摘要
针对信息物理系统(CPS)中物理连续进程与计算离散进程实时交互任务集的可调度性难以准确、快速地分析,提出一种基于有限状态机(FSM)的执行器状态自动机(ASA)分析方法.首先将CPS调度性问题转换为自动机状态位置的可达性问题进行分析,定义了状态转移约束条件,并采用超致密时间模型表达全局时间信号,然后建立ASA与FMS的状态关系映射,证明ASA可达性判定问题.最后提出一种基于决策树的ASA状态集分类搜寻策略(DT-ASA*),通过Ptolemy II平台建立DT-ASA*策略模型并分析其精确性、执行时间及内存使用率,仿真结果显示系统模型预测值与实际值基本一致,但仍然存在过度匹配的现象,使用模型预测任务状态能极大减少执行时间,但同时会消耗更多内存资源.
Aiming at the problem which the tasks set schedulability is difficult to analysis accurately and quickly when real-time interaction of continuous physical process and discrete computing process in cyber physical system. A analysis method based on finite state machine( FSM) and named actor state automata is proposed. First,it translates the schedulability analysis of CPS to the reachability analysis of the state locations in automata,and the state transition constraints are defined,the superdense time model is adopted for expressing global time signal,then the status mapping relationships between ASA and FSMare established,and the decision problem of reachability is proved. Lastly,a classified search strategy of state set for ASA based on decision tree and named DT-ASA*is proposed,and analyzes its accurateness,execution time and memory usage through establishes a model in Ptolemy II,and the simulation results showthat the predicted value and actual value are basically identical,but still exists the phenomenon of excessive matching,the model can greatly reduce the execution time,but at the same time will consume more memory resources.
引文
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