Safe and Efficient Intelligent Intersection Control of Autonomous Vehicles

In this dissertation, we address a problem of safe and efficient intersection crossing traffic management of autonomous and connected ground traffic. Toward this objective, we propose several algorithms to handle different traffic environments. First, an algorithm that is called the Discrete-time occupancies trajectory (DTOT) based Intersection traffic Coordination Algorithm (DICA) is proposed. All vehicles in the system are Connected and Autonomous Vehicles (CAVs) and capable of wireless Vehicle-to-Intersection communication. The main advantage of DICA is that it enables us to utilize the intersection space more efficiently resulting in less delay for vehicles to cross the intersection. In the proposed framework, an intersection coordinates the motions of CAVs based on their proposed DTOTs to let them cross the intersection efficiently while avoiding collisions. In case when there is a potential collision between vehicles\u27 DTOTs, the intersection modifies conflicting DTOTs to avoid the collision and requests CAVs to approach and cross the intersection according to the modified DTOTs. We also prove that the basic DICA is deadlock free and starvation free. We show that the basic DICA has a computational complexity of O(n2 L3m) where n is the number of vehicles granted to cross an intersection and Lm is the maximum length of intersection crossing routes. To improve the overall computational efficiency of the algorithm, the basic DICA is enhanced by several computational techniques. The enhanced algorithm has a reduced computational complexity of O(n2 Lm log2 Lm). The problem of evacuating emergency vehicles as quickly as possible through autonomous and connected intersection traffic is also addressed in this dissertation. The proposed Reactive DICA aims to determine an efficient vehicle-passing sequence which allows the emergency vehicle to cross an intersection as soon as possible while the travel times of other normal vehicles are minimally affected. When there are no emergency vehicles within the intersection area, the vehicles are controlled by DICA. When there are emergency vehicles entering communication range, we prioritize emergency vehicles through the optimal ordering of vehicles. Since the number of possible vehicle-passing sequences increases rapidly with the number of vehicles, finding an efficient sequence of vehicles in a short time is the main challenge of the study. A genetic algorithm is proposed to solve the optimization problem which finds the optimal vehicle sequence in real time that gives the emergency vehicles the highest priority. We then address an optimization problem of autonomous intersection control which provides the optimal trajectory for every entering vehicle. Based on the algorithm DICA, we improve the conservative way of trajectory generation which is the key part of DICA to be an optimization approach using mixed integer programming. The new algorithm is named Mixed integer programming based Intersection Coordination Algorithm (MICA) with the objective of maximizing the final position of a new head vehicle over a fixed time interval. Constraints from space conflicting vehicles are modeled using binary variables to represent the vehicle\u27s future crossing behavior. The influence of immediate front vehicles of the vehicle of interest is also modeled as constraints in the problem formulation to obtain a feasible optimal trajectory while potential collisions are safely avoided. Finally, based on MICA, we propose a novel vehicle-intersection interaction mechanism MICACO which is designed to handle imperfect communication, i.e., message delay and loss. To ensure the successful delivery of messages, we add two more message types and corresponding simple rules. State machines of intersection and vehicles are designed properly to ensure the safety of every vehicle. We verify the efficiency of the proposed algorithms through simulations using SUMO. The simulation results show that DICA performs better than another existing intersection management scheme: Concurrent Algorithm in [1]. The overall throughput, as well as the computational efficiency of the computationally enhanced DICA, are also compared with those of an optimized traffic light control. The efficiency of the proposed Reactive DICA is validated through comparisons with DICA and a reactive traffic light algorithm. The results show that Reactive DICA is able to decrease the travel times of emergency vehicles significantly in light and medium traffic volumes without causing any noticeable performance degradation of normal vehicles. The simulation results show that MICA is able to reduce congestions of an intersection significantly compared with DICA. We also show MICACO\u27s performance through comparisons with MICA and an optimized traffic light

Assessing the sustainability performance of inter-urban intelligent transport

The implementation of ITS to increase the efficiency of saturated highways has become increasingly prevalent. It is a high level objective for many international governments and operators that highways should be managed in a way that is both sustainable i.e. environmental, social and economically sound and supportive of a Low-Carbon-Energy Future. Some clarity is therefore needed to understand how Intelligent Transport Systems perform within the constraints of that objective. This thesis describes the development of performance criteria that reflect the contributions of Information Communication Technology (ICT) emissions, vehicle emissions and the embedded carbon within the physical transport infrastructure that typically comprises three types of Intelligent Transport System. Active Traffic Management, Intelligent Speed Adaptation and the Automated Highway System are a collection of systems designed to transform the road network into a highly efficient and congestion free transport solution and all possess varying levels of uncertainty in terms of sustainability performance. The performance criteria form part of a new framework methodology ‘EnvFUSION’ (Environmental Fusion for ITS) outlined here. An attributional LCA and c-LCA (consequential lifecycle assessment) are both undertaken which forms part of a data fusion process using data from various sources. The models forecast improvements for the three ITS technologies in-line with social acceptability, economic profitability and major carbon reduction scenarios up to 2050 on one of the UK's most congested highways. Analytical Hierarchy Process and Dempster-Shafer theory are used to weight criteria which form part of an Intelligent Transport Sustainability Index. Overall performance is then synthesized. Results indicate that there will be a substantial increase in socio-economic and emissions benefits, provided that the policies are in place and targets are reached which would otherwise delay their realisation. To conclude, an integrated strategic performance management framework is proposed which performs socio-technical comparisons of four key performance areas between ITS schemes in order to identify energy and emission hotspots

Evaluating the Impacts of Accelerated Incident Clearance Tools and Strategies by Harnessing the Power of Microscopic Traffic Simulation

Traffic incidents cause Americans delay, waste fuel, cause injuries, and create toxic emissions. Transportation professionals have implemented a variety of tools to manage these impacts and researchers have studied their effectiveness, illustrating a wide range between different tools and locations. To improve this state of knowledge, this dissertation sought to 1) identify prominent and effective incident management strategies, 2) model six selected incident management strategies within five highway corridors in South Carolina, and 3) apply benefit-cost analysis to evaluate the impact of various combinations of these strategies. To meet these objectives, the author evaluated published literature of the selected strategies, administered a nationwide survey of these strategies, conducted traffic simulation, and performed benefit-cost analysis. The literature review guided the author to fill gaps in knowledge regarding the effectiveness and expense of identified strategies. The nationwide survey identified effective incident management tools, the extent of their adoption, and their common problems. The author then applied PARAMICS traffic simulation software to evaluate the impact of six tools at five sites on metropolitan interstates throughout South Carolina. Finally, benefit-cost analysis was used to evaluate the benefits against costs at each study site. The survey provided many insights into both the effectiveness and collaboration within and among traffic incident management agencies and guided the author in selecting tools for evaluation. While the simulation study found that as the severity and duration of incident increases, so does the potential benefit of incident management tools, the frequency of incidents also produces significant impact on annual benefits. The benefit-cost analysis indicated that while all the incident management tools evaluated provided more benefits than costs, freeway service patrols and traffic cameras produced the highest return for incidents of varying severity. It was also found more advantageous to select one expensive but efficient incident management technology, rather than engage in the incremental deployment of various systems that might provide redundant benefits. Departments of transportation across the United States see the need to manage incidents more efficiently, consequently this dissertation developed data and analysis to compare benefits with costs to aid decision makers in selecting tools and strategies for future incident management endeavors

Optimization and Mathematical Modelling for Path Planning of Co-operative Intra-logistics Automated Vehicles

Small indoor Autonomous Vehicles have revolutionized the operation of pick-pack-and-ship warehouses. The challenges for path planning and co-operation in this domain stem from uncontrolled environments including workspaces shared with humans and human-operated vehicles. Solutions are needed which scale up to the largest existing sites with thousands of vehicles and beyond. These challenges might be familiar to anyone modelling road traffic control with the introduction of Autonomous Vehicles, but key differences in the level of decision autonomy lead to different approaches to conflict-resolution. This thesis proposes a decomposition of site-wide conflict-free motion planning into individual shortest paths though a roadmap representing the free space across the site, zone-based speed optimization to resolve conflicts in the vicinity of one intersection and individual path optimization for local obstacles. In numerical tests the individual path optimization based on clothoid basis functions created paths traversable by different vehicle configurations (steering rate limit, lateral acceleration limit and wheelbase) only by choosing an appropriate maximum longitudinal speed. Using two clothoid segments per convex region was sufficient to reach any goal, and the problem could be solved reliably and quickly with sequential quadratic programming due to the approximate graph method used to determine a good sequence of obstacle-free regions to the local goal. A design for zone-based intersection management, obtained by minimizing a linear objective subject to quadratic constraints was refined by the addition of a messaging interface compatible with the path adaptations based on clothoids. A new approximation of the differential constraints was evaluated in a multi-agent simulation of an elementary intersection layout. The proposed FIFO ordering heuristic converted the problem into a linear program. Interior point methods either found a solution quickly or showed that the problem was infeasible, unlike a quadratic constraint formulation with ordering flexibility. Subsequent tests on more complex multi-lane intersection geometries showed the quadratic constraint formulation converged to significantly better solutions than FIFO at the cost of longer and unpredictable search time. Both effects were magnified as the number of vehicles increased. To properly address site-wide conflict-free motion planning, it is essential that the local solutions are compatible with each other at the zone boundaries. The intersection management design was refined with new boundary constraints to ensure compatibility and smooth transitions without the need for a backup system. In numerical tests it was found that the additional boundary constraints were sufficient to ensure smooth transitions on an idealized map including two intersections

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: vehicular ad-hoc networks, security and caching, TCP in ad-hoc networks and emerging applications. It is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks

Proceedings of the 1993 Conference on Intelligent Computer-Aided Training and Virtual Environment Technology

The volume 2 proceedings from the 1993 Conference on Intelligent Computer-Aided Training and Virtual Environment Technology are presented. Topics discussed include intelligent computer assisted training (ICAT) systems architectures, ICAT educational and medical applications, virtual environment (VE) training and assessment, human factors engineering and VE, ICAT theory and natural language processing, ICAT military applications, VE engineering applications, ICAT knowledge acquisition processes and applications, and ICAT aerospace applications

Stabilisation operations as complex systems - order and chaos in the interoperability continuum

There is little knowledge in regards to the influence of complex systems thinking on the strategic modelling of stabilization operations. To better control the impact of information asymmetry in such context, this study focuses on gaining an understanding on how concepts and principles operate in theory and practice. Particularly, this study explores how the complexity of the environmental conditions influences stabilization operations as complex systems. Second, it addresses subsequent influences on a system’s required self-organizing ability to differentiate and integrate its various sub-systems, their organizational resources and competencies. Third, this study regards the development and adjustment of condition-dependent capabilities as key to reaching a state of dynamic equilibrium while processing, distributing and exchanging information. The aim of this study is both theoretical and practical: offering complex systems thinking as an alternative for the strategic modelling of stabilization operations and supporting the debate over the extent to which integration is feasible and desirable

Jagged blue frontiers: The police and the policing of boundaries in South Africa

Social and territorial boundaries have been fundamental to the approaches and practices of policing bodies in South Africa for centuries, from the mounted colonial paramilitary forces of the 1800s to the 21st century professional police. Boundaries have not only been a central mechanism that the police have consistently used to control and regulate the general population, but have also been catalysts for change in terms of operational policing strategies and tactics. This has typically been the case when a threat has been ascribed to a bounded area and/or populations that reside within the confines of the boundary, or on the other side of the boundary. The nature of the such a threat is considered to be even more severe when communities within the bounded space, or on the other side of the boundary, acquire significant quantities of firearms and ammunition, as this provides such populations with the lethal technology to defy and contest the police's coercive authority and ability to conserve boundaries relating to the maintenance of order and the enforcement of laws. South Africa is a distinctly relevant case study for an examination of the relationship between boundaries and the police as for the past three and a half centuries South Africa's diverse policing history has been profoundly framed by territorial, social and political boundaries. The police and the proto-police have been at the sharp edge of the application of authority by assorted forms of government, and have often acted to safeguard the interests of economic and political elites. That is, the police and formal policing bodies have been required to subdue and suppress groups and individuals that resisted or threatened the process of state building and resource extraction. The police were also regularly deployed to protect the territorial borders of South Africa from menacing others. By means of this historical analysis of South Africa, this thesis introduces a new concept, 'police frontierism', which illuminates the nature of the relationships between the police, policing and boundaries, and can potentially be used for future case study research. It is an alternative way of conceptualising policing, one in which police work is fundamentally framed by social and territorial boundaries. Such boundaries delineate perceived safe or 'civilised' spaces from dangerous or 'uncivilised' ones. The police tend to concentrate their resources in the frontier zone immediately adjacent to the boundary in order to preserve or extend the boundary of safety and 'civilisation', and restrict, subdue or eliminate those individuals, groups or circumstances from the 'uncivilised' spaces that a government authority or elites have deemed to be a threat to order and peace. An essential dynamic of this policing approach is that the boundary and the adjoining frontier zone strongly influence police practices and behaviour in this context. In particular, territorial and social delineations amplify and distort existing police prejudices against those communities on the other side of the boundary. The police often engage in othering, where the communities of interest are viewed negatively, and are predominantly seen as agents of disorder and law breaking. This othering may lead to an intensification of aggressive police behaviour towards the targeted communities