1995 Volume 7 Issue 5 Pages 1050-1061
In the paper, the concept of fuzzy die-time is defined in the vehicle routing and scheduling context. Usually customers' preferences for service can be classified into two kind of types : the tolerable interval of service time and the desirable time for service. Conventional approaches just consider the tolerable interval of service time and do not care for customers' desired time. The proposed fuzzy approach can handle both kind of customers' preferences simultaneously.Fuzzy due-time for each customers is given as a triangular fuzzy number and the membership function is corresponding to the grade of satisfaction of service time. Fuzzy vehicle routing problem is formulated with the concept of fuzzy due-time. The objectives considered here are to minimize the fleet size of vehicles, maximize the average grade of satisfaction over customers, minimize total travel distance, and total waiting time for vehicles.Genetic algorithm is investigated for solving the fuzzy vehicle routing problem. An insertion heuristic based crossover is designed towards to generate improved offspring. A push-bump-throw heuristic procedure is proposed to handle the fuzzy feature of the problem.Preliminary computational experiments on several randomly generated test problems have been executed and the results demonstrate that genetic algorithms and fuzziness approach can be a promising way for vehicle routing and scheduling problems.
