A real-time scheduling algorithm for hybrid tasks in networked control systems based on deferred subsequent subtasks

NCS is a widely used digital control system. A loop task in NCS includes two message subtasks and a control subtask. The three subtasks of a loop task run on different resources and must be executed in a certain order. In order to meet their real-time requirement and execution order constraint, a novel scheduling algorithm is presented. The algorithm guarantee the execution order of subtasks of a loop task by setting subtasks different starting time and subtasks running on a same resource is scheduled based RMS algorithm. The algorithm is investigated and schedulable condition is presented. A heuristic algorithm for assigning control subtasks is given based on first-fit method and “minimizing response time” principle. Finally, the simulation experiments are performed. The results of experiments show that the scheduling algorithm is feasible and effective.