ARTES
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Second Year Report: Integrated Control and Scheduling

2000-08-11

Karl-Erik Årzén                         Klas Nilsson
Dept of Automatic Control    Dept of Computer Science
Lund University                      Lund University

Project plan fulfillment

The project started 980501 and is intended as a 2+2 year ARTES project at 80% activity level. The first half of the project will, hence, terminate on 001031. The project plan from the original proposal and the updated project plan from the project evaluation 9908 have been followed without deviations and the licentiate theses for the two PhD students have been successfully presented (Patrik Persson, 000412, and Anton Cervin, 000526).
 

Main achievements

The project has so far been very successful. This can for example be seen in the recent ARTES evaluation by Andy Wellings where we cite:
"I think this project borders on VERY GOOD. There are good conference publications and journal publications are beginning to appear. The collaboration with Lui Sha is most welcome and important"
The evaluation also recommends that funding is maintained to allow completion of the PhDs.

The main achievements in the Feedback scheduling subproject are the following. An in-depth state-of-the-art survey of the field has been written. A first prototype of a simulator that allows co-simulation of control algorithms and feedback scheduling strategies has been developed. The scheduling of different parts of a control algorithm has been investigated and a new iterative deadline-based priority assignment scheme has been developed. The performance of different scheduling strategies under overload conditions and its influence on control performance have been studied. Experiments with feedback and feedforward-based scheduling strategies have been performed. A special invited session for the CDC 2000 in Sydney (Conference on Decision and Control, the most prominent annual major control conference), on Integrated Control and Scheduling has been organized and accepted.

The main achievements in the Interactive Execution Time Analysis subproject are the following.  A declarative way of implementing WCET has been developed based on reference attribute grammars. To correctly schedule automatic memory management  in hard real-time systems, we have presented a live memory analysis that allows this information to be automatically determined based on straight-forward programmer annotations.  The WCET analysis and the required annotations have also been extended to cope with virtual method calls and dynamic class loading, which is needed when developing flexible object-oriented real-time systems. Finally, for such system development, a first prototype of an interactive development environment (called Skånerost) utilizing the proposed techniques has been developed. Although much of our research is not restricted to any particular language, we use Java as our target language due to its popularity, portability, safety, and built-in support for concurrency (to which we add real-time support).

Embedded real-time control systems are of great importance to Swedish industry. There is currently a trend towards on-line scheduling in favor of static scheduling. There is also a trend towards using off-the-shelf computing platforms also for real-time control applications. As the embedded systems grow more complex due to customer demands, the need for using high-level languages for time-critical systems increases. Real-time Java plays a key role in this development. The interactive timing analysis in this project is an important prerequisite for this. In related projects work on real-time garbage collection and real-time Java run-time systems are performed, partly in collaboration with ABB, Ericsson, and Sun Microsystems.

All together this means that the results that have and will be developed in the project are very relevant for important parts of Swedish industry. The co-design and simulation environment, and the interactive WCET tool for obtaining the timing of specific control blocks, clearly are candidates for industrial application.
 

Industrial statement

"I den del av industrin vi jobbar d.v.s. telekom, verkstadsindustrin och medicinsk industri ser vi dagligen problemställningar som berör hur man på bästa sätt behandlar inbyggda system lösningar. Det arbete som bedrivs inom projektet avser att föra fram den svenska industrin så att man använder nya och effektivare sätt att tackl dessa problemställningar. Denna forskning med dess lösningar är ett måste för att svensk industri skall klara av den hårda konkurrensen som råder på världsmarknaden samt att  vi inom landet kan upprätthålla en god kompetensnivå inom dessa områden.

SES är att bolag som jobbar inom konsultbranschen. Detta innebär att vi ser många olika företags frågeställningar inom inbyggda system, dock gör vi ingen egen produktutveckling. Då det nu finns resultat och god substans i projektet, som kan visas upp för svensk industri, så har vi en god möjlighet att knyta ihop och fungera som en brygga mellan industrin och forskningen.

I den inledande fasen av projektet så har SES deltagit som diskussionspartner. Detta har till stor del inneburit att vi har försökt att ge en bild av vad som idag används av industrin inom de områden som projektet berör. Vi klan referera till hur industrin löser sina problem samt även peka på varför industrin löser dem på detta sätt.

SES har under den inledande fasen framförallt deltagit som diskussionspartner men ser nu att projektet har nått en stabilitet. Med stabilitet menar vi från SES att projektmedlemmarna har bygget upp en kunskapsbank och en färdighet som kommer att kunna användas på ett mycket konstruktivt sätt. Vi från SES avser att deltaga under den efterföljande tiden in te bara som diskussionspart utan även knyta ihop intressanta "verkliga" problemställningar som vi vet finns i industrin. SES hoppas verkligen att projektet kommer att erhålla vidrae finansiering, då vi under den gångna tiden har sett att det har genererats goda resultat, publikationer samt engagerade arbetsinsatser."

Malmö, 2000-08-16

Jan J Enejder

Manager Embedded Systems
Sigma Exallon Systems, SES

Publications

Theses

P. Persson: Predicting Time and Memory Demands of Object-Oriented Programs. Licentiate thesis, Department of Computer Science, Lund Institute of Technology, April 2000.
A. Cervin: Towards the Integration of Control and Real-Time Scheduling Design. Licentiate thesis, Department of Automatic Control, Lund Institute of Technology, May 2000.

Journal Articles

K.-E. Årzén and A. Cervin: A Simple Event-Based PID Controller. Accepted for Control Engineering Practice, 2000.
J. Eker, P. Hagander, and K.-E. Årzén: A Feedback Scheduler for Real-time Controller Tasks. To appear in Control Engineering Practice, 2000.
K.-E. Årzén, A. Cervin, J. Eker, B. Bernhardsson, L. Sha: Towards the Integration of Control and Real-Time Scheduling Design. In journal submission, 2000.

Conference Publications

P. Persson and G. Hedin: Interactive Execution Time Predictions using Reference Attributed Grammars. In Proceedings of WAGA '99, Second Workshop on Attribute Grammars and their Applications, Amsterdam, The Netherlands, March 1999.
P. Persson: Live Memory Analysis for Garbage Collection in Embedded Systems. In Proceedings of the ACM SIGPLAN 1999 Workshop on Languages, Compilers, and Tools for Embedded Systems, Atlanta, GA, May 1999.
A. Cervin: Improved Scheduling of Control Tasks. In Proceedings of the 11th Euromicro Conference on Real-Time Systems, York, England, June 1999.
P. Persson: Using Aliasing Information to Predict Real-Time Garbage Collection in Embedded Systems. Position paper presented at the Intercontinental Workshop on Aliasing in Object-Oriented Systems, Lisbon, Portugal, June 1999.
K.-E. Årzén: A Simple Event-Based PID Controller. In Proceedings of the IFAC World Congress, Beijing, China, July 1999.
J. Eker and A. Cervin: A Matlab Toolbox for Real-Time and Control Systems Co-Design. In Proceedings of the 6th International Conference on Real-Time Computing Systems and Applications, Hong Kong, China, December 1999.
P. Persson and G. Hedin: An Interactive Environment for Real-Time Software Development. In Proceedings of the 33rd International Conference on Technology of Object-Oriented Languages and Systems, St. Malo, France, June 2000.
K.-E. Årzén, A. Cervin, J. Eker, and L. Sha: An Introduction to Control and Real-Time Scheduling Co-Design. 39th IEEE Conference on Decision and Control, Sydney, Australia, December 2000.
A. Cervin and J. Eker: Feedback Scheduling of Control Tasks. 39th IEEE Conference on Decision and Control, Sydney, Australia, December 2000.

Technical Reports

K.-E. Årzén, B. Bernhardsson, J. Eker, A. Cervin, K. Nilsson, P. Persson, and L. Sha: Integrated Control and Scheduling. Internal report TFRT-7582, Department of Automatic Control, Lund Institute of Technology, August 1999.
A. Cervin: The Real-Time Control Systems Simulator---Reference Manual. Internal Report TFRT-7592, Department of Automatic Control, Lund Institute of Technology, April 2000.
P. Persson, A. Cervin, and J. Eker: Execution-Time Properties of a Hybrid Controller. Internal report TFRT-7591, Department of Automatic Control, Lund Institute of Technology, April 2000.

Karl-Erik Arzen and Klas Nilsson
Last modified: 2000-08-09
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