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Van-based Robot Routing Problem with Backhauls under Time-varying Traffic Conditions

Moosavi, Parisa | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55752 (01)
  4. University: Sharif University of Technology
  5. Department: Industrial Engineering
  6. Advisor(s): Akbari, Mohammad Reza
  7. Abstract:
  8. The rapid growth of e-commerce and home delivery has increased the number of vehicles on the streets. As a result of that, traffic congestion and, in return, air pollution have got worse. To prevent this trend, using electric vehicles is highly suggested, and in recent years, some companies have started using autonomous delivery robots. Since these robots can travel for a limited time, it is better to use them in conjunction with other vehicles, like vans. In this research, we propose a mixed-integer programming model to formulate a two-echelon time-dependent vehicle routing problem with simultaneous pick-up and delivery. In the first echelon, vans travel from a central depot to parking and customers, and in the second echelon, robots serve other customers. As mentioned above, there is are types of demand: delivering goods to a customer and picking up goods from a customer. The speed of vans varies based on traffic congestion and their travel time between every two places is calculated based on travel start time using linear approximation. Since CPLEX can only solve instances of very limited sizes, we propose two metaheuristics: A simulated Annealing algorithm (SA), and a hybrid algorithm based on the concepts of Variable Neighborhood Search (VNS) and Tabu Search (TS). Both algorithms are efficient in solving small instances, but the hybrid algorithm gives better solutions for large instances, although it takes a longer time to solve the problem. Comparing the proposed model with the same model that just uses vans for delivery shows that using robots leads to a major decrease in transportation costs. However, this reduction does not necessarily result in an increase in time or travel distance. The noteworthy point is that the results of sensitivity analysis on the robot's speed and maximum travel time indicates that transportation costs are not highly influenced by these factors and it is highly recommended that robots with low travel speed be used so that pedestrians will be safe. Using robots with more powerful batteries which ensures longer travel times may be profitable depending on the cost scale.
  9. Keywords:
  10. Vehicle Routing Problem ; Meta Heuristic Algorithm ; Unmanned Aerial Vehicles (UAV) ; Time-Dependent Routing ; Variable Neighborhood Search ; Tabu Search Algorithm

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