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.