CN117234106A - Satellite attitude and orbit control ground simulation system and reliability evaluation method thereof - Google Patents

Abstract

The application discloses a satellite attitude and orbit control ground simulation system and a reliability evaluation method thereof, belonging to the technical field of satellite simulation, wherein the ground simulation system comprises: the system comprises a GNC system, a dynamics simulation system, a motion system, a measurement system and a communication system; the run-time synchronization protocol between the systems ensures the timeliness of the simulation system as a whole and does not require additional hardware equipment. The reliability evaluation method is used for constructing an evaluation index system, an EARTH and expert scoring method is adopted to obtain a reliability index sequence, weight vectors of all layers of the evaluation node under evaluation of different expert importance levels are obtained through an AHP method, D-S evidence theory is utilized to fuse the weight vectors, evaluation vectors at all times in the reliability index sequence are obtained according to a fuzzy membership function, the total reliability of the system is comprehensively calculated from bottom to top through a fuzzy comprehensive evaluation method, influence of expert subjective factors on reliability evaluation is reduced, and consistency of dynamic indexes of the ground simulation system is comprehensively evaluated.

Description

Satellite attitude and orbit control ground simulation system and its credibility evaluation method

Technical Field

The present application relates to a satellite attitude and orbit control ground simulation system and a credibility assessment method thereof, and belongs to the field of satellite simulation technology.

Background Art

Modeling and simulation are considered to be the third way to understand the world in the information age, along with theoretical research and experimental research. Simulation technology uses models to study systems, and plays an indispensable role in industry, agriculture, commerce, education, military, transportation and other fields with its advantages of low cost, reusability, non-destructiveness and strong flexibility. Due to the long development cycle, high cost and complex process of spacecraft, the actual cost of spacecraft attitude control is extremely high and non-repeatable, so it is necessary to use spacecraft ground simulation technology to analyze and study the problem of spacecraft attitude control.

The credibility of a simulation system refers to "the degree of trust that the users of the simulation system have in the correctness of solving the defined problem in accordance with the results of the simulation test under certain conditions and in a certain environment", or "the degree of credibility that the simulation system, as a similar substitute system for the prototype system, can reproduce the prototype system at the overall structure and behavior level under the specific purpose and significance of modeling and simulation". With the in-depth study of complex simulation technology, simulation credibility assessment has received more and more attention and has become a research focus in the simulation field.

In "Research on Ground Simulation Verification Methods for Spacecraft Attitude and Orbit Control System" ("Full-text Database of Chinese Master's Degree Thesis (Engineering Technology Series II)", Issue 03, 2014, Harbin Institute of Technology, He Chaobin), the design and implementation methods of the ground simulation system of the spacecraft attitude and orbit control system, simulation schemes and other issues were studied in depth. In order to meet the large data volume communication between subsystems under hard real-time conditions, a fiber-optic reflective memory card is used to form a reflective memory network for data interaction and command control between subsystems. However, the construction of the fiber-optic reflective memory network requires the installation of additional fiber-optic reflective memory cards, which has a high overall cost and requires a wired connection. It is not suitable for test scenarios such as air flotation systems that require wireless transmission.

In "A Credibility Evaluation Method for Guidance Simulation System Based on DS/AHP and Gray Cloud Clustering" (Electronic Measurement Technology, 2017, 40(07), Pan Yunlong et al.), a simulation credibility evaluation model based on evidence theory and gray cloud clustering was proposed to address the subjectivity and uncertainty of the credibility quantification of complex guidance simulation systems. First, the opinions of multiple experts were obtained by group analytic hierarchy process, and the inconsistent opinions were integrated by evidence theory to obtain the indicator weights with higher credibility. Then, the gray cloud clustering method was used, and the gray cloud model was used as the whitening weight function to quantify the qualitative evaluation. Finally, the credibility of the simulation system was evaluated by calculating the gray clustering coefficient. This model was applied to evaluate the guidance semi-physical simulation system. The results were consistent with objective reality, indicating that the model is feasible and practical, and provides a new and effective way for simulation credibility evaluation and comprehensive evaluation. However, the acquisition of the underlying indicators depends on the scoring of four experts. This evaluation method is greatly affected by the subjective factors of the experts and requires more personnel participation.

The invention with application number 202210123783.7 discloses a method for evaluating the effectiveness of a satellite tracking, pointing and control ground simulation system, which includes: constructing a hierarchical model structure of a satellite high-precision tracking, pointing and control ground simulation system; determining the weight coefficients of each layer of similar elements and the similarity values of the similar elements in the hierarchical model structure; tracking and comparing the similarity between the simulation system and the actual system, and determining the similarity of each layer of similar elements in the simulation system based on the similarity values of the similar elements; determining the system similarity of the simulation system based on the weight coefficients of each layer of similar elements and the similarity of each layer of similar elements, and the system similarity is used to evaluate the effectiveness of the simulation system. The weight coefficient of each layer of similar elements is obtained by using the hierarchical analysis method based on the importance of a single expert to the similar elements of this layer relative to the similar elements of the upper layer, and is greatly affected by the subjective factors of the expert himself. At the same time, in terms of the underlying indicators, only some static indicators are considered, and dynamic indicators are not considered.

The invention with application number 202210165607.X discloses a method and device for detecting the performance of a spacecraft attitude and orbit control ground simulation system. The method can establish a simulation node model corresponding to the simulation system according to the implementation form of the designed satellite spacecraft attitude and orbit control ground simulation system, and then analyze and obtain the simulation performance of the entire simulation system, so as to verify the effectiveness and feasibility of the entire simulation system. The method includes: obtaining a simulation node information flow diagram of the spacecraft attitude and orbit control ground simulation system; obtaining the uncertainty of the performance of each simulation node based on the performance influencing factors corresponding to each simulation node in the simulation node information flow diagram; based on the connection relationship between the simulation nodes revealed in the simulation node information flow diagram, the uncertainty of the performance of each simulation node is integrated to obtain the performance uncertainty of the simulation system; based on the performance uncertainty of the simulation system, the total simulation performance of the simulation system is obtained. In terms of the underlying indicators, the method also only considers some static indicators such as the relative error between the disturbance torque achievable by the simulation system and the disturbance torque of the actual system, the information transmission delay value of the simulation system, and the simulation accuracy of the attitude angle, but does not consider dynamic indicators.

Summary of the invention

The purpose of this application is to provide a satellite attitude and orbit control ground simulation system and its credibility assessment method, which can effectively ensure the overall time consistency of the simulation system without the need for additional hardware equipment. In addition, a credibility assessment method is proposed for the satellite attitude and orbit control ground simulation system, which can reduce the impact of expert subjective factors on credibility assessment and comprehensively evaluate the consistency of dynamic indicators of the ground simulation system.

To achieve the above-mentioned purpose, the first aspect of the present application provides a satellite attitude and orbit control ground simulation system, comprising:

GNC system, dynamics simulation system, motion system, measurement system and communication system;

The communication system is connected to the GNC system, the dynamics simulation system, the motion system and the measurement system respectively, and is used to realize information transmission between the systems;

The GNC system is used to obtain control instructions based on the current attitude and orbit information of the simulated satellite output by the measurement system and the attitude and orbit information given by the outside world, and transmit the control instructions to the dynamic simulation system;

The dynamics simulation system is used to obtain the attitude information and orbit information of the simulated satellite through physical experiments or mathematical simulations according to the control instructions and transmit the information to the motion system;

The motion system is used to carry the simulated satellite and control the simulated satellite to move according to the attitude information and orbit information output by the dynamics simulation system;

The measurement system is used to measure the current attitude and orbit of the simulated satellite, obtain the current attitude and orbit information of the simulated satellite and transmit it to the GNC system;

The GNC system, the dynamics simulation system, the motion system and the measurement system all have their own clocks, and a time synchronization protocol is run between the systems based on the communication system to ensure synchronization of different clocks;

The time synchronization protocol includes:

The clock of any system is selected as the master clock, and the clocks of the other systems are selected as slave clocks. The master clock time is used as the standard, and each preset synchronization period is a time period. In each time period, the following steps are performed until the simulation ends:

S100: In the nth time period, the master clock and one of the slave clocks send messages to each other through the communication system, and calculate the delay from the master clock to the slave clock and the delay from the slave clock to the master clock in the current time period according to the time when the master clock sends the message and the time when the slave clock receives the message;

S110 obtains the clock offset and propagation delay of the current time period from the clock end through adaptive Kalman filtering;

S120 adjusts the clock frequency of the slave clock using a PI controller according to the clock offset to achieve time synchronization;

S130 determines whether all slave clocks have completed time synchronization with the master clock. If so, execute step S140. Otherwise, return to step S100.

S140 calculates the reliability of the communication system at the current moment by taking the maximum value of the clock offset between the master clock and all the slave clocks as the maximum clock offset at the current moment and taking the maximum value of the propagation delay between the master clock and all the slave clocks as the maximum propagation delay at the current moment.

In one embodiment, the dynamics simulation system is a digital simulation system or a semi-physical simulation system or a fully physical system;

The dynamics simulation system includes: an attitude dynamics simulation system for obtaining the attitude information, and a track dynamics simulation system for obtaining the track information.

The second aspect of the present application provides a credibility assessment method for performing credibility assessment on the satellite attitude and orbit control ground simulation system in the first aspect or any implementation of the first aspect, including:

Constructing an evaluation index system for the satellite attitude and orbit control ground simulation system, wherein the evaluation index system includes a plurality of evaluation nodes for performing credibility evaluation and a unidirectional connection line for connecting the evaluation nodes;

Based on the current attitude and orbit information of the simulated satellite obtained by the satellite attitude and orbit control ground simulation system, a credible indicator sequence of the bottom evaluation node in the evaluation indicator system is obtained through EARTH and expert scoring method;

The weight vectors between the evaluation nodes at different levels under different expert importance evaluations are obtained through the AHP method, and the weight vectors are fused through the D-S evidence theory to obtain the fused weight vector.

Confirm the fuzzy membership function of the underlying evaluation nodes in the evaluation index system;

Confirm the evaluation vector at each moment in the credible indicator sequence of the bottom evaluation node in the evaluation indicator system according to the fuzzy membership function;

According to the evaluation vector at each moment and the weight vector after fusion between the evaluation nodes at each layer, the fuzzy comprehensive evaluation method is used to comprehensively calculate the overall credibility of the satellite attitude and orbit control ground simulation system from bottom to top.

In one embodiment, the evaluation index system further includes a number of backtracking nodes for finding credibility defects and a one-way connection line for connecting the evaluation node with the backtracking node or connecting each backtracking node;

The method of using the fuzzy comprehensive evaluation method to comprehensively calculate the total credibility of the satellite attitude and orbit control ground simulation system from bottom to top also includes:

If the total credibility at a certain moment does not meet the preset conditions, the credibility index value of the underlying backtracking node under the evaluation node whose credibility does not meet the preset conditions at the current moment is calculated, and whether the underlying backtracking node is the source of the credibility defect is determined based on the credibility index.

In one embodiment, the trust indicator sequence of the bottom layer evaluation node includes a posture credibility time series, a position credibility time series, and a system interaction credibility time series;

The credible indicator sequence of the bottom evaluation node in the evaluation indicator system is obtained as follows:

Apply the same input as the actual satellite system to the satellite attitude and orbit control ground simulation system, obtain the output of the satellite attitude and orbit control ground simulation system and the actual satellite system at every preset evaluation period, seek consistency between each output of the satellite attitude and orbit control ground simulation system and the actual satellite system through the EARTH method and obtain a consistency index, and obtain an attitude credibility time series and a position credibility time series according to each consistency index;

The system interaction credibility time series is obtained through expert scoring method.

In one embodiment, the step of obtaining consistency of each output of the satellite attitude and orbit control ground simulation system and the actual satellite system by the EARTH method and obtaining a consistency index comprises:

Assume that A and B are the time series of the outputs of the actual satellite system and the satellite attitude and orbit control ground simulation system respectively, and use the calculation formula of the cross-correlation coefficient to calculate the phase shift steps and the phase error between A and B;

According to the phase shift steps, A and B are moved and the time series after the shift is obtained as follows: , for time series Perform dynamic time warping and calculate the amplitude error;

Time series after moving Taking the derivative at each point in the , and the derived sequence Perform dynamic time warping and calculate the topological error;

The consistency index characterizing the consistency of the curve is obtained based on the phase error, amplitude error and topological error.

In one embodiment, the method of obtaining the weight vectors between the evaluation nodes at different levels under different expert importance evaluations by the AHP method includes:

Compare the importance of child nodes relative to their parent nodes and construct a judgment matrix;

Calculate the weight vector according to the judgment matrix;

The random consistency ratio is obtained according to the weight vector, and it is determined whether the random consistency ratio is less than 0.1 or infinite. If so, the judgment matrix is consistent and the weight vector is usable. Otherwise, the judgment matrix is inconsistent and the judgment matrix is adjusted until it is consistent.

The third aspect of the present application comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the second aspect or any one of the embodiments of the second aspect when executing the computer program.

A fourth aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps in the second aspect or any implementation of the second aspect are implemented.

As can be seen from the above, the present application provides a satellite attitude and orbit control ground simulation system and a credibility assessment method thereof. The ground simulation system is a distributed simulation system. A time synchronization protocol runs between each system to limit the offset between the clocks of each system to a small range, thereby ensuring the overall time consistency of the ground simulation system. The time synchronization protocol uses the original communication system of the ground simulation system and does not require additional hardware equipment.

The present application also provides a credibility assessment method for the above-mentioned satellite attitude and orbit control ground simulation system, which is used to assess its credibility. The credibility finally obtained by the credibility assessment method is a time series related to the simulation time of the satellite attitude and orbit control ground simulation system, which can effectively solve the problem that the credibility of the ground simulation system is greatly different due to factors such as error accumulation and orbital perturbation in short-term and long-term simulation experiments, and a single credibility value cannot accurately express this feature. The use of D-S evidence theory to fuse weight vectors can reduce the influence of expert subjective factors on credibility assessment. The system verification method of EARTH can comprehensively evaluate the consistency of the dynamic indicators of the simulation system from three aspects: phase, amplitude, and topology, and can more accurately quantitatively evaluate the credibility of the satellite attitude and orbit control ground simulation system. Using an evaluation index system including evaluation nodes and backtracking nodes, in addition to the function of evaluating the overall credibility of the satellite attitude and orbit control ground simulation system, it can also find the source of credibility defects through backtracking nodes when the overall credibility is not ideal.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

FIG1 is a schematic diagram of the structure of a satellite attitude and orbit control ground simulation system provided in an embodiment of the present application;

FIG2 is a flowchart of an operation of a time synchronization protocol provided in an embodiment of the present application;

FIG3 is a schematic diagram of a process of mutual message transmission between a master clock M and a slave clock S in an nth time synchronization cycle provided by an embodiment of the present application;

FIG4 is a schematic diagram of the structure of a time synchronization system between a master clock M and a slave clock S provided in an embodiment of the present application;

FIG5 is a flow chart of a credibility evaluation method provided in an embodiment of the present application;

FIG6 is a schematic diagram of an evaluation index system model provided in an embodiment of the present application;

FIG7 is a schematic diagram of a flow chart of obtaining consistency between A and B using the EARTH method provided in an embodiment of the present application;

FIG8 is a schematic diagram of a process of obtaining weights by using the AHP method provided in an embodiment of the present application;

FIG. 9 is a schematic diagram of a membership function provided in an embodiment of the present application.

DETAILED DESCRIPTION

In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.

It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

The following is a clear and complete description of the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

Embodiment 1

The present application embodiment provides a satellite attitude and orbit control ground simulation system, as shown in FIG1 , the ground simulation system includes:

GNC system, dynamics simulation system, motion system, measurement system and communication system;

The communication system is connected to the GNC system, the dynamics simulation system, the motion system and the measurement system respectively, and is used to realize information transmission between the systems;

The GNC system is used to obtain control instructions based on the current attitude and orbit information of the simulated satellite output by the measurement system and the attitude and orbit information given by the outside world, and transmit the control instructions to the dynamic simulation system;

The dynamics simulation system is used to obtain the attitude information and orbit information of the simulated satellite through physical experiments or mathematical simulations according to the control instructions and transmit the information to the motion system;

The motion system is used to carry the simulated satellite and control the simulated satellite to move according to the attitude information and orbit information output by the dynamics simulation system;

The measurement system is used to measure the current attitude and orbit of the simulated satellite, obtain the current attitude and orbit information of the simulated satellite and transmit it to the GNC system to form a closed loop;

The GNC system, the dynamics simulation system, the motion system and the measurement system are all equipped with their own clocks, and a time synchronization protocol is run between the systems based on the communication system to ensure the synchronization of different clocks.

In one implementation, the GNC system, i.e., the satellite's guidance, navigation, and control subsystem, is responsible for specific navigation, guidance, and control calculations. In the embodiment of the present application, the input end of the GNC system is connected to the outside world and the measurement system through a communication system, receives the current attitude and orbit information of the simulated satellite output by the measurement system and the attitude and orbit information given by the outside world, performs navigation, guidance, and control calculations on the simulated satellite based on the attitude and orbit information provided by the two, and then obtains corresponding control instructions, and transmits the control instructions to the dynamics simulation system through the communication system at the output end.

Optionally, the dynamics simulation system is a digital simulation system or a semi-physical simulation system or a fully physical system;

The dynamics simulation system includes: an attitude dynamics simulation system for obtaining the attitude information, and a track dynamics simulation system for obtaining the track information.

In one embodiment, the attitude dynamics simulation system can be a digital simulation system based on computer simulation, a fully physical system based on a three-axis air bearing platform, or a semi-physical simulation system with one attitude based on a single-axis air bearing platform and the rest of the attitudes based on digital simulation. Similarly, the track dynamics simulation system also has three simulation system forms: digital, physical, and semi-physical.

In one implementation, the measurement system may use inertial navigation equipment or visual measurement to measure the attitude and orbit of the simulated satellite, and transmit the measurement to the GNC system through a communication system to form a closed loop.

In one embodiment, the satellite attitude and orbit control ground simulation system provided in the embodiment of the present application is a distributed simulation system, and each system included therein has its own clock, and there will inevitably be a certain offset between the clocks. Therefore, a time synchronization protocol is required between the systems to ensure the time synchronization of the entire simulation system. As shown in FIG2 , the time synchronization protocol includes: selecting the clock of any system as the master clock M, and the clocks of the other systems as the slave clocks S, taking the master clock M as the time, and synchronizing the clocks every preset synchronization period. is a time period, and the following steps are performed in each time period until the simulation ends:

S100 In the nth time period, the master clock M and the i-th slave clock S exchange messages through the communication system. According to the time when the master clock M sends the message and the time when the slave clock S receives the message, the delay from the master clock M to the slave clock S in the current time period is calculated. And the delay from clock S to master clock M ;

Specifically, as shown in FIG3 , in the nth time period, the process of the master clock M and the slave clock S sending messages to each other is as follows:

S101 master clock M sends a synchronization message to slave clock S and records the time when the message is sent ;

S102 receives the synchronization message from clock S and records the time of receiving the message ;

S103 master clock M will have The follow message of the information is sent to the slave clock S;

S104 sends a delay request message from the slave clock S to the master clock M and records the time when the message is sent. ;

S105 The master clock M receives the delay request message and records the time when the message is received ;

S106 Master Clock M will have The follow message of the information is sent to the slave clock S.

At this time, the following calculation is performed from the clock S end to obtain and :

S110 obtains the clock offset of the current time period through adaptive Kalman filtering from the clock end and propagation delay ;

Specifically, the state equation and observation equation required to implement the adaptive Kalman filter are as follows:

Among them, the state variable ; System matrix ; System noise ,in and are the system noises related to clock offset and propagation delay, respectively, which are considered to conform to normal distribution , is the system noise covariance matrix, where and are the system noise covariance matrices related to clock offset and propagation delay respectively; the observed variables ; Observation matrix ; Observation noise ,in, and Respectively and Correlated observation noise, which is assumed to be normally distributed , is the observation noise covariance matrix, where and Respectively and The associated observation noise covariance matrix. , , , It can be adjusted as appropriate according to the clock stability to achieve the best filtering effect of the Kalman filter.

The steps of adaptive Kalman filtering are as follows:

S1101 status prediction: ;

S1102 Covariance Prediction: ;

S1103 Innovation Covariance Calculation: ;

S1104 Kalman gain matrix calculation: ;

S1105 state optimal estimation: ;

S1106 Covariance Correction: ;

S1107 Calculation of normalized innovation square at the previous moment:

in is the filtered new information in the n-1th time period; is the normalized square of the new information in the n-1th time period;

S1108 reverse prediction of the previous moment state: ;

S1109 The reverse normalized square of the new information at the previous moment is calculated:

in is the reverse filtering information in the n-1th time period; is the reverse normalized square of the new information in the n-1th time period;

S1110 normalized innovation ratio:

like , then the filtering within this time period ends, and the estimated value in S1105 is the filter output; if , then recalculate the new information covariance :

Based on the recalculated innovation covariance , repeat S1104, S1105, S1106, and recalculate the Kalman gain matrix , optimal state estimation , Corrected covariance .

S120 storage clock offset and propagation delay In order to conduct subsequent system time synchronization analysis, according to the clock offset The clock frequency of the slave clock S is adjusted using a PI controller to achieve time synchronization;

Specifically, the time synchronization system between the master clock M and the slave clock S is shown in FIG4 , according to the delay from the master clock M to the slave clock S in the current time period And the delay from clock S to master clock M , obtain the clock offset of the current time period through adaptive Kalman filtering and propagation delay , and offset the clock and propagation delay Data storage; based on clock offset The PI controller is used to adjust the clock frequency of the slave clock S and perform core frequency locking, thereby achieving time synchronization between the master clock and the slave clock.

S130 determines whether all slave clocks S have completed time synchronization with the master clock M. If so, execute step S140. Otherwise, return to step S100 to perform time synchronization on the i +1th slave clock S.

S140 stores the data based on the master clock M and all slave clocks S. The maximum value is the maximum clock offset at the current time , with the propagation delay between the master clock M and all slave clocks S The maximum value of is the maximum propagation delay at the current moment , calculate the credibility of the communication system at the current moment.

Specifically, the credibility of the communication system at the current moment can be calculated by the following formula:

in is the credibility of the communication system at the current moment, is the factor related to clock offset, is the factor related to propagation delay.

As can be seen from the above, an embodiment of the present application provides a satellite attitude and orbit control ground simulation system, which is a distributed simulation system. A time synchronization protocol runs between each system, limiting the offset between the clocks of each system to a small range, thereby ensuring the overall time consistency of the ground simulation system; and the time synchronization protocol uses the original communication system of the ground simulation system and does not require additional hardware equipment.

Embodiment 2

The embodiment of the present application provides a credibility evaluation method based on consistency analysis, which is used to perform credibility evaluation on the satellite attitude and orbit control ground simulation system of any implementation method in Example 1. The credibility will be obtained in the form of an equally spaced time series to characterize the change of the trustworthiness of the system over time. As shown in FIG5 , the credibility evaluation method includes:

S200 constructs an evaluation index system for a satellite attitude and orbit control ground simulation system, wherein the evaluation index system includes a plurality of evaluation nodes for performing credibility evaluation and a unidirectional connection line for connecting the evaluation nodes;

Optionally, the evaluation index system also includes a number of backtracking nodes for finding credibility defects and a one-way connection line for connecting the evaluation node and the backtracking node or connecting each backtracking node. Each node represents an evaluation index time series that can measure the local credibility of the system. The evaluation index time series is an equally spaced time series like the credibility time series of the system, and the time interval of the two is the same. Let the time interval be the evaluation period Among them, the one-way connection line connects the lower-level node to the upper-level node. The type of the one-way connection line describes how to calculate the upper-level node index from the lower-level node index, including ordinary connection lines representing linear weighting, and backtracking connection lines between the backtracking node and the evaluation node or the backtracking node that only represent the upper-lower relationship.

In one embodiment, FIG6 is a schematic diagram of an evaluation index system model. In actual application, the model can be increased or decreased based on FIG6 according to the deviation in the actual simulation system structure. The following is a further explanation using the model as an example. In the figure, circles represent nodes, single arrows represent ordinary connecting lines, and hollow arrows represent backtracking connecting lines.

in, is the total credibility time series of the system; is the system attitude credibility time series; is the system position credibility time series; is the system interaction credibility time series. The system attitude and position credibility time series can be obtained through experiments and calculations. The system interaction credibility time series is basically not affected by the simulation time and is a constant series obtained in the form of expert scoring. The total credibility of the system can be directly calculated from the above three nodes, so the above three nodes and the root node are all evaluation nodes.

The remaining nodes are backtracking nodes: It is the credibility time series of the attitude dynamics full physical simulation system; Rotate the partial credibility time series for the motion system; is the credibility time series of attitude measurement system; It is the credibility time series of the orbital dynamics digital simulation system; is the partial credibility time series of the motion system translation; is the reliability time series of the position measurement system; is the communication system credibility time series; is the GNC system credibility time series; is the time series of overshoot of the rotating subsystem; is the time series of the rise time of the rotating subsystem; The time series for the stable time of the rotating subsystem; is the time series of overshoot of translation subsystem; is the time series of the rise time of the translation subsystem; is the stable time series of the translational subsystem.

S210 obtains a credible indicator sequence of a bottom evaluation node in an evaluation indicator system through EARTH (Enhanced Error Assessment of Response Time Histories) and an expert scoring method based on the simulated satellite current attitude and orbit information obtained by the satellite attitude and orbit control ground simulation system (also referred to as a ground simulation system);

Optionally, taking the evaluation index system in Figure 6 as an example, it is necessary to obtain the system's attitude credibility time series , location credibility time series Time series of system interaction credibility ;

In one embodiment, the system attitude credibility time series The evaluation method is as follows:

Apply the same input as the actual satellite system to the entire ground simulation system, and perform the evaluation every preset period in the pitch, yaw, and roll attitude outputs of the ground simulation system and the actual satellite system. Each intercept The verification method of EARTH is used to find the consistency of each output of the ground simulation system and the actual satellite system; for the consistency index of pitch, yaw and roll attitude at the same time, the maximum value is taken as the system attitude credibility at that time, and finally the system attitude credibility time series is obtained. .

System position credibility time series Find the method and Similarly, the X, Y, and Z output curves of the ground simulation system and the actual satellite system are used to obtain the consistency index and then obtain the final system position credibility time series. .

Assuming that the system interaction credibility is basically not affected by the simulation time, the system interaction credibility time series It is set as a constant sequence. Since its value is difficult to describe with quantitative indicators, the embodiment of the present application uses an expert scoring method to obtain it, and the scoring range is 0 to 1.

Optionally, as shown in FIG7 , the steps of obtaining the consistency between A and B using the EARTH method are as follows:

Assume A and B are the time series of the output of the actual satellite system and the ground simulation system respectively. A sequence The value of the moment, B sequence The value of the moment;

S211 uses the cross-correlation coefficient calculation formula to calculate the phase shift step number Phase Error ;

The calculation formula of the cross-correlation coefficient is as follows:

in is the number of moving steps, and N is the length of time series A and B.

Phase shift steps The calculation formula is as follows:

Here, argmax[…] means the size of the independent variable when the function value is maximum. It can be used to evaluate the phase difference between A and B sequences.

Since in most practical cases small phase shift steps are considered local errors, they do not need to be penalized on the consistency evaluation at the same rate as large phase shift steps.

So the phase error is set The calculation formula is as follows:

Among them, r is the growth rate and c is the starting point of the rise, which can be set according to actual problems and experience.

S212 moves A and B according to the phase shift step number and obtains the time series after the shift: , for time series Perform dynamic time warping (DTW) to minimize the impact of phase error and topological error on the time series, and use the vector norm to calculate the amplitude error ;

Specifically, move the B sequence in the direction of time growth Steps, and intercept the overlapping part of sequence A and sequence B after the move on the time axis, and record the time series after the move as For time series Perform dynamic time warping. The method of dynamic time warping is as follows:

Let the cost matrix d be The square matrix between the matrix and the number of rows and columns is The length of the sequence The elements in d It can be calculated by the following formula

in for sequence The value of the moment, for sequence The value of the moment, is the absolute value symbol, for time The time derivative of the series, for time The time derivative of a series.

Curved Path It is a set of ordered binary sequence number groups, defined as follows:

Curved Path The elements in are two-tuples , corresponds to a path from the lower left element to the upper right element of the d matrix, where For time series The sequence number of the element in For time series The sequence number of the element in For sequence In addition, the curved path The following three constraints need to be met:

(1) Boundary constraints

and Respectively represent the starting point and end point of the curved path, corresponding to the element number pairs in the lower left corner and upper right corner of the matrix d, so , .

(2) Continuity constraints

The curved path should be continuous, so the binary and are adjacent, satisfying: , .

(3) Monotonicity constraint

In order to ensure that the curved path is a one-way path from the lower left to the upper right, and Should meet: , .

The path that satisfies the above three constraints There are many. The embodiment of the present application selects a path that satisfies the following formula as the curved path of dynamic time bending: :

Let the two-tuple for The elements in , The time series after recording time distortion is , which is expressed as follows:

Amplitude error The calculation formula is as follows:

in Represents the L1 norm of the vector, which is the sum of the absolute values of the elements in the vector.

S213 time series after moving Taking the derivative at each point in the , and the derived sequence Perform dynamic time warping to obtain , using the vector norm to calculate the topological error ;

Specifically, the method of dynamic time warping is the same as that in step S212.

Topological Error The calculation formula is as follows:

in Represents the L1 norm of the vector, which is the sum of the absolute values of the elements in the vector.

S214 According to the phase error , Amplitude Error , topological error Obtaining an index to characterize the consistency of the curve .

in The consistency scores and curve phase errors of several pairs of output curves obtained in advance can be used. , Amplitude Error , topological error It can be obtained by fitting or directly taken out based on engineering experience.

S220 obtains the weight vectors between the evaluation nodes at different levels under the evaluation of different experts' importance through the AHP (Analytical Hierarchy Process) method, and fuses the weight vectors through the D-S (Dempster-Shafer's) evidence theory to obtain the fused weight vector;

Optionally, as shown in FIG8 , the steps of obtaining weights by the AHP method are as follows:

S221 compares the importance of lower-level nodes relative to their parent nodes in pairs, and constructs a judgment matrix J;

Where q is the total number of lower-level nodes, Represents the importance of the rth node and the sth node relative to the parent node. Its value is determined by experts according to Table 1 below and satisfies .

Table 1 The importance of the rth node and the sth node relative to the parent node

S222 calculates the weight vector according to the judgment matrix J;

Specifically, the judgment matrix J is normalized:

Sum the normalized matrix column by column:

After normalization, the weight vector W is obtained:

,

in is the symbol for matrix transpose.

S223 performs consistency check:

The weight vector W obtained in step S222 is essentially the eigenvector corresponding to the maximum eigenvalue of the judgment matrix J. The maximum eigenvalue of the judgment matrix J can be obtained based on W. :

in The vector after the A matrix is multiplied by the W vector. elements.

Can be based on Find the random consistency ratio :

in To judge the consistency index of the matrix, we can obtain it by looking up Table 2 according to the dimension of the judgment matrix J:

Table 2 Matrix consistency index

like <0.1 or is infinite, the judgment matrix J is consistent and the obtained weight vector W can be used directly. Otherwise, the judgment matrix J is inconsistent and needs to be adjusted until it is consistent.

In one embodiment, the method of D-S evidence theory fusion weights is as follows:

Assuming the The weight vector derived by experts , q is the total number of nodes in the lower layer (the dimension of the weight vector), and the fused weight can be calculated according to the following formula :

in is the total number of fused weight vectors.

S230 confirms the fuzzy membership function of the bottom evaluation node in the evaluation index system;

In one embodiment, let the comment set V = {untrustworthy, basically untrustworthy, less trustworthy, less trustworthy, generally untrustworthy, relatively trustworthy, trustworthy}, and the system attitude credibility time series As an example, the same membership function as shown in FIG9 can be constructed for all moments in the system attitude credibility time series.

S240 confirms the evaluation vector at each moment in the credible indicator sequence of the bottom evaluation node in the evaluation indicator system according to the fuzzy membership function;

In one implementation, the system attitude credibility time series is still used For example, if at the kth moment , then the evaluation results can be obtained by fuzzy set express:

It can also be written in vector form, namely the evaluation vector:

S250 uses the fuzzy comprehensive evaluation method to comprehensively calculate the overall credibility of the satellite attitude and orbit control ground simulation system from bottom to top based on the evaluation vector at each moment and the weight vector after fusion between the evaluation nodes at each layer.

In one implementation, the evaluation vector of the upper layer node at each moment can be calculated based on the weight vector between the upper and lower layers and the evaluation vector of the lower layer node at each moment, and the calculation formula is as follows:

in is the evaluation vector of the upper node index at the kth moment, is the weight vector between the upper and lower layers, is the comprehensive evaluation matrix at the kth moment, which is composed of the evaluation vectors of each node in the lower layer at the kth moment:

in For the lower level The evaluation vector of each node, is the total number of lower-level nodes.

“ The symbol is defined as:

in For vector Middle elements, For vector Middle elements, For the matrix Middle Line The elements of the column, To obtain the maximum value symbol, The symbol for taking the smaller value.

Calculated from bottom to top, the total credibility of the ground simulation system is also an evaluation vector, and a definite credibility index can be obtained by using the maximum membership method.

For example: The total credibility evaluation vector of the ground simulation system at the kth moment is , the corresponding credibility evaluation is relatively credible. If the comment set V is quantified, untrustworthy, basically untrustworthy, relatively untrustworthy, not very credible, generally untrustworthy, relatively credible, and credible correspond to 0.1, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.9 respectively, and the total credibility of the ground simulation system at the kth moment is 0.7.

Optionally, after using the fuzzy comprehensive evaluation method to comprehensively calculate the total credibility of the satellite attitude and orbit control ground simulation system from bottom to top, the method further includes: if the total credibility at a certain moment does not meet the preset conditions (such as the credibility is poorly evaluated), then the credibility index value of the bottom-level backtracking node under the evaluation node whose credibility does not meet the preset conditions at the current moment is calculated, and whether the bottom-level backtracking node is the source of the credibility defect is determined according to the credibility index. If the node credibility is low, the node is considered to be the source of the credibility defect.

In one embodiment, the credibility time series of the attitude dynamics full physics simulation system and orbital dynamics digital simulation system credibility time series and system attitude credibility time series and system position credibility time series The method for obtaining is similar, but it is only performed on subsystems.

Since the measurement system and the GNC system are usually the same as the actual satellite or even part of the actual satellite, their credibility sequences can be set to a constant sequence with a value of 1.

Communication system credibility time series , which can be calculated in real time by the time synchronization part. Transformed. Usually the evaluation cycle Generally longer than the synchronization period , the synchronization cycle needs to be The credibility sequence of Transformed into evaluation cycle Communication system credibility time series under , the specific method is as follows:

in, is the set of synchronization cycle moments contained in the kth evaluation cycle moment, k is the moment sequence number of the evaluation cycle, and n is the moment sequence number of the synchronization cycle.

As can be seen from the above, the credibility assessment method provided in the embodiment of the present application is used to conduct credibility assessment on the satellite attitude and orbit control ground simulation system provided in Example 1. The credibility finally obtained is a time series related to the simulation time, which can effectively solve the problem that the credibility of the ground simulation system in short-term and long-term simulation experiments is greatly different due to factors such as error accumulation and orbital perturbation, and a single credibility value cannot accurately express this feature. The use of D-S evidence theory to fuse weight vectors can reduce the influence of expert subjective factors on credibility assessment. Using the EARTH system verification method, the consistency of the dynamic indicators of the simulation system can be comprehensively evaluated from three aspects: phase, amplitude, and topology, and the credibility of the control ground simulation system can be quantitatively evaluated more accurately. Using an evaluation index system including evaluation nodes and backtracking nodes, in addition to the function of evaluating the overall credibility of the simulation system, it can also find the source of credibility defects through backtracking nodes when the overall credibility is not ideal.

Embodiment 3

The embodiment of the present application provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the memory is used to store software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory and the processor are connected via a bus. Specifically, the processor implements any step in the above-mentioned embodiment 2 by running the computer program stored in the memory.

It should be understood that in the embodiments of the present application, the processor may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

The memory may include a read-only memory, a flash memory, and a random access memory, and provides instructions and data to the processor. A part or all of the memory may also include a nonvolatile random access memory.

It should be understood that if the above-mentioned integrated module/unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The above-mentioned computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the above-mentioned computer program includes computer program code, and the above-mentioned computer program code can be in source code form, object code form, executable file or some intermediate form. The above-mentioned computer-readable medium may include: any entity or device capable of carrying the above-mentioned computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the above-mentioned computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the above-mentioned device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

It should be noted that the methods and detailed examples provided in the above embodiments can be combined with the devices and equipment provided in the embodiments, and references can be made to each other, and no further details will be given.

Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims (9)

1. A satellite attitude and orbit control ground simulation system, comprising:

The system comprises a GNC system, a dynamics simulation system, a motion system, a measurement system and a communication system;

the communication system is respectively connected with the GNC system, the dynamics simulation system, the motion system and the measurement system and is used for realizing information transmission among the systems;

the GNC system is used for obtaining control instructions according to the current attitude and orbit information of the simulated satellite output by the measurement system and the attitude and orbit information given by the outside and transmitting the control instructions to the dynamics simulation system;

the dynamics simulation system is used for obtaining attitude information and orbit information of the simulated satellite through physical experiments or mathematical simulations according to the control instruction and transmitting the attitude information and orbit information to the motion system;

the motion system is used for bearing the simulated satellite and controlling the simulated satellite to move according to the attitude information and the orbit information output by the dynamics simulation system;

the measurement system is used for measuring the current gesture and orbit of the simulated satellite, obtaining the current gesture orbit information of the simulated satellite and transmitting the current gesture orbit information to the GNC system;

the GNC system, the dynamics simulation system, the motion system and the measurement system are provided with respective clocks, and the synchronization protocols are operated among the systems based on the communication system so as to ensure the synchronism of different clocks;

The time synchronization protocol includes: selecting a clock of any system as a master clock, selecting clocks of other systems as slave clocks, taking the master clock time as a reference, taking every preset synchronous period as a time period, and executing the following steps in each time period until the simulation is finished:

s100, in an nth time period, the master clock and one of the slave clocks mutually send messages through a communication system, and according to the time when the master clock sends the messages and the time when the slave clock receives the messages, the delay from the master clock to the slave clock and the delay from the slave clock to the master clock in the current time period are calculated;

s110, clock offset and propagation delay of the current time period are obtained from a clock end through self-adaptive Kalman filtering;

s120, adjusting the clock frequency of the slave clock by using a PI controller according to the clock offset so as to achieve time synchronization;

s130, judging whether all slave clocks and the master clock finish one time of time synchronization, if so, executing a step S140, otherwise, returning to the step S100;

and S140, calculating the reliability of the communication system at the current moment by taking the maximum value of the clock offset of the master clock and all the slave clocks as the maximum clock offset at the current moment and taking the maximum value of the propagation delay of the master clock and all the slave clocks as the maximum propagation delay at the current moment.

2. The satellite attitude and orbit control ground simulation system according to claim 1, wherein the dynamics simulation system is a digital simulation system or a semi-physical simulation system or an all-physical system;

the dynamics simulation system includes: a gesture dynamics simulation system for obtaining the gesture information, and an orbit dynamics simulation system for obtaining the orbit information.

3. A reliability evaluation method for performing reliability evaluation on the satellite attitude and orbit control ground simulation system according to claim 1 or 2, comprising:

constructing an evaluation index system of the satellite attitude and orbit control ground simulation system, wherein the evaluation index system comprises a plurality of evaluation nodes for reliability evaluation and unidirectional connecting lines for connecting the evaluation nodes;

based on the current attitude and orbit information of the simulated satellite obtained by the satellite attitude and orbit control ground simulation system, a trusted index sequence of a bottom layer evaluation node in an evaluation index system is obtained through an EARTH and expert scoring method;

acquiring weight vectors of each layer of the evaluation node under the evaluation of different expert importance degrees by an AHP method, and fusing the weight vectors by a D-S evidence theory to obtain fused weight vectors;

Confirming a fuzzy membership function of a bottom layer evaluation node in an evaluation index system;

confirming evaluation vectors at all moments in a trusted index sequence of a bottom layer evaluation node in an evaluation index system according to the fuzzy membership function;

and comprehensively calculating the total credibility of the satellite attitude and orbit control ground simulation system from bottom to top by using a fuzzy comprehensive evaluation method according to the evaluation vectors at each moment and the weight vectors fused among all layers of the evaluation nodes.

4. The method of claim 3, wherein the evaluation index system further comprises a plurality of trace-back nodes for finding reliability defects and unidirectional connection lines for connecting the evaluation nodes and the trace-back nodes or each trace-back node;

the method for comprehensively calculating the total credibility of the satellite attitude and orbit control ground simulation system from bottom to top by using the fuzzy comprehensive evaluation method further comprises the following steps:

if the total reliability at a certain moment does not reach the preset condition, calculating the reliability index value of the bottom layer backtracking node under the evaluation node of which the reliability at the current moment does not reach the preset condition, and judging whether the bottom layer backtracking node is the source of the reliability defect according to the reliability index.

5. The method for evaluating the reliability according to claim 3 or 4, wherein the reliability index sequence of the bottom-level evaluating node comprises a posture reliability time sequence, a position reliability time sequence and a system interaction reliability time sequence;

The obtaining the trusted index sequence of the bottom layer evaluation node in the evaluation index system comprises the following steps:

applying the same input as the actual satellite system to the satellite attitude and orbit control ground simulation system, acquiring the outputs of the satellite attitude and orbit control ground simulation system and the actual satellite system every other preset evaluation period, obtaining consistency of each output of the satellite attitude and orbit control ground simulation system and the actual satellite system by an EARTH method, obtaining consistency indexes, and obtaining an attitude credibility time sequence and a position credibility time sequence according to each consistency index;

and obtaining a system interaction credibility time sequence by an expert scoring method.

6. The method of claim 5, wherein said obtaining consistency for each output of the satellite attitude and orbit control ground simulation system and the actual satellite system by the EARTH method and obtaining a consistency index comprises:

a, B is set to be the time sequence of the output of the actual satellite system and the satellite attitude and orbit control ground simulation system, and the phase error between the phase shift step number and A, B is calculated by using a calculation formula of the cross correlation coefficient;

shifting A, B according to the phase shift step number and obtaining a shifted time sequence as Time seriesPerforming dynamic time warping and calculating to obtain an amplitude error;

time series after movementThe derivative of each point in (2) gives the sequence +.>And deriving the sequence +.>Performing dynamic time warping and calculating to obtain a topology error;

and (5) obtaining a consistency index representing the consistency of the curve according to the phase error, the amplitude error and the topology error.

7. The method for evaluating the credibility of claim 3 or 4, wherein the obtaining the weight vector between layers of the evaluation node under the evaluation of different expert importance levels by using the AHP method comprises:

comparing importance of child nodes relative to father nodes in pairs, and constructing a judgment matrix;

calculating a weight vector according to the judgment matrix;

and obtaining a random consistency ratio according to the weight vector, judging whether the random consistency ratio is smaller than 0.1 or infinite, if so, judging that the matrix is consistent, wherein the weight vector is available, otherwise, judging that the matrix is inconsistent, and adjusting the judging matrix until the weight vector is consistent.

8. An electronic device, comprising: memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of claims 3 to 7 when the computer program is executed.

9. A computer readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the steps of the method according to any one of claims 3 to 7.