OPTIMAL PERIOD AND PRIORITY ASSIGNMENT FOR A NETWORKED CONTROL SYSTEM SCHEDULED BY A FIXED PRIORITY SCHEDULING SYSTEM |
M. SHIN, M. SUNWOO |
Hanyang University |
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ABSTRACT |
This paper addresses the problem of period and priority assignment in networked control systems (NCSs) using a fixed priority scheduler. The problem of assigning periods and priorities to tasks and messages is formulated as an optimization problem to allow for a systematic approach. The temporal characteristics of an NCS should be considered{{br}}by defining an appropriate performance index (PI) which represents the temporal behavior of the NCS. In this study, the{{br}}sum of the end-to-end response times required to process all I/Os with precedence relationships is defined as a PI.{{br}}Constraints are derived from the task and message deadline requirements to guarantee schedulability. Genetic algorithms{{br}}are used to solve this constrained optimization problem because the optimization formulation is discrete and nonlinear. By considering the effects of communication, an optimum set of periods and priorities can be holistically derived. |
Key Words:
Networked control system (NCS), Genetic algorithm (GA), Optimization, Performance measure, Fixed priority scheduling (FPS) |
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