Optimization Design Of MVB Periodic Dispatch Table Based On Improved Differential Evolution Algorithm

The reasonable scheduling of periodic data in multifunction vehicle bus(MVB)is of great importance for the reliability of the communication in the train communication network.And in the train communication network,the real-time capability of periodic data transmission depends on the periodic dispatch table.In order to balance the network load better and improve the reliability of train communication network,it is of great practical value to optimize the MVB periodic dispatch table further.First of all,the mathematic model of the scheduling problem is established.The evenness is set as the optimization objective function according to the IEC61375-1 international standard.The bandwidth allocation constraint condition is put forward,considering that there must be time left for the aperiodic data in the MVB dispatch table.To make the scheduling scheme meet the requirement of periodic dada deadline,the schedulability constraint condition is proposed at the same time.The whole modeling procedure follows the basic rule of periodic data schedule scheme,which is illustrated in the IEC61375-1 international standard.And the periodic data duration in every fundamental period is calculated through the timing principle of process data message,then the evenness is denoted by the standard deviation of these durations.Secondly,improved differential evolution algorithm is proposed in this paper,and the optimal scheme of MVB periodic dispatch table is obtained based on that.The improvement of the differential evolution algorithm is mainly embodied in the two stages of the algorithm operation: mutation operation and selection operation.In the mutation operation,a variety of mutation strategies are selected adaptively in order to improve the local search ability of differential evolution algorithm,making the algorithm focus on the global search in earlier iteration and the local search in later iteration,to ensure the diversity of the population and make the algorithm pick over the individual better.In the selection operation,the tolerance is introduced to ensure that the final solution meets the standard requirements of the train communication network,taking into account the constraint of the dispatch table.Lastly,the improved differential evolution algorithm is simulated on the three sets of equipment information data in the MATLAB,to verify the optimization effect of the proposed algorithm on the periodic dispatch table.And a scheduling scheme and the corresponding evenness are obtained finally.Then the improved differential evolution algorithm is compared with the differential evolution algorithm,Pareto ant colony algorithm and simulated annealing algorithm through the evenness and the bus utilization distribution map of the optimal solution obtained by these algorithms,respectively.