# Efficient Position Change Algorithms for Prolonging Driving Range of a Truck Platoon
###### Abstract  
Cooperative automated driving technology has emerged as a potential way to increase the efficiency of transportation systems and enhance traffic safety by allowing vehicles to exchange relevant information via wireless communication. Truck platooning utilizes this technology and achieves synchronized braking and acceleration, controlling two or more trucks simultaneously. This synchronized control makes driving with a very short inter-vehicle distance among trucks possible and reduces aerodynamic drag. This provides significant fuel consumption reduction, both in leading and trailing trucks, and achieves fuel-saving improvement. However, the static positioning sacrifices trucks in the front since they consume more fuel energy because of more air resistance than the rears. To solve this in-equivalent fuel consumption reduction benefit, this paper presents several heuristic algorithms to balance fuel consumption reduction and prolong the driving ranges by exploiting position changes among trucks in a platoon. Furthermore, the proposed algorithms try to reduce the number of position changes as much as possible to prevent any fuel waste caused by the unnecessary position change operations. In this manner, each truck in the platoon is likely to share a similar fuel consumption reduction with fewer position change counts, thus addressing the challenge of in-equivalent fuel savings distribution and obtaining optimal fuel efficiency. Our extensive simulation results show that the proposed algorithms can prolong the total distance by approximately 3% increased in two-truck platooning and even higher in six-trucks platooning of approximately 8%. Moreover, our proposed algorithms can decrease the position change count and ensure that trucks only switch to position arrangement once with no duplicate. Therefore, truck platooning obtains the maximum driving range with fewer position change counts, thus achieving efficient fuel saving. truck platooning fuel consumption; fuel reduction potential; autonomous vehicle; cooperative automated driving +
Footnote †: journal: Applied  
simultaneously, thereby achieving driving with a small safety inter-vehicle space in which human drivers may not perform better. As a consequence of the small inter-vehicle distance, this significantly helps to improve fuel efficiency by reducing aerodynamic drag [2], which brings down fuel consumption and cuts optional costs. Several simulations-based studies [3; 4; 5; 6; 7] have proved that truck platooning results in fuel-saving approximately 10% on average, since air friction becomes a problem only for the leading truck such that it benefits trailing trucks with a much smaller resistance. Although previous experiments present diverse results due to different conditions [8], all results still validate that fuel efficiency can be improved the best in trailing trucks, providing much higher fuel saving compared to the lead one. Even though truck platooning has already offered various benefits due to the lower fuel usage, we foresee that this technology can be improved to achieve a higher driving distance by changing the positions of the trucks within the platoon. The novel idea is based on the simple fact that trucks at the front consume more fuel energy than the rear trucks in the platoon. Thus, instead of having static positions during the entire driving, changing positions from time to time can redistribute the unequal fuel consumption rates evenly among the trucks. By exploiting such intuition, we have proposed preliminary position change algorithms in truck platooning [9]. The algorithms make trucks consume an almost similar amount of fuel by periodically changing the positions of trucks in the platoon until one runs out of energy. Theoretically, this algorithm allows truck platooning to drive longer because trucks with more fuel go to the front, where trucks with less energy can experience less air resistance at the rear positions.