数控系统;调度算法;软件容错, 主版本;替代版本

According to the characteristics of hybrid task set and high dependability of numerical control systems, a fault tolerant real time scheduling algorithm based on software fault-tolerant model was proposed to dispose of system transient faults. In order to provide the maximal execution time for the primaries, the FT-MT algorithm reserves time intervals as late as possible for all the alternates before their deadlines. At the same time, for the sake of preventing early failures in execution from giving rise to failures in the subsequent tasks, an executive rule for primaries was added into the FT-MT algorithm which improved the predictive quality of the primaries remarkably. The simulation experiments show that the FT-MT algorithm has much better fault resilience than that of the well-known algorithms so far.