Using an Embedded Active Database in a
Control System Architecture
Esa Falkenroth, Anders Törne, and Tore Risch
Dept. of Computer and Information Science, Linköping University, Sweden
ABSTRACT
Typical data management problems arise in control applications when the
controlled environment becomes complex and large volumes of data are
involved. This paper addresses this problem by embedding an active
object-relational database in a control system architecture. The database
stores an abstract model of the controlled environment. A control application
language, tightly integrated with the query processor, is used for high-level
specification of operations. A set of control algorithms running on a
separate real-time kernel performs the actual closed loop control of the
external environment. The primitive operation of the control application
language is an update of the database that will trigger the control
algorithms. In this way our architecture combines cyclic con trol algorithms
and an event driven operation language with data management capabilities. The
integrated architecture makes extensive use of the active rule facilities in
the database, both in the execution of the control application language and to
initiate appropriate control algorithms in the real-time kernel. We discuss
practical experiences of building a unified control system with tightly
integrated queries and active rules.
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Esa Falkenroth
<esafa@ida.liu.se>