01 is the positive direction of the Y-axis, and the positive direction of slit 02 is the positive direction of the X-axis. The polarity of the digital sun sensor is defined as follows: hold the slit with the right hand, and the thumb points to the positive direction of the slit. Assume that the digital sun sensor rotates. When the body of the digital sun sensor rotates around the positive direction of the slit in the direction of the other four fingers, the output angle of the digital sun sensor changes in the positive polarity direction. For example, if the field of view of the digital sun sensor is ±60°, the angle change trend is from -60° to 60°.

[0043] The method for judging the polarity of slit 01 is as follows:

[0044] At the initial position of the two-degree-of-freedom rotation mechanism, with the thumb pointing in the negative direction of the Y-axis, the inner frame rotates around the negative direction of the Y-axis, and the digital sun sensor remains stationary. The output angle of slit 01 of the digital sun sensor changes in the positive polarity direction. When the thumb points in the positive direction of the Y-axis and the inner frame rotates around the positive direction of the Y-axis, the output angle of slit 01 of the digital sun sensor changes in the negative polarity direction, which indicates that the polarity of slit 01 of the digital sun sensor is correct.

[0045] The method for judging the polarity of slit 02 is as follows:

[0046] In the initial position of the two-degree-of-freedom rotation mechanism, according to the right-hand rule, first rotate the outer frame by 90° with the reverse direction of the Z-axis as the thumb direction, so that the inner frame rotation axis is parallel to the X-axis of the digital sun sensor body coordinate system. With the negative direction of the X-axis as the thumb direction, the inner frame rotates around the negative direction of the X-axis, and the digital sun sensor remains stationary. The output angle of the slit of the digital sun sensor 02 changes in the positive polarity direction; when the inner frame rotates around the positive direction of the X-axis with the positive direction of the X-axis as the thumb direction, the output angle of the slit of the digital sun sensor 02 changes in the negative polarity direction, indicating that the polarity of the slit of the digital sun sensor 02 is correct.

[0047] As Figure 3 shown, it is the composition and information flow diagram of the ground test equipment. The function of this part is to realize the automatic test of the polarity of the small satellite digital sun sensor.

[0048] The ground test equipment is expanded based on an industrial control computer. The power supply module uses a PXI power board, and the motor drive module uses a DC motor drive module, which has the ability to drive the two-degree-of-freedom rigid frame to rotate uniformly forward or backward around its outer frame or inner frame. The rotation angular velocity range is from 0° / s to 20° / s, and the rotation angle range is from -90° to 90°.

[0049] Each module of the data processing unit needs to develop corresponding software module units, and the operating environment is the Windows operating system.

[0050] Among them, the data processing unit includes an instruction receiving module, a data broadcasting module, a data storage module, and a parameter configuration module; each module is developed according to the inherent format. It should be clear that:

[0051] The instruction receiving module can receive various instructions sent by the test network in the TCP / IP manner, including the enable and disable instructions for testing, the start and stop instructions for the optical system, the rotation speed setting instructions for the two-degree-of-freedom rotation mechanism, and the rotation control instructions for the two-degree-of-freedom rotation mechanism, and execute the instruction content and respond to the reply information of the instruction execution situation.

[0052] The data broadcasting module has the function of broadcasting the rotation angle data of the two-degree-of-freedom rotation mechanism to the test network in the UDP manner, and collects and forwards the rotation angle of the two-degree-of-freedom rotation mechanism.

[0053] The data storage module has the data storage function, and records the start time and end time of the test, the instruction receiving time, the working time of the two-degree-of-freedom rotation mechanism, and the rotation angle data.

[0054] The parameter configuration module configures the IP address and port number of the test network.

[0055] The method for performing the polarity test using the device of the present invention mainly includes the following steps:

[0056] S1. Install the optical system on the inner frame of the two-degree-of-freedom rotating mechanism, and then fix the two-degree-of-freedom rotating mechanism to the support structure. Adjust the support structure so that the initial position relationship between the two-degree-of-freedom rotating mechanism and the digital sun sensor meets the following requirements: the digital sun sensor is placed at a position 10 cm to 15 cm directly in front of the axis of the collimating lens and is parallel to the optical system. The axis of the inner frame rotation is parallel to the Y-axis of the body coordinate system of the digital sun sensor, and the preparation work for the polarity test is completed.

[0057] S2. Start the ground test equipment, configure the IP address and port number of the test network, and connect the ground test equipment to the test network.

[0058] S3. The data storage module of the ground test equipment records the start time of the test and the instruction reception time in real time.

[0059] S4. The test network sends a power supply instruction to the ground test equipment according to the TCP protocol. After the instruction receiving module of the ground test equipment receives and parses the instruction, it sends a power supply instruction to the power supply module, and the power supply module supplies power to the optical system and the two-degree-of-freedom rotating mechanism.

[0060] S5. The test network sends a motor drive instruction to the ground test equipment according to the TCP protocol. After the instruction receiving module of the ground test equipment receives and parses the instruction, it sends a drive instruction to the motor drive module, and the motor drive module drives the two-degree-of-freedom rotating mechanism to rotate according to the instruction.

[0061] S6. The two-degree-of-freedom rotating mechanism sends the working time and rotation angle data to the data broadcast module and the data storage module in real time. The data broadcast module broadcasts the working time and rotation angle data of the two-degree-of-freedom rotating mechanism to the test network according to the UDP protocol, and the data storage module stores the working time and rotation angle data of the rotating mechanism in the local database.

[0062] S7. The tester compares the rotation angle data of the two-degree-of-freedom rotating mechanism received by the test network with the telemetry data of the digital sun sensor to determine the correctness of the polarity of the digital sun sensor.

[0063] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention without departing from the spirit and scope of the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. An automated test system for the polarity of a small satellite digital sun sensor, characterized in that, It includes an optical system, a support structure, a two-degree-of-freedom rotation mechanism, ground test equipment, and a test network. The optical system is used to generate a simulated solar light source. The support structure is used to support the whole composed of the optical system and the two-degree-of-freedom rotation mechanism. The two-degree-of-freedom rotation mechanism realizes the automatic adjustment of the irradiation angle of the optical system. The ground test equipment receives test instructions, drives the two-degree-of-freedom rotation mechanism to change the irradiation angle of the optical system, adjusts the relative position relationship between the optical system and the digital sun sensor, and broadcasts the working time and rotation angle data of the two-degree-of-freedom rotation mechanism to the test network. The test network compares the rotation angle data of the two-degree-of-freedom rotation mechanism with the telemetry data of the digital sun sensor to determine the correctness of the polarity of the digital sun sensor. The digital sun sensor includes mutually perpendicular slits, denoted as the first slit and the second slit. The polarity of the digital sun sensor includes the polarity of the first slit and the polarity of the second slit. If both are correct, it indicates that the polarity of the digital sun sensor is correct; if any one is incorrect, the polarity of the digital sun sensor is incorrect. Among them, the method for testing the polarity of the first slit includes the following steps: S1. Adjust the support structure so that the initial position relationship satisfies: the digital sun sensor is placed at a position 10 cm to 15 cm directly in front of the axis of the collimating lens and is parallel to the optical system, and the inner frame rotation axis is parallel to the Y-axis of the digital sun sensor body coordinate system. Among them: the positive direction of the Y-axis of the digital sun sensor body coordinate system is the positive direction of the first slit, the positive direction of the X-axis is the positive direction of the second slit, and the Z-axis is parallel to the normal of the digital sun sensor. S2. The test network sends a motor drive instruction to the ground test equipment, and drives the inner frame motor to rotate with the negative direction of the Y-axis of the digital sun sensor body coordinate system as the rotation axis. S3. The two-degree-of-freedom rotation mechanism sends the working time and rotation angle data to the data broadcast module and the data storage module in real time, broadcasts the working time and rotation angle data to the test network, and stores them in the local database. S4. The test network compares the rotation angle data of the two-degree-of-freedom rotation mechanism with the telemetry data of the digital sun sensor. S5. The test network sends a motor drive instruction to the ground test equipment again, drives the inner frame motor to rotate in the reverse direction with the positive direction of the Y-axis of the digital sun sensor body coordinate system as the rotation axis, and repeats steps S3 to S4 to determine the correctness of the polarity of the first slit of the digital sun sensor.

2. The automated test system for the polarity of a small satellite digital sun sensor according to claim 1, characterized in that, The optical system is composed of a base, an LED array light source, and a collimating lens. The LED array light source is installed on the base, and the light emitted by the LED array light source is collimated by the collimating lens and then output.

3. The automated test system for the polarity of a small satellite digital sun sensor according to claim 2, characterized in that, The LED array light source is composed of 36 single-spectrum LED surface source chips with a beam divergence angle of -60° to 60° and a size of 1 mm × 1 mm. The wavelength band of the LED array light source is white light in the 415 nm to 765 nm band. The LED surface source chips are arranged in a 6×6 matrix on the base, and the grid spacing is 15 mm.

4. The automated test system for the polarity of a small satellite digital sun sensor according to claim 2, characterized in that, The front surface of the collimating lens is a quadratic surface. The back surface is fixed directly above the LED surface array light source in the same arrangement as the LED surface source chip. The material of the collimating lens is selected through LightTools software, and the initial surface radius and surface coefficient are set. The surface radius and surface coefficient are adjusted according to whether the divergence angle of the light distribution curve meets the requirements, so that the divergence angle of the light beam from the LED surface source chip is compressed to within -5° to 5° after passing through the collimating lens.

5. The automated test system for the polarity of a small satellite digital sun sensor according to claim 1, characterized in that, The two-degree-of-freedom rotation mechanism includes an inner frame, an outer frame, an inner frame motor, and an outer frame motor. Both the inner frame and the outer frame are rigid frames used to provide two rotational degrees of freedom. The inner frame is installed around the optical system base. The outer frame clamps the optical system and the inner frame and is connected to the midpoints of two parallel sides of the inner frame. The outer frame rotation axis is parallel to the Z-axis of the digital sun sensor body coordinate system, and the inner frame rotation axis passes through the two connection points of the outer frame and the inner frame and is perpendicular to the outer frame rotation axis. The inner frame motor is installed at any one of the two connection points of the inner and outer frames, and the outer frame motor is installed on the outer frame directly above the center of the optical system. The inner frame motor and the outer frame motor respectively drive the inner and outer frames to rotate around two degrees of freedom.

6. The automated test system for the polarity of a small satellite digital sun sensor according to claim 1, characterized in that, The ground test equipment consists of a power supply module, a motor drive module, and a data processing unit.

7. The automated test system for the polarity of a small satellite digital sun sensor according to claim 6, characterized in that, The data processing unit includes an instruction receiving module, a data broadcasting module, a data storage module, and a parameter configuration module. The instruction receiving module receives various instructions sent by the test network according to the TCP protocol, including test enabling and disabling instructions, optical system startup and shutdown instructions, two-degree-of-freedom rotation mechanism speed setting instructions, and two-degree-of-freedom rotation mechanism rotation control instructions, and executes the instruction content and responds to the reply information on the instruction execution status. The data broadcasting module has the function of broadcasting the rotation angle data of the two-degree-of-freedom rotation mechanism to the test network in UDP mode, and collects and forwards the rotation angle of the two-degree-of-freedom rotation mechanism. The data storage module has a data storage function, recording the start time and end time of the experiment, the instruction receiving time, the working time and rotation angle data of the two-degree-of-freedom rotation mechanism. The parameter configuration module configures the IP address and port number of the test network.

8. The automated test system for the polarity of a small satellite digital sun sensor according to claim 7, characterized in that, The polarity test method of the second slit includes the following steps: S1. Adjust the support structure so that the initial position relationship meets: the digital sun sensor is placed at 10 cm to 15 cm directly in front of the collimating lens axis and is parallel to the optical system, and the inner frame rotation axis is parallel to the Y-axis of the digital sun sensor body coordinate system. S2. The test network sends a motor drive instruction to the ground test equipment, rotates the outer frame motor by 90° with the Z-axis negative direction as the rotation axis, so that the inner frame rotation axis is parallel to the X-axis of the digital sun sensor body coordinate system. S3. Continue to send a motor drive instruction to drive the inner frame motor to rotate with the negative direction of the X-axis of the digital sun sensor body coordinate system as the rotation axis. S4. The two-degree-of-freedom rotation mechanism sends the working time and rotation angle data to the data broadcasting module and the data storage module in real time, broadcasts the working time and rotation angle data to the test network, and stores them in the local database. S5. The test network compares the angular data of the two-degree-of-freedom rotating mechanism with the telemetry data of the digital sun sensor. S6. Send the motor drive command again. Using the positive direction of the X-axis of the digital sun sensor's body coordinate system as the rotation axis, drive the inner frame motor to rotate in the reverse direction, and repeat steps S4 - S5 to determine the correctness of the polarity of the second slit of the digital sun sensor.

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