Mixed Inititiation for Cooperative Adaptive Cruise Control (original) (raw)
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Cooperative Adaptive Cruise Control
Transportation Research Record: Journal of the Transportation Research Board, 2015
Cooperative adaptive cruise control (CACC) includes multiple concepts of communication-enabled vehicle following and speed control. Definitions and classifications are presented to help clarify the distinctions between types of automated vehicle-following control that are often conflated with each other. A distinction is made between vehicle-to-vehicle (V2V) CACC, based on vehicle–vehicle cooperation, and infrastructure-to-vehicle CACC, in which the infrastructure provides information or guidance to the CACC system (such as the target set speed value). In V2V CACC, communication provides enhanced information so that vehicles can follow their predecessors with higher accuracy, faster response, and shorter gaps; the result would be enhanced traffic flow stability and possibly improved safety. A further distinction is made between CACC, which uses constant-time-gap vehicle following (forming CACC strings), and automated platooning, which uses tightly coupled, constant-clearance, vehicl...
Cooperative Adaptive Cruise Control (Cacc) Definitions and Operating Concepts
Cooperative Adaptive Cruise Control (CACC) includes multiple concepts of communicationenabled vehicle following and speed control. This paper presents definitions and classifications to help clarify the distinctions among different types of automatic vehicle following control that are often conflated with each other. A distinction is made between V2V CACC, based on vehicle-vehicle cooperation, and I2V CACC, in which the infrastructure provides information or guidance to the CACC system (such as the target set speed value). In V2V CACC, communication provides enhanced information so that vehicles can follow their predecessors with higher accuracy, faster response, and shorter gaps, resulting in enhanced traffic flow stability and possibly improved safety. A further distinction is made between CACC, which uses constant-time-gap vehicle following (forming CACC strings), and automated platooning, which uses tightly-coupled, constant-clearance, vehicle-following strategies. Although ACC ...
2018 21st International Conference on Intelligent Transportation Systems (ITSC), 2018
Connected and automated vehicles (CAVs) have the potential to address the safety, mobility and sustainability issues of our current transportation systems. Cooperative adaptive cruise control (CACC), for example, is one promising technology to allow CAVs to be driven in a cooperative manner and introduces system-wide benefits. In this paper, we review the progress achieved by researchers worldwide regarding different aspects of CACC systems. Literature of CACC system architectures are reviewed, which explain how this system works from a higher level. Different control methodologies and their related issues are reviewed to introduce CACC systems from a lower level. Applications of CACC technology are demonstrated with detailed literature, which draw an overall landscape of CACC, point out current opportunities and challenges, and anticipate its development in the near future.
Design and experimental evaluation of cooperative adaptive cruise control
2011 14th International IEEE Conference on Intelligent Transportation Systems (ITSC), 2011
Road throughput can be increased by driving at small inter-vehicle time gaps. The amplification of velocity disturbances in upstream direction, however, poses limitations to the minimum feasible time gap. String-stable behavior is thus considered an essential requirement for the design of automatic distance control systems, which are needed to allow for safe driving at time gaps well below 1 s. Theoretical analysis reveals that this requirement can be met using wireless intervehicle communication to provide real-time information of the preceding vehicle, in addition to the information obtained by common Adaptive Cruise Control (ACC) sensors. In order to validate these theoretical results and to demonstrate the technical feasibility, the resulting control system, known as Cooperative ACC (CACC), is implemented on a test fleet consisting of six passenger vehicles. Experiments clearly show that the practical results match the theoretical analysis, thereby indicating the possibilities for short-distance vehicle following.
Cooperative Adaptive Cruise Control (CACC) for Truck Platooning: Operational Concept Alternatives
RePEc: Research Papers in Economics, 2015
The concept of truck platooning has been the focus of many research projects over the years at the California PATH Program and around the world through such projects as CHAUFFEUR, SARTRE, KONVOI, Energy ITS, and COMPANION. These previous projects have included the automation of both lateral and longitudinal control in the following trucks because of the very close following distances targeted by those projects. Cooperative Adaptive Cruise Control (CACC) provides an intermediate step toward a longer-term vision of trucks operating in closely-coupled automated platoons on both long-haul and short-haul freight corridors. There are important distinctions between CACC and automated truck platooning. First, with CACC, only truck speed control will be automated, using V2V communication to supplement forward sensors. The drivers will still be responsible for actively steering the vehicle, lane keeping, and monitoring roadway and traffic conditions. Second, while truck platooning systems have relied on a Constant Distance Gap (CDG) control strategy, CACC has relied on a Constant-Time Gap (CTG) control strategy, where the distance between vehicles is proportional to the speed. For these reasons, a series of trucks using CACC is referred to as a string, rather than a platoon. This report mainly focuses on describing the various CACC operational concept alternatives at the level of individual vehicles, local groups of vehicles and their drivers, and which alternatives should be employed in this research project. These operational concepts can be broken into four categories: string formation, steady-state cruising, string split maneuvers, and faults or abnormal operating conditions.
Transportation Research Part A: Policy and Practice, 2019
Traffic simulation is a cost-effective way to test the deployment of Cooperative Adaptive Cruise Control (CACC) vehicles in a large-scale transportation network. By using a previously developed microscopic simulation testbed, this paper examines the impacts of four managed lane strategies for the near-term deployment of CACC vehicles under mixed traffic conditions. Network-wide performance measures are investigated from the perspectives of mobility, safety, equity, and environmental impacts. In addition, the platoon formation performance of CACC vehicles is evaluated with platoon-orientated measures, such as the percentage of platooned CACC vehicles, average platoon depth, and vehicle-hour-platooned that is proposed in this paper under the imperfect DSRC communication environment. Moreover, managed lane score matrices are developed to incorporate heterogeneous categories of performance measures, aiming to provide a more comprehensive picture for stakeholders. The results show that mixing CACC traffic along with non-CACC traffic across all travel lanes is an acceptable option when the market penetration (MP) is lower than 30% for roadways where a managed lane is absent. Providing CACC with priority access to an existing managed lane, if available, is also a good strategy for improving the overall traffic performance when the MP is lower than 40%. When the MP reaches above 40%, a dedicated lane for CACC vehicles is recommended, as it provides greater opportunity for CACC vehicles to form platoons. The facilitation of homogeneous CACC traffic flow could make further improvements possible in the future.
International Journal of Automation and Computing, 2014
Cooperative adaptive cruise control (CACC) vehicles are intelligent vehicles that use vehicular ad hoc networks (VANETs) to share traffic information in real time. Previous studies have shown that CACC could have an impact on increasing highway capacities at high market penetration. Since reaching a high CACC market penetration level is not occurring in the near future, this study presents a progressive deployment approach that demonstrates to have a great potential of reducing traffic congestions at low CACC penetration levels. Using a previously developed microscopic traffic simulation model of a freeway with an on-ramp -created to induce perturbations and trigger stop-and-go traffic, the CACC system s effect on the traffic performance is studied. The results show significance and indicate the potential of CACC systems to improve traffic characteristics which can be used to reduce traffic congestion. The study shows that the impact of CACC is positive and not only limited to a high market penetration. By giving CACC vehicles priority access to high-occupancy vehicle (HOV) lanes, the highway capacity could be significantly improved with a CACC penetration as low as 20%.
Cooperative Adaptive Cruise Control (CACC) For Partially Automated Truck Platooning:Final Report
RePEc: Research Papers in Economics, 2018
Cooperative Adaptive Cruise Control (CACC) provides an intermediate step toward a longerterm vision of trucks operating in closely-coupled automated platoons on both long-haul and short-haul freight corridors. There are important distinctions between CACC and automated truck platooning. First, with CACC, only truck speed control will be automated, using V2V communication to supplement forward sensors. The drivers will still be responsible for actively steering the vehicle, lane keeping, and monitoring roadway and traffic conditions. Second, while truck platooning systems have relied on a Constant Distance Gap (CDG) control strategy, CACC has relied on a Constant-Time Gap (CTG) control strategy, where the distance between vehicles is proportional to the speed. A CACC system has been implemented on three Volvo Class-8 truck tractors and has been tested under a variety of conditions to assess its potential impacts if introduced into public use. The vehicle-following control system performance has been tested to demonstrate its ability to maintain accurate spacing between the trucks with reasonably smooth ride quality, and to respond safely to cut-in maneuvers by drivers of other vehicles. The energy saving potential of the close formation driving of the trucks has been tested through an extensive set of test-track experiments under a range of speeds, with and without aerodynamic improvements to the trailers, showing that the closer separations and trailer aerodynamic improvements have a more than additive contribution to fuel economy. Truck driver responses to the CACC system have been assessed through an on-road experiment with nine test drivers, who provided their opinions about the system in questionnaire responses and demonstrated which gap settings they preferred to use while driving in mixed public traffic on California freeways. The larger-scale impacts of truck CACC on traffic flow and energy consumption were assessed in a traffic microsimulation of a high-density urban freeway with heavy truck traffic. A baseline condition with all manual driving was compared with a scenario in which all the heavy trucks used CACC, showing how this could relieve traffic bottlenecks and improve the speed and smoothness of traffic for all vehicles on the freeway. The trucks saved time and energy in this scenario, and because the speeds were only moderate the energy savings were primarily from the reductions in speed variations rather than from aerodynamic drag reductions.
Cooperative adaptive cruise control, design and experiments
Proceedings of the 2010 American Control Conference, 2010
The design of a CACC system and corresponding experiments are presented. The design targets string stable system behavior, which is assessed using a frequency-domain-based approach. Following this approach, it is shown that the available wireless information enables small inter-vehicle distances, while maintaining string stable behavior. The theoretical results are validated by experiments with two CACC-equipped vehicles. Measurement results showing string stable as well as string unstable behavior are discussed.