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Data Acquisition and
Control System
for Test Bed Set-Ups in R&D
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Institute of Space Propulsion of the
German Aerospace Center (DLR) in Lampoldshausen, Germany
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DLR - The German Aerospace Center |
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The Institute of Space Propulsion is one of 30 institutes, test and operating facilities run
by DLR, the German Aerospace Center. DLR is Germany‘s national aerospace center
and carries out comprehensive Research & Development projects in national cooperations.
As Germany‘s space agency DLR also manages the country‘s space activities on
behalf of the German government. The German Aerospace Center employs more than 4,500
people in eight locations.
The Institute of Space Propulsion at the DLR location of Lampoldshausen focuses
on three main areas: the development of advanced technologies for future transport
systems, the operation of large test beds for the European industry, and the
continuous development of testing and control systems as well as process
engineering required for these test beds. The institute presently employs
a total of 230 scientists and other staff.
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| Fields of Research of the Institute of Space Propulsion |
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The Institute of Space Propulsion conducts fundamental research on the development and
optimization of space propulsion systems with focus on fuel conditioning, especially
of liquid oxygen and hydrogen, and the processes of combustion and materials testing.
The tests and studies on the different topics of research are carried out on several experimental test beds.
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| Task: Modernizing Experiment Test Beds
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Within the scope of re-equipping and upgrading the existing research and
test beds the DLR was looking for a data acquisition and control system that
would meet two fundamental requirements: High level of system security and maximum flexibility.
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| High Level of System Security
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Working with explosive and dangerous materials implies particular demands
on the system’s operational and failure safety. The current test bed condition
must be monitored continuously in order to be able to return to a safe state
at any time without any delay. Damages and hazards to the test beds as well
as to the staff should be excluded or at least be minimized.
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| Maximum System Flexibility
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For examining the different material properties, optimizing the processes inside the engines,
and of exploring new technologies the research test beds are operated in constantly
changing configurations based on different set-ups and media. Therefore, a data
acquisition and control system must be capable of handling a wide range of
physical parameters and diversified scenarios. At the same time, the users
require minimum set-up times to reconfigure the test bed without comprimising
flexibility. For this reason, the data acquisition and control system must
enable the user to adjust to specific requirements only through software settings.
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| Data Acquisition and Control System driven by Database and Templates
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In order to meet these requirements Werum Software & Systems had to develop
a highly flexible, configurable generic system to be integrated into the
existing infrastructure. Werum decided for a template-based approach:
In a first step, Werum analyzed the possible test scenarios on the test beds
in cooperation with the end users. The initial objective was to identify
common features, for instance in tasks, sensors used, and the flow of experiments.
It was found that in all the research areas a model combustion chamber has to be
supplied with different sorts of gas or liquids through pipe and nozzle systems.
Besides, various temperatures and pressures have to be measured and displayed at
different locations. Layout and placement of the sensors, however, vary depending
on the task and, therefore, are subject to frequent modifications.
Based on these findings Werum established a classification system to group individual
tests and experiments with similar properties. This structuring into experiment
classes is the basis for the template-based approach of the solution.
The templates will be used to derive the particular test set-ups and workflows.
In view of the large variety of sensors and actuators required, and the various
groups of users with different profiles, Werum has recommended to use a database
system to administer and make available these parameters and data.
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| Creating Templates and Definitions for Experiments
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To facilitate the creation of experiment templates (basic configurations) Werum has
integrated the graphical development environment LabVIEW® by National Instruments.
This tool enables the user to completely map the physical layout of a test bed merely
by arranging the graphical elements, such as controls and display elements.
The result is a clearly structured flow chart.
The system provides a user dialog to support the definition of individual
measuring points. First of all, the user selects the required sensor from
the sensor database. Then he defines a symbolic name and specifies the measuring
device used in this experiment. The symbolic name for a measuring point ensures
that an already defined experiment can also be used with a different measurement
equipment. Experiment layout and data acquisition hardware do not directly depend on each other.
The definition of a current experiment requires additional parameters apart from a
flow chart and a list of measuring points. In addition to the limit values for
individual sensors - the exceeding of which results in a pre-defined test bed
shutdown - the control sequences controlling the test bed have to be specified
as well. For this task, too, the system provides appropriate user dialogs guiding
the user safely through the process of setting parameters.
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| Integrated Database System
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For an easy acquisition and management of all relevant data Werum has integrated
their real-time database system BAPAS®-DB. In addition to the components for managing sensor
and actuator data, the system also provides a component for the management of test
data. It administers all further information about test bed configuration, conducted
experiments and their results. Finally, there is the user administration component
which makes it possible to create and administer a large number of different users
with their various roles and rights. All these data are acquired and managed via
graphical dialogs.
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| The Sensor Database
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The sensor database is the core component of the test data management system.
It administers all the sensors, actuators, and amplifiers as well as the configuration
and measurement data. Moreover, the user can choose the best suitable sensor for his
purposes from the pool of sensors being available in the institute and can set the
sensor parameters accordingly. In order to allow the use of commercial sensors at
their specification limits, user-related linearization polynomials can be defined in
addition to standard ones. Thus, the user can adapt even to extreme situations.
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| Test Data Management
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The test data management system furnishes the user with all the functions he
needs to manage the measurement results associated to an experiment together with
the underlying configuration data.
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| Fields of Application
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The described system is applied in research for acquiring and analyzing
thermodynamic processes involving gases and liquids. Due to its modular
and customizable design, the system may also be used for other processes
in the field of gas and liquids thermodynamics.
Applications would, for instance, be possible in test beds for
- turbo-machinery and compressors for petrochemical industry
- gas and steam turbines in the field of energy and heat generation
- jet engine test beds for the development and maintenance of aircraft engines
- rocket and satellite engines
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| Technologies Applied
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Data acquisition board by National Instruments
- NI PCI/PXI 607xE
- NI PCI/PXI 653x
- NI SCXI signal conditioning
- NI SCC signal conditioning
Software
- LabView® 6.x, National Instruments
- BAPAS®-DB realtime database system, Werum Software & Systems
- Windows 2000® Professional, Microsoft
Computer systems
- Standard industrial PCs
- Single and dual processor systems
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| Further Information
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For more information on the Institute of Space Propulsion please visit www.dlr.de
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DLR
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