Automated Highway Systems Research Articles

Cellular automata model for traffic flow with safe driving conditions

In this paper, a recently introduced cellular automata (CA) model is used for a statistical analysis of the inner microscopic structure of synchronized traffic flow. The analysis focuses on the formation and dissolution of clusters or platoons of vehicles, as the mechanism that causes the presence of this synchronized traffic state with a high flow. This platoon formation is one of the most interesting phenomena observed in traffic flows and plays an important role both in manual and automated highway systems (AHS). Simulation results, obtained from a single-lane system under periodic boundary conditions indicate that in the density region where the synchronized state is observed, most vehicles travel together in platoons with approximately the same speed and small spatial distances. The examination of velocity variations and individual vehicle gaps shows that the flow corresponding to the synchronized state is stable, safe and highly correlated. Moreover, results indicate that the observed platoon formation in real traffic is reproduced in simulations by the relation between vehicle headway and velocity that is embedded in the dynamics definition of the CA model.

Evaluation of automated electric transportation deployment strategies: integrated against isolated

This study considers deployment paths for automated vehicles, evaluating the new approach of an evolutionary process of isolated deployment. Here, isolated, fully automated systems are developed from the ground-up in areas with the greatest need/opportunity; over time, such systems can expand and become interconnected. This is an alternative to the integrated deployment strategies developed by the automated highway systems (AHS) program. Tellingly, AHS never settled on a specific deployment strategy because of disagreements among many of its members, but much of the research did include an integrated approach, whereby the technology progresses over time from manual driving to full automation. This study compares the two approaches, arguing that integrated deployment is fundamentally hampered by institutional hurdles and the difficulty of encouraging the large-scale adoption necessary to achieve the most significant benefits of automation, including increased lane capacity and vehicle speed. It proposes that a predominantly isolated approach, accomplished with protocols and standards to allow for eventual interoperability of systems, can offer a superior path forward. This is especially attractive for bus rapid transit applications and electrification via in-motion power, as proposed by the Automated Electric Transportation program.

Optimal routing for automated highway systems

We present a routing guidance approach that can be used in Automated Highway Systems (AHS). We consider automated highway systems in which intelligent vehicles organised in platoons drive to their destination, controlled by a hierarchical control framework. In this framework there are roadside controllers that provide speed and lane allocation instructions to the platoons. These roadside controllers typically manage single stretches of highways. A collection of highways is then supervised by so-called area controllers that mainly take care of the route guidance instructions for the platoons and that also coordinate the various roadside controllers in their area. In this paper we focus on the optimal route choice control problem for the area controllers. In general, this problem is a non-linear integer optimisation problem with high computational requirements, which makes the problem intractable in practice. Therefore, we first propose a simplified but fast simulation model to describe the flows of platoons in the network. Next, we show that the optimal route choice control problem can be approximated by a mixed-integer linear problem. Later, we describe a new METANET-like model to describe the flow of platoons in the AHS. With a simple case study we illustrate that both approaches result in a balanced trade-off between optimality and computational efficiency.

Decentralised direct adaptive fuzzy control for a class of large-scale nonaffine nonlinear systems and application to AHS

A novel decentralised direct adaptive fuzzy controller design is presented for a class of large-scale nonaffine uncertain nonlinear systems in this article. By integrating a fuzzy logic system and H ∞ tracking technique, the designed controller is able to adaptively compensate for interconnections and disturbances with unknown bounds, but none of the control and adaptation laws contains a sign function so that control chattering can be shunned. The closed-loop large-scale system is guaranteed to be asymptotically stable and obtain good H ∞ tracking performance. The control approach developed is applied to the following control problem of a string of vehicles within an automated highway system (AHS) and simulation results verify its validity.

A New Approach to Automated Highway Systems: Puppet Master

In this research, a novel system is designed in scope of automated highways. The aim of this system is to provide safe, secure and fast transportation on highways. This system uses both road sensors and GNSS (Global Navigation Satellite System). Since no human interaction is allowed in this system, the driver mistakes are reduced to zero. Based on the road sensors and the GNSS, the system is able to adjust the speeds and the following distances between vehicles. The messaging system is also designed for this puppet master architecture, which allows vehicles to communicate with the central components of the system. 

Techno-economic assessment of the potential of intelligent transport systems to reduce CO 2 emissions

This study assesses the technical feasibility, economic affordability and social acceptability of low-greenhouse gas (GHG) emissions intelligent transport systems (ITS) that could be implemented in the European road infrastructure over the next 40 years for passenger and freight traffic. Three ITS applications are considered: driver assistance systems and the automated highway system (AHS) for passenger traffic and commercial vehicle operations for freight traffic. These technologies are anticipated to lead to a more efficient use of the existing road network, while potentially reducing GHG emissions generated by vehicles. The impact of ITS on road capacity and vehicle's CO2 emissions is determined. Assessment is based on a reference system, which consists of the average new vehicle in the road network of the EU-27 countries. The various opportunities offered by the selected ITS technologies are specified and the major constraints for reducing GHG emissions are identified. Cost-effectiveness and sensitivity analysis is carried out. The results are validated by a suitably designed expert-based survey. It is found that ITS have the potential to improve capacity and reduce emissions. The most significant benefits are offered by the deployment of AHS. Social acceptability issues such as privacy and liability need to be further addressed to facilitate wide deployment of ITS.

Advanced driver assistance system for AHS over communication links with random packet dropouts

In this paper, we propose an advanced driver assist system (ADAS) for platoon based automated highway system (AHS) with packet loss in inter-vehicle communication. Using the concept of rigidity, we first show that vehicles in a platoon tend to fall apart in the event of a packet loss among vehicles. To overcome this, we propose an estimation based dynamic platooning algorithm which employs the state estimate to maintain the platoon. Communication among the vehicle is reduced by using minimum spanning tree (MST) in state estimation algorithm. Effectiveness of the proposed ADAS scheme is illustrated by simulation wherein, dynamic platoons of holonomic vehicles with integrator dynamics are considered. Simulation studies indicate that the proposed algorithm maintains the platoon up to a packet loss rate of 48%. State transmission scheme proposed in our algorithm has three significant advantages, they are: (1) it handles packet loss in inter-vehicle communication, (2) reduces the effect of error in measured output, and (3) reduces the inter-vehicle communication. These advantages significantly increase the reliability and safety of the AHS.

Simulation of Natural Environment Impacts on Intelligent Vehicle Based on a Virtual Reality Platform

Studies show that variable or adverse Natural Environment (NE) could increase the probability of traffic accidents. However, NE impacts were largely ignored in current researches of Intelligent Transportation System (ITS)/Automated Highway System (AHS). To fill this research gap, in this paper, based on the NE conceptual model for intelligent vehicle and Virtual Reality (VR), a new method is presented to analyze and simulate the NE effects on intelligent vehicle to help designing more appropriate intelligent vehicle controllers. It is realized on the Intelligent Vehicles Virtual Reality (IVVR) platform in which several experiments with proposed simulation architecture are carried out to analyze the NE impacts through not only curves or data but also comprehensible simulation results presented visually in a 3-D virtual world.

Traffic Management for Automated Highway Systems Using Model-Based Predictive Control

We present an integrated traffic management and control approach for automated highway systems (AHS). The AHS consist of interacting roadside controllers and intelligent vehicles that are organized in platoons with short intraplatoon distances and larger distances between platoons. All vehicles are assumed to be fully automated, i.e., throttle, braking, and steering commands are determined by an automated onboard controller. The proposed control approach is based on a hierarchical traffic control architecture for AHS, and it also takes the connection and transition between the nonautomated part of the road network and the AHS into account. In particular, we combine dynamic speed limits and lane allocation for the platoons on the AHS highways with access control for the on-ramps using ramp metering, and we propose a model-based predictive control approach to determine optimal speed limits and lane allocations, as well as optimal release times for the platoons at the on-ramps. To illustrate the potential of the proposed traffic control method, we apply it to a simple simulation example.

AUTOMATED DRIVING SYSTEMS: COMMON GROUND OF AUTOMOBILES AND ROBOTS

This article reviews R&D activities on automated highway systems (AHSs) since 1950s with emphasis on recent ones. AHSs in the 1950s and 1960s were featured by a cooperative system between roads and vehicles; those in the 1970s and 1980s were by autonomous systems. Intelligent transport system (ITS) projects since 1980s regarded AHS as an important system, not only a single automated vehicle but also an automated platoon were developed. In recent years, the R&D focuses on automated transit buses aiming at precision docking and driving along a narrow lane and automated truck platoons aiming at energy saving. The automated driving can be common ground of automobiles and robots.

Platooning over packet-dropping links

Automated Highway Systems (AHSs) used for eliminating highway congestion in urban areas, require platooning of vehicles. Platooning usually involves communication channels among the vehicles in a platoon and as well as the platoons. One major challenge in the implementation of platoons is the packet dropouts in the communication channels, as they affect the rigidity of the platoon. In our investigations, we first show that the rigidity of the platoon is lost in the presence of packet losses. Later, we propose an estimation based platooning algorithm for vehicles connected using communication links with random packet dropouts. We also examine the problem of minimal channel utilisation by employing the estimate. Furthermore, we explore the data that is to be transmitted given that a packet dropout has occurred. The obtained results are illustrated using simulations conducted on a platoon of holonomic point vehicles.

Lateral Control of Autonomous Vehicles Using Multi-Model and Fuzzy Approaches

This paper discusses the fundamental issues in vehicle lateral motion control within Automated Highway Systems. Lane keeping control and lane changing control are concerned. One major challenge for lateral controller design is the smoothness and robustness under different vehicle conditions. A multi-model fuzzy controller, which includes four local controllers, is then proposed for both the operations of lane keeping and lane changing. These four local controllers are set up for four vehicle speed regions respectively. A fusion block is then introduced to ensure smooth and accurate transition between the different local controllers. The proposed controller inherits the advantages of both the multi-model control and fuzzy control. Simulations show that it could get good performances in the whole range of operation speed, and could also repel the system uncertainties such as changes in vehicle load, movement inertia and wheel cornering stiffness. Furthermore, the calculation procedure of the proposed controller is not complex, and is rather rapid. It appears a promising control algorithm for realtime embedded applications.

Lane assignment problem using a genetic algorithm in the Automated Highway Systems

This paper deals with lane assignment problem in the automated highway systems (AHS). The purpose of lane assignment strategies is to increase the throughput on multi-lane highways with many entry and exit points, based on the itineraries of vehicles using the highway (point of entry, time of entry and exit point) and effects of maneuvers. Using the partitioned lane assignment strategies, the lane assignment problem is formulated as an optimal problem to find proper positions of partitions on an itinerary matrix. Then the optimal problem is solved with genetic algorithm (GA). The validation of the proposed algorithm is conducted by comparing it with a random strategy in a realistic situation.

Microscopic modeling and control logic for incident-responsive automatic vehicle movements in single-automated-lane highway systems

Automatic response to lane-blocking incidents is a critical issue in the field of automated highway systems (AHS). Accordingly, this paper presents a microscopic vehicular control methodology for automatic-control (AC) vehicular movements in response to lane-blocking incidents in the AHS environment. The embedded traffic control logic is based on the basic safety requirements for automatic-control lane traffic maneuvers responding to lane-blocking incidents in the single-automated-lane AHS environment. Accordingly, respective automated vehicular control models are proposed to deal with AC vehicles moving in three corresponding sequential phases, i.e., (1) AC platoon approaching the incident site from the blocked lane, (2) mandatory lane changing and mixed car following in the adjacent lane, and (3) AC platoon reforming downstream from the incident site in the blocked automated lane. Using a microscopic simulation model which embeds these proposed models, preliminary tests are conducted to investigate the relative performance of the proposed method in various traffic flow and control scenarios. The resulting numerical results, including simplified sensitivity analyses, indicate that the proposed microscopic traffic control logic permits regulating automatic-control vehicular movements in response to the effects of lane-blocking incidents on traffic flows either in control-free lanes or in the automatic-control lanes. Implications of the results and some findings are discussed for further research.

Contact bridging dampers for back-up on automated highways

Automated Highway Systems (AHS) are under development to address congestion, inefficient energy use and inadequate safety margins. As more intelligence is applied to highway and vehicles, the system increasingly relies on secure communications and control, with potentially hazardous consequences in the event of technical failure. The authors propose an active, intelligently controlled extended fender which permits vehicles to operate in lengthy, stable platoons in direct but ‘soft’ contact, allowing fault support for an AHS. Simulation studies have indicated that stable operation may be retained with only a simple ‘leader’ broadcast signal and that good longitudinal ride quality is also retained, providing results similar to the fully co-operative system. The device also provides potential for additional safety in the event of a collision and for selective power reduction for a co-operative system at steady speed.

Statechart-based representation of hybrid controllers for vehicle automation

Recently, designs for the automated highway systems (AHS) to improve the safety and efficiency of highways have attracted much attention. However, such large-scale and complex dynamic systems present a number of control issues. Part of the complication comes from the hybrid nature of these systems, which consists of both time-driven and event-driven dynamics. In this paper, an object-oriented representation towards a hybrid controller design for automated vehicles in an AHS is proposed. The traditional discrete statechart of unified modelling language is extended to model the continuous dynamics of hybrid controllers in a hierarchical and natural representation. The proposed modelling approach provides a clear and natural representation of the interaction between the discrete and continuous behaviours.(A)

Vehicle sorting for platoon formation: Impacts on highway entry and throughput

Automated highway systems (AHS) are intended to increase the throughput and safety of roadways through computer control, communication and sensing. In the “platoon” concept for AHS, vehicles travel on highways in closely spaced groups. To maximize benefits, it is desirable to form platoons that are reasonably large (five or more vehicles), and it is also desirable to ensure that platoons remain intact for considerable distances. This paper develops and evaluates strategies for organizing vehicles into platoons at highway entrances, with the objective of maximizing the distance that platoons stay intact, so that they do not need to be regrouped into new platoons on the highway itself. Fundamentally, this entails grouping vehicles according to their destination. We evaluate various strategies in which vehicles are sorted on entrance ramps, with respect to platoon sizes, throughput and platoon formation time.

A collaborative driving system based on multiagent modelling and simulations

Collaborative driving is a growing domain of intelligent transportation systems (ITS) that makes use of communications to autonomously guide cooperative vehicles on an automated highway system (AHS). In this paper, we address this issue by using a platoon of cars considered as more or less autonomous software agents. To achieve this, we propose a hierarchical driving agent architecture based on three layers (guidance layer, management layer and traffic control layer). This architecture has been used to develop centralized platoons, where the driving agent of the head vehicle coordinates other driving agents by applying strict rules, and decentralized platoons, where the platoon is considered as a group of driving agents with a similar degree of autonomy, trying to maintain a stable platoon. The latter decentralized model mainly considers an agent teamwork model based on a multiagent architecture, known as STEAM. The centralized and decentralized coordination models are finally compared using results from simulation scenarios that highlight safety, time efficiency and communication efficiency aspects for each model.

LONGITUDINAL CONTROL OF PLATOON FOR ELECTRIC VEHICLE USING ADAPTIVE NEURAL NETWORKS

In AHS(Automated Highway Systems) project which is one of the ITS (Intelligent Highway Systems), the platoon control is developed. In this paper, a platoon control law based on Adaptive Neural Network (ANN) to lower level and Semi-Autonomous Adaptive Cruise Control (SAACC) to upper level is proposed. Moreover, there is “Delay” with the communication and the sensor. We design their compensators, and did stability analysis that takes those error into consideration. We confirmed that the closed loop system is stable, and confirmed the effectiveness in the numerical simulation.

LTV controller design for vehicle lateral control under fault in rear sensors

This work focuses on vehicle lateral control for automated highway systems (AHSs) studied as a part of the California Partners for Advanced Transit and Highways (PATH) Program. In the PATH lateral control system, magnetometers are installed under both front and rear bumpers of the vehicle; these magnetometers measure the lateral deviation of the vehicle relative to the magnets buried along the centerline of each automated lane. Lateral controllers have been designed and tested successfully provided that there is no fault in magnetometers. It has been argued that these controllers are NOT tolerant to the fault in magnetometers. The focus of This work is the degraded-mode lateral control under fault in rear magnetometers. The aim of the controller design is to accomplish adequate performance with the remaining set of magnetometers, the front magnetometers. The effects of the fault are examined, and the significance of the linear time-varying (LTV) property of the front-magnetometer-based vehicle lateral dynamics is recognized. Popular control methods for LTV systems generally involve gain scheduling by switching between several linear time-invariant (LTI) controllers. Such methods are complicated and it is difficult to prove the stability of the switching mechanism. To derive a simple effective LTV controller, feedback linearization is applied to approximately cancel out the time-varying terms in the plant and to function as a gain scheduler. However, due to the weakly damped zeroes of the plant, feedback linearization with state feedback or matched observer state feedback results in weakly damped internal dynamics. In order to tune the internal dynamics, a mismatched observer is designed based on H-infinity optimal control techniques. Experimental results are presented to show the effectiveness of the controller design.