Freight transport demand has escalated and will continue to do so as economies grow. As the traffic intensity increases, the drivers are faced with increasingly complex tasks and traffic safety is a growing issue. Simultaneously, fossil fuel usage is escalating. Heavy duty vehicle (HDV) platooning is a plausible solution to these issues.
Even though there has been a need for introducing automated HDV platooning systems for several years, they have only recently become possible to implement. Advancements in on-board and external technology have ushered in new possibilities to aid the driver and enhance the system performance.
Each vehicle is able to serve as an information node through wireless communication; enabling a cooperative networked transportation system. Thereby, vehicles can semi-autonomously travel at short intermediate spacings, effectively reducing congestion, relieving driver tension,improving fuel consumption and emissions without compromising safety.
This thesis presents contributions to a framework for the design and implementation of HDV platooning. The focus lies mainly on establishing and validating real constraints for fuel optimal control for platooning vehicles. Nonlinear and linear vehicle models are presented together with a system architecture, which divides the complex problem into manageable subsystems.
The fuel reduction potential is investigated through simulation models and experimental results derived from standard vehicles traveling on a Swedish highway. It is shown through analytical and experimental results that it is favorable with respect to the fuel consumption to operate the vehicles at a much shorter intermediate spacing than what is currently done in commercially available systems.
The results show that a maximum fuel reduction of 4.7–7.7 % depending on the inter-vehicle time gap, at a set speed of 70 km/h, can be obtained without compromising safety. A systematic design methodology for inter-vehicle distance control is presented based on linear quadratic regulators (LQRs). The structure of the controller feedback matrix can be tailored to the locally available state information.
The results show that a decentralized controller gives good tracking performance, a robust system and lowers the control effort downstream in the platoon. It is also shown that the design methodology produces a string stable system for an arbitrary number of vehicles in the platoon, if the vehicle conﬁgurations and the LQR weighting parameters are identical for the considered subsystems. With the results obtained in this thesis, it is argued that a vast fuel reduction potential exists for HDV platooning. Present commercial systems can be enhanced signiﬁcantly through the introduction of wireless communication and decentralized optimal control.
Author: Alam, Assad