OPERATIONS UNIFICATION & AUTOMATION : APPLICATION ON A SATELLITE FLEET

Transcription

1 OPERATIONS UNIFICATION & AUTOMATION : APPLICATION ON A SATELLITE FLEET François LECOUAT, Jean-Michel DUSSAUZE, Pierrick GRANDJEAN ASTRIUM - Ground Segment and Applications Directorate 31, Avenue des Cosmonautes Toulouse, France Tel: , Fax: , francois.lecouat@astrium-space.com The automation of operations and their unification for a fleet of satellites are key issues for reducing operations costs and improving satellites safety and service availability. This paper introduces the requirements for unified and automated operations of a satellite fleet (from two satellites to several dozens). Then it describes the approach proposed by Astrium and the products that support this approach. Two applications are presented : the INTELSAT fleet of telecommunication satellites and the GALILEO constellation. 1. Requirements for Unified and Automated Operations of a Satellite Fleet 1.1 Unified Operations for Fleets and Constellations In many control centers, operators are in charge of a fleet of several satellites that have been delivered by several manufacturers over a long period of time. This often leads to a multiplication of the control functions dedicated to only one kind of satellite, and thus to a growing diversity and complexity of the operations with the growth of the fleet size. This has a negative impact on safety, efficiency, operations costs and software/hardware maintenance costs. Whatever the size of the fleet, from two satellites to several dozens, the first objective of operators is safety : everything must be done to prevent the loss of a satellite. The second priority is to maximize the availability of the services provided by the satellites. Finally operations costs must be kept as low as possible. Operations unification is an approach to manage complexity of fleet management and to improve safety and availability. It consists in using the same model and the same functions for the main operations of all the satellites under control. Two key items of the model are a global schedule of all the operations of the fleet and a common procedure language to describe operations to be done on all satellites. Planning the operations for the entire fleet is particularly useful as soon as resources are shared between satellites (antennas, ground equipment, staff). In that case global optimization leads to better results than independent local decisions. Implementing all operations procedures in a single language may require to convert existing procedures (often through an automated translation) to get the benefits of simplification (including mobility of operators, reduction of errors, simplified training and maintenance). 1

2 Unification also means using a common way to describe a maximum of operations constraints in the global schedule and in the procedures (required resources, backup requirements, precedence and temporal constraints, etc). This requires powerful operations management functions that avoid the multiplication of costly custom software add-ons that increases diversity and complexity. Thus the unification approach goes further than using a set of common functions. As such it is an approach of operations that can prove very useful for constellation management, such as in the GALILEO system. 1.2 Automated Operations Motivations for automation can be separated in two classes: Operate more satellites with the same staff. Automated operations allow an optimized off-line preparation of operations by experts during working hours. Operators are relieved from detailed continuous monitoring of each satellite and from routine or time-consuming tasks. They can devote themselves to important monitoring activities. Improve safety of operations and availability of the space system. Automated operations reduce the risk of human errors thanks to a complete, rigorous, repetitive and fast execution of planned operations. Moreover they allow a larger number of verifications, a reduced reaction time upon anomalies and a dynamic optimization given the available ground and space resources. High automation requires powerful Operations Functions including global schedule preparation and execution, procedures preparation and execution, automated data analysis and report generation, maneuvers automation (through an integration of the flight dynamics software with commanding functions). PROCEDURE PREPARATION FLIGHT DYNAMICS DATABASE MANAGEMENT TELEMETRY AUTHENTICATION OPERATIONS FUNCTIONS PLANNING & SCHEDULING OPERATIONS COMMAND & CONTROL LAYER SYNOPTICS TELECOMMAND ARCHIVE PROCEDURE EXECUTION DATA ANALYSIS NETWORK MANAGEMENT Figure 1: Operations Functions are the key elements that shape the operations concept and determine operations unification and automation capabilities. They are supported by a Command & Control Layer whose main task is to process telemetry and to release single commands or groups of commands. 1.3 Progressive deployment Unified operations improves efficiency and safety of operations but is not mandatory to have all software functions shared by the entire fleet to get most of these benefits. The key point is to unify functions that are at the heart of the operations concept. Low level functions that are hidden or where operators spend little time may remain satellite specific if necessary. For instance the software that sends commands and 2

3 processes the telemetry may be spacecraft specific, while the procedure management and planning functions are unified. A common concern of operators is to allow progressive automation of operations in order to tune the operations concept and build confidence of the staff. Defining a new operations concept must be done carefully because it can deeply affect the organization of the team, the safety of the operations and the availability of the satellites. Thus, it appears essential for the operations automation functions to be able to be progressively deployed so the pace of automation (procedures preparation and execution, plan preparation an execution, ground system monitoring and control) can be precisely adapted to the control team plans and constraints. 2. Astrium Approach to Operations Automation To meet the requirements of operations unification and automation described above, Astrium has developed an approach that is based on a line of products called OPSWARE. This is a set of scalable products, suited for all kinds of missions involving spacecraft from any manufacturer, that can be plugged on top of various command & control layers and supporting progressive deployment and progressive automation. Operations Preparation TIMELINE Plan Preparation OPSAT Procedures Preparation FOST System Database OPSEXECUTER Procedure Execution Commanding Operations Execution TIMELINE Plan Execution QUARTZ++ Flight Dynamics Localization SAT-ANALYST Data Analysis Telemetry Processing AUTOMATED OPERATIONS ASSISTED OPERATIONS MANUAL OPERATIONS Figure 2: Typical architecture for operations automation based on OPSWARE. The first layer on top of telemetry processing and commanding functions provides assisted operations based on automatic procedures execution. The second layer implements automated operations based on plan execution. 2.1 Objectives The OPSWARE products are the result of a continuous effort to develop software for operations preparation and execution, to optimize Astrium internal processes (operations preparation, integration and validation, spacecraft control, in-orbit follow-up), and to provide high value software products for Astrium customers. 3

4 Since several years Astrium products have demonstrated a significant return on investment on many satellite programmes in telecommunication, observation and science. A new step has been reached in 2001 when the third major versions of these products have been installed at INTELSAT to implement an advanced control center to run highly automated operations of the INTELSAT satellites fleet (30 satellites from 7 series). These products are supporting the following key operations preparation and execution tasks: Procedures Preparation and Execution (OPSAT and OPSEXECUTER), Plan Preparation and Execution (TIMELINE), Data Analysis and Report Generation (SAT-ANALYST), Flight Dynamics (QUARTZ++), System Database Management (FOST). These products are marketed as part of complete solutions for command and control provided by Astrium or partners or as add-on functions on top of existing command and control software. They have been designed to have a large scope of application: Suited for all kinds of missions in GEO and LEO orbits, from simple missions to large constellations, Independent from any spacecraft design and thus usable to operate spacecraft from any manufacturer, Fully integrated, so the complete solution is immediately operational, Independent from each other, to allow progressive deployment. Each product provides an extended Application Programmer s Interface (API) in order to facilitate: Connection of the product to existing infrastructures (system database, command and control layer), Customization of the product to the local operations concept, Extension of the product with new user-defined functions. These APIs ensure both a complete independence from the core command & control layer and permit an easy integration. A client-server architecture supports the deployment of completely distributed solutions that allow all the authorized users to get remote views on operations. This feature can facilitate lights-out operations with the minimum intervention of on-call operations engineers and almost no on-site travel. 3. Application on INTELSAT Control Center The INTELSAT fleet of communication satellites is one of the world s largest. Astrium was awarded a major contract from INTELSAT to develop a new generation control center, the Flight Dynamics and Commanding system (FDC) with the objective to replace a large part of the existing control infrastructure and reduce costs through operations unification and automation. In its current configuration the FDC system delivered by Astrium can operate up to 30 satellites of seven different series from various manufacturers (including INTELSAT V, VI, VII, K, VIII, IX, X) and a 4

5 network of six ground stations around the world including about 50 antennas and hundreds of key devices (e.g. antenna control units, modulators, amplifiers, receivers). The FDC allows to operate the fleet and the ground stations from the INTELSAT headquarters in Washington DC, from the backup facility, or from any station. FDC functions include operations scheduling, flight dynamics, ranging, satellites commanding, ground stations commanding, and alarms management. They provide a very high level of automation. Advanced features include continuous optimization of the operations schedule (thousands of tasks), automatic scheduling of orbital maneuvers, automatic execution of commanding procedures, automatic reconfiguration of ground station devices, global view of operations with drill-down facilities, easy system upgrade (e.g. to add new satellites and new user defined functions). The system is designed with stringent requirements on performance and availability, 24 hours a day, 365 days per year. Astrium solution is based on world class products : essentially the OPSWARE products suite for operations preparation and automation and third party products (network monitoring, database management, etc). The system architecture is based on a redundant hardware and software configuration to ensure a high availability of the functions. In case of failure the system is restored automatically, at the headquarters or at the backup facility. This distributed architecture provides broad and secure access to the functions from anywhere (control room, office, ground stations, home). It permits to benefit from specialists expertise at any time. The development of the FDC system was a challenging project because of the ambitious technical and operational objectives. Four releases of the system have been delivered. The first two releases (1Q99 and 4Q99) allowed INTELSAT to validate the FDC operational concept, to migrate and prepare the operational data, to identify useful FDC enhancements and to train the FDC operators. The third release has been delivered mid-2000, as planned since the beginning of the project. An additional and final release has been accepted by INTELSAT in February Overview of OPSWARE Latest Features for Fleet Management 4.1 Procedures Preparation and Execution All the operations of a spacecraft are, in principle, completely defined by a large manual of operations procedures. Since they are the source of most of the decisions and actions made by operators, it is natural to place procedures at the heart of automation, through a computerization of procedures that allows automated execution as well as the generation of paper documents. Several procedure concepts have been experimented at Astrium including a graphical procedure representation (enabled by an expert system shell that is now outdated). The main lessons learnt were that it is essential to consider the performances, robustness and durability of underlying technologies, and to 5

6 consider as equally important preparation and execution tasks in order to achieve an overall improvement of operations. Moreover, as control centers operate larger fleet of satellites, it becomes mandatory that Procedures Preparation allows both to implement a unified concept of operations and permits to efficiently handle series of similar satellites. This eases procedures writing and maintenance, favors experience capitalization and minimizes operators training, which, in turn, ensures safe operations by reducing the human risk factor. These requirements have been taken into account in the OPSAT and OPSEXECUTER products for procedures preparation and execution. The high level functions provided by OPSAT are: a specialized editor which supports "assisted editing" in a formal language with a syntax close to the natural language of users. It provides on-line browsing capabilities of the system data (TM, TC, etc.) and numerous on-line helps (syntax-driven editing, etc.) for more efficient procedures writing. a database to save and distribute procedures. It provides multi-user access, functions for managing several flight models, and powerful functions for searching impacts of modifications of the system data upon the procedures (e.g. find all procedures using a given command). a procedures compiler which generates an internal object tree representing each procedure, detects syntactic errors and verifies the consistency of procedures with respect to the system database. a procedures formatter which automatically generates high-quality corporate-standard procedure documents. A single procedure or a complete operations manual can be formatted at a time. Procedures prepared with OPSAT can be exported to OPSEXECUTER for execution. There is no need to recode them in a computer representation that may be obscure to operators: OPSEXECUTER is acting on the validated procedures of the procedures manual. Two execution modes are provided: a manual mode in which the user must acknowledge the execution of each instruction of a procedure; an automatic mode in which a procedure is executed without interruption. In both modes, a procedure can be displayed on the screen with the current instruction highlighted. All information acquired during execution (TM values, TC pre-execution checks and post execution verifications, etc.) are automatically reported in this display in front of the corresponding instruction: a good observability is thus ensured (operators would not be confident with an approach based on scripts that run in a black box printing messages from now and then). The tool automatically generates an "asrun" procedure document, showing a detailed trace of the execution in front of each procedure instruction (date, result). This file is saved in a database that constitutes a structured history of operations that is complementary to traditional logbooks. The user can get back in the loop at any time, in order to return to manual mode, skip or abort the current instruction, stop the procedure, send an individual command (Immediate, 1-step, 2-step and 3-step commanding modes are supported). 6

7 Figure 3: OPSEXECUTER Graphical User Interface. Situation awareness is ensured through several layers of reporting. The user is always in control of the execution and can get back in the loop at any time For each kind of procedure instruction the tool takes care of contingency management (delays, bad TM, failed commands...). This permits to limit the number of instructions written by users. Recent features useful for fleet management include: Version control functions to define the applicability / approval of procedures (target satellites), High level views on the procedures under execution that gives a synthetic report on the execution status, The possibility to write and manage procedures that are running continuously to monitor the health of a spacecraft and release commands in case of anomaly. 4.2 Plan Preparation and Execution The traditional approach on mission planning and operations execution relies on three sequential steps. First, an operation plan is prepared off-line. Then, this plan is translated into a schedule composed of timed commands. Finally, the commands are released at the planned time. Schedule update is then a painful and risky process. With this approach resource availability dates have to be predicted during plan 7

8 preparation. This may lock more resources than necessary to secure operations (e.g. extra antennas, spare equipment, etc.). The key idea of the approach proposed with TIMELINE is to integrate scheduling and automated execution in the same application in short-loop interaction. It permits to optimize resource allocation while enabling at the same time to modify the schedule dynamically at any time, and control execution in realtime. The planning model permits to explicitly represent the constraints of a plan. This allows the scheduling and the plan execution modules to optimize activities given available resources, to build robust plans that can resist to small anomalies, and to replan quickly when assumptions change or unexpected events happen. TIMELINE is at the same time a scheduling server and an execution controller. At the heart of the control center, it acts as the orchestra conductor: it manages resources allocation to tasks, drives ground segment equipment configuration, starts tasks at proper dates and monitors tasks execution. All operation tasks, ground resources and on-board resources are managed, scheduled and executed in the frame of a consistent operation concept : tasks are created, modified and executed by client applications and are managed together in a global schedule. In a satellite control center, clients may include the Commanding subsystem, the Telemetry subsystem, the Ranging subsystem, the Data analysis subsystem, or the Flight Dynamics subsystem. TIMELINE can also interface with a Resource Manager that is in charge of configuring and monitoring ground segment equipment (this interface is optional). Figure 4: TIMELINE Graphical Display for scheduling operations of the INTELSAT fleet This display provides a global view of all activities for 25 satellites arranged within a structured and configurable layout. 8

9 Mastering the complexity of a multi-mission multi-satellite operation center calls for a highly configurable, distributed, powerful and ergonomic Graphical User Interface (GUI). A TIMELINE GUI can display either a graphical (GANTT) view of the plan or a tabular view (Figure 4). Several GUIs can be opened simultaneously by different operators. Each operator can customize his view of the plan in many ways by defining filters in order to focus on what he wants to monitor and partitioning the display as he needs. Filters can be defined to see only one or some satellites, one or some activity types, or activity execution state, etc. The user can get back in the loop at any time to modify the plan if necessary or to acknowledge critical operations. Thus the level of automation is adaptable. Recent features useful for fleet management include: An upgraded capacity, to be able to handle thousands of activities. Templates defining sets of default values and constraints, defined for each activity type. Series of activities can be defined. Series are sets of identical activities automatically generated at regular time intervals on a given period of time. Series can be interrupted on time intervals and resumed at any time. This is especially useful for daily operations or any kind of routine tasks. Tasks may be saved in files and re-imported and merged within the current schedule. This is particularly useful to define schedule blocks that can be re-used several times. A hierarchical representation of task is available: several activities using the same set of resources can be gathered and scheduled within a global task. 4.3 Flight Dynamics QUARTZ++ is a Flight Dynamics product designed for both Station Keeping operations, transfer preparation and LEOP. It is organized around a generic framework that provides generic function to the flight dynamics algorithms, enabling the integration of new satellites or new flight dynamics functions to be completely handled by flight dynamics experts. Main QUARTZ++ Framework functions are: an evolutionary database generic Graphical User Interface definition for algorithms inputs and outputs as well as database edition data acquisition services (for telemetry and track & range measurement processing) plot services reports and broadcast services (transmission of various data through the network) algorithms execution management. Both interactive and batch modes are available (batch mode is used for automatic scheduling of various flight dynamics tasks) 9

10 The flight dynamics functions provided by QUARTZ++ include a complete set of flight proven station keeping and collocation functions including orbit determination, maneuver computation, orbital and sensor event predictions. Flight proven LEOP functions are also available such as transfer planning optimization, attitude determination and attitude maneuvers planning for spin stabilized satellites. It also supports pre-launch mission analysis task such as launch window computation and dispersion analyses. Two QUARTZ++ features are very useful for fleet management : the possibility to easily add a new spacecraft within the framework, the automation level achieved with the automatic translation of maneuvers into scheduled operations with the proper parameters, thanks to the integration with OPSEXECUTER. 4.4 Progressive Automation with OPSWARE OPSWARE products permit to automate operations with an incremental approach: Procedure execution (for ground procedures and satellite procedures) on operator request (in manual or automatic mode) with OPSEXECUTER. Scheduling of procedures in OPSEXECUTER stack. Automatic transfer of maneuvers from QUARTZ++ to OPSEXECUTER stack. Display of on-going activities with TIMELINE in monitoring mode (no activation) Activation of activities with TIMELINE (acknowledge may be required if necessary). Automatic switch to back-up resources with TIMELINE Automatic ground equipment activation from TIMELINE (through procedure or network supervision COTS) Switching from one level to another is entirely mastered by the Operations Manager as it is done simply by system configuration. If appropriate, the user can at any time quickly return to manual mode. 5. Application of OPSWARE to Galileo Operations The Galileo system is composed of 30 satellites on three different orbit planes. The Ground Segment is composed of two main control units, the Ground Control Segment (GCS) and the Mission Control Segment (MCS), five main TT&C stations (control and mission TT&C) and five others TT&C stations (mission TT&C only). The number of satellites and the objective of limited operations cost require that operations are planned and automated at both the GCS and the MCS. In 2001 Astrium conducted a study for ESA on the Galileo Mission Planning and Control concept. The OPSWARE products provide a reliable, operational and available solution to both control and mission operations planning and automation. Satellite control operations require few routine contacts (typically 2 per day per satellite), but on a limited set of antennas, and the scope may also encompass non-routine operations such as fleet management (launch, IOT, spare satellite transfer phases, etc.). 10

11 Mission control operations require far more contacts (up to 14 par day par satellite), and must guarantee the time interval between two successive contacts on the satellite (typically up to 100 minutes). Figure 5: Operations planning and scheduling of Galileo constellation. Each satellite must receive its specific mission data at regular time intervals, using one of the available antennas under visibility. Each horizontal domain corresponds to one of the 30 satellites of the constellation. Items in the graph represent satellite-ground contacts that are linked together by precedence constraints (arrows). Both satellite and mission control operations must synchronize with the visibility pattern of each satellite with respect to each station (which is far from being regular) and the usage time of each antenna must be shared between all operations. While automating routine operations is a must, the correct and smooth management of non-nominal situations (e.g. failure recovery) is of particular importance to avoid service outage. The TIMELINE product provides a solution for both off-line and on-line scheduling: Off-line contact schedule elaboration, distributing operations among the set of stations and antennas, under visibility and operational constraints. On-line operations schedule automation, monitoring and supervision of operations and ground equipment, allowing on-the-fly schedule modifications for coping with unexpected events and smoothly handling failures. In addition, TIMELINE is a powerful product during the system engineering phase for evaluating alternative operations concepts and optimizing ground system sizing. 11

12 6. Conclusion Users feedback shows that the OPSWARE products support operations concepts that allow very significant efficiency and safety improvements. They completely address preparation tasks instead of only focusing on operations execution. They allows a high degree of automation, while being adaptable in contexts where less automation is required and supporting a progressive automation deployment scheme. They permit to react safely to events and anomalies, and to optimize the performances of the operated system. A complete set of published APIs enable the OPSWARE products to fit on top of most existing command & control layers and to adapt to a wide range of operations philosophies. By supporting the company's vision rather than constraining it, it is easily accepted by the end-users and builds operator confidence. References 1. J.M. Dussauze, F. Lecouat, Can Operations Automation Reduce Cost and Improve Safety? The OPSWARE Approach, Proceedings of the 4th International Symposium on Reducing the Cost of Spacecraft Ground Systems and Operations, Laurel, Maryland, USA, April P. Grandjean, F. Lecouat, Resource Optimization and Automated Operations Supervision : a winning Pair towards Operations Cost Reduction, Proceedings of the 4th International Symposium on Reducing the Cost of Spacecraft Ground Systems and Operations, Laurel, Maryland, USA, April F. Lecouat, J.M. Darroy, Tools for Operations Preparation and Automation: the OPSWARE Approach, Proceedings of SpaceOps 2000, Toulouse, France, June J.M. Darroy, F. Copin, INTELSAT FDC: A new Era in Satellite Operations, Proceedings of SpaceOps 2000, Toulouse, France, June J.M.Darroy, F.Lecouat, J.M.Brenot, A.de Saint Vincent, OPSWARE: A new generation of software tools for making space operations faster, better and cheaper, Proceedings of the 44th Congress of the International Astronautical Federation, Craz, Austria, Oct