Handling Execution Overruns in Hard Real-Time Control Systems

In many real-time control applications, the task periods are typically fixed and worst-case execution times are used in schedulability analysis. With the advancement of robotics, flexible visual sensing using cameras has become a popular alternative to the use of embedded sensors. Unfortunately, the execution time of visual tracking varies greatly. In such environments, control tasks have a normally short computation time, but also an occasional long computation time; therefore, the use of worst-case execution time is inefficient for controlling performance optimization. Nevertheless, to maintain the control stability, we still need to guarantee the schedulability of the task set, even if the worst case arises. In this paper, we propose an integrated approach to control performance optimization and task scheduling for control applications where the execution time of each task can vary greatly. We present an innovative approach to overrun management that allows us to fully utilize the processor for optimizing the control performance and yet guaranteeing the schedulability of all tasks under worst-case conditions.

[1]  Kang G. Shin,et al.  QoS negotiation in real-time systems and its application to automated flight control , 1997, Proceedings Third IEEE Real-Time Technology and Applications Symposium.

[2]  Lui Sha,et al.  Elastic feedback control , 2000, Proceedings 12th Euromicro Conference on Real-Time Systems. Euromicro RTS 2000.

[3]  Seongsoo Hong,et al.  Toward Automatic Synthesis of Schedulable Real-Time Controllers , 1998, Integr. Comput. Aided Eng..

[4]  Sang Hyuk Son,et al.  The case for feedback control real-time scheduling , 1998, Proceedings of 11th Euromicro Conference on Real-Time Systems. Euromicro RTS'99.

[5]  Louis E. Rosier,et al.  On Preemptive Scheduling of Periodic, Real-Time Tasks on One Processor , 1990, MFCS.

[6]  Sang Hyuk Son,et al.  Design and evaluation of a feedback control EDF scheduling algorithm , 1999, Proceedings 20th IEEE Real-Time Systems Symposium (Cat. No.99CB37054).

[7]  Jane W.-S. Liu,et al.  Performance of algorithms for scheduling real-time systems with overrun and overload , 1999, Proceedings of 11th Euromicro Conference on Real-Time Systems. Euromicro RTS'99.

[8]  Giorgio C. Buttazzo,et al.  QoS guarantee using probabilistic deadlines , 1999, Proceedings of 11th Euromicro Conference on Real-Time Systems. Euromicro RTS'99.

[9]  Marco Spuri,et al.  Efficient aperiodic service under earliest deadline scheduling , 1994, 1994 Proceedings Real-Time Systems Symposium.

[10]  Kang G. Shin,et al.  Adaptation and graceful degradation of control system performance by task reallocation and period adjustment , 1999, Proceedings of 11th Euromicro Conference on Real-Time Systems. Euromicro RTS'99.

[11]  Marco Spuri,et al.  Scheduling aperiodic tasks in dynamic priority systems , 1996, Real-Time Systems.

[12]  Lui Sha,et al.  On task schedulability in real-time control systems , 1996, 17th IEEE Real-Time Systems Symposium.

[13]  Francesco Zanichelli,et al.  Rate modulation of soft real-time tasks in autonomous robot control systems , 1999, Proceedings of 11th Euromicro Conference on Real-Time Systems. Euromicro RTS'99.

[14]  Chenyang Lu,et al.  Feedback control real-time scheduling , 2001 .

[15]  Kang G. Shin,et al.  QoS negotiation in real-time systems and its application to automated flight control , 1997, Proceedings Third IEEE Real-Time Technology and Applications Symposium.

[16]  L. Abeni,et al.  A new kernel approach for modular real-time systems development , 2001, Proceedings 13th Euromicro Conference on Real-Time Systems.

[17]  James W. Layland,et al.  Scheduling Algorithms for Multiprogramming in a Hard-Real-Time Environment , 1989, JACM.

[18]  Giuseppe Lipari,et al.  Elastic task model for adaptive rate control , 1998, Proceedings 19th IEEE Real-Time Systems Symposium (Cat. No.98CB36279).

[19]  Krithi Ramamritham,et al.  The Spring System: Integrated Support for Complex Real-Time Systems , 1999, Real-Time Systems.

[20]  Giorgio C. Buttazzo,et al.  Integrating multimedia applications in hard real-time systems , 1998, Proceedings 19th IEEE Real-Time Systems Symposium (Cat. No.98CB36279).

[21]  Marco Spuri,et al.  Robust aperiodic scheduling under dynamic priority systems , 1995, Proceedings 16th IEEE Real-Time Systems Symposium.

[22]  Giuseppe Lipari,et al.  Sharing resources among periodic and aperiodic tasks with dynamic deadlines , 1999, Proceedings 20th IEEE Real-Time Systems Symposium (Cat. No.99CB37054).

[23]  Theodore P. Baker,et al.  Stack-based scheduling of realtime processes , 1991, Real-Time Systems.

[24]  Joseph Y.-T. Leung,et al.  On the complexity of fixed-priority scheduling of periodic, real-time tasks , 1982, Perform. Evaluation.