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


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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