Skip to main content

2009 | Buch

Simulating Spacecraft Systems

verfasst von: Jens Eickhoff

Verlag: Springer Berlin Heidelberg

Buchreihe : Springer Aerospace Technology

insite
SUCHEN

Über dieses Buch

Satellite development worldwide has significantly changed within the last decade and has been accelerated and optimized by modern simulation tools. The classic method of developing and testing several models of a satellite and its subsystems with the aim to build a pre-flight and finally a flight model is being replaced more and more by a considerably faster and more inexpensive method. The new approach no longer includes functional test models on entire spacecraft level but a system simulation. Thus overall project runtimes can be shortened. But also significantly more complex systems can be managed and success oriented tests on integration and software level can be realized before the launch. Applying modern simulation infrastructures already during spacecraft development phase, enables the consistent functionality checking of all systems both in detail and concerning their interaction. Furthermore, they enable checks of the system's proper functionality, their reliability and safety / redundancy. But also analysis regarding aging and lifetime issues can be performed by simulation. Project-related simulations of operational scenarios, for example with remote sensing satellites, and the checking of different operational modes are of similar importance. On the whole, risk is reduced significantly and the satellite can be produced in a considerably more cost efficient way, with higher quality and in shorter periods of time. Therefore "Simulating Spacecraft Systems" - the title of the present book - is an important domain of modern system engineering, which meanwhile has successfully established a position in many other sectors of industry and research, too.

Inhaltsverzeichnis

Frontmatter

Simulation based System Development

1. Complex Systems in Spaceflight
Abstract
Complex systems require detailed system engineering for their design, construction, verification, and finally for testing their completion and final validation. For many years system engineering has been supported by computer based system simulation techniques. In fact, as early as the Apollo program, NASA and its contractors applied such methods. However with today's significantly more powerful computers and sophisticated software tools, one can derive much greater performance from simulation infrastructures.
Jens Eickhoff
2. System Simulation in System Engineering
Abstract
The system development of spacecraft is divided into four developmental phases, plus an operational phase and - if necessary - a disposal phase, as depicted in the figure below. The system manufacturer, e.g. of an entire satellite or a subunit, usually participates in the first four phases as well as in the start up at the beginning of phase E. Established during this development process are some important milestone reviews with the customer (which for a spacecraft usually is a space agency or a commercial contractor, for a subsystem it is the spacecraft prime contractor).
Jens Eickhoff
3. Simulation Tools for System Analysis and Verification
Abstract
The main development tasks within the different development phases of spacecraft are grouped together by phase in the following table. From these tasks the requirements for the spacecraft development and verification infrastructures can be derived directly.
Jens Eickhoff
4. Testbench Components in Detail
Abstract
The detailed description of test and simulation facility components is the subject of the following section. It begins with the more non-central elements to subsequently lead over to the central simulator kernel, the models and to numeric topics. In this flow the control consoles of are first treated.
Jens Eickhoff
5. Spacecraft Functionality to be Modeled
Abstract
The term "functional" simulation of spacecraft has already been mentioned. A precise definition is given below. More detailed aspects of the different spacecraft components and the space environment which both have to be modeled in the frame of a functional simulation are treated afterwards. The modeling criteria cited in the following subsections are focused on the satellite domain. However, they can similarly be applied to other spacecraft like shuttles, launchers and transfer vehicles, too.
Jens Eickhoff

Simulator Technology

Frontmatter
6. Numerical Foundations of System Simulation
Abstract
Simulation technology has been applied for years now in computer-based system design in various application fields, from ship building to space technology. It also covers the full scope of problems to be analyzed, ranging from the design of a system component for specific stationary load cases up to overall system simulations for analyses of dynamic system operation.
Jens Eickhoff
7. Aspects of Real-time Simulation
Abstract
During simulation runs, telemetry data packets are generated by the on-board software and also simulator telemetry data packets from the simulator side, both being routed to the control console. Spacecraft telecommands and respectively simulator commands are sent from control console to spacecraft on-board software and respectively to the simulator core. All these packets are stamped with time signatures to be able to track the ongoing activities chronologically. However different types of time information have to be distinguished to avoid misinterpretations. Therefore the most important time definitions are covered again below.
Jens Eickhoff
8. Object Oriented Architecture of Simulators and System Models
Abstract
The following subsections describe the most common software engineering techniques used in spacecraft system simulators. As apparent from the explanation of the complexity of simulation-based test benches and their real-time requirements as well as from the section on underlying mathematics, the software engineering implementation of such systems becomes very challenging. In fact it is so complex, that the code for such a simulator cannot be implemented simply by simply being typed into an editor.
Jens Eickhoff
9. Simulator Development Compliant to Software Standards
Abstract
By means of the simulation based testbenches, amongst other components, the spacecraft on-board software is verified - first as pre-verification on the SVF, then with the hardware / software compatibility tests on an STB and finally in an EFM configuration. Since the on-board software is one of the most critical elements of a spacecraft, immediately on the spacecraft customer side, questions concerning software quality and verification state of the simulators and testbenches arise.Therefore the compliance to an according set of software standards of the spacecraft customer always will be an essential requirement for testbench development.
Jens Eickhoff
10. Simulation Tools in a System Engineering Infrastructure
Abstract
System simulators, especially those integrated in SVFs and hybrid testbenches, in the real engineering process of a spacecraft in fact are no standalone tools. They are integrated into an entire system engineering infrastructure from which they receive their characterization data. Verified system characteristic parameters are stored back into the engineering environment.
Jens Eickhoff

Advanced Technologies

Frontmatter
11. Service Oriented Simulator Kernel Architectures
Abstract
In chapter 6.8 on simulator numerics the complexity of a simulator kernel was elaborated. A simulator kernel which is able to import the spacecraft system model topology to be simulated at simulator initialization time and which is able to register the components at the simulator kernel and at the solver is a quite advanced infrastructure and by far these days is not yet state of the art.
Jens Eickhoff
12. Consistent Modeling Technology for all Development Phases
Abstract
The phases A to E of a spacecraft system development have already been treated in an overview in chapter 3 please also refer to table 3.2. However, especially the early phases of development shall now be covered in a bit more detail.
Jens Eickhoff
13. Knowledge-Based Simulation Applications
Abstract
Since the beginning of the 70's, a special field of computer science, "Artificial Intelligence", (AI), has made significant progress even though the early hype meanwhile has calmed down. From the early fundamental research during the 80's the first commercial products evolved, the "Expert Systems" or knowledge-based systems. By means of such software tools knowledge is formalizable, storable and processable in the form of objects, cases and rules. The deduction of facts is achieved through instantiation of cases and rules with real object data and evaluation of these rules by a deducing algorithm called "Inference Engine".
Jens Eickhoff
14. Simulation of Autonomous Systems
Abstract
Testing on-board software, (OBSW), is one of the main use cases for system simulators throughout spacecraft development. Simulation based testing has been proven as successful approach both for tests of simple OBSW data management functions as a well as for higher control and monitoring layers.
Jens Eickhoff
Backmatter
Metadaten
Titel
Simulating Spacecraft Systems
verfasst von
Jens Eickhoff
Copyright-Jahr
2009
Verlag
Springer Berlin Heidelberg
Electronic ISBN
978-3-642-01276-1
Print ISBN
978-3-642-01275-4
DOI
https://doi.org/10.1007/978-3-642-01276-1

    Premium Partner