Space inertial sensor undragged control mode switching method and system
Patent Information
- Application Number
- CN202611346711.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-01
- Publication Date
- 2026-10-16
AI Technical Summary
[0005]本申请提供了一种空间惯性传感器无拖曳控制模式切换方法与系统，基于频谱熵分析，旨在解决现有技术中无拖曳控制工作模式单一、模式切换缺乏频域辨识能力、无拖曳控制与惯性传感器工作参数之间缺乏协同优化以及复杂空间扰动条件下误判率高等问题
（1）本申请首次引入频谱熵作为核心判别指标，有效区分单频/窄带扰动与宽带随机扰动，显著降低复杂空间环境下的误切换率。
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Figure CN122915434A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of inertial sensor technology, and more specifically, to a method and system for switching drag-free control modes of a space inertial sensor. Background Technology
[0002] Space gravitational wave detection missions require spacecraft platforms to have extremely high stability, the core of which lies in drag-free control technology. Drag-free control uses a test mass suspended in the vacuum cavity inside the satellite as an inertial reference. Thrust is applied through micro-thrusters to drive the satellite to follow the test mass, thereby counteracting interference from non-conservative forces such as solar radiation pressure and atmospheric drag, achieving ultra-low noise and high stability of the satellite platform.
[0003] Currently, drag-free control of space inertial sensors faces the following key technical challenges: (1) The working mode of dragless control is relatively simple, usually using fixed control law parameters, and lacks the ability to dynamically switch between multiple working modes according to the characteristics of space environment disturbances. In actual on-orbit operation, the disturbances experienced by spacecraft range from quasi-static solar radiation pressure to transient mechanical actions, and then to extreme impacts such as micrometeorite impacts. The frequency domain characteristics and amplitudes vary significantly, and the fixed control mode is difficult to simultaneously meet the optimal control accuracy and energy efficiency. (2) The working mode switching relies on ground commands or simple threshold judgment. It lacks frequency domain identification capability for complex space disturbance signals, and is prone to switching due to instantaneous interference. Furthermore, the fixed threshold parameters are difficult to adapt to different space environments. (3) There is a lack of coordinated design between the drag-free control mode and the inertial sensor working mode. When the disturbance characteristics change, the inertial sensor may work in an inappropriate range or bandwidth, affecting the overall performance and robustness of the loop. (4) There is a lack of effective means for pattern discrimination based on signal structure characteristics. Traditional energy detection methods cannot effectively distinguish disturbances with similar root mean square amplitudes but different sources.
[0004] Therefore, there is an urgent need for a method and system that can autonomously and accurately switch between multiple drag-free control modes based on the frequency domain structured characteristics of space environment disturbance signals. Summary of the Invention
[0005] This application provides a method and system for switching drag-free control modes of a space inertial sensor. Based on spectral entropy analysis, it aims to solve the problems in the prior art such as the single drag-free control working mode, the lack of frequency domain identification capability for mode switching, the lack of coordinated optimization between drag-free control and inertial sensor working parameters, and the high misjudgment rate under complex space disturbance conditions.
[0006] To achieve the above objectives, this application provides a method for switching drag-free control modes of a space inertial sensor, comprising: acquiring displacement or acceleration signals of the test mass relative to the spacecraft platform in the inertial sensor as input signals; performing frequency domain transformation on the input signals within a preset sliding time window to obtain the power spectral density distribution of the signals, and calculating the spectral entropy value of the signals based on the power spectral density distribution; calculating the time-domain statistical characteristic value of the input signals within the preset sliding time window; determining a target drag-free control mode that matches the current space environment disturbance state based on the spectral entropy value, the time-domain statistical characteristic value, and a preset multi-level switching judgment logic; and controlling the drag-free control system to switch to the target drag-free control mode.
[0007] Furthermore, the calculation process for the spectral entropy value is as follows: The power spectral density is normalized according to frequency intervals to obtain the relative power proportion of each frequency interval; the spectral entropy value is calculated according to the following formula: , Where H is the spectral entropy value, P(fᵢ) is the relative power ratio of the i-th frequency interval, and the summation range is all frequency intervals within the preset sliding time window.
[0008] Furthermore, the time-domain statistical characteristic values include the root mean square value of the input signal within a preset sliding time window.
[0009] Furthermore, the multi-level switching determination logic includes a preset entropy threshold and a preset root mean square threshold, wherein: the preset entropy threshold includes a first entropy threshold, a second entropy threshold, and a third entropy threshold, which increase sequentially; the preset root mean square threshold includes a first root mean square threshold, a second root mean square threshold, and a third root mean square threshold, which increase sequentially.
[0010] Furthermore, based on the spectral entropy value and the preset entropy threshold, as well as the root mean square value and the preset root mean square threshold, a target drag-free control mode that matches the current space environment disturbance state is determined.
[0011] Furthermore, the target drag-free control mode includes an ultra-fine drag-free control mode, a standard drag-free control mode, a robust drag-free control mode, and a safety protection mode. Specifically: when the spectral entropy value is less than the first entropy threshold and the root mean square (RMS) value is less than the first RMS threshold, the target drag-free control mode is determined to be the ultra-fine drag-free control mode; when the spectral entropy value is greater than or equal to the first entropy threshold and less than the second entropy threshold, and the RMS value is greater than or equal to the first RMS threshold and less than the second RMS threshold, the target drag-free control mode is determined to be the standard drag-free control mode; when the spectral entropy value is greater than or equal to the second entropy threshold or the RMS value is greater than or equal to the second RMS threshold, and the safety protection mode condition is not triggered, the target drag-free control mode is determined to be the robust drag-free control mode; when the RMS value is greater than or equal to the third RMS threshold, or the spectral entropy value is greater than or equal to the third entropy threshold, or the displacement signal exceeds a preset range ratio, the target drag-free control mode is determined to be the safety protection mode.
[0012] Furthermore, controlling the drag-free control system to switch to the target drag-free control mode includes: sending a control law parameter update command to the drag-free control system; and sending an operating parameter configuration command to the inertial sensor, the operating parameter configuration command including the set values of the inertial sensor's output data rate, range, and electrostatic negative stiffness.
[0013] Furthermore, when the drag-free control system switches to the target drag-free control mode, a smooth transition strategy is adopted: within the preset transition time window, the actual control output of the drag-free control system is determined by weighting the control output of the current mode and the control output of the target mode, wherein: the weight of the control output of the current mode gradually decreases over time, and the weight of the control output of the target mode gradually increases over time.
[0014] Furthermore, in addition to the safety protection mode, the switching between various working modes adopts a hysteresis strategy: when switching from the standard drag-free control mode to the robust drag-free control mode, or from the ultra-fine drag-free control mode to the standard drag-free control mode, the judgment condition must be met for a continuous duration exceeding the first holding time; when switching from the robust drag-free control mode to the standard drag-free control mode, or from the standard drag-free control mode to the ultra-fine drag-free control mode, the judgment condition must be met for a continuous duration exceeding the second holding time; the first holding time is less than the second holding time.
[0015] Furthermore, this application also provides a drag-free control mode switching system for space inertial sensors, comprising: a signal acquisition module for acquiring displacement or acceleration signals of the test mass relative to the spacecraft platform in the inertial sensor as input signals; a spectrum entropy calculation module for performing frequency domain transformation on the signal within a preset sliding time window to obtain the power spectral density distribution of the signal, and calculating the spectrum entropy value of the signal based on the power spectral density distribution; a time domain statistics module for calculating the time domain statistical characteristic values of the input signal within the preset sliding time window; a mode decision module for determining a target drag-free control mode that matches the current space environment disturbance state based on the spectrum entropy value, the time domain statistical characteristic values, and a preset multi-level switching judgment logic; and a mode switching execution module for controlling the drag-free control system to switch to the target drag-free control mode.
[0016] The drag-free control mode switching method and system for space inertial sensors provided in this application have the following advantages: (1) This application introduces spectral entropy as the core discrimination index for the first time, which effectively distinguishes between single-frequency / narrowband disturbances and broadband random disturbances, and significantly reduces the false handover rate in complex space environments. (2) This application constructs a four-level mode system of ultra-fine, standard, robust and safe protection. Each mode synchronously links the drag-free control law parameters and core parameters such as the range of the inertial sensor, the output data rate, and the electrostatic negative stiffness, so as to realize the coordinated optimization of the control strategy and the sensing front end. (3) This application avoids abrupt changes in control commands through weighted fusion, ensuring the stability of the closed-loop circuit during mode switching. Setting an asymmetric upgrade / downgrade hold time effectively avoids repeated switching caused by fluctuations in signal statistical characteristics near the threshold. (4) This application reduces the need for ground intervention by operating autonomously. It can be executed entirely autonomously in the onboard processor, improving the system's response timeliness and making it suitable for application scenarios with large communication delays, such as deep space exploration. Attached Figure Description
[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings: Figure 1 This is a flowchart illustrating the method for switching the drag-free control mode of a space inertial sensor according to an embodiment of this application. Figure 2 This is a schematic diagram of a drag-free control mode switching system for a space inertial sensor provided according to an embodiment of this application; Figure 3 This is a schematic diagram of the process for switching the target drag-free control mode according to the embodiments of this application; Figure 4 This is a schematic diagram of the spectral entropy calculation process provided in the embodiments of this application; Figure 5 This is a timing diagram of the smooth transition strategy provided according to the embodiments of this application. Detailed Implementation
[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0019] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0020] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.
[0021] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.
[0022] In addition, the term "multiple" should mean two or more.
[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0024] like Figure 1 As shown, this application provides a method for switching drag-free control modes of a space inertial sensor. Based on spectrum analysis, it can adaptively switch modes and is applied to the drag-free control system of a spacecraft for detecting gravitational waves. The spacecraft carries an electrostatically levitated inertial sensor, using a test mass as an inertial reference. Micro-thrusters are used to achieve motion control of the test mass by the spacecraft platform. The specific steps include: Step 1: Collect the displacement or acceleration signal of the test mass relative to the spacecraft platform from the inertial sensor as the input signal; Specifically, the three-axis displacement signals of the inspection mass relative to the spacecraft platform are continuously acquired at the current output data rate of the inertial sensor. In this embodiment, the displacement signals are acquired through a capacitive displacement sensing circuit, achieving a resolution at the picometer level, which is sensitive to minute positional changes in the inspection mass.
[0025] Step 2: Within a preset sliding time window, perform frequency domain transformation on the input signal to obtain the power spectral density distribution of the signal, and calculate the spectral entropy value of the signal based on the power spectral density distribution; Specifically, a sliding time window (window length N = 1024 sampling points, time resolution approximately 10 seconds, overlap rate 50%) is used to perform a Fast Fourier Transform (FFT) on the displacement signal acquired within the window to obtain the power spectral density estimate S(f); subsequently, the spectral entropy value of the signal is calculated based on the power spectral density distribution, such as... Figure 4 As shown: First, the frequency range is divided into M frequency intervals (M=128, with a frequency resolution on the order of 0.1Hz), and the power spectrum integral value in each frequency interval is calculated. Then, the power values in each frequency range are normalized to obtain the normalized power percentage: , Finally, calculate the spectral entropy value H according to the formula: , Where H is the spectral entropy value, P(fᵢ) is the relative power ratio of the i-th frequency interval, and the summation range is all frequency intervals within the preset sliding time window.
[0026] The spectral entropy value H ranges from [0, logM]. When H approaches 0, it indicates that the signal power is highly concentrated on a very small number of frequency components, corresponding to a quasi-single-frequency micro-vibration disturbance state; when H approaches logM, it indicates that the signal power is nearly uniformly distributed in the frequency domain, corresponding to a broadband random impulse or noise disturbance state.
[0027] Step 3: Calculate the time-domain statistical characteristic values of the input signal within a preset sliding time window; Furthermore, the time-domain statistical characteristic values include the root mean square (RMS) value of the input signal within a preset sliding time window, which is used to characterize the overall energy level of the signal.
[0028] Step 4: Based on the spectral entropy value, time-domain statistical characteristic value, and preset multi-level switching judgment logic, determine the target drag-free control mode that matches the current space environment disturbance state; Furthermore, the multi-level switching determination logic includes a preset entropy threshold and a preset root mean square threshold, wherein: the preset entropy threshold includes a first entropy threshold, a second entropy threshold, and a third entropy threshold, which increase sequentially; the preset root mean square threshold includes a first root mean square threshold, a second root mean square threshold, and a third root mean square threshold, which increase sequentially.
[0029] Furthermore, based on the spectral entropy value and the preset entropy threshold, as well as the root mean square value and the preset root mean square threshold, a target drag-free control mode that matches the current space environment disturbance state is determined.
[0030] Furthermore, the target drag-free control mode includes an ultra-fine drag-free control mode, a standard drag-free control mode, a robust drag-free control mode, and a safety protection mode. Specifically: when the spectral entropy value is less than the first entropy threshold and the root mean square (RMS) value is less than the first RMS threshold, the target drag-free control mode is determined to be the ultra-fine drag-free control mode; when the spectral entropy value is greater than or equal to the first entropy threshold and less than the second entropy threshold, and the RMS value is greater than or equal to the first RMS threshold and less than the second RMS threshold, the target drag-free control mode is determined to be the standard drag-free control mode; when the spectral entropy value is greater than or equal to the second entropy threshold or the RMS value is greater than or equal to the second RMS threshold, and the safety protection mode condition is not triggered, the target drag-free control mode is determined to be the robust drag-free control mode; when the RMS value is greater than or equal to the third RMS threshold, or the spectral entropy value is greater than or equal to the third entropy threshold, or the displacement signal exceeds a preset range ratio, the target drag-free control mode is determined to be the safety protection mode.
[0031] Specifically, the spectral entropy value H and root mean square value RMS calculated in steps 2 and 3 are input into a preset multi-level handover determination logic. In this embodiment, the preset entropy threshold is: the first entropy threshold H th1=1.5, second entropy threshold H th2 =3.0, third entropy threshold H th3 =4.5; The preset root mean square threshold is: the first root mean square threshold R th1 =1×10 -10 m, second root mean square threshold R th2 =5×10 -9 m, third root mean square threshold R th3 =1×10 -7 m.
[0032] So if Figure 3 As shown, the specific logic for determining the target's drag-free control mode is as follows: Ultra-precise drag-free control mode determination criteria: H <H th1 And RMS <R th1 This mode corresponds to the spacecraft being in the scientific observation phase, where quasi-static disturbances such as solar radiation pressure experienced by the platform have been largely eliminated through feedforward compensation, resulting in extremely low residual disturbances. In this mode, the drag-free control system employs a high-gain, narrow-bandwidth control law to achieve optimal suppression of residual disturbances; the inertial sensors are configured with the highest output data rate (e.g., 200Hz) and the smallest range (e.g., ±1×10⁻⁶). -7 m), to obtain the highest displacement measurement resolution.
[0033] Standard drag-free control mode determination criteria: H th1 ≤H <H th2 And R th1 ≤RMS <R th2 This mode corresponds to the spacecraft being in a normal orbital operation phase, where disturbances such as solar radiation pressure and Earth's infrared radiation pressure are within normal ranges. In this mode, the drag-free control system employs a control law with medium gain and medium bandwidth; the inertial sensors are configured with a medium output data rate (e.g., 100Hz) and a medium range (e.g., ±5×10⁻⁶). -7 m).
[0034] Robust drag-free control mode determination condition: H≥H th2 Or RMS≥R th2 And RMS <R th3 This mode corresponds to the spacecraft platform experiencing multi-frequency coupled disturbances, such as the superposition effect of flywheel harmonic vibrations from attitude control devices and solar radiation pressure. In this mode, the drag-free control system employs a low-gain, wide-bandwidth robust control law, sacrificing some low-frequency suppression accuracy in exchange for stability margins against broadband disturbances; the inertial sensors are configured with high output data rates (e.g., 200Hz) and large ranges (e.g., ±1×10⁻⁶). -6 m).
[0035] Security protection mode determination criteria: RMS ≥ R th3 , or H≥Hth3 Or, the instantaneous value of any axis in the three-axis displacement signal exceeds 80% of the current range of the inertial sensor. This mode corresponds to extreme events, such as micrometeorite impacts or propulsion system anomalies. In this mode, the no-drag control system triggers a protective control strategy, and the micro-thruster output maintains a safe thrust limit; the inertial sensor switches to its maximum range configuration (e.g., ±5×10). -6 m) and maximum output data rate (e.g., 400Hz).
[0036] Among the above judgment conditions, the priority of each mode judgment is as follows: once the safety protection mode condition is met, the mode is directly entered; the remaining modes are judged in the following order: ultra-fine drag-free control mode, standard drag-free control mode, and robust drag-free control mode.
[0037] Step 5: Switch the drag-free control system to the target drag-free control mode.
[0038] Furthermore, controlling the drag-free control system to switch to the target drag-free control mode includes: sending a control law parameter update command to the drag-free control system; and sending an operating parameter configuration command to the inertial sensor, the operating parameter configuration command including the set values of the inertial sensor's output data rate, range, and electrostatic negative stiffness.
[0039] Furthermore, when the drag-free control system switches to the target drag-free control mode, a smooth transition strategy is adopted: within the preset transition time window, the actual control output of the drag-free control system is determined by weighting the control output of the current mode and the control output of the target mode, wherein: the weight of the control output of the current mode gradually decreases over time, and the weight of the control output of the target mode gradually increases over time.
[0040] Specifically, based on the determination result in step 4, the target drag-free control mode is determined, and the following operations are performed: (1) Sending control law parameter update instructions to the drag-free control system. In this embodiment, the drag-free control system adopts a PID control structure, and the control parameters for each mode are shown in Table 1: (2) Send the operating parameter configuration command to the inertial sensor, as shown in Table 2: The electrostatic negative stiffness is generated by the electrostatic actuator inside the inertial sensor. By adjusting the electrostatic negative stiffness, the equivalent suspension stiffness of the inspection quality can be changed, thereby affecting the sensor's response characteristics to low-frequency signals.
[0041] (3) Use a smooth transition strategy to perform mode switching. like Figure 5 As shown, in the transition time window Ttrans Within a given timeframe of 5 seconds, the actual control output U(t) is calculated using the following formula: , Where a(t) = t / T trans That is, the control output U of the current mode. current (t) and target mode control output U target (t) performs linear weighted fusion, with the weighting coefficients changing linearly from 0 to 1 over time to avoid abrupt changes in control commands.
[0042] Furthermore, in addition to the safety protection mode, the switching between various working modes adopts a hysteresis strategy: when switching from the standard drag-free control mode to the robust drag-free control mode, or from the ultra-fine drag-free control mode to the standard drag-free control mode, the judgment condition must be met for a continuous duration exceeding the first holding time; when switching from the robust drag-free control mode to the standard drag-free control mode, or from the standard drag-free control mode to the ultra-fine drag-free control mode, the judgment condition must be met for a continuous duration exceeding the second holding time; the first holding time is less than the second holding time.
[0043] Specifically, to avoid frequent changes in operating mode near threshold boundaries, a hysteresis strategy is used for switching between all modes except the safety protection mode: When switching from standard drag-free control mode to robust drag-free control mode, or from ultra-fine drag-free control mode to standard drag-free control mode, the target mode determination condition must be met for more than the first holding time T1, preferably 30 seconds, to prevent unnecessary mode switching due to instantaneous disturbances. When switching from robust drag-free control mode to standard drag-free control mode, or from standard drag-free control mode to ultra-fine drag-free control mode, the target mode determination condition must be met for a continuous duration exceeding the second hold time T2, preferably 120 seconds, to ensure that the disturbance has truly decayed to a quasi-static level.
[0044] The safety protection mode switches immediately upon triggering, with no hold time; when returning from the safety protection mode to the robust drag-free control mode, the robust drag-free control mode conditions must be met for more than T2.
[0045] The first hold time is shorter than the second hold time to achieve asymmetric hysteresis. The upgrade decision uses a shorter hold time to ensure that the system can respond quickly to a sudden increase in disturbance. The downgrade decision uses a longer hold time to ensure that the disturbance is fully attenuated before switching back to the high-precision mode, preventing repeated switching at the disturbance boundary.
[0046] In addition, such as Figure 2 As shown, this application also provides a drag-free control mode switching system for space inertial sensors, comprising: The signal acquisition module is used to acquire displacement or acceleration signals of the test mass relative to the spacecraft platform from the inertial sensor as input signals; Specifically, the signal acquisition module receives the displacement signal output by the capacitive displacement sensing unit of the inertial sensor through a high-precision analog-to-digital converter, achieving picometer-level displacement detection. The inertial sensor is an electrostatic levitation inertial sensor, with the inspection mass suspended in an electrode cage via electrostatic levitation. The displacement signal is acquired through the capacitive displacement sensing circuit, achieving a resolution at the picometer level, and is capable of sensitively detecting minute positional changes in the inspection mass.
[0047] The spectrum entropy calculation module is used to perform frequency domain transformation on the signal within a preset sliding time window to obtain the power spectral density distribution of the signal, and calculate the spectrum entropy value of the signal based on the power spectral density distribution. Specifically, the spectrum entropy calculation module uses an FPGA hardware acceleration unit to perform fast Fourier transform operations and real-time spectrum entropy calculations. It supports 1024-point sliding window fast Fourier transforms with a latency controlled within 10ms, meeting real-time requirements.
[0048] The time-domain statistics module is used to calculate the time-domain statistical characteristic values of the input signal within a preset sliding time window. The root mean square value of the sliding window is calculated by the DSP processor. The mode decision module is used to determine the target drag-free control mode that matches the current space environment disturbance state based on the spectral entropy value, time-domain statistical characteristic value and preset multi-level switching judgment logic. The mode decision module has an embedded finite state machine, which includes four stable states (corresponding to the above four drag-free control working modes) and corresponding state transition condition judgment logic, and includes a hysteresis counter.
[0049] The mode switching execution module is used to control the drag-free control system to switch to the target drag-free control mode. The module converts the target mode identifier output by the mode decision module into specific control law parameter update instructions (sent to the drag-free control system via the SPI interface) and inertial sensor operating parameter configuration instructions (sent to the inertial sensor configuration register via the I²C interface). The control law parameter update instructions include adjustments to the gain coefficient of the PID control parameters; the operating parameter configuration instructions include adjustments to the setpoints of the output data rate, range, and electrostatic negative stiffness.
[0050] Specifically, the signal acquisition module, spectrum entropy calculation module, time-domain statistics module, mode decision module, and mode switching execution module can all be integrated into the same DSP+FPGA architecture onboard processor, and communicate with the electrostatic levitation inertial sensor and micro-thruster controller via SPI / I 2 C-bus communication.
[0051] More specifically, the drag-free control mode switching system for space inertial sensors provided in this application embodiment can be directly integrated into the built-in microcontroller of the inertial sensor, forming an integrated intelligent inertial sensor with the capacitive displacement sensing unit and the electrostatic actuation unit. To adapt to resource-constrained microcontroller platforms, the spectral entropy calculation module can adopt a simplified strategy: approximating the frequency domain energy concentration of the signal by statistically analyzing the distribution histogram of the zero-crossing intervals of the signal, and using this to construct an alternative criterion, significantly reducing computational complexity while maintaining mode recognition capabilities.
[0052] Furthermore, the switching method provided in this application can be embedded as computer-executable instructions and stored in a non-transitory computer-readable storage medium (such as a solid-state drive, SD memory card, or onboard computer memory). When this storage medium is executed by one or more processors, the processors automatically execute all the above-mentioned switching processes, including signal acquisition, spectral entropy calculation, time-domain statistics, mode determination, and switching execution. This storage medium can be integrated into the onboard test computer of the satellite integrated test system. During the on-orbit operation phase, only the operator needs to confirm the system status, and the system can automatically complete the mode monitoring and switching process, significantly reducing the need for ground-based manual intervention.
[0053] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for switching drag-free control modes of a space inertial sensor, characterized in that, include: The displacement or acceleration signal of the test mass relative to the spacecraft platform is collected from the inertial sensor and used as the input signal; Within a preset sliding time window, the input signal is subjected to frequency domain transformation to obtain the power spectral density distribution of the signal, and the spectral entropy value of the signal is calculated based on the power spectral density distribution. Calculate the time-domain statistical characteristic value of the input signal within the preset sliding time window; Based on the spectral entropy value, the time-domain statistical characteristic value, and the preset multi-level switching judgment logic, a target drag-free control mode that matches the current space environment disturbance state is determined. Switch the drag-free control system to the target drag-free control mode.
2. The method for switching the drag-free control mode of a space inertial sensor according to claim 1, characterized in that, The calculation process for the spectral entropy value is as follows: The power spectral density is normalized according to frequency range to obtain the relative power proportion of each frequency range; Calculate the spectral entropy value using the following formula: ， Where H is the spectral entropy value, P(fᵢ) is the relative power ratio of the i-th frequency interval, and the summation range is all frequency intervals within the preset sliding time window.
3. The method for switching the drag-free control mode of a space inertial sensor according to claim 2, characterized in that, The time-domain statistical feature value includes the root mean square value of the input signal within the preset sliding time window.
4. The method for switching the drag-free control mode of a space inertial sensor according to claim 3, characterized in that, The multi-level switching determination logic includes a preset entropy threshold and a preset root mean square threshold, wherein: The preset entropy thresholds include a first entropy threshold, a second entropy threshold, and a third entropy threshold, wherein the first entropy threshold, the second entropy threshold, and the third entropy threshold increase sequentially. The preset root mean square thresholds include a first root mean square threshold, a second root mean square threshold, and a third root mean square threshold, with the first root mean square threshold, the second root mean square threshold, and the third root mean square threshold increasing sequentially.
5. The method for switching the drag-free control mode of a space inertial sensor according to claim 4, characterized in that, Based on the spectral entropy value and the preset entropy threshold, and the root mean square value and the preset root mean square threshold, a target drag-free control mode that matches the current space environment disturbance state is determined.
6. The method for switching the drag-free control mode of a space inertial sensor according to claim 5, characterized in that, The target drag-free control modes include ultra-fine drag-free control mode, standard drag-free control mode, robust drag-free control mode, and safety protection mode, wherein: When the spectral entropy value is less than the first entropy threshold and the root mean square value is less than the first root mean square threshold, the target drag-free control mode is determined to be the ultra-fine drag-free control mode. When the spectral entropy value is greater than or equal to the first entropy threshold and less than the second entropy threshold, and the root mean square value is greater than or equal to the first root mean square threshold and less than the second root mean square threshold, the target drag-free control mode is determined to be the standard drag-free control mode. When the spectral entropy value is greater than or equal to the second entropy threshold or the root mean square value is greater than or equal to the second root mean square threshold, and the security protection mode condition is not triggered, the target drag-free control mode is determined to be the robust drag-free control mode. When the root mean square value is greater than or equal to the third root mean square threshold, or the spectral entropy value is greater than or equal to the third entropy threshold, or the displacement signal exceeds the preset range ratio, the target drag-free control mode is determined to be the safety protection mode.
7. The method for switching drag-free control modes of a space inertial sensor according to claim 6, characterized in that, Switching the drag-free control system to the target drag-free control mode includes: Send control law parameter update commands to the drag-free control system; Send an operating parameter configuration command to the inertial sensor, the operating parameter configuration command including the set values of the output data rate, range and electrostatic negative stiffness of the inertial sensor.
8. The method for switching the drag-free control mode of a space inertial sensor according to claim 7, characterized in that, When the drag-free control system switches to the target drag-free control mode, a smooth transition strategy is adopted: Within a preset transition time window, the actual control output of the drag-free control system is determined by a weighted average of the control output of the current mode and the control output of the target mode, wherein: The weight of the control output in the current mode gradually decreases over time, while the weight of the control output in the target mode gradually increases over time.
9. The method for switching the drag-free control mode of a space inertial sensor according to claim 8, characterized in that, In addition to the aforementioned safety protection mode, a hysteresis strategy is used for switching between various operating modes: When switching from the standard drag-free control mode to the robust drag-free control mode, or from the ultra-fine drag-free control mode to the standard drag-free control mode, the judgment condition must be met for a continuous duration exceeding the first holding time. When switching from the robust drag-free control mode to the standard drag-free control mode, or from the standard drag-free control mode to the ultra-fine drag-free control mode, the judgment condition must be met for a period of more than the second holding time. The first holding time is shorter than the second holding time.
10. A drag-free control mode switching system for a space inertial sensor, characterized in that, include: The signal acquisition module is used to acquire displacement or acceleration signals of the test mass relative to the spacecraft platform from the inertial sensor as input signals; The spectrum entropy calculation module is used to perform frequency domain transformation on the signal within a preset sliding time window to obtain the power spectral density distribution of the signal, and calculate the spectrum entropy value of the signal based on the power spectral density distribution. The time-domain statistics module is used to calculate the time-domain statistical characteristic values of the input signal within the preset sliding time window; The mode decision module is used to determine the target drag-free control mode that matches the current space environment disturbance state based on the spectrum entropy value, the time domain statistical characteristic value and the preset multi-level switching judgment logic. The mode switching execution module is used to control the drag-free control system to switch to the target drag-free control mode.