On-orbit modal parameter identification ground design verification system for space large-scale flexible structure

Abstract

The invention discloses a spatial large-scale flexible structure in-orbit modal parameter identification ground design verification system, which comprises a task planning module, an identification working condition design module and an in-orbit implementation process design module which run in a planning unit, and a sensor interface simulation module running in a measurement simulation unit, the data receiving and storing module and the image analyzing and three-dimensional coordinate resolving module run in the data processing unit, and the identification module runs in the identification unit. The ground design verification system aims at the on-orbit modal parameter identification system, and is a digital verification tool which can adapt to the whole period from ground scheme design and development to on-orbit identification tasks. According to the ground design verification system, a design process, a simulation tool and an on-orbit test process related to on-orbit modal parameter identification of a space large-scale flexible structure are solidified in a software function module form, a scheme design mode, a semi-physical simulation mode and a flight control support mode are provided, and the efficiency of design simulation and on-orbit identification can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of on-orbit modal parameter identification of large-scale flexible space structures, and in particular to a ground design verification system for on-orbit modal parameter identification of large-scale flexible space structures. Background Art

[0002] Large flexible spacecraft carry large flexible solar panels, large-scale flexible antennas and truss structures, large robotic arms and other flexible components. After these components are deployed in orbit, their dynamics have the characteristics of high modal order, low frequency and low damping, which have an adverse effect on the attitude and orbit control of the spacecraft. Measuring and identifying structural modal parameters in orbit is an important way to achieve high-performance control of large flexible spacecraft.

[0003] The solar wing of my country's space station is composed of large-scale extendable support trusses and large-size flexible solar cell arrays. The core module uses self-powered accelerometers installed at the four corners of the solar wing and binocular cameras outside the cabin as measurement sensors to carry out on-orbit measurement and identification of the solar wing flexibility. Through data analysis, the on-orbit modal parameters and dynamic response characteristics of the solar wing can be accurately obtained. The on-orbit modal parameter identification system of large-scale flexible structures in space includes an excitation module, a measurement module, and a data acquisition module, such as Figure 1 shown.

[0004] The excitation module is used to provide an external excitation signal with certain spectral characteristics, directly or indirectly acting on the large flexible structure of the space under test, to achieve the excitation of the free response characteristics of the object under test. From the perspective of the excitation signal generation method, the excitation module includes two parts: active excitation simulation and passive excitation simulation. Active excitation refers to the active application of a certain external force / torque in the form of a pre-set signal to the cabin / flexible structure through the actuator on the spacecraft, which will not cause the spacecraft attitude to become unstable or cause structural damage, and achieve the purpose of stimulating the inherent vibration of the flexible structure under test. Passive excitation refers to the use of the disturbance or impact on the cabin / flexible structure caused by the space environment disturbance or the routine flight events of the spacecraft in orbit to achieve the purpose of stimulating the inherent vibration of the flexible structure under test.

[0005] The measurement module is used to measure the vibration acceleration, displacement, angular velocity and other information of large flexible structures using various measurement sensors such as accelerometers, optical cameras, gyroscopes, strain gauges, laser radars, etc. The layout of general measurement sensors must meet the requirements for effective observation of the measured area / measurement point of the flexible structure to be measured.

[0006] The data acquisition module is responsible for reliably and stably collecting the output data of each measurement sensor and storing it in the required file format according to a certain storage format. The data acquisition function can be realized by a dedicated device arranged on the spacecraft, or by transmitting the output of the measurement module to a dedicated device on the ground in real time.

[0007] Conventional modal identification tests of flexible structures carried out on the ground are usually special tasks, and the optimal design can be achieved in terms of measurement sensor layout, excitation location and strength, data acquisition and identification methods. The solar wing flexibility measurement and identification system of the space station is an auxiliary support technology serving the main mission in the construction and operation of the space station. The system design must meet the principles of safe operation of the space station on orbit, not affecting the implementation process of the main mission, and not changing the existing overall design status. Therefore, there are many constraints and difficulties in the design and specific implementation strategies:

[0008] (1) The number of measurement sensors selected and their installation and layout cannot affect the main line design status of the space station and must meet the measurable requirements within the constraints of installation.

[0009] (2) High-safety and high-precision identification must take into account conditions such as the space station test flight attitude, test window, test duration, and safety constraints of the entire cabin and flexible structure. It is generally a suboptimal incentive design problem under strong constraints. At the same time, different identification results are obtained by combining different measurement data types, data quality, measurement duration, and different identification algorithms. The entire identification process involves many links, a long chain, and many coupling factors, making suboptimal design difficult and inefficient.

[0010] (3) During the on-orbit flight, in order to ensure the safety of the space station during the stimulation period and the requirement for 25 minutes of rapid identification before the rapid rendezvous and docking of the experimental module, an on-orbit identification flight control support system with mission simulation, rapid data processing and identification result evaluation is required to assist in completing the stimulation condition review, simulation, rapid identification and other tasks.

[0011] In the future, more and more spacecraft with large flexible structures (such as dual-antenna SAR satellites, antenna satellites, nuclear reactor power supply system detectors, distributed satellites, etc.) will have urgent needs for on-orbit modal parameter identification, and will also face design and verification difficulties similar to the flexibility identification of space station solar panels. Summary of the invention

[0012] In response to the above needs, this patent, based on the summary of the application experience of the space station solar wing flexibility identification system, proposes an on-orbit modal parameter identification design verification system and method for large-scale flexible space structures that supports the entire life cycle from scheme design simulation, semi-physical simulation and on-orbit flight control, and provides a design architecture system, software toolset and simulation method.

[0013] In the first aspect, a ground design verification system for on-orbit modal parameter identification of a large-scale flexible structure in space is provided, comprising:

[0014] Planning unit, used to realize task planning, test condition design, and test process design functions;

[0015] A measurement simulation unit, used to simulate the vibration measurement sensor communication interface and measurement data format;

[0016] Data processing unit, used to realize data collection and storage of measurement sensors, and carry out raw data processing, including optical image analysis, feature point extraction, three-dimensional coordinate solution, and multi-source measurement data time alignment;

[0017] The identification unit is used to receive the multi-source measurement data after time synchronization output by the data processing unit, and call the identification algorithm to complete the identification of frequency, damping, vibration mode parameters and result evaluation.

[0018] In combination with the first aspect, in certain implementations of the first aspect, the ground design verification system has seven types of software function modules supporting simulation verification, including a task planning module, an identification condition design module, and an on-orbit implementation process design module running in a planning unit, a sensor interface simulation module running in a measurement simulation unit, a data receiving and storage module, an image analysis and three-dimensional coordinate solution module running in a data processing unit, and an identification module running in an identification unit.

[0019] In combination with the first aspect, in some implementations of the first aspect, the mission planning module is used to perform theoretical modal parameter calculation, excitation signal design, flight attitude design, and test window design to obtain mission planning working conditions; the working conditions obtained by the mission planning module are input into the identification working condition design module to perform simulation scene setting, and are also input into the on-orbit implementation process design module to perform on-orbit implementation process design;

[0020] The identification condition design module includes a dynamic simulation toolset and a test constraint evaluation simulation toolset; the dynamic simulation toolset is used to complete the simulation scene setting; among them, the initial moment is set through the solar and lunar ephemeris models; the initial orbit is set through the orbit dynamics model, and the real-time orbit output by the orbit dynamics model is input to the rigid-flexible coupling attitude dynamics model; the initial attitude is set through the rigid-flexible coupling attitude dynamics model, and the modal coordinates and control instructions output by the rigid-flexible coupling attitude dynamics model are input to the flexible structure finite element model to obtain the finite element node vibration displacement, and input to the measurement sensor model; the measurement sensor model is set according to the simulation scene layout, and the analog measurement digital quantity is output to the identification module; the test constraint evaluation simulation toolset includes an optical camera dynamic stray light simulation model, a target point motion measurement simulation model, an excitation safety constraint evaluation simulation model, and a ground measurement and control arc simulation model; the dynamic simulation toolset outputs ambient lighting conditions, orbit position, attitude, finite element node response displacement and force analysis to the test constraint evaluation simulation toolset to complete the test constraint evaluation; the test constraint evaluation results are returned to the mission planning module to guide the mission planning adjustment;

[0021] The on-orbit implementation process design module is used to perform measurement sensor parameter settings and state preparation. According to the preliminary frequency distribution, the frequency of small-amplitude active excitation conditions is explored. After the safety boundary is confirmed, the passive excitation condition frequency is initially explored, and then the excitation intensity and spectrum are selected, and the frequency, damping, and vibration mode of the active excitation condition are precisely measured. The output results of the on-orbit implementation process design module are used to return to the mission planning module to guide the optimization of mission planning.

[0022] The sensor interface simulation module generates simulated original measurement physical quantities of the sensor according to the communication interface and data format definition of each sensor;

[0023] The data receiving and storing module receives and stores the measured physical quantity;

[0024] The image analysis and three-dimensional coordinate solution module performs time alignment of multi-source data, image analysis and three-dimensional coordinate solution, and outputs the processed measurement digital quantity;

[0025] The identification module obtains the analog measurement digital quantity from the identification condition design module, completes the measurement data processing, modal parameter identification, identification result analysis and evaluation, and report generation; the identification evaluation results output by the identification module are returned to the task planning module to guide the task planning adjustment.

[0026] In combination with the first aspect, in certain implementations of the first aspect, the system supports a design simulation mode, a semi-physical simulation mode, and an on-orbit flight control mode. The design simulation mode is used to provide a digital simulation environment for designers to review the rationality of the scheme during the scheme design stage; the semi-physical simulation mode is used to provide a semi-physical simulation environment for designers to verify the correctness of the interaction relationship, information timing, and handling process of the entire test system during the ground semi-physical verification stage; and the on-orbit flight control mode is used to assist designers in completing data processing and identification result evaluation during the flight control support stage during the on-orbit flight of the spacecraft.

[0027] In combination with the first aspect, in some implementations of the first aspect, the planning unit and the identification unit are operated in the design simulation mode, the planning unit provides the vibration measurement digital quantity simulated by dynamic calculation to the identification unit according to the excitation signal of the current simulation working condition, the identification unit gives the identification result of the current simulation working condition based on the excitation signal, and optimizes the iterative design of the task planning, working condition, and process according to the evaluation situation;

[0028] The planning unit, measurement simulation unit, data processing unit and identification unit are operated in the semi-physical simulation mode; the planning unit provides the vibration measurement digital quantity simulated by dynamic calculation to the measurement simulation unit according to the excitation signal of the current simulation working condition; the measurement simulation unit generates the simulated original measurement physical quantity of the sensor according to the communication interface and data format definition of each sensor; the data processing unit receives and stores the measurement physical quantity, and performs multi-source data time alignment, image analysis and three-dimensional coordinate solution, and outputs the processed measurement digital quantity; the identification unit gives the identification result of the current simulation working condition according to the measurement data volume, and optimizes the iterative design of the task planning, working condition and process according to the evaluation situation;

[0029] The planning unit, data processing unit and identification unit operate in the on-orbit flight control support mode; the data processing unit receives and stores the real-time data or delayed data of the actual vibration measurement of the space flexible structure through the space-ground measurement and control network, and performs multi-source data time alignment, image analysis and three-dimensional coordinate solution, and outputs the processed measurement digital quantity; the identification unit gives the identification result of the current identification condition according to the measurement data volume, and reviews the rationality of the subsequent mission planning, working conditions, and process strategy arrangements according to the evaluation results.

[0030] In conjunction with the first aspect, in some implementations of the first aspect, the system is used in a task planning module to perform the following steps:

[0031] ① Load the finite element model of the spacecraft flexible structure constructed on the ground and output the modal parameters of theoretical analysis;

[0032] ② Under the premise that the spacecraft's on-orbit operation is safe and the normal flight mission is not affected, the spectrum energy of the active excitation signal is optimized to meet the requirements of identifying the excitation response characteristics of the object under test;

[0033] ③ Under the constraints of energy supply, measurement and control transmission, spacecraft thermal control, structural safety, and control envelope, carry out flexible identification on-orbit flight attitude design to meet the conditions for effective measurement of vibration measurement sensors;

[0034] ④ Under the constraints of lighting conditions and ambient temperature conditions of optical cameras, accelerometers, and gyroscope measurement sensors, carry out the design of flexible identification on-orbit test windows to confirm that the measurement, control, communication, and lighting conditions meet the minimum duration of a single identification test.

[0035] In combination with the first aspect, in some implementations of the first aspect, the identification working condition design module includes a dynamics simulation toolset and a test constraint evaluation simulation toolset. The dynamics simulation toolset is used to perform rigid-flexible coupling attitude dynamics and orbital dynamics simulation. The test constraint evaluation simulation toolset is used to perform simulation evaluation on the output results of the dynamics simulation toolset based on the compliance of the test constraint conditions.

[0036] The Dynamics Simulation Toolset is used to perform the following steps:

[0037] ① Set up simulation scenarios according to the working conditions to be simulated given by the task planning module;

[0038] ② Calculate the spacecraft attitude and orbit as well as the flexible vibration of the flexible structure through rigid-flexible coupling attitude dynamics, orbital dynamics and flexible structure finite element model;

[0039] ③Simulate ambient lighting conditions through the solar and lunar ephemeris model;

[0040] ④Simulate the digital output of gyroscope, accelerometer, optical camera and strain gauge through the measurement sensor model;

[0041] The Experimental Constraint Evaluation simulation toolset is used to perform the following steps:

[0042] ① According to the sun-moon vector and spacecraft orbit data under given working conditions, the relative relationship between sunlight, moonlight, and earth's atmospheric light on the optical axis of the optical camera is analyzed, and the dynamic stray light simulation model of the optical camera is used to evaluate the impact of dynamic stray light on optical measurement during the measurement process;

[0043] ② Based on the target point motion measurement simulation model, use the optical camera to simulate and predict the dynamic measurement of the target point in the specified area of ​​the flexible structure to be measured, analyze the continuous measurement of the target point under a given excitation signal, and analyze whether the measurement data of sufficient duration is obtained;

[0044] ③ Based on the excitation safety constraint assessment simulation model, analyze the spacecraft attitude angle and attitude angular velocity constraints, thermal control constraints, force and maximum amplitude constraints of the tested flexible structure, and force constraint compliance of the communication antenna, robotic arm, and pointing control turntable during the excitation period;

[0045] ④ Use STK software to analyze the coverage satisfaction of the relay measurement and control link during the excitation period to confirm whether the ground measurement and control arc can meet the requirements of the on-orbit identification test.

[0046] In combination with the first aspect, in some implementations of the first aspect, the on-orbit implementation process design module is used to select and sort the candidate operating condition design sequence output by the identification operating condition design module from the aspects of safety and high efficiency, so as to achieve the optimal identification result with the minimum number of identifications; the on-orbit implementation process design module is used to perform the following steps:

[0047] ① According to the working design conditions, first set the measurement sensor parameters, including time synchronization, camera exposure parameters, data storage parameters, and installation calibration parameters;

[0048] ② Using attitude maneuvers, orbit control, flexible mechanism drive servo, and passive excitation conditions of thermal stress in the space environment, a preliminary survey of the modal parameter distribution is conducted;

[0049] ③ Using the results of passive excitation working condition identification, we specifically designed the active excitation signal spectrum for the basic working condition. We first used a series of small-amplitude pulse excitation signals to find out the relationship between the excitation signal intensity and the motion response intensity of the flexible structure and the spacecraft body. By comparing with the ground prediction results, we corrected the active excitation signal design model to ensure the safety of the spacecraft and the flexible structure for active excitation. Through pseudo-random excitation, we preliminarily explored the modal frequency composition and its intensity distribution.

[0050] ④ Carry out active excitation tests under precise working conditions, and further optimize the excitation signal according to the modal frequency survey to ensure that the main modes can be excited as much as possible under safe conditions and the frequency, damping and vibration mode information can be accurately identified.

[0051] In combination with the first aspect, in some implementations of the first aspect, the identification module includes four parts: measurement data processing, parameter identification, identification result analysis and evaluation, and report generation.

[0052] The identification module is used in the design simulation mode to perform the following steps:

[0053] ① Data preprocessing including filtering, de-wiring, detrending and interpolation of the original measurement data;

[0054] ② Use FFT and ERA identification methods to identify the modal frequency, damping, and vibration mode parameters of the tested flexible structure;

[0055] ③ According to the working conditions of this simulation, a quantitative prediction of the modal parameter identification accuracy is given from the aspects of measurement data error, data processing error and identification method error;

[0056] ④Automatically output the identification results in the form of a report;

[0057] The identification module is used to perform the following steps in semi-physical simulation mode or orbital flight control support mode:

[0058] ① Data preprocessing including filtering, de-wiring, detrending and interpolation of the original measurement data;

[0059] ② Use FFT and ERA identification methods to identify the modal frequency, damping, and vibration mode parameters of the tested flexible structure;

[0060] ③ Quantitative comparison and evaluation based on the output data of multiple measurement sensors and the identification results given by multiple identification algorithms;

[0061] ④Automatically output the identification results in the form of a report.

[0062] In combination with the first aspect, in some implementations of the first aspect, the sensor interface simulation module is used to perform the following steps:

[0063] ① Definition of analog interface circuit type, communication rate, communication interface form and data format of communication timing sensor;

[0064] ② Output the original measured physical quantity of the simulated sensor;

[0065] The data receiving and storing module is used to perform the following steps:

[0066] ① Receive and store the measured physical quantity output by the real sensor or interface simulation module;

[0067] ②Decode multi-source data and perform time alignment processing;

[0068] The image analysis and three-dimensional coordinate solution module is used to perform the following steps:

[0069] ①Analyze the image data transmitted by the optical camera;

[0070] ②Extract all characteristic target points in the image;

[0071] ③ Calculate the three-dimensional coordinates of the feature points.

[0072] Compared with the prior art, the solution provided by this application includes at least the following beneficial technical effects:

[0073] Conventional scheme design verification, subsystem design verification, and flight control support system are all independent systems and tools. Simulation and verification at each level only support a certain local verification requirement. It is necessary to define the functions and interfaces between the simulation systems in advance. There is a lack of correlation between them, and joint design simulation cannot be performed. It is usually a serial design process, which is relatively low in design efficiency and system cost-effectiveness. The present invention breaks the framework of serial design and simulation, and proposes an integrated design and simulation method that supports the entire life cycle, which is a significant improvement.

[0074] (1) The present invention defines the composition of the on-orbit modal parameter identification system, which is a specific carrier system for implementing the on-orbit modal parameter identification;

[0075] (2) The present invention designs a systematic architecture that supports the entire life cycle from scheme design simulation, semi-physical simulation, and on-orbit flight control. There is no similar application in existing patents.

[0076] (3) The present invention defines the hardware architecture of the integrated design verification system and the software tool set running on it.

[0077] (4) The present invention provides an integrated design and simulation method for on-orbit modal parameter identification that supports the entire life cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 Schematic diagram of the design architecture for the on-orbit modal parameter identification system.

[0079] Figure 2 Schematic diagram of the top-level system architecture for ground design verification.

[0080] Figure 3 Design simulation mode workflow diagram.

[0081] Figure 4 This is the workflow diagram of the semi-physical simulation mode.

[0082] Figure 5 This is the workflow diagram for the on-orbit flight control support mode. DETAILED DESCRIPTION

[0083] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0084] The present invention provides a ground design verification system for on-orbit modal parameter identification of large-scale flexible structures in space. Figure 2 As shown in the figure, the ground design verification system includes a planning unit, a measurement simulation unit, a data processing unit, and an identification unit. The planning unit is used to realize the functions of task planning, test condition design, test process design, etc. The measurement simulation unit is used to simulate the communication interface and measurement data format of the vibration measurement sensor. The data processing unit is used to realize the data acquisition and storage of the measurement sensor, and carry out the necessary raw data processing work, such as optical image analysis, feature point extraction and three-dimensional coordinate solution, time alignment of multi-source measurement data such as gyroscopes, accelerometers, optical cameras, etc. The identification unit is used to receive the multi-source measurement data (vibration acceleration, displacement, angular velocity, etc.) output by the data processing unit after time synchronization, and call various identification algorithms to complete the identification and result evaluation of modal parameters such as frequency, damping, and vibration mode.

[0085] The present invention combines Figure 3 , specifically explain the functional module design of the ground design verification system. The ground design verification system has seven types of software functional modules that support simulation verification, including the mission planning module, identification condition design module and on-orbit implementation process design module running in the planning unit, the sensor interface simulation module running in the measurement simulation unit, the data receiving and storage module, image analysis and three-dimensional coordinate solution module running in the data processing unit, and the identification module running in the identification unit.

[0086] The mission planning module is used to perform theoretical modal parameter calculation, excitation signal design, flight attitude design, and test window design to obtain mission planning working conditions. The working conditions obtained by the mission planning module are input into the identification working condition design module for simulation scenario setting, and can also be input into the on-orbit implementation process design module for on-orbit implementation process design.

[0087] The identification condition design module includes a dynamic simulation tool set and a test constraint evaluation simulation tool set. The dynamic simulation tool set is used to complete the simulation scene setting. Among them, the initial moment is set by the solar and lunar ephemeris models. The initial orbit is set by the orbit dynamics model, and the real-time orbit output by the orbit dynamics model can be input into the rigid-flexible coupling attitude dynamics model. The initial attitude is set by the rigid-flexible coupling attitude dynamics model, and the modal coordinates and control instructions output by the rigid-flexible coupling attitude dynamics model are input into the flexible structure finite element model to obtain the finite element node vibration displacement and input into the measurement sensor model. The measurement sensor model can output the analog measurement digital quantity to the identification module according to the simulation scene layout setting. The test constraint evaluation simulation tool set includes an optical camera dynamic stray light simulation model, a target point motion measurability simulation model, an excitation safety constraint evaluation simulation model, and a ground measurement and control arc segment simulation model. The dynamic simulation tool set can output ambient lighting conditions, orbit position, attitude, finite element node response displacement and force analysis to the test constraint evaluation simulation tool set to complete the test constraint evaluation. The test constraint evaluation results can be returned to the mission planning module to guide the mission planning adjustment.

[0088] The on-orbit implementation process design module can be used to perform measurement sensor parameter settings and state preparation. According to the preliminary frequency distribution, the frequency of small-amplitude active excitation conditions is explored. After the safety boundary is confirmed, the passive excitation condition frequency is initially explored, and then the excitation intensity and spectrum are selected, and the frequency, damping, and vibration mode of the active excitation condition are precisely measured. The output results of the on-orbit implementation process design module can be used to return to the mission planning module to guide the optimization of mission planning.

[0089] The sensor interface simulation module can generate simulated sensor original measurement physical quantities according to the communication interface and data format definition of each sensor.

[0090] The data receiving and storing module can receive and store the measured physical quantity.

[0091] The image analysis and three-dimensional coordinate solution module can perform time alignment of multi-source data, image analysis and three-dimensional coordinate solution, and output the processed measurement digital quantity.

[0092] The identification module can obtain analog measurement digital quantities from the identification condition design module to complete measurement data processing, modal parameter identification, identification result analysis and evaluation, and report generation. The identification evaluation results output by the identification module can be returned to the mission planning module to guide mission planning adjustments.

[0093] The following describes the three usage modes supported by the ground design verification system, which are design simulation mode, semi-physical simulation mode and on-orbit flight control mode, and describes the design verification method in each usage mode respectively.

[0094] (1) Design simulation mode

[0095] Main function: Provides a digital simulation environment for designers to review the rationality of the scheme during the scheme design stage. Figure 3 As shown, only the planning unit and the identification unit are run in the design simulation mode.

[0096] The planning unit provides the vibration measurement digital quantity simulated by dynamic calculation to the identification unit according to the excitation signal of the current simulation working condition. The identification unit then gives the identification result of the current simulation working condition and optimizes the iterative design of the task planning, working condition, process, etc. according to the evaluation situation. The main steps are as follows.

[0097] a) Carry out the following designs in the mission planning module:

[0098] ① Load the finite element model of the spacecraft flexible structure constructed on the ground and output the modal parameters of theoretical analysis.

[0099] ② Under the premise that the spacecraft is safe in orbit and the normal flight mission is not affected, the spectrum energy of the active excitation signal is optimized to meet the requirements of identifying the excitation response characteristics of the object under test. The design principle is to achieve effective identification of the main modal parameters of the flexible structure through fewer excitation times and improve the identification efficiency.

[0100] ③ Under the constraints of energy supply, measurement and control transmission, spacecraft thermal control, structural safety, control envelope, etc., flexible identification on-orbit flight attitude design should be carried out, and the conditions for effective measurement of vibration measurement sensors should be met, such as layout and installation constraints, information links, etc.

[0101] ④ Under the constraints of lighting conditions and ambient temperature conditions of optical cameras, accelerometers, gyroscopes and other measurement sensors, carry out the design of flexible identification on-orbit test window to confirm that the measurement, control, communication and lighting conditions meet the minimum duration of a single identification test.

[0102] b) The identification condition design module includes two parts: the dynamic simulation tool set and the test constraint evaluation simulation tool set, and carries out the following designs in sequence:

[0103] b.1) First, use the dynamics simulation toolset to simulate rigid-flexible coupling attitude dynamics, orbital dynamics, etc.:

[0104] ① Set up simulation scenarios according to the working conditions to be simulated given by the task planning module;

[0105] ② Calculate the spacecraft attitude and orbit as well as the flexible vibration of the flexible structure through rigid-flexible coupling attitude dynamics, orbital dynamics and flexible structure finite element model;

[0106] ③Simulate ambient lighting conditions through the solar and lunar ephemeris model;

[0107] ④Simulate the output of digital quantities such as gyroscopes, accelerometers, optical cameras, strain gauges, etc. through the measurement sensor model;

[0108] b.2) Then, the test constraint evaluation simulation tool set is used to simulate and evaluate the conformity of the output results of the dynamics simulation tool set from the following four aspects of the test constraint conditions:

[0109] ① According to the sun-moon vector and spacecraft orbit data under given working conditions, the relative relationship between sunlight, moonlight, and earth's atmospheric light on the optical axis of the optical camera is analyzed, and the dynamic stray light simulation model of the optical camera is used to evaluate the impact of dynamic stray light on optical measurement during the measurement process;

[0110] ② Based on the simulation model of the motion measurability of the target point, an optical camera is used to simulate and predict the dynamic measurability of the target point in the specified area of ​​the flexible structure to be tested (usually the main mode-intensive area), and the continuous measurability of the target point under a given excitation signal is analyzed to analyze whether measurement data of sufficient duration can be obtained;

[0111] ③ Based on the excitation safety constraint assessment simulation model, the compliance of the spacecraft attitude angle and attitude angular velocity constraints, thermal control constraints, the force and maximum amplitude constraints of the tested flexible structure, and the force constraints of other active mechanisms (communication antenna, robotic arm, pointing control turntable, etc.) during the excitation period are analyzed;

[0112] ④ Use STK software to analyze the coverage satisfaction of the relay measurement and control link during the excitation period to confirm whether the ground measurement and control arc can meet the requirements of the on-orbit identification test.

[0113] c) Based on a series of alternative working condition design sequences output by the identification working condition design module, the on-orbit implementation process design module is used to reasonably select and sort them from the aspects of safety and efficiency to achieve the best identification result with the minimum number of identifications. The following designs are carried out in sequence:

[0114] ① According to the working design conditions, first set the measurement sensor parameters, such as time synchronization, camera exposure parameters, data storage parameters, installation calibration parameters, etc.;

[0115] ② Using passive excitation conditions such as attitude maneuvers, orbit control, flexible mechanism drive servo, and space environment thermal stress, a preliminary survey of the modal parameter distribution is conducted;

[0116] ③ Using the results of passive excitation condition identification, we specifically design the active excitation signal spectrum for the basic working conditions. Generally, we first use a series of small-amplitude pulse excitation signals to find out the relationship between the excitation signal intensity and the motion response intensity of the flexible structure and the spacecraft body. By comparing with the ground prediction results, we modify the active excitation signal design model to ensure the safety of the spacecraft and the flexible structure for active excitation. Through pseudo-random excitation, we preliminarily explore the possible modal frequency composition and its intensity distribution;

[0117] ④ Carry out active excitation tests under precise working conditions, and further optimize the excitation signal according to the modal frequency situation, so as to ensure that the main modes are excited as much as possible under safe conditions and the frequency, damping and vibration mode information are accurately identified.

[0118] d) The identification module consists of four parts: measurement data processing, parameter identification, analysis and evaluation of identification results, and report generation. It is generally implemented by special equipment on the ground. Perform the following steps in sequence:

[0119] ⑤ Perform necessary data preprocessing such as filtering, eliminating wild values, removing trends, and interpolation on various types of raw measurement data;

[0120] ⑥ Use FFT, ERA and other identification methods to identify the modal parameters such as modal frequency, damping, vibration mode and so on of the tested flexible structure;

[0121] ⑦ According to the working conditions of this simulation, a quantitative prediction of the modal parameter identification accuracy is given from the aspects of measurement data error, data processing error, identification method error, etc.;

[0122] ⑧ Automatically output the identification results in the form of a report.

[0123] (2) Semi-physical simulation mode

[0124] Main functions: In the ground semi-physical verification stage, it provides a semi-physical simulation environment for designers to verify the correctness of the interaction relationship, information timing, and handling process of the entire test system. Figure 4 As shown, the planning unit, measurement simulation unit, data processing unit and identification unit are operated in the semi-physical simulation mode.

[0125] The planning unit provides the vibration measurement digital quantity simulated by dynamic calculation to the measurement simulation unit according to the excitation signal of the current simulation working condition; the measurement simulation unit generates the simulated original measurement physical quantity of the sensor according to the communication interface and data format definition of each sensor; the data processing unit receives and stores the measurement physical quantity, and performs multi-source data time alignment, image analysis and three-dimensional coordinate solution, and outputs the processed measurement digital quantity; the identification unit gives the identification result of the current simulation working condition according to the measurement data quantity, and optimizes the iterative design of task planning, working conditions, processes, etc. according to the evaluation situation. The main steps are as follows.

[0126] a) Carry out relevant design in the mission planning module: same as design simulation mode.

[0127] b) Carry out relevant designs in the identification condition design module: same as the design simulation mode.

[0128] c) Carry out relevant designs in the on-orbit implementation process design module: same as the design simulation mode.

[0129] d) Carry out the following design in the sensor interface simulation module:

[0130] ③Simulate the communication interface form of each sensor (including interface circuit type, communication rate, communication timing, etc.) and data format definition;

[0131] ④ Output the original measured physical quantity of the simulated sensor.

[0132] e) Carry out the following design in the data receiving and storage module:

[0133] ③ Receive and store the measured physical quantity output by the real sensor or interface simulation module;

[0134] ④Perform multi-source data decoding and time alignment processing.

[0135] f) Carry out the following design in the image analysis and three-dimensional coordinate solution module:

[0136] ④Analyze the image data transmitted by the optical camera;

[0137] ⑤Extract all characteristic target points in the image;

[0138] ⑥ Calculate the three-dimensional coordinates of the feature points.

[0139] g) Carry out the following design in the identification module:

[0140] ⑤ Perform necessary data preprocessing such as filtering, eliminating wild values, removing trends, and interpolation on various types of raw measurement data;

[0141] ⑥ Use FFT, ERA and other identification methods to identify the modal parameters such as modal frequency, damping, vibration mode and so on of the tested flexible structure;

[0142] ⑦ Quantitative comparison and evaluation based on the output data of multiple measurement sensors and the identification results given by multiple identification algorithms;

[0143] ⑧ Automatically output the identification results in the form of a report.

[0144] (3) On-orbit flight control support mode

[0145] Main functions: Assist designers to efficiently complete data processing and identification result evaluation during the flight control support phase of the spacecraft during its on-orbit flight. Figure 5 As shown, the planning unit, data processing unit and identification unit are operated in the on-orbit flight control support mode.

[0146] The data processing unit receives and stores the real-time or delayed data of the actual vibration measurement of the space flexible structure through the ground-ground measurement and control network, and performs multi-source data time alignment, image analysis and three-dimensional coordinate solution, and outputs the processed measurement digital quantity; the identification unit gives the identification result of the current identification condition according to the measurement data volume, and reviews the rationality of the subsequent task planning, working conditions, processes and other strategic arrangements according to the evaluation situation. The main steps are as follows.

[0147] a) Carry out relevant design in the mission planning module: same as design simulation mode.

[0148] b) Carry out relevant designs in the identification condition design module: same as the design simulation mode.

[0149] c) Carry out relevant designs in the on-orbit implementation process design module: same as the design simulation mode.

[0150] d) Carry out relevant design in the data receiving and storage module: the same as the semi-physical simulation mode.

[0151] e) Carry out relevant designs in the image analysis and three-dimensional coordinate solution modules: the same as the semi-physical simulation mode.

[0152] f) Carry out relevant design in the identification module: the same as the semi-physical simulation mode.

[0153] The present invention provides a ground design verification system for on-orbit modal parameter identification of large-scale flexible structures in space. The ground design verification system is a set of digital verification tools that can adapt to the entire cycle of ground scheme design and development to on-orbit identification tasks for the above-mentioned on-orbit modal parameter identification system. The ground design verification system solidifies the design process, simulation tools and on-orbit test process related to on-orbit modal parameter identification of large-scale flexible structures in space in the form of software function modules. It has three operating modes: scheme design mode, semi-physical simulation mode, and flight control support mode, which helps to improve the efficiency of design simulation and on-orbit identification.

[0154] Although the present invention is disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims of the present invention.

Claims

1. A ground design verification system for on-orbit modal parameter identification of large-scale space flexible structures, characterized in that: include: Planning unit, used to realize task planning, test condition design, and test process design functions; A measurement simulation unit, used to simulate the vibration measurement sensor communication interface and measurement data format; Data processing unit, used to realize data collection and storage of measurement sensors, and carry out raw data processing, including optical image analysis, feature point extraction, three-dimensional coordinate solution, and multi-source measurement data time alignment; The identification unit is used to receive the multi-source measurement data after time synchronization output by the data processing unit, and call the identification algorithm to complete the identification of frequency, damping, vibration mode parameters and result evaluation.

2. The system according to claim 1, characterized in that The ground design verification system has seven types of software functional modules supporting simulation verification, including a task planning module, an identification condition design module and an on-orbit implementation process design module running in the planning unit, a sensor interface simulation module running in the measurement simulation unit, a data receiving and storage module, an image analysis and three-dimensional coordinate solution module running in the data processing unit, and an identification module running in the identification unit.

3. The system according to claim 2, characterized in that The mission planning module is used to perform theoretical modal parameter calculation, excitation signal design, flight attitude design, and test window design to obtain mission planning working conditions; The working conditions obtained by the mission planning module are input into the identification working condition design module for simulation scenario setting, and are also input into the on-orbit implementation process design module for on-orbit implementation process design; The identification condition design module includes a dynamic simulation toolset and a test constraint evaluation simulation toolset; the dynamic simulation toolset is used to complete the simulation scene setting; among them, the initial moment is set through the solar and lunar ephemeris models; the initial orbit is set through the orbit dynamics model, and the real-time orbit output by the orbit dynamics model is input to the rigid-flexible coupling attitude dynamics model; the initial attitude is set through the rigid-flexible coupling attitude dynamics model, and the modal coordinates and control instructions output by the rigid-flexible coupling attitude dynamics model are input to the flexible structure finite element model to obtain the finite element node vibration displacement, and input to the measurement sensor model; the measurement sensor model is set according to the simulation scene layout, and the analog measurement digital quantity is output to the identification module; the test constraint evaluation simulation toolset includes an optical camera dynamic stray light simulation model, a target point motion measurement simulation model, an excitation safety constraint evaluation simulation model, and a ground measurement and control arc simulation model; the dynamic simulation toolset outputs ambient lighting conditions, orbit position, attitude, finite element node response displacement and force analysis to the test constraint evaluation simulation toolset to complete the test constraint evaluation; the test constraint evaluation results are returned to the mission planning module to guide the mission planning adjustment; The on-orbit implementation process design module is used to perform measurement sensor parameter settings and state preparation. According to the preliminary frequency distribution, the frequency of small-amplitude active excitation conditions is explored. After the safety boundary is confirmed, the passive excitation condition frequency is initially explored, and then the excitation intensity and spectrum are selected, and the frequency, damping, and vibration mode of the active excitation condition are precisely measured. The output results of the on-orbit implementation process design module are used to return to the mission planning module to guide the optimization of mission planning. The sensor interface simulation module generates simulated original measurement physical quantities of the sensor according to the communication interface and data format definition of each sensor; The data receiving and storing module receives and stores the measured physical quantity; The image analysis and three-dimensional coordinate solution module performs time alignment of multi-source data, image analysis and three-dimensional coordinate solution, and outputs the processed measurement digital quantity; The identification module obtains the analog measurement digital quantity from the identification condition design module, completes the measurement data processing, modal parameter identification, identification result analysis and evaluation, and report generation; the identification evaluation results output by the identification module are returned to the task planning module to guide the task planning adjustment.

4. The system according to claim 2, characterized in that The system supports design simulation mode, semi-physical simulation mode and on-orbit flight control mode. The design simulation mode is used to provide a digital simulation environment for designers to review the rationality of the scheme during the scheme design stage. The semi-physical simulation mode is used to provide a semi-physical simulation environment for designers to verify the correctness of the interaction relationship, information timing, and handling process of the entire test system during the ground semi-physical verification stage; The on-orbit flight control mode is used to assist designers in completing data processing and identification result evaluation during the flight control support phase of the spacecraft during its on-orbit flight.

5. The system according to claim 4, characterized in that The planning unit and identification unit are operated in the design simulation mode. The planning unit provides the vibration measurement digital quantity simulated by dynamic calculation to the identification unit according to the excitation signal of the current simulation working condition. The identification unit gives the identification result of the current simulation working condition and optimizes the iterative design of the task planning, working condition and process according to the evaluation situation. Run the planning unit, the measurement simulation unit, the data processing unit and the identification unit in a semi-physical simulation mode; The planning unit provides the vibration measurement digital quantity simulated by dynamic calculation to the measurement simulation unit according to the excitation signal of the current simulation working condition; the measurement simulation unit generates the simulated original measurement physical quantity of the sensor according to the communication interface and data format definition of each sensor; the data processing unit receives and stores the measurement physical quantity, performs multi-source data time alignment, image analysis and three-dimensional coordinate solution, and outputs the processed measurement digital quantity; The identification unit gives the identification result of the current simulation working condition according to the amount of measured data, and optimizes the iterative design of task planning, working conditions and processes according to the evaluation results; Operate the planning unit, data processing unit and identification unit in the on-orbit flight control support mode; The data processing unit receives and stores the real-time data or delayed data of the actual vibration measurement of the space flexible structure through the ground-ground measurement and control network, and performs multi-source data time alignment, image analysis and three-dimensional coordinate solution, and outputs the processed measurement digital quantity; The identification unit gives the identification result of the current identification condition according to the amount of measurement data, and reviews the rationality of the subsequent task planning, working conditions, and process strategy arrangements based on the evaluation results.

6. The system according to claim 2, characterized in that The system is used in the mission planning module to perform the following steps: ① Load the finite element model of the spacecraft flexible structure constructed on the ground and output the modal parameters of theoretical analysis; ② Under the premise that the spacecraft's on-orbit operation is safe and the normal flight mission is not affected, the spectrum energy of the active excitation signal is optimized to meet the requirements of identifying the excitation response characteristics of the object under test; ③ Under the constraints of energy supply, measurement and control transmission, spacecraft thermal control, structural safety, and control envelope, carry out flexible identification on-orbit flight attitude design to meet the conditions for effective measurement of vibration measurement sensors; ④ Under the constraints of lighting conditions and ambient temperature conditions of optical cameras, accelerometers, and gyroscope measurement sensors, carry out the design of flexible identification on-orbit test windows to confirm that the measurement, control, communication, and lighting conditions meet the minimum duration of a single identification test.

7. The system according to claim 2, characterized in that The identification working condition design module includes two parts: a dynamics simulation tool set and a test constraint evaluation simulation tool set. The dynamics simulation tool set is used to perform rigid-flexible coupling attitude dynamics and orbital dynamics simulation. The test constraint evaluation simulation tool set is used to simulate and evaluate the output results of the dynamics simulation tool set from the compliance of the test constraint conditions. The Dynamics Simulation Toolset is used to perform the following steps: ① Set up simulation scenarios according to the working conditions to be simulated given by the task planning module; ② Calculate the spacecraft attitude and orbit as well as the flexible vibration of the flexible structure through rigid-flexible coupling attitude dynamics, orbital dynamics and flexible structure finite element model; ③Simulate ambient lighting conditions through the solar and lunar ephemeris model; ④Simulate the digital output of gyroscope, accelerometer, optical camera and strain gauge through the measurement sensor model; The Experimental Constraint Evaluation simulation toolset is used to perform the following steps: ① According to the sun-moon vector and spacecraft orbit data under given working conditions, the relative relationship between sunlight, moonlight, and earth's atmospheric light on the optical axis of the optical camera is analyzed, and the dynamic stray light simulation model of the optical camera is used to evaluate the impact of dynamic stray light on optical measurement during the measurement process; ② Based on the target point motion measurement simulation model, use the optical camera to simulate and predict the dynamic measurement of the target point in the specified area of ​​the flexible structure to be measured, analyze the continuous measurement of the target point under the given excitation signal, and analyze whether the measurement data of sufficient length is obtained; ③ Based on the excitation safety constraint assessment simulation model, analyze the spacecraft attitude angle and attitude angular velocity constraints, thermal control constraints, force and maximum amplitude constraints of the tested flexible structure, and force constraint compliance of the communication antenna, robotic arm, and pointing control turntable during the excitation period; ④ Use STK software to analyze the coverage satisfaction of the relay measurement and control link during the excitation period to confirm whether the ground measurement and control arc can meet the requirements of the on-orbit identification test.

8. The system according to claim 2, characterized in that The on-orbit implementation process design module is used to select and sort the candidate working condition design sequence output by the identification working condition design module from the aspects of safety and high efficiency, so as to achieve the optimal identification result with the minimum identification number; the on-orbit implementation process design module is used to perform the following steps: ① According to the working design conditions, first set the measurement sensor parameters, including time synchronization, camera exposure parameters, data storage parameters, and installation calibration parameters; ② Using attitude maneuvers, orbit control, flexible mechanism drive servo, and passive excitation conditions of thermal stress in the space environment, a preliminary survey of the modal parameter distribution is conducted; ③ Using the results of passive excitation working condition identification, we specifically designed the active excitation signal spectrum for the basic working condition. We first used a series of small-amplitude pulse excitation signals to find out the relationship between the excitation signal intensity and the motion response intensity of the flexible structure and the spacecraft body. By comparing with the ground prediction results, we corrected the active excitation signal design model to ensure the safety of the spacecraft and the flexible structure for active excitation. Through pseudo-random excitation, we preliminarily explored the modal frequency composition and its intensity distribution. ④ Carry out active excitation tests under precise working conditions, and further optimize the excitation signal according to the modal frequency survey to ensure that the main modes can be excited as much as possible under safe conditions and the frequency, damping and vibration mode information can be accurately identified.

9. The system according to claim 2, characterized in that The identification module includes four parts: measurement data processing, parameter identification, identification result analysis and evaluation, and report generation. The identification module is used in the design simulation mode to perform the following steps: ① Data preprocessing including filtering, de-wiring, detrending and interpolation of the original measurement data; ② Use FFT and ERA identification methods to identify the modal frequency, damping, and vibration mode parameters of the tested flexible structure; ③ According to the working conditions of this simulation, a quantitative prediction of the modal parameter identification accuracy is given from the aspects of measurement data error, data processing error and identification method error; ④Automatically output the identification results in the form of a report; The identification module is used to perform the following steps in semi-physical simulation mode or orbital flight control support mode: ① Data preprocessing including filtering, de-wiring, detrending and interpolation of the original measurement data; ② Use FFT and ERA identification methods to identify the modal frequency, damping, and vibration mode parameters of the tested flexible structure; ③ Quantitative comparison and evaluation based on the output data of multiple measurement sensors and the identification results given by multiple identification algorithms; ④Automatically output the identification results in the form of a report.

10. The system according to claim 2, characterized in that The sensor interface simulation module is used to perform the following steps: ① Definition of analog interface circuit type, communication rate, communication interface form and data format of communication timing sensor; ② Output the original measured physical quantity of the simulated sensor; The data receiving and storing module is used to perform the following steps: ① Receive and store the measured physical quantity output by the real sensor or interface simulation module; ②Decode multi-source data and perform time alignment processing; The image analysis and three-dimensional coordinate solution module is used to perform the following steps: ①Analyze the image data transmitted by the optical camera; ②Extract all characteristic target points in the image; ③ Calculate the three-dimensional coordinates of the feature points.

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