The Satellite Operation System (SOS) has been developed for a low earth orbiting remote sensing satellite, Korea Multipurpose Satellite-I, to monitor and control the spacecraft as well as to perform the mission operation. SOS was designed to operate on UNIX in the HP workstations. In the design of S...
The Satellite Operation System (SOS) has been developed for a low earth orbiting remote sensing satellite, Korea Multipurpose Satellite-I, to monitor and control the spacecraft as well as to perform the mission operation. SOS was designed to operate on UNIX in the HP workstations. In the design of SOS, flexibility, reliability, expandability and interoperability were the main objectives. In order to achieve these objectives, a CASE tool, a database management system, consultative committee for space data systems recommendation, and a real-time distributed processing middle-ware have been integrated into the system. A database driven structure was adopted as the baseline architecture for a generic machine-independent, mission specific database. Also a logical address based inter-process communication scheme was introduced for a distributed allocation of the network resources. Specifically, a hotstandby redundancy scheme was highlighted in the design seeking for higher system reliability and uninterrupted service required in a real-time fashion during the satellite passes. Through various tests, SOS had been verified its functional, performance, and inter-face requirements. Design, implementation, and testing of the SOS for KOMPSAT-I is presented in this paper.
The Satellite Operation System (SOS) has been developed for a low earth orbiting remote sensing satellite, Korea Multipurpose Satellite-I, to monitor and control the spacecraft as well as to perform the mission operation. SOS was designed to operate on UNIX in the HP workstations. In the design of SOS, flexibility, reliability, expandability and interoperability were the main objectives. In order to achieve these objectives, a CASE tool, a database management system, consultative committee for space data systems recommendation, and a real-time distributed processing middle-ware have been integrated into the system. A database driven structure was adopted as the baseline architecture for a generic machine-independent, mission specific database. Also a logical address based inter-process communication scheme was introduced for a distributed allocation of the network resources. Specifically, a hotstandby redundancy scheme was highlighted in the design seeking for higher system reliability and uninterrupted service required in a real-time fashion during the satellite passes. Through various tests, SOS had been verified its functional, performance, and inter-face requirements. Design, implementation, and testing of the SOS for KOMPSAT-I is presented in this paper.
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제안 방법
The SOS test was conducted to demonstrate its capabilities, and to verify whether it satisfies the intended specifications. The trace-driven data set prepared a priori was used to test SOS.
The results were displayed on the monitor or in the event message log. The subsystem test was preceded by the module tests using static simulator, to verify correctness of individual modules of SOS. After verifying the telemetry functions with a fixed pattern of telemetry, which was known, SOS was connected with the KOMPSAT-I dynamic simulator for simulated telemetry processing and telecommand processing, where telemetry was provided via LAN.
The subsystem test was preceded by the module tests using static simulator, to verify correctness of individual modules of SOS. After verifying the telemetry functions with a fixed pattern of telemetry, which was known, SOS was connected with the KOMPSAT-I dynamic simulator for simulated telemetry processing and telecommand processing, where telemetry was provided via LAN. Note that the KOMPSAT-I dynamic simulator (SIM) is another subsystem of MCE and verified via its own test tools before its usage for SOS verification.
The TCPB test items comprise of command generation and transmission, validation of real-time, absolute-time, and relative timed commands for OBC, RDU and ECU on-board processor. This test was also performed utilizing the KOMPSAT-I simulator focusing more on functional aspects rather than on the quantitative characterization. Of course it also showed a good performance as in TMPB, ibr transmitting various types of telecommand groups in a given time slot.
Of course it also showed a good performance as in TMPB, ibr transmitting various types of telecommand groups in a given time slot. For functional verification, selected telecommands according to a mission scenario were transmitted to the KOMPSAT-I simulator and corresponding verifications were tested for the correctness of respective processes and response timing.
System test was conducted to veriiy that the complete MCE system meets its functional, peribrmance, and interface requirements from an operational point of view. Test cases were developed according to daily operation scenarios, LEOP operation activities, and short-term or long-term activities. In daily operations, contact operation and non-contact operation test cases were tested separately.
They were also checked up in a realistic way with the actual telemetry data files recorded during the satellite integration and test. Through a repeated test for normal cases and abnormal cases, for which the simulator acts as a test tool and harness, all the MCE functional and performance requirements were successfully verified and were qualified to go ahead to the KOMPSAT-I level testing.
The end-to-end test was conducted to qualify MCE as an element of the KOMPSAT-I ground segment ready to provide required support for KOMPSAT-I flight operation. In other words, the objectives of this test were to demonstrate the flight readiness of the KOMPSAT-I ground system and to verify end-to-end command and telemetry data flow between spacecraft and MCE It was intended to verify the adequacy of MCE spacecraft command planning and preparation capability, as well as message and information communication with the ground station elements. The flight model of KOMPSAT-I was connected with MCE ground system via either RF or direct line for this test.
The project was funded by the Ministry of Inibrmation and Communications of Korea as a part of R&D activity related to the KOMPSAT-I program. The authors gratefully acknowledge the contributions of the Hyundai Space and Aircraft Co. who contributed in implementing the KOMPSAT-I SOS software.
From the subsystem level to systemlevel testing, test plans and accordingly generated test procedures were prepared and subsequent testing activities have been carried out along with the integration of subsystems into system. After the MCE level verification, KOMPSAT system level verification including RF compatibility test and end-to- end test were conducted with the satellite on the ground for a full compatibility of interface and data verification. Figure 11 shows the test hierarchy and configuration of the system from the view of SOS, where various test tools were applied respectively or in combination according to verification level and test phase: static simulator, dynamic simulator, flight software test bed, and flight model KOMPSAT-I.
대상 데이터
The SMB test items included security check function for essing of the stored telemetry data and telemetry display. The important issue of robustness was achieved by testing TMPB against the erroneous event occurrences of telemetry frame in terms of format error, broken frames, and missing frames.
이론/모형
It has been confirmed that the real-time processing performance of SOS exceeds much more than required. All the functions as well as the databases were verified completely in an end-to-end test with the flight model of KOMPSAT-I. Currently, the SOS has been successfully used for the KOMPSAT-I ground control system.
성능/효과
A processing delay due to GUI display loads had been overcome by a one-to-one assignment of process instance per display window and by displaying only those telemetry items whose values have changed. The test showed that telemetry processing gave a sufficient margin in time to satisfy the realtime processing requirement. Table 2 shows the performance of telemetry processing.
Table 2 shows the performance of telemetry processing. In the test, twelve alphanumeric display windows were open in both primary and backup workstations and out-of-range telemetry items change rate were set at ab이it 20 percentage to increase workload in processing. Although the frame to frame variation is typically minor, we have purposely chosen to use items that caused frequent updates to test the limits of the system.
Although the frame to frame variation is typically minor, we have purposely chosen to use items that caused frequent updates to test the limits of the system. It was observed that the processing was completed well within minor frame time without any missing data and the peribrmance of processing was observed to be as fast as 4 times with respect to minor frame rate. Without display on-line, the processing time performance is even more increased so that we have much more time margin with processing of recorded telemtery processing even after replaying at 4 times fast rate.
참고문헌 (1)
Landis, S.J., Mulholland, J.E..
Low cost satellite ground control facility design.
IEEE aerospace and electronic systems magazine,
vol.8,
no.6,
35-49.
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