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Feedback-Feedforward Scheduling of Control Tasks

Cervin, Anton LU ; Eker, Johan; Bernhardsson, Bo LU and Årzén, Karl-Erik LU (2002) In Real-Time Systems 23(1-2). p.25-53
Abstract
A scheduling architecture for real-time control tasks is proposed. The scheduler uses feedback from execution-time measurements and feedforward from workload changes to adjust the sampling periods of the control tasks so that the combined performance of the controllers is optimized. The performance of each controller is described by a cost function. Based on the solution to the optimal resource allocation problem, explicit solutions are derived for linear and quadratic approximations of the cost functions. It is shown that a linear rescaling of the nominal sampling frequencies is optimal for both of these approximations. An extensive inverted pendulum example is presented, where the performance obtained with open-loop, feedback, combined... (More)
A scheduling architecture for real-time control tasks is proposed. The scheduler uses feedback from execution-time measurements and feedforward from workload changes to adjust the sampling periods of the control tasks so that the combined performance of the controllers is optimized. The performance of each controller is described by a cost function. Based on the solution to the optimal resource allocation problem, explicit solutions are derived for linear and quadratic approximations of the cost functions. It is shown that a linear rescaling of the nominal sampling frequencies is optimal for both of these approximations. An extensive inverted pendulum example is presented, where the performance obtained with open-loop, feedback, combined feedback and feedforward scheduling, and earliest-deadline first scheduling are compared. The performance under earliest-deadline first scheduling is explained by studying the behavior of periodic tasks under overload conditions. It is shown that the average values of the sampling periods equal the nominal periods, rescaled by the processor utilization. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
performance optimization, resource distribution, real-time control, feedback scheduling
in
Real-Time Systems
volume
23
issue
1-2
pages
25 - 53
publisher
Kluwer
external identifiers
  • wos:000175487100003
  • scopus:0036642331
ISSN
1573-1383
DOI
10.1023/A:1015394302429
language
English
LU publication?
yes
id
57138b7c-23ce-488a-9caf-1735b11c9635 (old id 161964)
date added to LUP
2007-06-21 14:21:00
date last changed
2017-12-10 04:27:43
@article{57138b7c-23ce-488a-9caf-1735b11c9635,
  abstract     = {A scheduling architecture for real-time control tasks is proposed. The scheduler uses feedback from execution-time measurements and feedforward from workload changes to adjust the sampling periods of the control tasks so that the combined performance of the controllers is optimized. The performance of each controller is described by a cost function. Based on the solution to the optimal resource allocation problem, explicit solutions are derived for linear and quadratic approximations of the cost functions. It is shown that a linear rescaling of the nominal sampling frequencies is optimal for both of these approximations. An extensive inverted pendulum example is presented, where the performance obtained with open-loop, feedback, combined feedback and feedforward scheduling, and earliest-deadline first scheduling are compared. The performance under earliest-deadline first scheduling is explained by studying the behavior of periodic tasks under overload conditions. It is shown that the average values of the sampling periods equal the nominal periods, rescaled by the processor utilization.},
  author       = {Cervin, Anton and Eker, Johan and Bernhardsson, Bo and Årzén, Karl-Erik},
  issn         = {1573-1383},
  keyword      = {performance optimization,resource distribution,real-time control,feedback scheduling},
  language     = {eng},
  number       = {1-2},
  pages        = {25--53},
  publisher    = {Kluwer},
  series       = {Real-Time Systems},
  title        = {Feedback-Feedforward Scheduling of Control Tasks},
  url          = {http://dx.doi.org/10.1023/A:1015394302429},
  volume       = {23},
  year         = {2002},
}