Browsing by Subject "Vehicles"

Now showing 1 - 4 of 4

Modeling and analysis of wireless networks with correlation and motion
(2019-06-13) Choi, Chang-sik; Baccelli, F. (François), 1954-; de Veciana, Gustavo; Heath, Robert W; Andrews, Jeffrey G; Sirbu, Mihai
The use of stochastic geometry allows the analysis of the typical performance of a wireless network. Specifically, under a stationary framework, the network performance at a typical receiver represents the network performance spatially-averaged over all receivers. This approach has been applied to the Poisson point processes whose points are independently located in space. The Poisson point process expresses a total independence type randomness in network architectures. Its tractability leads to its wide use in modeling various wireless networks, e.g., cellular networks, ad hoc networks, and vehicular networks. However, a network analysis using the Poisson point process might be inaccurate when the network components are geometrically correlated or in motion, as in heterogeneous cellular networks, or vehicular networks. For instance, macro base stations are deployed far from each other. Vehicles are located on roads, i.e., lines, and they move on the lines. As a result, the analysis of these networks can be improved by new spatial models that capture these spatial and dynamic features. In my first contribution, I derive the signal-to-interference ratio (SIR) coverage probability of a typical user in heterogeneous cellular networks where base stations are modeled by the sum of a Poisson point process and a stationary square grid. In my second contribution, I develop a stationary framework based on the sum of a Cox point process and a Poisson point process to model random cellular networks with linear base stations and linear users on straight lines. I derive the SIR coverage probability of the typical user and characterize its association. In the third contribution, I investigate the statistical properties of the Cox point process, exploring the nearest distance distribution and the convergence of the Cox-Voronoi cell. In the above three contributions, I analyze the performance of wireless networks by focusing on their correlated structures, extracting results which cannot be obtained from models based only on Poisson point processes. In my fourth contribution, I propose a new technology for harvesting Internet-of-Things (IoT) data based on mesh relaying with vehicles as sinks. I derive the network capacity and compare it to the traditional approach, which is based on static base stations. In the fifth contribution, I derive the SIR distribution of direct communication from roadside devices to vehicles. By characterizing the evolution of the network snapshots, I derive the behavior of vehicles' service coverage area and the network latency. In my sixth contribution, I propose a data harvesting technology for the ground-based data devices, based on the use of unmanned aerial vehicles (UAVs). I derive the total data transmitted from a typical device by characterizing the evolution of network geometry with respect to time. These last three contributions are built on a combination of network snapshot analysis and network evolution analysis.
Modular autonomous intersection management simulation for stochastic and priority auction paradigms
(2021-12-03) Liao, Carlin; Boyles, Stephen David, 1982-; Claudel, Christian; Kumar, Krishna; Stone, Peter
Automated intersections, when combined with the proliferation of autonomous vehicles (AVs), allow for more precise and innovative methods to control traffic at these integral choke points in the road system. In this dissertation, I develop a refined, modular framework for autonomous intersection management (AIM) simulation and implement it as a software library with robust documentation and testing to support present and future research in this field. Demonstrating this framework's efficacy, I apply it to study two topic areas in the AIM space: stochastic movement and priority auctions. Stochastic AIM is introduced as an extension of traditional AIM that permits probabilistic reservations of space and time in an intersection. Its use case is motivated by the integration of human-driven vehicles into AIM using augmented reality guidance to behave more accurately to AV movement, while still making some stochastic deviations from AV-identical trajectories. These deviations are quantified using experimental data from human drivers in a driving simulator merged into a stochastic vehicle movement model. Experimental results suggest that, with this paradigm, AIM can decrease delay significantly, even at low AV penetration levels (less than 20%). Finally, I conceptualize intersection priority auctions into the newly developed AIM framework as itself a modular framework that supports the dispatch of multiple vehicles simultaneously from either separate lanes or a single lane without relying on preset signal phases. This auction framework further supports three payment formulas for the winner of the priority auction: first-price, second-price, or a novel externality payment mechanism. Using experiments implemented in the novel AIM simulator, my results demonstrate significant reduction in value-weighted delay using the multiple dispatch configuration and novel payment mechanism compared to other configurations, with the novel formula incentivizing truthful reporting of valuations more than its alternatives.
Operational criteria for battlefield vehicles
(2014-08) Hamill, Scott Bowes; Tesar, Delbert
Modern military ground vehicles are no longer able to respond effectively to the rapidly changing mission requirements of modern military conflicts. Military vehicle architectures, which utilize passive suspension components and traditional drivetrain/steering systems, do not provide the operational flexibility to meet the demands of the operator. Advances in intelligent actuation technology allow for the development of a new vehicle architecture - the Intelligent Corner Vehicle (ICV). The ICV utilizes intelligent actuator technology to actively control the four degrees of freedom of each wheel of the vehicle - drive, camber, steering, and suspension. The utilization of intelligent actuation requires the characterization of the motions and behavior of the tire and the vehicle chassis in order to effectively apply the tire to the road surface - the development of vehicle performance criteria. A brief review of the state of wheeled military systems is presented. Many modern military vehicles were designed to improve protection at the expense of mobility - a process that has had negative effects on vehicle capability. An overview of the pneumatic tire used for wheeled vehicles is presented, highlighting the nonlinearities of tire behavior. The complexity of tire force generation drives the need for the application of intelligent actuation. Traditional actuation of wheel motion is presented along with a variety of current efforts to apply intelligent actuation to individual degrees of freedom of the tire. These efforts can be shown to improve vehicle performance, but intelligent actuation must be applied to all aspects of tire motion, requiring the use of the ICV architecture and the generation of performance criteria by which the complex motion of the vehicle may be evaluated. The Robotics Research Group has a history of developing and evaluating performance criteria for complex dynamic systems. and review of performance criteria developed for serial chain robotics is presented. These criteria address task independent actuator motion in addition to actuator ranges and limits, and their application to the ICV is discussed. A brief overview of several important concepts of classical vehicle dynamics are presented. The application of criteria derived from these concepts to the ICV architecture is discussed. This report presents the complexities of tire behavior and vehicle motion, the need for alternative architectures (the ICV), and a variety of performance criteria required to evaluate vehicle motion in real time. Criteria that are presented are summarized along with their definition and physical meaning. Future work for the development of the ICV involves the generation of a vehicle model for evaluating the application and range values of the presented criteria.
Robust Precise Location
(2017-09-27) Humphreys, Todd