ORGANIZATION OF COMPLEX TESTING OF THE SPACECRAFT COMMAND AND MEASURING SYSTEM

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Introduction. Ground tests are one of the most impor- tant stages of the spacecraft systems development life cycle [1]. Tests let to determine the compliance of on- board systems to the specified requirements, and thereby enhance their resiliency and lifespan [2; 3]. The high cost and complexity of repairs after the spacecraft is put into operation increase the importance of ground tests [4]. There are autonomous and complex ground tests. Autonomous testing involves testing a fully assembled unit (system) to determine its readiness to participate in further tests or to stand-alone operation without connect- ing paired systems [5]. Complex tests are testing of all or part of the conjugate elements of the spacecraft, united in a single system, with simulation of regular and possible non-standard modes of operation of the spacecraft [6]. Each checked system, for carrying out autonomous and complex tests, has a specialized hardware and software complex- test and control equipment [7]. The use of com- puter technology can improve the quality, reduce the costs and the time of testing [2]. Test and control equipment (TCE) software is responsible for the collection, storage and convenient presentation of information about the sys- tems tests of the spacecraft [8]. The command and measuring system is responsible for the communication of the spacecraft with the ground control system. Communication takes place through the exchange of data packets. The command and measuring system receives telecommand packages from the ground control complex, identifies them and sends them to the appropriate onboard systems of the spacecraft. Also, the command and measuring system transmits telemetry packets containing information about the state of the on- board systems of the spacecraft to the ground control complex. The structure of the telecommand packages and telemetry are set by standards ESA PSS-04-107 [9] and ESA PSS-04-106 [10], respectively. For carrying out autonomous and complex tests of command and measuring system the special hardware and software complex - test and control equipment is used. Test and control equipment of the command and measuring system solves the problem of autonomous testing. Test and control equipment software (TCE SOFTWARE) provides users with the functions of forming a test script, provides it with the value of the controlled variables in a user-friendly form, and also solves a num- ber of other tasks when conducting autonomous tests [11-13]. The article presents a software subsystem that pro- vides testing of the spacecraft command and measuring system, ensuring the interaction of the automated test complex and test and control equipment. Research objective. Complex tests are carried out with the help of an automated test complex (ATC), which works as a simulator of the ground control complex. The main task of the automated test complex is the transfer of control commands to the control and testing equipment of the spacecraft systems, as well as the reception of teleme- try packets about the state of the onboard systems and test and control equipment. The automated test complex should interact with the test and control equipment of the command and measur- ing system according with the transport and information protocol. The transport protocol defines the logic of inter- action between the automated test complex and the soft- ware of the test and control equipment on the issues of network interaction, imposes the requirements for the hardware of the test and control equipment and the SNTP (Simple Network Time Protocol) [14], describes the struc- tures and types of packets for data transmission. The in- formation protocol defines the procedures of information exchange between the software complex of test and con- trol equipment and the automated test complex, sets the logic of information exchange and specific types of data packets. Information exchange is the transfer of data packets of different types between the automated test complex and the software of test and control equipment. The transport protocol of interaction of the automated test complex and the test and control equipment software of the command and measuring system defines six types of data packets. An automated test system may send the software checkout equipment control commands packages and arrays of command and program information (CPI). Software test and control equipment sends to an auto- mated test system acknowledgement for the used com- mands, address and positional telemetry, and various messages to the test protocol (fig. 1). The control command is a data package on which the equipment must perform certain actions. There are three types of commands: commands for test and control equipment, commands for command and measuring sys- tem and commands for the control unit of the onboard control complex. The command type determines which hardware the command is addressed to. An array of com- mand and program information is a package containing the necessary data for the control unit of the on-board control complex. In response to the control command, the test and con- trol equipment software sends an acknowledgement (ACK) to the automated test complex with the informa- tion about the execution of the command or with the error code. All error codes are described in the communication information protocol. The ACK is necessary for synchro- nization of work and prevention of a situation when commands are not identified by the test and control equipment. Telemetry packets sent to the automated test complex provide information about the values of certain measured parameters that need to be monitored. There are two types of telemetry packets: address and positional. Address te- lemetry contains the parameters of the test and control equipment, and the positional parameters of onboard sys- tems. At the beginning of the tests, the automated test complex expects a packet of address telemetry with the value of all the parameters of the test and control equip- ment, then once a second receives a telemetry packet con- taining only the changed parameters. Positional telemetry packets are transmitted to the automated test complex as they are received from the command and measuring system. The protocol provides for the possibility of issuing messages to the automated test complex in the test proto- col. Such messages are used, for example, to diagnose malfunctions or to comment on the test and control equip- ment operators. For the organization of interaction between the auto- mated test complex and the control and test equipment the software subsystem of the organization of carrying out complex tests was created. Subsystem of organization of carrying out complex tests. The main purpose of the subsystem of the organiza- tion of complex tests is to support the interaction between the automated test complex and the test and control equipment of the command and measuring system during complex tests according to the protocols of transport and information interaction. The main functions of the subsys- tem: - reception from the automated test complex sent control commands and arrays of command and program information; - transfer to the automated test complex of the ACK on control commands about their successful performance or with the code of the received error; - conversion of automated test complex packages into a format acceptable for the command and measuring system and vice versa; - recording of package exchange between the auto- mated test complex and the command and measuring sys- tem in the test protocol; - implementation of the possibility of entering into the test protocol messages from the test and control equip- ment operator; - checking of the tests carried out. Interface of the complex test subsystem (fig. 2). The subsystem of complex tests contains the follow- ing windows: “Commands to CMS”, “Commands from ATC”, “Log”, “Messages to ATC”, “Parameters of address telemetry”, “Telemetry monitor”. The “Log” window contains information about the processes that take place during complex tests: receiving commands and arrays of command and software informa- tion from the automated test complex, sending acknowl- edgements, address and position telemetry to the auto- mated test complex, and description of other actions that need to be recorded in the protocol. Fig. 1. Information exchange Рис. 1. Информационный обмен Fig. 2. Interface of the complex test subsystem Рис. 2. Интерфейс подсистемы проведения комплексных испытаний Fig. 3. Messages to the automated testing complex Рис. 3. Сообщения на автоматизированный испытательный комплекс “Messages to ATC” window displays messages gen- erated automatically or created by the operator in the process of testing (fig. 3). “Parameters of address telemetry” window contains the values of test and control equipment parameters. The parameters of the test and control equipment are divided into two types: the parameters of the state of the equip- ment and the parameters, the value of which determines the various settings of the transmission channel between the test and control equipment and the command and measuring system, as well as between the command and measuring system and other onboard systems of the spacecraft. The status parameters of the test and control equip- ment are the values of the sensors of various devices that are part of the test and control equipment, for example, the value of the humidity sensor of the rack control unit or the alarm flag of the first power distributor. Subsystem receives these values through a survey of the equipment in multi-threaded mode using the SNMP protocol [15]. The parameters responsible for the data channels spec- ify certain settings necessary for tests, such as the mode of exchange with the board or the address of the decoder. The value of the parameters of this type is set by commands for test and control equipment, and has a default value. The default value is required to avoid setting of each of the parameters at the beginning of complex tests. “Telemetry monitor” window displays the telemetry transmitted by the monitored object. The length of the telemetry frame according to the ESA PSS-04-106 stan- dard is 508 bytes. The software allows viewing any te- lemetry package that needs to be transferred to an auto- mated test complex. “Commands to CMS”, “Commands from ATC” win- dows display commands and arrays of control program data transmitted from the automated test complex. The “Commands from ATC” window contains all the pack- ages received from the automated test complex, and clearly displays their structure, provided by the transport interaction protocol. The “Commands to CMS” window displays the packets to be sent to the command and meas- uring system and displays their structure, provided by the international standard ESA PSS-04-107 (fig. 4). The structure of the package transferred to the com- mand and measuring system differs from the structure of the package transferred from the automated test complex. To convert the package structure and insert the necessary data, the values of which are contained in the address pa- rameters of the test and control equipment, the subsystem “Data packet editor” is used (fig. 5). The “Data packet editor” subsystem allows creating a tree-structured packet, consisting of elements that are represented by other structures. An address parameter for each item can defined. The value of this parameter will be inserted into the associated element when the packet is transferred to the object of control. It is also possible to set a default value for each element. In the data packet editor, structures of all types of data packets were created according to the ESA PSS-04-106 and ESA PSS-04-107 standards and the protocol of trans- port interaction of the automated test complex and the test and control equipment software. Elements are defined for structures, the value of which must correspond to certain address parameters during the transmission of the packet to the command and measuring system. When a command packet is received, the subsystem identifies the command type. Fig. 4. The structure of the packet transmitted to the command and measuring system Рис. 4. Структура пакета, передаваемого на командно-измерительную систему Fig. 5. The “Data packet editor” subsystem Рис. 5. Подсистема «Редактор пакетов данных» Fig. 6. Reproduction of passed tests Рис. 6. Воспроизведение пройденных испытаний If a command needs to be sent to the command and measuring system, the subsystem determines the list of address parameters required to configure the command. Then there is the formation of a command packet to be sent to the command and measuring system and the inser- tion of address parameters in the corresponding fields of the generated packet. After that, the received packet is sent to the test and control equipment for further sending to the command and measuring system. After conducting complex tests, it is necessary to be able to analyze them. For this purpose the problem of preservation of tests and realization of functions of repro- duction of earlier carried out tests was solved. Reproduc- tion of passed tests is shown in fig. 6. Visualization of the tests is performed using a time- line. Using the timeline, you can reproduce complex tests from any point in time in real-time or accelerated mode, showing all actions that have occurred by that moment. Conclusion. The developed subsystem is imple- mented in the software and hardware complex of test and control equipment of the command and measuring system and provides support for the application of the command and measuring system in complex tests of the spacecraft. The subsystem interacts with the automated test complex according to the protocols of transport and information interaction. The subsystem receives commands and exe- cutes them if they belong to the test and control equip- ment or transfers them to the object of control, having previously converted them into a clear command and measuring system structure. For each command, the sub- system sends an acknowledgement of correct identifica- tion, or with an error code according to the information exchange protocol. The subsystem receives telemetry from the command and measuring system, converts it according to the trans- port interaction protocol and sends it to the automated test complex. In addition to the telemetry of the object of con- trol, the subsystem sends to the automated test complex telemetry of test and control equipment, which contains the parameters of sensors of various equipment of control and testing equipment, as well as the parameters neces- sary to config ure the transmission channel between the test and control equipment and the command and measur- ing system or between the command and measuring sys- tem and other systems of the spacecraft. All the process of complex tests is recorded in the test protocol. The subsystem has the ability to record mes- sages from the operator of test and control equipment. All tests are saved and it is possible to reproduce them for analysis. The subsystem solves the task of the interaction of automated test complex and test and control equipment for complex tests of command-measuring system of the spacecraft.

作者简介

L. Nozhenkova

Institute of Computational Modelling SB RAS

50/44, Akademgorodok, Krasnoyarsk, 660036, Russian Federation

O. Isaeva

Institute of Computational Modelling SB RAS

50/44, Akademgorodok, Krasnoyarsk, 660036, Russian Federation

A. Koldyrev

Institute of Computational Modelling SB RAS

Email: raventus@icm.krasn.ru
50/44, Akademgorodok, Krasnoyarsk, 660036, Russian Federation

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