DO385-based ACAS X parameter data item file operation method
The parameter data item files in the ACAS X system are parsed and assigned through data slice method, which solves the problem of undisclosed file operation methods, ensures the security and integrity of the file, and improves the functional effectiveness of the system and aviation flight. Safety.
Patent Information
- Application Number
- CN202411338234.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2024-12-31
AI Technical Summary
In the existing ACAS X system, the operation, analysis and use methods of the five parameter data items specified in DO385 have not been disclosed, which makes it difficult to ensure the correct application and safety of the files, which affects the functional effectiveness of the system and the safety of aviation flight.
The binary file is divided, parsed and assigned layer by layer by layer through the classification of auxiliary fields and target fields, and multiple verifications such as MD5 verification ensure the integrity and correctness of the file, so as to realize the reading, parsing and reading of the file and Assign values to form a data structure that complies with the DO385 standard.
It realizes the accurate and reliable operation of parameter data item files in ACAS X system, ensures the availability and integrity of the files, and supports the implementation of the system's anti-collision function and aviation flight safety.
Smart Images
Figure CN119226031A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of a new generation collision avoidance system ACAS X, and more specifically, to an ACASX parameter data item file operation method based on DO385. Background Art
[0002] Aviation flight safety is an eternal theme in the aviation industry. With the continuous growth of global military and civil aviation traffic, the number and density of aircraft in the airspace continue to increase, and the potential risk of mid-air collision accidents also increases. Therefore, it is urgent to improve the existing air situation awareness and collision avoidance capabilities of aircraft. The mandatory installation of the air traffic warning and collision avoidance system TCAS worldwide has been proven to be the last barrier and the most effective means to solve mid-air collision accidents after long-term application. The current collision avoidance system mainly uses TCAS II. The collision avoidance logic unit of TCAS II has complex heuristic rules and a series of processes. It is extremely difficult to upgrade and improve the design, with a long verification cycle and high cost. It cannot adapt to the ever-changing modern flight environment and challenges. It is not suitable for specific flight scenarios and diverse aircraft such as drones. At the same time, there is a false alarm problem that pilots widely complain about.
[0003] To address the drawbacks and shortcomings of the TCAS II system, the International Civil Aviation Organization (ICAO) and the Federal Aviation Administration (FAA) of the United States have developed a new generation of airborne collision avoidance system ACAS X. Its collision avoidance unit models the scenario of aircraft mid-air collision encounters as a Markov decision process, uses a dynamic programming-based method to solve the model, and generates a series of collision avoidance logic tables. Based on these logic tables, the TCAS II rule-based heuristic collision avoidance logic is converted into a digital table lookup logic based on probability and cost values, and the optimal collision avoidance decision recommendation is selected based on the cost value. The international general standard DO385 standardizes the above collision avoidance logic table and publishes five parameter data item files as normative annexes of the standard for the design and development of ACAS X. The five parameter data item files specified in Appendix F.1 of DO385 are detailed in Table 1.
[0004] Table 1 Basic information table of parameter data item file Serial number File name illustrate Size / Bytes 1 DO-385_q_31ec_minBlocks.dat Minimum data block index table 3216534 2 DO-385_q_31ec_allSplits.dat Equivalency Class Cost Table 25972792 3 DO-385_entry_horiz.dat Horizontal collision avoidance cost table 9027555 4 DO-385_entry_horiz_active_cspo3k.dat Active Monitoring Horizontal Collision Avoidance Cost Table 9252915 5 DO-385_entry_vert.dat Vertical collision avoidance cost table 1315690
[0005] The size of the five parameter data item files in Table 1 ranges from several megabytes to tens of megabytes. The International Civil Aviation Organization (ICAO) uses them as normative annex to general technical standards and forces equipment manufacturers to use them.
[0006] DO385 stipulates that ACAS X includes a surveillance and tracking module and a traffic decision module. The former realizes the surveillance and tracking of moving targets in the airspace; the latter provides collision avoidance suggestions. The specific implementation is based on a large-scale global parameter structure specified in the standard. This structure defines a series of parameters necessary for the realization of system functions. In terms of assignment method, the members of the global parameter structure are divided into two categories. The first category is directly defined parameters, which are parameters directly assigned according to the parameter name and parameter value specified in the standard; the second category is file definition parameters, which obtain the parameter value of the specific data structure by reading, parsing and assigning values to the 5 parameter data item files.
[0007] These parameter data item files are all binary data. The specific information of the file cannot be directly observed, and it is even more impossible to define it by direct assignment. Before use, it must first be read, decoded, and other operations must be performed, and necessary verification methods must be used to ensure that the file operation is safe and reliable. Common verification methods include MD5 algorithm, checksum algorithm, etc. Among them, MD5 (Message Digest Algorithm 5) verification is a commonly used data verification method and a summary algorithm. The principle is to generate a fixed-length summary value by performing MD5 algorithm operation on the data to be verified. Taking the communication system as an example, the method of use is that the sender transmits the summary value as the verification value together with the original data, and the receiver performs MD5 algorithm operation on the original data again to obtain the summary value, and then compares it with the received verification value. If the two summary values are equal, it means that the data integrity has not been destroyed, thereby verifying the integrity of the data and preventing the data from being tampered with or damaged during transmission or use.
[0008] The technical problem in the development of ACAS X is that DO385, as the minimum operating performance standard for the new generation of airborne collision avoidance system ACAS X, does not disclose the specific methods of operating, parsing and using the five parameter data item files. In addition, there is no public report on the relevant technology based on the existing technical information and literature published at home and abroad.
[0009] In summary, ACAS X involves aviation flight safety and is a safety-critical device for aviation flight. The safety and effectiveness of its functions are based on the correct application of five parameter data item files. Therefore, a complete and effective file operation method is urgently needed to read, parse and use the files through software operation, so as to realize the correct and effective assignment of the ACAS X global parameter structure and support the realization of the complete collision avoidance function. Summary of the invention
[0010] In view of the shortcomings of the prior art, the present invention discloses an ACAS X parameter data item file operation method based on DO385. The method can accurately and reliably operate five parameter data item files, realize file reading, verification, parsing and assignment, and ensure the availability and integrity of file information through verification and file recovery measures. The method can provide technical support for the design and development of ACAS X engineering equipment.
[0011] The technical solution design of the present invention complies with the following basic prerequisites: 1) The parameter data item file format is "binary 01 sequence" and cannot be directly observed and used; 2) The binary data structure in the file is clear, with a unified and clear structure and arrangement order; 3) The data type of the target field that needs to be decoded and converted is clear and fixed; 4) DO385 does not provide data parsing methods or specific usage of data fields; 5) The parameter data item file is a normative annex. DO385 requires accurate, complete and safe use, and is the basis for the ACAS X system collision avoidance warning.
[0012] Based on the above prerequisites, the design ideas and principles of this solution are: 1) From the beginning to the end of the file, the sequence is segmented, parsed, and assigned values layer by layer using a data slicing method; 2) Make full use of the field information of the binary file itself and classify it into auxiliary fields and target fields according to the field content. The former is used for "data slicing" of the file to determine the data type and length to locate the data field or for verification; the latter is converted into the data structure specified by DO385; 3) Functional requirements: The parsed data can be used for ACAS X design and integration; multiple verifications are performed to ensure that the parsed files are correct and complete, and that the parsing process is correct and effective; 4) The input is a file of parameter data items. No matter what programming language is used, the file should be opened and read first to obtain a specific data type, including but not limited to array or pointer; 5) The output is in the data structure format specified by DO385.
[0013] This solution analyzes the data fields provided by the standard and classifies them, including auxiliary fields and target fields, and proposes their specific uses. See Table 2 Parameter Data Item File Parsing Information Table.
[0014] Table 2 Parameter data item file parsing information table Primitive Types Data field name Conversion Type Field Description Field usage Binary Data magic_number Integer Magic Word Auxiliary field, used for verification Binary Data file_type String File Type Auxiliary field, used for verification Binary Data auxiliary_data_size Integer Number of bytes in the auxiliary field Auxiliary fields, used for positioning Binary Data dimension_count Integer Number of data categories Auxiliary fields, used for positioning Binary Data cut_counts Integer array Bytes per category Target field, parsing assignment Binary Data cuts_names String Array Quantity Category Name Target field, parsing assignment Binary Data cuts Double precision floating point array Each category data value Target field, parsing assignment Binary Data index_type String Index Type Auxiliary field, used for verification Binary Data data_type String Data Types Auxiliary field, used for verification Binary Data count_included String Include count value flag Auxiliary fields, used for positioning Binary Data maximum_block_elements Integer Block data quantity Auxiliary fields, used for positioning Binary Data index_element_count Integer Number of indexes Auxiliary field, used for verification Binary Data data_element_count Integer Cost data quantity Auxiliary field, used for verification Binary Data index Integer array Indexing Data Target field, parsing assignment Binary Data data Half-precision floating point array Cost data value Target field, parsing assignment According to the information provided in Table 2, the ACAS X parameter data item file operation method based on DO385 disclosed in the present invention includes the following steps: S1: Open and read the parameter data item file, obtain the file data to be operated, and enter S2; S2: According to the order of the file data to be operated from front to back, based on the DO385 parameter data item file structure and the classification of auxiliary fields and target fields, the file information is intercepted and decoded from the beginning to the end of the data, which specifically includes the following sub-steps: S21: Setting the start and end flags of the current information field to be decoded; S22: based on the file data obtained in step S1, extracting a data segment from the start mark to the end mark; S23: Convert the intercepted data fragment into a corresponding data type. If the field is an auxiliary field, locate the following data according to its information, or use it for file integrity verification; if the field is a target field, assign it to the data structure specified by DO385; S24: Execute S21 to S23 in a loop until the operation of the entire file content is completed and enter S3; S3: Check the integrity of the file, including the following steps: S31: Check the MD5 check value of the parameter data item file. If the check is passed, go to S32. Otherwise, set the check failure flag to true and go to S32. S32: Check the size of the parameter data item file. If the check is successful, proceed to S33. Otherwise, set the check failure flag to true and proceed to S33. S33: Check the correctness of the auxiliary fields in the parameter data item file. If the check is passed, the data structure specified by DO385 is returned and the process ends. Otherwise, the check failure flag is set to true and the process goes to S4. S4: Determine whether the file needs to be restored. If so, replace the current file as a whole with the backup file, then return to S1 to reparse the file. If not, report an error and end.
[0015] Furthermore, in step S32, the method for checking the size of the parameter data item is: according to Table 1, check whether the number of file bytes specified by DO385 is equal to the number of file data bytes to be operated obtained in step S1. If they are equal, the check passes, otherwise the check fails.
[0016] Furthermore, in step S33, the auxiliary fields to be checked include: magic_number, file_type, index_type, data_type; the checking method is: (1) Check that magic_number is the decimal number 1634; (2) Check that file_type is the string "fixedblockdictionary" or "varblockdictionary"; (3) Check that index_type is the string "space uint32"; (4) Check that data_type is the string "space half"; If (1), (2), (3), and (4) are all met, the inspection is passed; otherwise, the inspection is failed.
[0017] Furthermore, the method for determining whether the file needs to be restored in step S4 is: if the file check failure flag is true and the file has no history of restoration operations, then the file needs to be restored; otherwise, the file does not need to be restored.
[0018] The technical effect of the present invention is as follows: the file operation method disclosed in the present invention can solve the shortcomings and defects of the current technology. ACAS X can conveniently and reliably complete the assignment of the file definition part of the global parameter structure required for the operation of ACAS X software through this method. Moreover, this method ensures the correctness of the parameter data item file itself and the correctness of the file operation process through multiple verification. Based on this method, ACAS X can realize anti-collision logic table lookup, and finally provide efficient and accurate air collision threat detection and anti-collision maneuvering flight suggestions; the technical solution of the present invention can be applied to the field of air traffic anti-collision technology, and provide strong support for the development of ACAS X equipment, a new generation of anti-collision system in my country. Scientific research and engineering technicians in this field can conveniently and quickly realize parameter data item file operation based on this method, so that they can focus more on the engineering design, system integration and verification of the equipment, improve the quality of research and development, shorten the development cycle, and through the installation and application of ACAS X equipment on Chinese aircraft, the upgrading of existing TCAS II equipment can greatly improve the flight safety and use efficiency of my country's national airspace. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0020] Attached Figure 1 It is a schematic diagram of the software module design of the present invention.
[0021] Attached Figure 2 It is a file operation flow chart of the present invention. DETAILED DESCRIPTION
[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples.
[0023] This embodiment provides an ACAS X parameter data item file operation method based on DO385. Figure 1 As shown in the software module design diagram, the ACAS X software includes four modules: interface module, global parameter structure definition module, traffic decision module, and surveillance and tracking module. The technical solution of the present invention is located in the global structure parameter definition module during software design. The purpose of the embodiment is to provide a global parameter structure definition that complies with the DO385 standard for the ACAS X surveillance and tracking module and the threat decision module, and the implemented function is located in the file parsing definition part in the global parameter structure definition module.
[0024] During implementation, when designing the global structure definition module, firstly, based on the requirements of Appendix F of DO385, the directly defined parameters are defined and assigned. The standard has clear provisions, which will not be repeated here. According to the ACAS X parameter data item file operation method based on the DO385 standard disclosed in the present invention, the variables in the file definition part are assigned. According to the provisions of DO385, these variables are in the form of structures, including 5 in total, corresponding to the five parameter data item files introduced in the background technology of the specification. The task of the embodiment is to convert the files in Table 2 into corresponding structure variables one by one. The corresponding relationship is shown in Table 3.
[0025] Table 3 Correspondence between structure variables and files Serial number Structure variable name Corresponding file name 1 horizontal_table_content DO-385_entry_horiz.dat 2 horizontal_active_table_content DO-385_entry_horiz_active_cspo3k.dat 3 vertical_table_content DO-385_entry_horiz.dat 4 minblocks_table_content DO-385_q_31ec_minBlocks.dat 5 equiv_class_table_content DO-385_q_31ec_allSplits.dat
[0026] Furthermore, the data structures of the five structural variables in Table 2 are the same, and their data member definitions are detailed in Table 4.
[0027] Table 4 Data structure variable member definition Serial number Structure member name Type and description 1 cut_names String array, the data name of each dimension 2 cut_counts Integer array, number of splits for each dimension 3 cuts Floating point array, split point value for each dimension 4 index Integer array, table index 5 data Half-precision floating-point array, data table specific data values
[0028] The binary data in Table 2 is converted into the data structure specified in Table 4 by the method provided by the present invention. Figure 2 , the specific implementation steps of file operations include: S1: Open and read the parameter data item file, obtain the file data to be operated, and enter S2; S2: According to the order of the file data to be operated from front to back, based on the DO385 parameter data item file structure and the classification of auxiliary fields and target fields, the file information is intercepted and decoded from the beginning to the end of the data, which specifically includes the following sub-steps: S21: Setting the start and end flags of the current information field to be decoded; S22: based on the file data obtained in step S1, extracting a data segment from the start mark to the end mark; S23: Convert the intercepted data fragment into a corresponding data type. If the field is an auxiliary field, locate the following data according to its information, or use it for file integrity verification; if the field is a target field, assign it to the data structure specified by DO385; S24: Execute S21 to S23 in a loop until the operation of the entire file content is completed and enter S3.
[0029] To more clearly illustrate the operation method of the present invention, file operations are performed according to the information provided in Table 2, wherein the first field starts from the first byte, the starting position of other fields is "the end position of the previous field + 1", and the end position is "the end position of the previous field + the length of this field", and the field length is in bytes. The following is an example of the above steps combined with specific data fields: The first field is magic_number, which is an integer with a length of 4 bytes, a starting position of 1, and an ending position of 4. After converting it to an integer, the information of this field is obtained. This is an auxiliary field used for data verification, and its value should be decimal "1634"; The second field "file_type" is of character type, with the format of space + character itself, length 21 or 19, starting position 5, and ending position 25 or 23. It is converted into a string for data verification, and its content should be "fixedblockdictionary" or "varblockdictionary". The third field is "auxiliary_data_size", an integer auxiliary field with a length of 4 bytes, a start position of 26 or 24, and an end position of 29 or 27; The fourth field is "dimension_count", an integer auxiliary field with a length of 4 bytes, starting at "the end value of the previous field + 1" and ending at "the end position of the previous field + 4"; The fifth field is "cut_counts", integer array, auxiliary field, the length of the array = dimension_count, the start position of the Nth member of the array (N=1,2...dimension_count) is "the end value of the previous field or member + 1", and the end position is "the end value of the previous field or member + 4*N"; According to the above method, parse each field one by one. For example, the 7th field "cuts", the target field, the double-precision floating-point array, the starting position of the Mth member of the array (M=1,2...SUM[cut_counts]) is "the end value of the previous field or member + 1", and the end position is "the end value of the previous field or member + 8*M"; intercept the cuts member according to the starting and ending positions and convert it into double-precision floating-point data, and assign it to the member cuts of the data structure in Table 3 in sequence.
[0030] The technicians in this professional field can complete the parsing and assignment of data content item by item according to the method disclosed in the present invention, and can realize the reading, parsing and assignment operations of parameter data item files without paying any creative labor.
[0031] Enter S3: Check the integrity of the file, including the following steps: S31: Check the MD5 check value of the parameter data item file. The checking method is to obtain a check value by executing the MD5 algorithm on the parameter data item file, and compare it with the MD5 value provided by DO385. If they are equal, the check passes, otherwise it fails. If the check passes, enter S32, otherwise set the check failure flag to true and enter S4; S32: Check the size of the parameter data item file. If the check is successful, proceed to S33. Otherwise, set the check failure flag to true and proceed to S4. S33: Check the correctness of the auxiliary fields in the parameter data item file. If the check passes, return to the data structure specified by DO385 (the member definition of the structure is shown in Table 3) and end. Otherwise, set the check failure flag to true; enter S4.
[0032] S4: Determine whether the file needs to be restored. If so, replace the current file as a whole with the backup file, then return to S1 to reparse the file. If not, report an error and end.
[0033] The method of checking the size of the parameter data item in step S32 is: checking whether the number of file bytes specified by DO385 (see Table 1) is equal to the number of bytes of the file data to be operated obtained in step S1. If they are equal, the check passes, otherwise the check fails.
[0034] In step S33, the auxiliary fields to be checked include: magic_number, file_type, index_type, data_type. The criteria for passing the check are: magic_number is the decimal number 1634, file_type is the string "fixedblockdictionary" or "varblockdictionary", index_type is the string "space uint32", data_type is the string "space half", if all of the above are met, the check is passed, otherwise the check is failed.
[0035] In step S4, the criterion for determining whether the file needs to be restored is: the file check failure flag is true, and the file has no history record of being restored.
[0036] The data entry file is parsed according to the embodiment. Taking the DO-385_entry_horiz.dat file as an example, after parsing, it is stored as a structure variable named horizontal_table_content, where the data member information is shown in Table 5.
[0037] Table 5 Parameter data item file data member information Variable Name type Variable value (partial) cut_names String array, length 3 "rho", "drho", "dtheta" cut_counts Integer array, length 3 137、89、37 cuts Floating point array, length 263 0.0、500.0、1000.0… index Integer array, length 451142 0、40、80… data Single-precision floating-point array, length 3610400 0.0、0.4539、0.002058…
Claims
1. ACAS X parameter data item file operation method based on DO385, characterized in that: The field content of the parameter data item file provided by DO385 is divided into auxiliary fields and target fields. The former is used for data auxiliary positioning or verification, and the latter is used to assign values to the data structure specified by DO385 after data parsing to implement file parsing operations. The following steps are involved: S1: Open and read the parameter data item file, obtain the file data to be operated, and enter S2; S2: According to the order of the file data to be operated from front to back, based on the DO385 parameter data item file structure and the classification of auxiliary fields and target fields, the file information is intercepted and decoded from the beginning to the end of the data, which specifically includes the following sub-steps: S21: Setting the start and end flags of the current information field to be decoded; S22: based on the file data obtained in step S1, extracting a data segment from the start mark to the end mark; S23: Convert the intercepted data fragment into a corresponding data type. If the field is an auxiliary field, locate the following data according to its information, or use it for file integrity verification; if the field is a target field, assign it to the data structure specified by DO385; S24: Execute S21 to S23 in a loop until the operation of the entire file content is completed and enter S3; S3: Check the integrity of the file, including the following steps: S31: Check the MD5 check value of the parameter data item file. If the check is passed, go to S32. Otherwise, set the check failure flag to true and go to S32. S32: Check the size of the parameter data item file. If the check is successful, proceed to S33. Otherwise, set the check failure flag to true and proceed to S33. S33: Check the correctness of the auxiliary fields in the parameter data item file. If the check is passed, the data structure specified by DO385 is returned and the process ends. Otherwise, the check failure flag is set to true and the process goes to S4. S4: Determine whether the file needs to be restored. If so, replace the current file as a whole with the backup file, then return to S1 to reparse the file. If not, report an error and end.
2. The method according to claim 1, characterized in that In the step S32, the size of the parameter data item file is checked, and if the check passes, the process proceeds to S33, otherwise, the check failure flag is set to true; the specific method for checking the size of the parameter data item file is as follows: Check whether the number of file bytes specified by DO385 is equal to the number of bytes of the file data to be operated obtained in step S1. If they are equal, the check passes; otherwise, the check fails.
3. The method according to claim 1, characterized in that In step S33, the auxiliary fields to be checked include: magic_number, file_type, index_type, data_type; the checking method is: (1) Check that magic_number is the decimal number 1634; (2) Check that file_type is the string "fixedblockdictionary" or "varblockdictionary"; (3) Check that index_type is the string "space uint32"; (4) Check that data_type is the string "space half"; If (1), (2), (3), and (4) are all met, the inspection is passed; otherwise, the inspection is failed.
4. The method according to claim 1, characterized in that: In the step S4, it is determined whether the file needs to be restored. If it needs to be restored, the current file is replaced as a whole by the backup file, and then the process returns to S1 to reparse the file. If it does not need to be restored, an error is reported and the process ends. The method for determining whether the file needs to be restored is: If the file check failure flag is true and the file has no history of recovery operations, the file needs to be restored; otherwise, the file does not need to be restored.