A large-dynamic star sensor integrated with a high-precision MEMS gyro and its working method

Abstract

A large-dynamic star sensor integrated with a high-precision MEMS gyro and its working method, belonging to the technical field of star sensors. To provide a large-dynamic star sensor integrated with a high-precision MEMS gyro, the present invention includes a star sensor, and an MEMS gyro combination is installed on the base of the star sensor. The MEMS gyro combination includes a main body structure and three single-axis MEMS gyros. The three single-axis MEMS gyros are installed on the front side, left side, and upper side of the main body structure, and the installation directions of the three single-axis MEMS gyros coincide with the three coordinate axes of the star sensor coordinate system. The present invention realizes the complementary advantages of the star sensor and the gyro inside the product, improving the accuracy and stability; the data fusion processing is realized in the star sensor, and the integrated product reduces the dependence on external auxiliary equipment, realizes data interaction and processing inside the product, and enhances the autonomy; improves the response speed and flexibility; reduces the product volume.

Description

Technical Field

[0001] The present invention belongs to the technical field of star sensors, and particularly relates to a large-dynamic-range star sensor integrated with a high-precision MEMS gyroscope and a working method thereof. Background Art

[0002] A star sensor is a key component of a high-precision space vehicle, mainly used for measuring the components of the stellar vector in the coordinate system of the star sensor, identifying the star map, and using the exact positions of known stars to determine the three-axis attitude of the space vehicle relative to the inertial coordinate system. It has the advantages of high positioning accuracy, small mass, low power consumption, high autonomy, and no attitude accumulation error, and is the most accurate attitude sensor among all current attitude sensors.

[0003] A gyroscope can continuously and real-time measure the angular velocity of a satellite, has high short-term stability, and can provide instant information on the dynamic motion of the satellite. However, over time, the gyroscope will accumulate drift errors, resulting in a decrease in long-term accuracy.

[0004] Under high-dynamic flight conditions, such as during rapid satellite orbit changes or the ascent stage of a launch vehicle, traditional star sensors are vulnerable to strong vibrations and high-speed rotations, leading to difficulties in star map recognition and a decrease in positioning accuracy. Although existing technologies have attempted to reduce these effects through complex algorithms and external auxiliary devices, the performance bottleneck in the large dynamic range has not been fully resolved. Therefore, there is an urgent need for a star sensor design that can directly integrate high-precision attitude sensing elements and enhance anti-interference capabilities.

[0005] Currently, the commonly used attitude determination scheme for satellite platforms is a combination of a star sensor and a gyroscope. However, both the star sensor and the gyroscope are independent products, and there is no product that integrates a star sensor and a gyroscope. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a large-dynamic-range star sensor integrated with a high-precision MEMS gyroscope, and to propose a large-dynamic-range star sensor integrated with a high-precision MEMS gyroscope and a working method thereof.

[0007] To achieve the above object, the present invention is realized through the following technical solutions:

[0008] A large-dynamic-range star sensor integrated with a high-precision MEMS gyroscope includes a star sensor, and an MEMS gyroscope assembly is installed on the base of the star sensor. The MEMS gyroscope assembly includes a main body structure and three single-axis MEMS gyroscopes. The three single-axis MEMS gyroscopes are installed on the front side, left side, and upper side of the main body structure, and the installation directions of the three single-axis MEMS gyroscopes coincide with the three coordinate axes of the star sensor coordinate system.

[0009] Further, the deviation between the measurement axis of each single-axis MEMS gyro and the coordinate axis of the corresponding star sensor is less than 0.05°.

[0010] Further, based on the accurate angular rate information collected by the MEMS gyro combination, the star sensor realizes accurate attitude prediction and processing.

[0011] Further, the star sensor and each single-axis MEMS gyro use independent SPI communication lines for data interaction. The star sensor uses FPGA to implement the SPI interface with the single-axis MEMS gyro, parallelly collects the data of three single-axis MEMS gyros, and sends it to the CPU in the star sensor for data processing.

[0012] Further, the installation and adjustment process of the single-axis MEMS gyro is as follows: after welding the single-axis MEMS gyro to the flexible printed circuit board, bond the bottom surface of the gyro ceramic housing of the single-axis MEMS gyro to the installation plane of the main structure; first, ensure that the bottom surface of the gyro ceramic housing is parallel to the installation surface of the main structure by bonding, and then calibrate the transfer matrix of the MEMS gyro combination relative to the optical axis of the star sensor through a high-precision turntable, confirm the relative position relationship between the MEMS gyro combination and the star sensor, and finely adjust the installation of the single-axis MEMS gyro until the installation accuracy requirements are met.

[0013] A working method of a large-dynamic star sensor integrated with high-precision MEMS gyros is realized relying on the described large-dynamic star sensor integrated with high-precision MEMS gyros, and includes the following steps:

[0014] S1. The MEMS gyro combination measures the angular rate information on the three axes of the star sensor body coordinate system, and transmits the collected angular rate information on the three axes to the star sensor through the SPI interface;

[0015] S2. Based on the angular rate information on the three axes obtained in step S1, the star sensor performs accurate attitude prediction, star map recognition and matching, and attitude calculation, and then fuses the predicted attitude and the measured attitude to obtain the finally output attitude information and angular rate information.

[0016] Further, in step S1, set x st 、y st 、z st as the x-axis coordinate, y-axis coordinate, and z-axis coordinate of the star sensor, and x me 、y me 、z me as the x-axis coordinate, y-axis coordinate, and z-axis coordinate of the MEMS gyro combination.

[0017] Further, the specific implementation method of fusing the predicted attitude and the measured attitude in step S2 includes the following steps:

[0018] S2.1. Set the estimated angular rate measured by the MEMS gyroscope combination The expression is as follows:

[0019]

[0020] where ω g,k is the angular rate output by the MEMS gyroscope combination in the k-th frame, are the estimated angular rates of the x-axis, y-axis, and z-axis of the k-th frame of the MEMS gyroscope combination respectively, is the estimated value of the constant drift of the k-th frame of the MEMS gyroscope combination;

[0021] S2.2. Predict the attitude of the next measurement period based on the estimated angular rate measured by the MEMS gyroscope combination obtained in step S2.1. The expression is as follows:

[0022]

[0023] where Q k is the attitude of the k-th frame, Q k+1 / k is the predicted attitude of the (k + 1)-th frame, T is the data update period, λ is the angle rotated within one period, ω x，k+1 is the x-axis angular rate output by the MEMS gyroscope combination in the (k + 1)-th frame, ω y, k+1 is the y-axis angular rate output by the MEMS gyroscope combination in the (k + 1)-th frame, ω z, k+1 is the z-axis angular rate output by the MEMS gyroscope combination in the (k + 1)-th frame;

[0024]

[0025] S2.3. Set the state variable as where q e is the error quaternion, and δd is the gyro drift error;

[0026] S2.4. Set the initial value of the state variable X0 = 0 6*1 and the initial value of the state covariance P0 = 1*10 -10 I 6*6 and the initial value of the gyro constant drift Perform state prediction, measurement update, and state correction, and fuse to obtain the updated state variable. The expression is as follows:

[0027]

[0028] where X k+1 is the state variable of the (k + 1)-th frame, q e,k+1 is the error quaternion of the (k + 1)-th frame, and δd k+1 is the zero bias error of the (k + 1)-th frame;

[0029] Then, correct the estimated attitude and gyro drift;

[0030]

[0031] where Q k+1 is the attitude of the (k + 1)-th frame, is the estimated value of the constant drift of the (k + 1)-th frame of the MEMS gyroscope assembly.

[0032] Furthermore, in view of the influence of temperature change on the performance of the MEMS gyroscope assembly and the star sensor optical component, select aluminum matrix silicon carbide as the material for manufacturing the mechanical structure of the star sensor and the mechanical structure of the MEMS gyroscope assembly, and adopt a semiconductor cooler and a PID control method based on pulse width modulation to control the cooler, so as to achieve high-precision temperature control of the mounting surface and ensure the stable working performance of the star sensor in different temperature ranges.

[0033] Advantages of the present invention:

[0034] For a large-dynamic star sensor integrated with a high-precision MEMS gyroscope according to the present invention, data fusion processing is realized in the star sensor, and there is no need for additional hardware devices to separately receive the data of the star sensor and the MEMS gyroscope and then perform data fusion.

[0035] For a large-dynamic star sensor integrated with a high-precision MEMS gyroscope according to the present invention, through the integration of the star sensor and the MEMS gyroscope, the advantages of the star sensor and the gyroscope are complementary inside the product, improving the accuracy and stability.

[0036] For a large-dynamic star sensor integrated with a high-precision MEMS gyroscope according to the present invention, the integrated product reduces the dependence on external auxiliary devices, realizes data interaction and processing inside the product, and enhances the autonomy.

[0037] For a large-dynamic star sensor integrated with a high-precision MEMS gyroscope according to the present invention, the integrated product can quickly respond to attitude changes through an internally optimized data processing algorithm, improving the response speed and flexibility.

[0038] For a large-dynamic star sensor integrated with a high-precision MEMS gyroscope according to the present invention, it reduces the volume, weight and power consumption of the product, and realizes the miniaturization and low-cost design of the product. Description of the Drawings

[0039] Figure 1 is a schematic structural diagram of a large-dynamic star sensor integrated with a high-precision MEMS gyroscope according to the present invention;

[0040] Figure 2 is a perspective view of a large-dynamic star sensor integrated with a high-precision MEMS gyroscope according to the present invention;

[0041] Figure 3 This is a flowchart of the working method of a large-dynamic star sensor integrated with a high-precision MEMS gyro according to the present invention;

[0042] Figure 4 This is the internal data flow diagram of the large-dynamic star sensor integrated with a high-precision MEMS gyro according to the present invention Specific embodiments

[0043] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the specific embodiments described are only a part of the embodiments of the present invention, rather than all of the specific embodiments. Usually, the components of the specific embodiments of the present invention described and shown in the accompanying drawings herein can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0044] Therefore, the following detailed description of the specific embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents the selected specific embodiments of the present invention. All other specific embodiments obtained by those skilled in the art based on the specific embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0045] To further understand the content, features and effects of the present invention, the following specific embodiments are exemplified and combined with the attached Figure 1 - Attached Figure 4 The details are as follows:

[0046] Embodiment 1:

[0047] A large-dynamic star sensor integrated with a high-precision MEMS gyro includes a star sensor 1. An MEMS gyro combination is installed on the base of the star sensor 1. The MEMS gyro combination includes a main body structure 4 and three single-axis MEMS gyros 5. The three single-axis MEMS gyros 5 are installed on the front side, left side and upper side of the main body structure 4, and the installation directions of the three single-axis MEMS gyros 5 coincide with the three coordinate axes of the star sensor 1 coordinate system respectively.

[0048] Furthermore, the deviation between the measurement axis of each single-axis MEMS gyro 5 and the corresponding coordinate axis of the star sensor 1 is less than 0.05°.

[0049] Furthermore, based on the accurate angular rate information collected by the MEMS gyro combination, the star sensor realizes accurate attitude prediction and processing.

[0050] Further, the star sensor 1 and each single-axis MEMS gyro 5 use independent SPI communication lines 3 for data interaction. The star sensor 1 uses an FPGA to implement the SPI interface with the single-axis MEMS gyro 5, collect the data of the three single-axis MEMS gyros 5 in parallel, and send it to the CPU in the star sensor 1 for data processing, such as Figure 4 as shown

[0051] Further, the alignment process of the single-axis MEMS gyro 5 is as follows: after welding the single-axis MEMS gyro 5 to the flexible printed circuit board, bond the bottom surface of the gyro ceramic housing of the single-axis MEMS gyro 5 to the installation plane of the main body structure 4; first, ensure that the bottom surface of the gyro ceramic housing is parallel to the installation surface of the main body structure 4 during bonding, and then calibrate the transfer matrix of the MEMS gyro combination relative to the optical axis of the star sensor 1 through a high-precision turntable, confirm the relative position relationship between the MEMS gyro combination and the star sensor 1, and finely adjust the installation of the single-axis MEMS gyro 5 until the installation accuracy requirements are met.

[0052] The large dynamic star sensor integrated with high-precision MEMS gyro in this embodiment realizes the complementary advantages of the star sensor and the gyro inside the product through the integration of the star sensor and the MEMS gyro, improving the accuracy and stability; the integrated product reduces the dependence on external auxiliary equipment, realizes data interaction and processing inside the product, and enhances the autonomy; the integrated product can quickly respond to attitude changes through internal optimized data processing algorithms, improving the response speed and flexibility; reduces the product volume, weight and power consumption, and realizes the miniaturization and low-cost design of the product.

[0053] Embodiment 2:

[0054] A working method of a large dynamic star sensor integrated with high-precision MEMS gyro is realized relying on the large dynamic star sensor integrated with high-precision MEMS gyro described in Embodiment 1, and includes the following steps:

[0055] S1. The MEMS gyro combination measures the angular rate information on the three axes of the star sensor body coordinate system, and transmits the collected angular rate information on the three axes to the star sensor through the SPI interface;

[0056] Further, in step S1, set x st 、y st 、z st as the x-axis coordinate, y-axis coordinate, and z-axis coordinate of the star sensor, and x me 、y me 、z me as the x-axis coordinate, y-axis coordinate, and z-axis coordinate of the MEMS gyro combination;

[0057] S2. Based on the angular rate information on the three axes obtained in step S1, the star sensor performs accurate prediction of the attitude, recognition and matching of the star map, and calculation of the attitude. Then, the predicted attitude and the measured attitude are subjected to data fusion to obtain the finally output attitude information and angular rate information;

[0058] Furthermore, the specific implementation method for data fusion of the predicted attitude and the measured attitude in step S2 includes the following steps:

[0059] S2.1. Set the expression of the angular rate estimation value measured by the MEMS gyroscope combination as: as:

[0060]

[0061] where ω g,k is the angular rate output by the MEMS gyroscope combination in the k-th frame, are respectively the estimated angular rates of the x-axis, y-axis, and z-axis of the MEMS gyroscope combination in the k-th frame, is the estimated value of the constant drift of the MEMS gyroscope combination in the k-th frame;

[0062] S2.2. Predict the attitude in the next measurement period based on the angular rate estimation value measured by the MEMS gyroscope combination obtained in step S2.1. The expression is:

[0063]

[0064] where Q k is the attitude in the k-th frame, Q k+1 / k is the predicted attitude in the (k + 1)-th frame, T is the data update period, λ is the angle rotated within one period, ω x，k+1 is the x-axis angular rate output by the MEMS gyroscope combination in the (k + 1)-th frame, ω y,k+1 is the y-axis angular rate output by the MEMS gyroscope combination in the (k + 1)-th frame, ω z,k+1 is the z-axis angular rate output by the MEMS gyroscope combination in the (k + 1)-th frame;

[0065]

[0066] S2.3. Set the state variable as where q e is the error quaternion, and δd is the gyro drift error;

[0067] S2.4. Set the initial value of the state variable X0 = 0 6*1 , the initial value of the state covariance P0 = 1 * 10 -10 I 6*6 , and the initial value of the gyro constant drift Perform state prediction, measurement update, and state correction, and fuse to obtain the updated state quantity. The expression is as follows:

[0068]

[0069] Among them, X k+1 is the state quantity of the (k + 1)-th frame, q e,k+1 is the error quaternion of the (k + 1)-th frame, and δd k+1 is the bias error of the (k + 1)-th frame;

[0070] Then correct the estimated attitude and gyro drift;

[0071]

[0072] Among them, Q k+1 is the attitude of the (k + 1)-th frame, is the estimated value of the constant drift of the (k + 1)-th frame of the MEMS gyroscope assembly.

[0073] Furthermore, in view of the influence of temperature change on the performance of the MEMS gyroscope assembly and the star sensor optical component, select aluminum matrix silicon carbide as the material for the mechanical structure of the star sensor and the mechanical structure of the MEMS gyroscope assembly, and use a semiconductor refrigerator and a PID control method based on pulse width modulation to control the refrigerator, so as to achieve high-precision temperature control of the mounting surface and ensure the stable working performance of the star sensor in different temperature ranges.

[0074] It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0075] Although the present application has been described above with reference to specific embodiments, various modifications can be made thereto and components thereof can be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the features in the specific embodiments disclosed in the present application can be combined with each other in any way, and the exhaustive description of these combinations is not given in this specification only for the sake of saving space and resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for operating a large dynamic star sensor integrated with a high-precision MEMS gyroscope, the large dynamic star sensor integrated with a high-precision MEMS gyroscope comprising a star sensor (1), a MEMS gyroscope assembly being mounted on a base of the star sensor (1), the MEMS gyroscope assembly comprising a main structure (4), and three single-axis MEMS gyroscopes (5), the three single-axis MEMS gyroscopes (5) being mounted on a front side surface, a left side surface, and an upper side surface of the main structure (4), and the mounting directions of the three single-axis MEMS gyroscopes (5) respectively coincide with three coordinate axes of a coordinate system of the star sensor (1); It is characterized in that The working method includes the following steps: S1. The MEMS gyro combination measures the angular rate information on the three axes of the star sensor body coordinate system, and uses the SPI interface to transmit the collected angular rate information on the three axes to the star sensor; S2. The star sensor performs accurate attitude prediction, star map recognition and matching, and attitude calculation based on the angular rate information on the three axes obtained in step S1, and then fuses the predicted attitude and the measured attitude to obtain the final output attitude information and angular rate information; The specific implementation method of data fusion of the predicted posture and the measured posture in step S2 includes the following steps: S2.

1. Set the angular rate estimate measured by the MEMS gyro assembly The expression is: Among them, ω g,k is the angular rate of the MEMS gyro combination output at the kth frame, [ω x，k ω y，k ω z，k ] are the estimated angular rates of the kth frame of the MEMS gyro assembly, respectively, on the x-axis, y-axis, and z-axis. is the estimated value of the k-th frame constant drift of the MEMS gyro assembly; S2.

2. Predict the attitude of the next measurement cycle based on the estimated angular rate measured by the MEMS gyro combination obtained in step S2.1, expressed as: Among them, Q k is the k-th frame pose, Q k+1 / k is the predicted k+1th frame posture, T is the data update period, λ is the rotation angle within a period, ω x，k+1 is the x-axis angular rate output by the MEMS gyro combination in the k+1th frame, ω y,k+1 is the y-axis angular rate output by the MEMS gyro combination in the k+1th frame, ω z,k+1 is the z-axis angular rate output by the MEMS gyro combination in the k+1th frame; S2.

3. Set the state quantity to where q e is the error quaternion, δd is the gyro drift error; S2.

4. Set the initial value of the state variable X0 = 0 6*1 , initial value of state covariance P0 = 1*10 -10 I 6*6 , gyro constant drift initial value Perform state prediction, measurement update and state correction, and integrate to obtain the updated state quantity, which is expressed as: Among them, X k+1 is the state quantity of the k+1th frame, q e,k+1 is the error quaternion of the k+1th frame, δd k+1 is the zero bias error of the k+1th frame; The estimated attitude and gyro drift are then corrected; Where Q k+1 is the posture of the k+1th frame, is the estimated value of the k+1th frame constant drift of the MEMS gyro combination.

2. The working method of a large dynamic star sensor integrated with a high-precision MEMS gyroscope according to claim 1, characterized in that: In step S1, set x st ,y st 、z st are the x-axis coordinate, y-axis coordinate, and z-axis coordinate of the star sensor, me ,y me 、z me are the x-axis coordinate, y-axis coordinate, and z-axis coordinate of the MEMS gyroscope combination.

3. The working method of a large dynamic star sensor integrated with a high-precision MEMS gyroscope according to claim 2, characterized in that: In view of the impact of temperature changes on the performance of MEMS gyroscope combination and star sensor optical components, aluminum-based silicon carbide is selected to make the mechanical structure of the star sensor and the mechanical structure of the MEMS gyroscope combination. A semiconductor cooler and a PID control method based on pulse width modulation are used to control the cooler, thereby achieving high-precision temperature control of the mounting surface and ensuring that the star sensor maintains stable working performance in different temperature domains.

4. The working method of a large dynamic star sensor integrated with a high-precision MEMS gyroscope according to claim 3, characterized in that: The deviation between the measurement axis of each single-axis MEMS gyroscope (5) and the coordinate axis of the corresponding star sensor (1) is less than 0.05°.

5. The working method of a large dynamic star sensor integrated with a high-precision MEMS gyroscope according to claim 4, characterized in that: Based on the accurate angular rate information collected by the MEMS gyro combination, the star sensor (1) realizes accurate attitude prediction and processing.

6. The method for operating a large dynamic star sensor integrated with a high-precision MEMS gyroscope according to claim 5, characterized in that: The star sensor (1) and each single-axis MEMS gyroscope (5) use an independent SPI communication line (3) to exchange data. The star sensor (1) uses an FPGA to realize an SPI interface with the single-axis MEMS gyroscope (5), collects data from three single-axis MEMS gyroscopes (5) in parallel, and sends the data to a CPU in the star sensor (1) for data processing.

7. The method for operating a large dynamic star sensor integrated with a high-precision MEMS gyroscope according to claim 6, characterized in that: The installation and adjustment process of the single-axis MEMS gyroscope (5) is as follows: after the single-axis MEMS gyroscope (5) is welded to the flexible printed circuit board, the bottom surface of the gyroscope ceramic tube shell of the single-axis MEMS gyroscope (5) is bonded to the installation plane of the main structure (4); first, bonding is performed to ensure that the bottom surface of the gyroscope ceramic tube shell is parallel to the installation surface of the main structure (4), and then a transfer matrix of the MEMS gyroscope assembly relative to the optical axis of the star sensor (1) is calibrated by a high-precision turntable, the relative position relationship between the MEMS gyroscope assembly and the star sensor (1) is confirmed, and the installation of the single-axis MEMS gyroscope (5) is finely adjusted until the installation accuracy requirement is met.

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