Study On The Dynamic Pick-up Vehicle Scheduling Problems

Along with the variation of time, new customer requests, cancellation of the customer requests, modification of customer requests, variation in travelling time and other dynamic events often appear in the pick-up vehicle scheduling problems. With the rapid development of the logistics industry and society, customer service quality and timeliness are increasingly in high demand, which requires scheduling plan makers to collect real-time information of customer demands, to monitor road network conditions and operation of vehicles, and then to adjust the vehicle scheduling plan in time to make the system objective be superior. In this case, it's necessary to study the theory and methods of the dynamic pick-up vehicle scheduling problems, which can be adapt to deal with a variety of dynamic information.Focusing on the dynamic pick-up vehicle scheduling problems, the following were done in this paper:(1) The dynamic events and appropriate response strategies were analyzed systematically for the dynamic pick-up vehicle scheduling probems.(2) A new method for calculating the degree of dynamism of the problem was proposed in this paper, which is suitable for the dynamic pick-up vehicle scheduling problems with a variety of dynamic events.(3) The solving strategy was designed, including dynamic events response strategy and the setting of the rolling horizons.(4) The pick-up vehicle scheduling problem with soft time windows and new customer requests was studied. The solving strategies were analyzed and model for the problem was established. Examples with different degrees of dynamism were designed. Six solving strategies under the rolling horizons with equal time interval and the rolling horizons with unequal time interval were designed for the examples. The Performances of six strategies were compared and better strategies were obtained.(5) The pick-up vehicle scheduling problem with soft time windows and changes of customer requests was studied. The solving strategies were analyzed and model for the problem was established. Based on the conclusion of the study on the pick-up vehicle scheduling problem with soft time windows and dynamic customer requests, two better solving strategies were selected for solving the pick-up vehicle scheduling problem with soft time windows and changes of customer requests (including the dynamic arrival of new customer requests, the cancellation of customer requests and modification of customer requests). Simulated annealing algorithm with dynamic neighborhood and tabu search algorithm with dynamic neighborhood were used to solve the problem. Examples with different degrees of dynamism were designed. For each algorithm, the performances of the two solving strategies were compared and analyzed. For the same solving strategy, the performances of different algorithms were compared and analyzed.Finally, the better algorithm and strategy for the dynamic pick-up vehicle with certain degree of dynamism were obtained.(6) The pick-up vehicle scheduling problem with changes of customer requests and vehicle travel time was studied. The solving strategies were analyzed and model for the problem was established. Based on the conclusion of the pick-up vehicle scheduling problem with soft time windows and changes of customer requests, simulated annealing algorithm with dynamic neighborhood and corresponding solving strategy were used to solve the problem. Then, best scheduling plan was obtained.