Advertisement

Real-Time Systems

, Volume 27, Issue 3, pp 215–236 | Cite as

A Task Model to Reduce Control Delays

  • Patricia Balbastre
  • Ismael Ripoll
  • Josep Vidal
  • Alfons Crespo
Article

Abstract

Industrial control applications are usually developed in two phases: control design and real-time system implementation. In the control design stage a regulator is obtained and later it is translated into an algorithm in the implementation phase. Traditionally, these two phases have been developed in separate ways. Recently, some works have pointed out the necessity of the integration of the control design and its implementation. One of these works reduce the delay variance of control tasks (defined as the control action interval (CAI) and data acquisition interval (DAI) parameters) splitting every task into three parts. The CAI reduction method highly reduces the delay variance and improves the control performance. This work shows how to evaluate these delays under static and dynamic scheduling policies. A new task model is proposed in order to reduce the CAI and DAI parameters, which implies an improvement in the control performance. The new task model will be implemented in a real process, and the experimental measurements will show how, effectively, the control performance is highly improved with the methods presented in this paper.

timing jitter control design schedulability analysis multi-rate controllers 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Albertos, P., Crespo, A., Ripoll, L, Vallés, M., and Balbastre, P. 2000a. RT control scheduling to reduce control performance degrading. In Proceedings of the 39th IEEE Conference on Decision and Control.Google Scholar
  2. Albertos, P., Salgado, M., and Olivares, M. 2000b. Are delays in digital control implementation always bad? In Asian Control Conference, Shangai.Google Scholar
  3. Audsley, N. 1991. Resource Control for Hard Real-Time Systems: A Review. Technical Report YCS 159, University of York, Department of Computer Science.Google Scholar
  4. Audsley, N., Burns, A., Tindell, K., Richardson, M., and Wellings, A. 1993. Applying new schedulability theory to static priority pre-emptive scheduling. Software Engineering Journal 8(5): 284-292.Google Scholar
  5. Baker, T. P. 1991. Stack-based scheduling of realtime processes. The Journal of Real-Time Systems 3(1): 67-100.Google Scholar
  6. Barabanov, M., and Yodaiken, V. 1996. Real-time linux. Linux Journal.Google Scholar
  7. Baruah, S., Mok, A., and Rosier, L. 1990. Preemptively scheduling hard real-time sporadic tasks on one processor. In IEEE Real-Time Systems Symposium, pp. 182-190.Google Scholar
  8. Cervin, A., and Ecker, J. 2000. Feedback scheduling of control tasks. In Proceedings of the 39th IEEE Conference on Decision and Control.Google Scholar
  9. Crespo, A., Ripoll, I., and Albertos, P. 1999. Reducing delays in RT control: the control action interval. IFAC World Congress Beijing.Google Scholar
  10. Iserman, R. 1989. Digital Control Systems. Springer Verlag.Google Scholar
  11. Joseph, M., and Pandya, P. 1986. Finding response times in a real-time system. The Computer Journal 29(5): 390-395.Google Scholar
  12. Lehoczky, J., Sha, L., and Ding, Y. 1989. The rate monotonic scheduling algorithm: Exact characterization and average case behavior. In IEEE Real-Time Systems Symposium, pp. 166-171.Google Scholar
  13. Liu, C., and Layland, J. W. 1973. Scheduling algorithms for multiprogramming in a hard real-time environment. JACM 23: 46-68.Google Scholar
  14. Martí, P., Fuertes, J. M., and Fohler, G. 2001. Jitter compensation for real-time control systems. In IEEE Real-Time Systems Symposium.Google Scholar
  15. Mok, A. 1983. Fundamental Design Problems of Distributed Systems for the Hard Real-Time Environment. MIT/LCS/TR-297, Laboratory of Computer Science, MIT.Google Scholar
  16. Ripoll, I., Crespo, A., and García-Fornes, A. 1995. An optimal algorithm for scheduling soft aperiodic tasks in dynamic-priority preemptive systems. IEEE Transactions on Software Engineering 23(6): 388-400.Google Scholar
  17. Ripoll, I., Crespo, A., and Mok, A. 1996. Improvement in feasibility testing for real-time tasks. Journal of Real-Time Systems 11: 19-40.Google Scholar
  18. Seto, D., Lehoczky, J., and Sha, L. 1998. Task period selection and schedulability in real-time systems. In IEEE Real-Time Systems Symposium, pp. 188-198.Google Scholar
  19. Sha, L., Rajkumar, R., and Lehoczky, J. 1990. Priority inheritance protocols: an approach to real-time synchronisation. IEEE Transactions on Computers 39(9): 1175-1185.Google Scholar
  20. Spuri, M. 1996. Analysis of Deadline Scheduled Real-Time Systems. Rapport de Recherche RR-2772, INRIA, Le Chesnay Cede, France.Google Scholar
  21. Torngren, M. 1998. Fundamentals of implementing real-time control applications in distributed computer systems. The Journal of Real-Time Systems 14(3): 3-34.Google Scholar

Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  • Patricia Balbastre
    • 1
  • Ismael Ripoll
    • 1
  • Josep Vidal
    • 1
  • Alfons Crespo
    • 1
  1. 1.Department of Computer EngineeringTechnical University of ValenciaValenciaSpain

Personalised recommendations