Development of the Satellite Ground Control System for Multi-mission Geostationary Satellite COMS

Transcription

1 SpaceOps 2010 Conference<br><b><i>Delivering on the Dream</b></i><br><i>Hosted by NASA Mars April 2010, Huntsville, Alabama AIAA Development of the Satellite Ground Control System for Multi-mission Geostationary Satellite COMS Byoung-Sun Lee 1, Won Chan Jung 2, Jeomhoon Lee 3, Sanguk Lee 4, Yoola Hwang 5, In Jun Kim 6, Soojeon Lee 7, Taehee Kim 8, Seongkyun Jeong 9, and Jaehoon Kim 10 Electronics and Telecommunications Research Institute (ETRI), Daejeon , South Korea A multi-mission GEO satellite, COMS has three payloads including Ka-band communications, GOCI, and MI. COMS SGCS is the only system for monitor and control of the satellite in orbit. In order to fulfill the mission operations of the three payloads and spacecraft bus, COMS SGCS performs the following functions such as reception and processing of telemetry data via S-band link, planning and transmission of telecommand, tracking and ranging of the satellite, control and monitoring of SGCS equipment, analysis and simulation of the satellite, processing and analysis of flight dynamics data, and mission scheduling and reporting. By the proper functional allocations, COMS SGCS is divided into five subsystems such as TTC,, MPS, FDS, and CSS. COMS SGCS is linked with MSC, KOSC, and IDACS for satellite related data exchange. The software in the COMS SGCS is designed using the object-oriented methodology and implemented using Microsoft C#.NET environment on Intel microprocessor based computers. The hardware in the COMS SGCS includes 13-m S-band mono-pulse Cassegrain antenna and RF/BB equipment. In this paper, development of the COMS SGCS is described with respect to system functional allocations, software and hardware design, system implementation, and system test. Nomenclature C&M = Control and Monitoring COMS = Communications, Ocean, and Meteorological Satellite CSS = COMS Simulator Subsystem CTES = Communications Test Earth Station DSSS = Dynamic Satellite Simulator System EADS = European Aerospace and Defense System ETRI = Electronics and Telecommunications Research Institute FDS = Flight Dynamics Subsystem GAU = Ground Authentication Unit GEO = Geostationary Earth Orbit GOCI = Geostationary Ocean Color Imager HRIT = High Rate Information Transmission IDACS = Image Data Acquisition and Control System KARI = Korea Aerospace Research Institute KMA = Korea Meteorological Administration KOMPSAT= Korea Multi-Purpose Satellite 1 Principal Researcher, Satellite System Research Team, lbs@etri.re.kr, Member AAS. 2 Principal Researcher, Satellite System Research Team, wcjung@etri.re.kr. 3 Principal Researcher, Satellite Navigation Research Team, hoonlee@etri.re.kr. 4 Principal Researcher, Team Leader, Satellite Navigation Research Team, slee@etri.re.kr, Member AIAA. 5 Senior Researcher, Satellite System Research Team, ylhwang@etri.re.kr, Member AIAA, AAS. 6 Senior Researcher, Satellite System Research Team, ijkim@etri.re.kr. 7 Senior Researcher, Satellite System Research Team, soojeonlee@etri.re.kr. 8 Senior Researcher, Satellite Navigation Research Team, thkim72@etri.re.kr. 9 Senior Researcher, Satellite Navigation Research Team, skjeong@etri.re.kr. 10 Principal Researcher, Team Leader, Satellite System Research Team, jhkim@etri.re.kr. 1 Copyright 2010 by the, Inc. All rights reserved.

2 KORDI = Korea Ocean Research and Development Institute LEO = Low Earth Orbit LHCP = Left Hand Circular Polarization LRIT = Low Rate Information Transmission MCE = Control Element MI = Meteorological Imager MMSC = Multi- Satellite Control MPS = Planning Subsystem MSC = Meteorological Satellite Center NAS = Network-Attached Storage RHCP = Right Hand Circular Polarization = Realtime Operations Subsystem SGCS = Satellite Ground Control System SOC = Satellite Operations Center SOH = State Of Health TTC = Telemetry, Tracking and Command I. Introduction multi-mission GEO satellite, COMS has three payloads including Ka-band communications, GOCI, and MI. ACOMS system has been jointly developed by KARI, ETRI, KORDI, KMA, and many industries. EADS ASTRIUM in Toulouse, France is the prime contractor for manufacturing of the COMS. ETRI has developed COMS Ka-band communication payload and SGCS. The COMS will be put into orbit by an Ariane-5 launcher in April, In order to carry out three missions, COMS system consists of three payloads, a spacecraft bus and ground segment as shown in Figure 1. From a functional point of view, COMS ground segment comprises SGCS for satellite operation, IDACS for MI and GOCI data processing, and CTES for Ka-band communications. SGCS and IDACS are installed in SOC and MSC as cross backup for the redundancy of the satellite control and image data reception. COMS SGCS is the only system for monitor and control of the satellite in orbit. In order to fulfill the mission operations of the three payloads and spacecraft bus, COMS SGCS performs the following functions such as reception and processing of telemetry data via S-band link, planning and transmission of telecommand, tracking and ranging, control and monitoring of SGCS equipment, analysis and simulation of the satellite, processing and analysis of flight dynamics data, and mission scheduling and reporting. By the proper functional allocations 1, COMS SGCS is divided into five subsystems such as TTC,, MPS, FDS, and CSS as presented in Figure 2. COMS SGCS has been developed using the heritages of developing the MCE for LEO satellite KOMPSAT-1 2 and KOMPSAT-2 3 which were launched in 1999 and 2006, respectively. In this paper, development of the COMS SGCS is described with respect to system functional allocations, software and hardware design, system implementation, and system test. L-band link S/L-band link COMS S/L-band link Ka-band link S-band link COMS Satellite Ground Control System (SGCS) Planning Subsystem Plannig Subsystem (MPS) (MPS) - Request Gathering - Scheduling - Schedule Reporting Korea Ocean Satellite Center (KOSC) Meteorological Satellite Center (MSC) Satellite Operations Center (SOC) Communications Test Earth Station (CTES) Telemetry, Tracking, and Command (TTC) - Telemetry Reception - Command Transmission - Tracking and Ranging - Control and Monitoring Real-time Operations Subsystem () - Telemetry - Telemetry Analysis - Command Planning - Telecommand Flight Dynamics Subsystem (FDS) - Orbit Determination and Prediction - Station-Keeping and Re-location Planning - Satellite Event Prediction - Satellite Fuel Accounting Image Data Acquisition & Control System (IDACS) GOCI Image Data Acquisition & Control System (IDACS) SD Satellite Ground Control System (SGCS) Satellite Ground Control System (SGCS) - Tracking, Telemetry,& Commanding - Satellite Operations - Planning -Flight Dynamics Operation - Satellite Simulation Image Data Acquisition & Control System (IDACS) - Satellite Communications - Communication System Monitoring and Control Dynamic Satellite Simulator System (DSSS) by ASTRIUM - SGCS Operational Acceptance Test COMS Simulator Subsystem(CSS) - Satellite Dynamic/Static Simulation - Command Verification - Anomaly Simulation Figure 1. COMS system architecture Figure 2. COMS SGCS functional allocations 2

3 II. COMS SGCS Design A. TTC Subsystem TTC receives the satellite control command data from and modulates the command data into command signal, up-converts, and transmits the command signal via S-band link. Also, TTC receives the antenna pointing data from FDS and performs the satellite tracking and ranging. The subsystem also receives the telemetry data from the COMS satellite. TTC has a function of polarization diversity for the downlink signals of RHCP and LHCP in order to receive the telemetry signal during the attitude anomaly of the satellite. TTC demodulates the received telemetry data and transfers it to. TTC transfers the satellite tracking and ranging data to FDS. The antenna equipment and a part of TTC are co-used for MSC. TTC comprises antenna equipment, RF equipment, MODEM/BB equipment, timing equipment, C&M equipment. Figure 3 shows the functional structure of TTC and Figure 4 presents the TTC C&M software architecture. HRIT/LRIT(S-band) SD(L-band), HRIT/LRIT(S-band) IDACS Antenna Equipment S-band /L-band GPS IF RF Equipment Time Code Timing Timing Pulse Equipment Reference Frequency NTP... MODEM Unit Baseband Ranging Unit MODEM/BB Equipment TTC Control /Status Ranging/Tracking C&M Equipment Main Signal Control/Status Time & Frequency Packet TTC Control /Status Ranging/T racking Communication Interface External Signal Figure 3. TTC hardware architecture Packet Ant.Pointing Ranging/T racking for simulation on-station FDS DSSS MMSC Figure 4. TTC C&M architecture B. Subsystem provides real-time monitoring of the satellite status and transmits the telecommands to control the satellite. has network links to TTC, MPS, and FDS in order to send telecommands, to receive telemetry data from the satellite, and to analyze the mission of the satellite. extracts satellite SOH data from telemetry data received from TTC, displays it for monitoring, and sends it to FDS. stores real-time telemetry data for the future analysis. reprocesses the stored data and analyzes the trend of the data. receives mission timeline from MPS, prepares command plan and telecommand procedures in order to process the mission timeline generated by MPS and sends telecommand to TTC. is composed of computers like PC servers and clients, I/O devices, and software to control and monitor the COMS satellite. Figure 5 shows the functional allocations and Figure 6 presents computer allocations. / TC TTC DSSS Telemetry Telecommand Simulated Real-time Operations Subsystem() Telemetry System Management Telemetry Analysis FDS Data Ancillary Data Ancillary Data FDS MSC KOSC CSS Simulated TC for Simulation Database Management Ancillary Data IDACS in SOC MPS Timeline Execution Log Telecommand Command Planning LEOP Data/ MMSC LEOP TC Log Astrium Figure 5. functional architecture Figure 6. computer allocations C. MPS Subsystem MPS gathers mission requests from the mission requesters, which are CTES, KOSC and MSC. Thereafter, with its own mission scheduling algorithm, MPS generates mission timeline by collecting and analyzing the mission requests and event information received from FDS. The mission timeline is transmitted to to be used for command planning. The mission timeline is also converted into a mission schedule and the mission schedule is transmitted to the mission requesters. Figure 6 shows the MPS functional allocations. Figure 7 presents MPS computer allocations. 3

4 Planning Subsystem (MPS) Scheduling PC (Primary) CTES MSC KOSC IDACS in SOC Request/ IMC Data Schedule/ Event File Request Gathering Schedule Reporting Scheduling Event Prediction/ Orbit Maneuver Request Timeline Execution Log FDS MSC Terminal KOSC Terminal External Network Firewall Laser Printer Web Server Security Check Internal Network Scheduling PC (Backup) Figure 7. MPS functional allocations Figure 8. MPS computer allocations D. FDS Subsystem FDS provides spacecraft flight dynamics operations support. Flight dynamics operations support includes spacecraft orbit determination, orbit prediction, event prediction, fuel accounting, station-keeping maneuver planning, and station-relocation maneuver planning. In general, FDS is a computer-based system, which is comprised of flight dynamics software and computer hardware. FDS in the COMS SGCS includes only the functions required for the geostationary orbit spacecraft operations. Figure 8 shows the FDS functional allocations. Figure 9 presents FDS computer allocations. TTC Tracking & Ranging Data/ Antenna Pointing FDS Data Orbit Determination Orbit Prediction Event Prediction Flight Dynamics Subsystem (FDS) Graphical User Interface System Management Database Management Thruster Modeling Station-Keeping Maneuver Station- Relocation Manuever Fuel Accounting Figure 9. FDS functional allocations Event Prediction/ Orbit Maneuver MPS FDS Primary Real-time Operations Subsystem () Ethernet Telemetry, Tracking and Command Subsystem (TTC) Redundant Planning Subsystem (MPS) SGCS LaserJet Printer External Link Image Data Acquisition and Control System (IDACS) in SOC Korea Ocean Satellite Center (KOSC) Meteological Satellite Center (MSC) Figure 10. FDS computer allocations E. CSS Subsystem CSS is a software system of simulating the dynamic and static behavior of COMS by use of mathematical models. CSS is utilized for command verification, operator training, satellite control procedure validation, and anomaly simulation. CSS models each of satellite subsystems as accurate as possible with the constraint of real operation condition, and display status of satellite including orbit and attitude in alphanumeric and graphical format. CSS receives telecommands from, distributes them to corresponding subsystems, and sends the simulated results to in telemetry frame format. CSS is capable of operating in on-line as well as stand-alone modes. CSS, also, supports real-time and variable speeds simulation in terms of multiple or fraction of real-time, anomaly simulation for analysis purpose etc. In addition, CSS supports simulation for the spacecraft status by various events and initialization data. Figure 11 shows CSS functional allocations. Figure 12 presents CSS computer with two monitors. Model AOCS Simulated Data Simulation Input Data DM PC CPS DYN ENV EPS PLD TC&R CMD Simulation Result Display Flight S/W CMD /SDT Data TC TC Simulated Data Simulated TC for Simulation Tower-type PC SGCS LAN 2 LCD Monitors TCS GRS CMD SM Mouse Keyboard CSS Main Computer Figure 11. CSS functional allocations Figure 12. CSS computer allocation 4

5 F. COMS SGCS Interface The SGCS has the external interface with the COMS satellite, CTES, KOSC, MSC, IDACS in SOC, and MMSC in ASTRIUM, Toulouse. The SGCS gives and takes the data relevant to mission operation request to/from CTES, KOSC, MSC and IDACS. The SGCS also sends the data needed for image processing to KOSC, MSC and IDACS. IDACS in SOC co-uses TTC antenna of SGCS. Thus the SGCS has the interface at the level of RF signal with IDACS in SOC. As another external interface, the SGCS is able to not only receive the LEOP data and TC log from MMSC in LEOP operations but also send the data to MMSC in on-station operations, if required. The SGCS has the internal interface among TTC,, MPS, FDS, CSS, and DSSS. The DSSS is connected to the MODEM/BB of TTC and, and plays a role as simulator. Figure 13 presents overall structure of the COMS SGCS interface. The SGCS consists of primary system and backup system. This interface is used for the operational data transfer between the primary TTC and backup /FDS or vice versa. Also, the interface is used to exchange the data between the same subsystems in primary and backup SGCS. The primary-backup SGCS interface is shown in Figure 14. Figure 13. COMS SGCS interface structure III. COMS SGCS Implementation Figure 14. Primary and backup interfaces Figure 15 shows the COMS SGCS hardware implementation including TTC,, MPS, FDS, and CSS 5. Microsoft Windows based operating system is applied to workstations and servers equipped with the microprocessor from INTEL. Microsoft C#.NET environment is applied to the SGCS software implementation. SIM and TTCSIM are implemented for test purposes. Figure 15. COMS SGCS hardware implementation 5

6 A 13-m mono-pulse Cassegrain type antenna with polarization diversity is established for S-band TT&C. Figure 16 shows the antenna and RF/BB equipments for TTC. Figure 16. TTC antenna and equipment Figure 17. TTC C&M computer is implemented in two PC servers, 4 client computers and one NAS. Figure 18 shows COMS main window, command executor, and trend analysis. COMS specific functions 4 including dwell management, dump management, spy management, on request management, error recorder, and master schedule management are also implemented in. Figure 18. main window, command executor window, and trend analysis window MPS is implemented in one gateway computer and two planning computers. Figure 19 presents MI mission planning window and GOCI mission planning window, and Gantt chart for mission scheduling. Every day, MSC and KOSC request MI and GOCI missions to SOC for COMS payload mission operations. Figure 19. MI mission planning window, GOCI mission planning window, and Gantt chart 6

7 FDS is implemented in two PCs for redundancy. COMS specific functions 4 including wheel off-loading parameter computation, orbital oscillator update, sensor interference prediction, and on-station Earth acquisition are also implemented. Figure 20 shows FDS main window, orbit determination window, and station-keeping maneuver planning window. Figure 20. FDS main window, orbit determination window, and station-keeping maneuver planning window CSS is implemented in a PC with two display monitors. Figure 21 presents CSS main window, MI operations simulation, and GOCI operations simulation. Figure 21. CSS main window, MI imaging simulation window, and GOCI imaging simulation window IV. COMS SGCS Test After implementation of the five subsystems in COMS SGCS, formal subsystem tests are carried out. Although all of the subsystems in SGCS are interrelated, the major focus in each subsystem test is tested as a single isolated system. During the testing, numerous operations are performed following the test steps in the test procedure. In general, test setup should be checked first and then the test execution follows on the test procedure for the specific test item. There are many checking points in the test procedure to verify a specific function and/or numbers. Test data and test harness are prepared for the subsystem tests. Subsystem interface test is performed after the successful completion of the five subsystem tests. Overall SGCS system test is performed in ETRI as a factory acceptance test. Then, the COMS SGCS system is installed in KARI. 7

8 Figure 22 shows the COMS SGCS computers and monitors after installed in KARI site. The computers are installed in the separated air conditioned room and the display monitors with keyboard and mouse are located in the office for the acceptance test. The COMS SGCS equipment is moved to the formal COMS satellite control center after the completion of the formal acceptance test. Figure 22. COMS SGCS computers and monitors in KARI Test philosophy used in the development of SGCS acceptance test procedure is based on testing the system functions on a test-by-test basis. It is assumed that all of the subsystem functions in SGCS are checked through the subsystem test, subsystem interface test, and SGCS system test. Therefore, the test items that are checked in SGCS system acceptance test are for the verification of the system requirements for SGCS to perform its function as a system. In the COMS SGCS acceptance test, all of the data exchanges among the subsystems are tested. The acceptance test of the COMS SGCS system was performed during 6 days 6. Before starting of the official test, SGCS acceptance test procedure was completed and signed off. Test readiness review meeting was held before the test. Daily test result review meeting was held after test. The test was performed for the 13 test items in the COMS SGCS test procedure. All of the tests were successfully passed and then, test review board approved the COMS SGCS acceptance test. Table 1 shows COMS SGCS system acceptance test items. (Table 1) COMS SGCS acceptance test items TEST No. Title of the test TEST No. Title of the test TEST-01 Real-time Telemetry TEST-08 TTC Operation TEST-02 Telemetry Distribution and Analysis TEST-09 Orbit Determination TEST-03 Event Prediction and Station-Keeping TEST-10 Satellite Simulation TEST-04 Planning and Scheduling TEST-11 Switch Over TEST-05 Execution TEST-12 Robustness TEST-06 Telecommand processing TEST-13 SGCS Long-Run TEST-07 TTC TEST-01 test is related with real time telemetry processing from TTC modem/bb, DSSS, and CSS. Simulated telemetry data is used for the test. TEST-2 test is for off-line processing of the stored telemetry data and distribution of the data to the external system. Harness computers are used for external system such as MSC, KOSC, and IDACS in SOC. TEST-03 test is related with FDS operations for event prediction and station-keeping maneuver planning. The event prediction results are transferred to MPS for mission planning and scheduling in TEST-04 test. timelines are transferred to MSC, KOSC, and IDACS in SOC for payload data processing. timeline is also transferred to for command planning. TEST-05 test is for command planning using mission timeline. Flight Operation Procedures (FOP) for Meteorological Imager (MI), Geostationary Ocean Color Imager (GOCI), and Image Motion Compensation (IMC) commanding are used. TEST-06 test is for command execution to DSSS and IF/RF loop operation. Ground Authentication Unit (GAU) operation is also included in the test. TEST-07 test is for loop back test. Control and monitor of the TTC equipment are also tested. In TEST-08 test, FDS generates and transfers the antenna pointing data for TTC antenna to point MTSAT-2 satellite in geostationary orbit. In TEST- 09 test, TTC collects antenna tracking data and transfers the data to FDS after the acquisition of the MTSAT-2 satellite signal. Then, FDS determines satellite orbit using tracking data. FDS generates and transfers the orbit 8

9 ephemeris data to MSC, KOSC, and IDACS in SOC. TEST-10 is to demonstrate the CSS processing functionality. CSS stand-alone mode and link mode are tested. Spacecraft anomaly simulation and resolution functionalities are also tested. TEST-11 test is to demonstrate the functionality of switch over between primary and backup servers. Switch over by process anomaly and network anomaly is tested. TEST-12 test is for the robustness of the telemetry processing in case of wrong telemetry input such as wrong synchronization word, wrong frame number, and wrong packet identification. TEST-13 test is for the long run telemetry processing. Although the COMS satellite telemetry is processed for 24 hours a day, 7 days a week, 365 days a year, and 7 years of the satellite design lifetime, more than 60 hours of the continuous telemetry processing is carried out as a demonstration in this test. After the completion of the formal acceptance test of the COMS SGCS, many ground segment level tests has been performed for technical qualification and operational qualification of the system. V. Concluding Remarks Development of the COMS SGCS has been described with respect to subsystem functional allocations, software and hardware design, implementation and test. Although the COMS satellite has been manufactured in France, COMS SGCS has been successfully developed in Korea with the COMS satellite related documents and design review meetings. COMS SGCS is the first Korean built GEO satellite control system. The technology in the COMS SGCS will be used for the future GEO communications satellite system development. On the other hand, development of the two MCEs for LEO KOMPSAT-5 and KOMPSAT-3 are in the final test phases for the launch of the satellite in 2010 and 2011, respectively. The satellite control technology for the GEO and LEO satellite will be matured by the COMS and KOMPSAT series satellites operations. Now, the COMS SGCS is ready for the launch of the satellite in April, References 1 Lee, B.-S., Jung, W. C., Lee, S., Lee, J.-H., and Kim, J, Design of the COMS satellite ground control system, Journal of the Korea Society of Space Technology, Vol. 1, No.2, 2006, pp Lee, B.-S., Lee, S., Lee, H.-J., and Lee, S.-P., Performance Verification of the KOMPSAT-1 MCE in the aspects of orbit and attitude operations, Proceedings of KJJC-SAT 2000 Conference, Dec. 7-8, Jung, W. C., Lee, B.-S., Lee, S., and Kim, J., Control System for KOMPSAT-2 Operations, Journal of the Korea Society of Space Technology, Vol. 1, No. 2, 2006, pp Lee, B.-S., Jung, W. C., and Kim, J., Design and implementation of COMS specific functions in satellite ground control system, Proceedings of 25 th AIAA International Communications Satellite Systems Conference (ICSSC), 2007, AIAA Jung, W. C., Lee, B.-S., Lee, J.-H., and Kim, J., Development of the COMS Satellite Ground Control System, IEICE Technical Report-JC-SAT 2009, Vol. 109, No. 254, SAT , pp Lee, B.-S., Jung, W. C., Lee, J.-H., Hwang, Y., Kim, I. J., Kim, T., Kim, H.-Y., Jeong, S., Lee, S., and Kim, J., Test of the COMS Satellite Ground Control System, Proceedings of the 2008 KSAS Fall Conference, Nov , 2008, KSAS , pp