The Large Error First (LEF) Scheduling Policy for Real-Time Control Systems

Most of the real-time scheduling algorithms are based on "open-loop" strategies that do not take application demands into account. This precludes the scheduler to dynamically adjust task executions in order to optimize application performance. To overcome this limitation, we focus on scheduling techniques that are able to take scheduling decisions based on continuous feedback of the application performance. Focusing on control applications, we present an early specification of a novel scheduling technique: Large Error First (LEF). It uses feedback information from each controlled plant in order to dynamically assign priorities to each control task. For a given simulation set-up, comparing the performance of LEF versus classical open-loop scheduling techniques, encouraging simulation results have been obtained.

[1]  Karl Johan Åström,et al.  Computer-controlled systems (3rd ed.) , 1997 .

[2]  Anton Cervin,et al.  A Matlab toolbox for real-time and control systems co-design , 1999, Proceedings Sixth International Conference on Real-Time Computing Systems and Applications. RTCSA'99 (Cat. No.PR00306).

[3]  George A. Perdikaris.  Computer Controlled Systems , 1991 .

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

[5]  Karl-Erik Årzén,et al.  Feedback–Feedforward Scheduling of Control Tasks , 2002, Real-Time Systems.

[6]  Gerhard Fohler,et al.  Improving quality-of-control using flexible timing constraints: metric and scheduling , 2002, 23rd IEEE Real-Time Systems Symposium, 2002. RTSS 2002..

[7]  Sang Hyuk Son,et al.  Feedback Control Real-Time Scheduling: Framework, Modeling, and Algorithms* , 2001, Real-Time Systems.