Traffic flow theory : a monograph

Heavy-duty vehicles driving close behind each other, also known as platooning, experience a reduced aerodynamic drag, which reduces the overall fuel consumption up to 20% for the trailing vehicle. However, due to each vehicle being assigned with different transport missions (with different origins, destinations, and delivery times), platoons should be formed, split, and merged along the highways, and vehicles have to drive solo sometimes. In this paper, we study how two or more scattered vehicles can cooperate to form platoons in a fuel-efficient manner. We show that when forming platoons on the fly on the same route and not considering rerouting, the road topography has a negligible effect on the coordination decision. With this, we then formulate an optimization problem when coordinating two vehicles to form a platoon. We propose a coordination algorithm to form platoons of several vehicles that coordinates neighboring vehicles pairwise. Through a simulation study with detailed vehicle models and real road topography, it is shown that our approach yields significant fuel savings.

Heavy-Duty Vehicle Platoon Formation for Fuel Efficiency

The analytical basis of manual vehicular control theory is a combination of feedback systems analysis and mathematical models for human operators engaged in control tasks. Simplified representations for the operator-system combination are provided by the 'crossover model', which is described in detail. The system dynamics and average performance of the crossover model system are developed. With these as bases, case studies are presented to illustrate the types of result which can be obtained from application of the operator-vehicle control theory. Two aircraft control examples illustrate the use of the theory and its empirical correlates to estimate operator dynamic characteristics, system performance, pilot ratings, pilot commentary, design implications, and some experimental guidelines. A driver automobile example is presented to illustrate the use of the theory in structuring the key guidance and control features of the driver's visual field. A comprehensive bibliography of operator-vehicle system analysis applications is also provided.

Theory of Manual Vehicular Control

An extended model for car-following

Vehicle platooning has become important for the vehicle industry. Yet conclusive results with respect to the fuel reduction possibilities of platooning remain unclear, in particular when considering constraints imposed by the topography. The focus of this study is to establish whether it is more fuel-efficient to maintain or to split a platoon that is facing steep uphill and downhill segments. Two commercial controllers, an adaptive cruise controller and a look-ahead cruise controller, are evaluated and alternative novel control strategies are proposed. The results show that an improved fuel-efficiency can be obtained by maintaining the platoon throughout a hill. Hence, a cooperative control strategy based on preview information is presented, which initiates the change in velocity at a specific point in the road for all vehicles rather than simultaneously changing the velocity to maintain the spacing. A fuel reduction of up to 14% can be obtained over a steep downhill segment and a more subtle benefit of 0.7% improvement over an uphill segment with the proposed controller, compared to the combination of the commercially available cruise controller and adaptive cruise controller that could be used for platooning. The findings show that it is both fuel-efficient and desirable in practice to consider preview information of the topography in the control strategy.

https://people.kth.se/~kallej/papers/vehicle_itsc13alam.pdf

Look-ahead cruise control for heavy duty vehicle platooning

The results of a series of experiments carried out to determine the characteristics of single-lane bus flow are reported. Using pairs of buses theoretical "car-following" models of single-lane traffic flow, which had been shown by previous work to be valid for automobiles, are examined for this type of heavy vehicle and found to provide a good representation of the detailed manner in which one bus follows another. Flow characteristics of buses were also determined by using platoons of up to ten buses. Both of these approaches, which can be termed microscopic and macroscopic, respectively, indicated that a single lane of buses form a stable stream of traffic and have an optimal flow of about 1,450 buses/hour at a speed of 33 miles/ hour for an expressway type facility.

R. Silver

Papers

Analysis of Experiments on Single-Lane Bus Flow