Optimization of a service logistic system using multi-objective multi-period travelling salesman problem with repair-pickup

Nowadays, intense competition among the service companies has made it necessary to employ a responsive logistics system, to offer short lead times, and respond to customer needs in a timely fashion. Applying operations research approaches in the design of logistics operations can contribute a lot to this trend. The so-called Travelling Salesman Problem (TSP) is one of the best known combinatorial optimization problems which can be used in this respect. This paper sought to propose a new extension to the TSP to represent the problem in an after-sale service case. The objective function in the proposed model consists of transportation time, and the lead time as the most important factor influencing customer service level.