ACAS X test case input file operation method based on DO385

Abstract

The invention belongs to the technical field of ACAS X, a new generation collision avoidance system, and discloses an ACAS X test case input file operation method based on DO385. The method implements file operation according to the test start time, test end time, data item start index, and data item end index of the test scenario input file, and performs data parsing and processing according to the nominal operation cycle of the airborne collision avoidance system of 1 second as a period, correctly and reliably implements the operation of the test scenario input file, and can identify the test scenario with 1 second or more seconds of data missing for targeted processing, meets the requirements of DO385, the minimum operation performance standard of the new generation collision avoidance system, provides a data source for the operation and test of the ACAS X core algorithm, can support the development of the new generation collision avoidance system, and its application can improve the flight safety and use efficiency of my country's national airspace.

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 test case input 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] In order to solve 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 rule-based heuristic collision avoidance logic of TCAS II is converted into a digital lookup table logic based on probability and cost value, and the optimal collision avoidance decision recommendation is selected based on the cost value. The international general standard DO385 is the minimum operating performance standard for the new generation of collision avoidance system ACAS X. The standard stipulates that the collision avoidance processing logic includes two core functions: the monitoring and tracking module and the traffic decision module. The former realizes the monitoring and tracking of airspace target aircraft and the aircraft, and the latter realizes collision threat detection and collision avoidance warning based on the output of the former, the lookup table method and the cost value; the standard also stipulates that after the collision avoidance logic design is implemented, it must be tested, and its operation input and output must comply with 7 groups of 422 test scenarios. Each test scenario includes 4 types of JSON files.

[0004] Here, JSON (JavaScript Object Notation) is a data exchange format file with the suffix .json, which is usually used to store and transmit structured data. JSON files represent objects and arrays in a simple text form, which is easy for humans to read and write, and easy for machines to parse and generate. The basic syntax of JSON files includes:

[0005] Object, surrounded by curly braces {}, key-value pairs separated by commas;

[0006] Array: surrounded by square brackets [], elements are separated by commas;

[0007] Data types: support strings, numbers, Boolean values, objects, arrays, and null;

[0008] In general, files with the suffix .json are an indispensable part of modern software development and are widely used in scenarios such as data transmission, storage, and configuration.

[0009] There are four types of files. Specifically, one type is the test scenario input file. The anti-collision logic needs to read and parse these files as input conditions for operation. The other three types are standardized test result output files output by the anti-collision logic. When the anti-collision logic reads and parses the input data according to the test scenario input file and runs to generate three types of output files, these three types of output files are compared with the output files provided as normative appendices of the standard. If they meet the tolerance requirements, the test scenario is considered to have passed the test, otherwise it is considered to have failed the test. The naming and content formats of each of the above four types of files are unified. The names and descriptions of the four types of files are detailed in Table 1.

[0010] Table 1 Test scenario file information table

[0011]

[0012] The four types of test scenario files in Table 1 are normative annexes of the general technical standard DO385 specified by the International Civil Aviation Organization (ICAO) and the Federal Aviation Administration (FAA) of the United States. They are mandatory for equipment manufacturers to use for standard compliance testing after the anti-collision logic is implemented.

[0013] In summary, after the collision avoidance logic design of the new generation collision avoidance system ACAS X is implemented, it must undergo standard compliance testing. The first step of the test is to operate the test scenario input file, including file reading and parsing. In addition, the file operation must be coupled with the operation of the subsequent ACAS X core algorithm - surveillance tracking module and threat decision module according to the nominal operation cycle of the collision avoidance logic of 1 second. At the same time, it must also be designed for the operation cycle where file data is missing to ensure that the output of these cycles can still meet the standard output requirements. The file operation is required to be carried out according to the structure of the test scenario input file EncounterXXXXAircraft1Input.json, and its data structure is shown in Table 2.

[0014] Table 2 Test scenario input file data structure

[0015]

[0016] The technical problem in the design and 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 provide specific operations and usage methods for test scenario output files. In addition, there are no public reports on related technologies from existing public technical data and literature at home and abroad. Therefore, during the equipment design and development process, designers must explore on their own to realize the reading, parsing and processing of test scenario input files to solve the current technical gap.

[0017] 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 various rigorous testing processes, including 422 test scenarios corresponding to the anti-collision logic design compliance test. Therefore, a complete and effective test scenario input file operation method is urgently needed to read, parse and use the file through software operation. This is the basis for realizing the operation of the 422 test scenarios of the ACAS X anti-collision logic. Summary of the invention

[0018] Aiming at the shortcomings of the prior art in the test scenario input file operation method, the present invention discloses an ACAS X test case input file operation method based on DO385. The method can accurately, completely and reliably operate 422 test scenario input files, realize file reading, parsing and processing, and can effectively connect and couple with the ACAS X monitoring and tracking module and the threat decision module.

[0019] The technical solution of the present invention is to implement file operations according to the test start time, test end time, data item start index and data item end index of the test scenario input file, and perform data parsing and processing according to the nominal operation cycle of the airborne collision avoidance system of 1 second; wherein the test start time comes from the "start_time" data value in the file header information, and the test end time comes from the arrival time toa data value of the last data item in the file; the data item start index is 1, and the data item end index is the total number of data items contained in the test scenario input file.

[0020] Further, during the file operation process, for each piece of data read, compare the relative magnitudes of the current processing cycle time Ti and the current data arrival time toa. When Ti < toa, it means that at time Ti, there is no prefabricated corresponding data. Therefore, it indicates that there is a data loss in the processing cycle where Ti is located. The processing method is to immediately jump out of the file scenario parsing operation of this processing cycle and enter the processing processes of the subsequent collision avoidance system's monitoring and tracking function and threat decision-making function. In this way, it is possible to automatically identify the situation where there is a data item loss of 1 second or more in the data file, so as to correctly perform file operations and subsequent processing in this case.

[0021] Further, the specific implementation of this method includes the following steps:

[0022] S1: Read the test scenario file and obtain the structured data inside the file;

[0023] S2: Assign values to the test start time, test end time, data item start index, and data item end index according to the structured data. The specific method is as follows:

[0024] S21: The test start time is the "start_time" data value of the "playback_header" sub-structure in the structured data in step S1;

[0025] S22: The test end time is the ceiling value of the "report_time" data value of the last piece of data in the "acasx_reports" structure array in the structured data in step S1;

[0026] S23: Initialize the data item start index to 1;

[0027] S24: The data item end index is the total number of data items in the structured data in step S1, which is equal to the length of the "acasx_reports" structure array in the structured data;

[0028] S3: The file operation includes the following two-layer loop. The first-layer loop is to perform data operations in integer seconds from the test start time to the test end time and record the current processing time Ti. The second-layer loop is to perform file operations according to the data item index within each second and record the current data arrival time toa;

[0029] S4: At each integer second moment, perform the processing of the collision avoidance system's monitoring and tracking function and threat decision-making function.

[0030] Technical effects of the present invention: The file operation method disclosed in the present invention can solve the shortcomings and defects of the current technology, correctly and reliably realize the operation of the test scene input file, and can identify the test scene file with 1 second or more seconds of data missing, meet the requirements of the minimum operating performance standard DO385 of the new generation collision avoidance system, and can provide a data source for the operation and test of the ACAS X core algorithm, support the development of the new generation collision avoidance system, and through the application of ACAS X, realize the upgrading of the current TCAS II equipment, which can improve the flight safety and utilization efficiency of my country's national airspace. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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.

[0032] Attached Figure 1 It is a schematic diagram of the position of the present invention in the ACAS X software development process.

[0033] Attached Figure 2 It is a design implementation flow chart of the present invention. DETAILED DESCRIPTION

[0034] 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.

[0035] Example:

[0036] This embodiment provides an implementation scheme of the method of the present invention. The design and implementation of this embodiment is based on the Julia programming language. It should be pointed out that without paying creative labor, technicians in this field can use other programming languages ​​to implement the method of the present invention.

[0037] When implemented, according to the method provided by the present invention, combined with the Julia language code, the detailed implementation steps are as follows:

[0038] S1: Read the test scenario file and obtain the structured data inside the file; this embodiment implements this function through the JSON file operation library function provided by Julia voice, and it is necessary to use "using JSON" in the program source file to declare the use of the library file; further, the specific steps are as follows, S11: enter the folder where the test case input file is located, the code line is as follows: cd("$root_path / TestSuiteDO385-encounters"), where $root_path is the root path, such as C: / , which means that the root path is the C drive; TestSuiteDO385-encounters is the specific folder where the test case input file is located; then enter S21: call the JSON library function to obtain the structured data of the dictionary type, the code is rEndata=JSON.parsefile(EncounterXXXXAircraft1Input.json), where readData is the returned dictionary type variable, JSON.parsefile is the interface function name, the parameter EncounterXXXXAircraft1Input.json is the JSON file name to be read, and XXXX is the four-digit file number;

[0039] Enter S2: According to the structured data, assign values ​​to the test start time, test end time, data item start index, and data item end index. The specific method is as follows:

[0040] S21: The test start time is the data value of "start_time" of the "playback_header" substructure of the structured data in step S1. The implementation code is start_time::Float64=rEndata["playback_header"]["start_time"];

[0041] S22: The test end time is the data value of "report_time" of the last item in the "acasx_reports" structure array of the structured data in step S1, rounded up. The implementation code is, endT::Uint16=ceil(rEndata["acasx_reports"][end]["report_time"] );

[0042] S23: The data item start index is initialized to 1, and the implementation code is, beginI::Uint16=1;

[0043] S24: The data item end index is the total number of data items of the structured data in step S1, which is equal to the length of the "acasx_reports" structure array of the structured data. The implementation code is, endI::Uint16=length(eachindex(rEndata["acasx_reports"]));

[0044] So far, the time and index parameters required for file operation have been obtained, and then step S3 is entered. S3: The file operation includes the following two loops. The first loop is to perform data operation according to integer seconds from the test start time to the test end time, and record the current processing time Ti; the second loop is to perform file operation according to the data item index within each second, and record the current data arrival time toa; the implementation code is:

[0045] for i in beginT:endT

[0046] for j in beginI:endI

[0047] dType = rEndata["acasx_reports"][j]["acas_xaxo_do385"]["data_type"]

[0048] toa = rEndata["acasx_reports"][j]["report_time"]

[0049] Jnext = min((j + 1), endI)

[0050] toaNext = rEndata["acasx_reports"][Jnext]["report_time"]

[0051] AircraftInput(dType, i, j, endI, rEndata)

[0052] if (toaNext>i)|| (Ti <toa)

[0053] break

[0054] end

[0055] end

[0056] # ACAS X core algorithm code runs here, including monitoring and tracking module and WeChat decision module

[0057] end

[0058] The above are specific implementation steps provided for the embodiment.

Claims

1. A method for operating an ACAS X test case input file based on DO385, characterized in that: File operation is implemented according to the test start time, test end time, data item start index, and data item end index of the test scenario input file, and data parsing and processing are performed according to the nominal operation cycle of the airborne collision avoidance system of 1 second as a cycle; the test start time comes from the "start_time" data value of the file header information, the test end time comes from the data value of the arrival time toa of the last data item in the file, the data item start index is 1, and the data item end index is the total number of data items included in the test scenario input file; during the file operation, by comparing the relative size of the current processing cycle time Ti and the current data arrival time toa, it is identified that the file has a data item missing of 1 second or more seconds. In this case, the current processing cycle file reading and processing operation is terminated, and the operation operation of the ACAS X core algorithm is entered; the method comprises the following steps: S1: Read the test scenario file and obtain the structured data inside the file; S2: According to the structured data, assign values ​​to the test start time, test end time, data item start index, and data item end index. The specific method is as follows: S21: the test start time is the data value of "start_time" of the "playback_header" substructure of the structured data in step S1; S22: The test end time is the data value of "report_time" of the last item in the "acasx_reports" structure array of the structured data in step S1; S23: The data item start index is initialized to 1; S24: the data item end index is the total number of data items of the structured data in step S1, which is equal to the length of the "acasx_reports" structure array of the structured data; S3: File operation includes the following two loops. The first loop is to perform data operation according to integer seconds from the test start time to the test end time, and record the current processing time Ti. The second loop is to perform file operation according to the data item index within each second, and record the current data arrival time toa. S4: At every integer second, the collision avoidance system performs monitoring and tracking functions and threat decision functions.

2. The method according to claim 1, characterized in that In step S3, when the current processing cycle time Ti<the current data arrival time toa, it is considered that data is missing in the current data processing cycle, and the file reading and processing operation in the current processing cycle is terminated, and the operation of the ACAS X core algorithm is entered.

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