MODELING AND OPTIMIZING A VEHICLE NAVIGATION SYSTEM BY G-NETWORK

Authors : Mohammad Kouchaki Pahnekolae, Morteza Romoozi, Mahshid Ghorbani, Hamideh Babaei

Pages : 26-37

View : 16 | Download : 8

Publication Date : 2019-12-20

Article Type : Research

Abstract :Increasing the production of vehicles and ne- cessity to use private and public cars have led to heavy traffic that has negative effects in that respect. The aim of intelligent transportation systems (ITS) is improving the quality of transportation, re- ducing travelling time and reducing fuel consump- tion via advanced technologies. Clearly, analyzing the routing problems of vehicles and finding opti- mized routes are among the considerable challenges in intelligent transportation systems. Vehicle navigation systems are the systems used for leading and routing. Using GPRS communica- tion, these systems provide on-line services for col- lecting instant traffic information, such as vehicles coordination, speed and type, for enhancing them for efficient routing of vehicles. Furthermore, they can prepare diverse traffic reports regarding time, period, max. and min. speeds, the total driven dis- tance in a desired specific date or time limit. Many navigation systems have used offline city maps and pre-set maps together with the history of nav- igation data obtained from GPS. These systems are not suitable due to rapid changes in the traffic con- ditions. Since, online systems are preferred. Focusing on online navigation systems and dynamic VRP, we pre- sented a navigation system for the vehicles to receive updated traffic information on reaching each junc- tion, and select the best route with lower traffic to their destination, in case they are permitted to move in it. In this paper, we used G-Network for modeling the proposed vehicles navigation system. G-Networks are queuing networks with the idea of considering negative customers against positive ones. Negative customers or signals can be considered actual or virtual, operating in different manners in the net- work. They can destruct positive customers in a queue , cause momentary passing of the customers to another queue, or remove a group of customers from the network. Vehicles in our proposed model are positive cus- tomers and routing decisions are negative custom- ers, here with considered virtual. The queue net- work is the map of an assumed city. Vehicles may be of different types, such as cars, heavy vehicles and rescue vehicles. Therefore, positive customers in the modeling include different classes. In this graph, each junction and also segments distribut- ed uniformly in each pathway establish the queues of the queuing network. Accordingly, the relevant performance metrics of the network are presented. The given model provide the possibility for us to use gradient descent method for optimization of the routing. Gradient descent is a first order op- timization algorithm, used for finding the mini- mum rate of functions. In optimizing the behavior of the network, it was attempted to minimize the cost function, which includes parameters such as the probability of passing a type of vehicle from a junction and also probability of a routing decision in the junction. The obtained results from optimization show that the routing problems are improved by con- sidering different criteria including average delay for the vehicles, average delay for routing decisions, average delay for the whole network and average usefulness.
Keywords : Vehicle routing, navigation system, G-Network