数控系统的混合任务模型及其最优调度算法研

针对数控系统中多种类型任务并存,且任务之间在时序、资源等方面存在相关性的特点,建立了混合任务系统模型,并引入计算机人工智能领域的启发式最佳优先搜索算法来实现该模型任务集的最优调度.该算法通过搜索问题的状态空间树,在符合所有约束条件的状态节点中寻找使得启发式评估函数取到极小（或极大）值的节点,最终得到系统的最优调度集.实例研究和算法性能分析表明,该算法解决了传统实时系统调度算法不适用于混合任务系统的问题,对于并发任务数量不大的数控系统,能有效地实现任务的最优调度.

Hybrid tasks model of NC system and its optimal scheduling algorithm

To describe the characteristics of numerical control(NC) system,which is a hybrid tasks system consisting of a variety of tasks that are not independent of the existence of precedence order and resource hazard,a new hybrid tasks system(HTS) model was presented.As the traditional real-time scheduling algorithms are no longer suitable for characteristics of NC system,a heuristic best-first search(BFS) algorithm was introduced to schedule HTS model tasks.The BFS algorithm searches state node matching constraint conditions and minimizing(maximizing) the value of heuristic evaluation function in the state-space tree,so that it can work out the problem with an optimal solution.Case study and computation complexity analysis proved that BFS algorithm can schedule tasks in NC system effectively.