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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Formulation of an interactive ruled-based design envelope for ensuring aftermarket vehicle dynamics compliance

Zhou, Xianjie 01 February 2017 (has links)
<p> The objective of this research is to develop an integrated system engineering methodology for the customization design to maximize vehicle performance upgrade freedom while ensuring vehicle dynamics compliance.</p><p> A post-delivery modification framework, which is led by an aftermarket umbrella organization and involve various stakeholders has been established. The umbrella organization will be in charge of developing the design envelope and distribute to various aftermarket kit suppliers to generate specific products according to their brand essence.</p><p> A generic mathematical representation of a (proprietary) ESC system has been developed for virtual certification purposes. This approach is a cost-effective alternative to physical on-road testing and hardware-in-the-loop (HiL) simulations. Furthermore, based on the stability control model, the modification impacts on the vehicle dynamics and stability performance was assessed using the Taguchi design of experiment (DOE) method. DOE results provide three distinct ways for supporting aftermarket modifications. First, main effects help customizers to understand which modification bring benefits or risks. Second, a regression model of the lateral offset metrics helps suppliers to predict closed-loop performances with open-loop testing information which require much less time and cost. Finally, the pass/fail criteria regarding federally mandated ESC compliance (FMVSS 126) brought on the &lsquo;Pass Region&rsquo; which consisted of feasible configurations such that customizers may configure their options within a safe zone. Each of these methods complements others for supporting the aftermarket modification.</p><p> In order to improve the computation efficiency, two lower fidelity models were developed: A linear model and a surrogate model. The linear model is derived from the high fidelity model with reduced degrees of freedom (DOF) and linearized parameters. Tire cornering stiffness is treated as constants for gentle maneuvers, and varying parameters for high-dynamic driving maneuver. The linear system is either a linear time-invariant (LTI) system or a linear parameter-varying (LPV) system depending on the application context. The PD yaw stability control algorithm, which is inherited from the high fidelity model, was simplified but retained with critical nonlinear features. A quadratic regression model that was dedicated for compliance metrics was developed as a surrogate model incorporated in an interactive rule-based design envelope. </p><p> An interactive design envelope has been created incorporating the rules established using computational efficient linear and surrogate models. The constraint satisfaction problem is described in the nonlinear programming context and solved using sequential quadratic programming. The quasiconvexity of the design space, which is the necessary condition for the proposed approach, is also investigated by inspecting the constraint functions. Finally, two case studies were developed to demonstrate the framework developed which was validated against the high fidelity co-simulation model.</p>

Flocking Modeling, Control, and Optimization of Connected and Automated Vehicles for Safe and Efficient Mobility

January 2020 (has links)
abstract: In large modern urban areas, traffic congestion and fatality have become two serious problems. To improve the safety and efficiency of ground mobility, one promising solution is the cooperative control of connected and automated vehicle (CAV) systems, which can avoid human drivers’ incapability and errors. Taking advantage of two-dimensional (2D) vehicular control, this dissertation intends to conduct a thorough investigation of the modeling, control, and optimization of CAV systems with flocking control. Flocking is a dynamic swarm congregating behavior of a group of agents with self-organizing features, and flocking control of CAV systems attempts to achieve the maintenance of a small and nearly constant distance among vehicles, speed match, destination cohesion, and collision and obstacle avoidance. Concerning artificial multi-agent systems, such as mobile robots and CAV systems, a set of engineering performance requirements should be considered in flocking theory for practical applications. In this dissertation, three novel flocking control protocols are studied, which consider convergence speed, permanent obstacle avoidance, and energy efficiency. Furthermore, considering nonlinear vehicle dynamics, a novel hierarchical flocking control framework is proposed for CAV systems to integrate high-level flocking coordination planning and low-level vehicle dynamics control together. On one hand, using 2D flocking theory, the decision making and motion planning of engaged vehicles are produced in a distributed manner based on shared information. On the other hand, using the proposed framework, many advanced vehicle dynamics control methods and tools are applicable. For instance, in the low-level vehicle dynamics control, in addition to path trajectory tracking, the maintenance of vehicle later/yaw stability and rollover propensity mitigation are achieved by using additional actuators, such as all-wheel driving and four-wheel steering, to enhance vehicle safety and efficiency with over-actuated features. Co-simulations using MATLAB/Simulink and CarSim are conducted to illustrate the performances of the proposed flocking framework and all controller designs proposed in this dissertation. Moreover, a scaled CAV system is developed, and field experiments are also completed to further demonstrate the feasibility of the proposed flocking framework. Consequently, the proposed flocking framework can successfully complete a 2D vehicular flocking coordination. The novel flocking control protocols are also able to accommodate the practical requirements of artificial multi-agent systems by enhancing convergence speed, saving energy consumption, and avoiding permanent obstacles. In addition, employing the proposed control methods, vehicle stability is guaranteed as expected. / Dissertation/Thesis / Doctoral Dissertation Systems Engineering 2020

Modeling, Energy Optimization and Control of Vapor Compression Refrigeration Systems for Automotive Applications

Zhang, Quansheng 30 December 2014 (has links)
No description available.

Calibration of Automotive Aftertreatment Models through Co-Simulation with MATLAB Optimization Routines

Mack, James 21 September 2016 (has links)
No description available.

Methods for advancing automobile research with energy-use simulation

Geller, Benjamin M. 22 October 2014 (has links)
<p> Personal transportation has a large and increasing impact on people, society, and the environment globally. Computational energy-use simulation is becoming a key tool for automotive research and development in designing efficient, sustainable, and consumer acceptable personal transportation systems. Historically, research in personal transportation system design has not been held to the same standards as other scientific fields in that classical experimental design concepts have not been followed in practice. Instead, transportation researchers have built their analyses around available automotive simulation tools, but conventional automotive simulation tools are not well-equipped to answer system-level questions regarding transportation system design, environmental impacts, and policy analysis. </p><p> The proposed work in this dissertation aims to provide a means for applying more relevant simulation and analysis tools to these system-level research questions. First, I describe the objectives and requirements of vehicle energy-use simulation and design research, and the tools that have been used to execute this research. Next this dissertation develops a toolset for constructing system-level design studies with structured investigations and defensible hypothesis testing. The roles of experimental design, optimization, concept of operations, decision support, and uncertainty are defined for the application of automotive energy simulation and system design studies. </p><p> The results of this work are a suite of computational design and analysis tools that can serve to hold automotive research to the same standard as other scientific fields while providing the tools necessary to complete defensible and objective design studies.</p>

Evaluation of power-assist hydraulic and electric hybrids for medium- and heavy-duty vehicle applications

Wagner, Justin Taylor 23 October 2014 (has links)
<p> Under pressure from rising fuel costs, emissions constraints, and new government regulations on medium- and heavy-duty vehicles, hybrid technologies for these classes of vehicles are becoming more prevalent. A variety of technologies have been proposed to meet these requirements including power-assist hybrid electric and hybrid hydraulic systems. Although there has been great discussion about the benefits surrounding each of the technologies individually, no direct comparisons are available on the basis of economics and fuel economy. This study focuses on comparing these power-assist technologies on these bases as well as determines the ability of these technologies to fulfill the newly adopted fuel economy regulations. </p><p> In order to accomplish this goal, three computational models of vehicle dynamics, thermal behavior and fuel economy were created and validated to simulate the conventional vehicle and hydraulic and electric hybrids. These models were simulated over the Heavy-Duty Urban Dynamometer Driving Schedule, the HTUF Class 4 Parcel Delivery Cycle, and the Orange County Bus cycle. These drive cycles were chosen on their ability to characterize the variety of operating conditions observed in medium- and heavy-duty vehicles. Using these models, cross technology comparisons were constructed comparing commercially available systems, systems with a fixed mass, and systems with a fixed incremental cost. </p><p> The results of the commercially available systems showed that the Azure Dynamics HEV provided greater fuel economy improvement than the Lightning Hybrids HHV for drive cycle kinetic intensities less than 3.19 miles<sup> -1</sup>. Although this system showed a cost of fuel savings over the HHV, it was seen that the incremental cost of the HEV exceeded the cost of fuel savings over the HHV. The fixed mass comparison case, which compared vehicles with equal cargo carrying utility, showed similar results to that of the commercially available case. Although the increase in incremental cost for the varying HEV systems designed for the fixed mass case correlated to an improvement in fuel savings, the cost associated with the systems surpassed the savings seen. Lastly, the fixed cost case provided results which were also similar to the commercially available case. Due to the fixed system cost, it was seen that for these systems, the fuel economy benefits and associated cost showed the greatest benefits for the HEV. </p><p> This study concluded that given the evaluation, the HEV was the only power-assist hybrid technology which could fulfill the regulated fuel economy improvement of 15%. Although the HEV was the only technology which could fulfill the requirements, the HHV showed an improvement upwards of 7% greater than the HEV for the Orange County Bus Drive Cycle.</p>

Volume optimization of a simple planetary gear set

Deake, Jeremy J. 07 July 2015 (has links)
<p>This thesis describes a custom algorithm developed to optimize a simple planetary gear set. The optimization minimizes volume for one simple planetary gear set using American Gear Manufacturers Association stress equations, custom design constraints, and material constraints. Through predetermined reactions to adjustments, component features and planetary variables are modified systematically to obtain the target solution. This thesis demonstrates that the defined approach is an effective means of balancing all three components of a simple planetary gear set, thus resulting in a solution that has been optimized for volume. </p>

Numerical analysis and modelling of transmission systems for hybrid electric vehicles and electric vehicles

Ren, Qinglian January 2010 (has links)
Interest in hybrid electric vehicles (HEVs) and electric vehicles (EVs) has increased rapidly over recent years from both industrial and academic viewpoints due to increasing concerns about environmental pollution and global oil usage. In the automotive sector, huge efforts have been invested in vehicle technology to improve efficiency and reduce carbon emissions with, for example, hybrid and electric vehicles. This thesis focuses on one design area of these vehicles – the transmission – with the aim of investigating the potential benefits of improved transmissions for HEVs and EVs. For HEVs, a novel transmission developed by Nexxtdrive based on a twin epicyclic design is analysed using a matrix method and its performance is compared with the more common single epicyclic arrangement used successfully in the Toyota Prius. Simulation models are then used to compare the performance of a typical HEV passenger car fitted with these two transmissions over standard driving cycles. The conclusion is that the twin epicyclic offers substantial improvements of up to 20% reduction in energy consumption, though the benefits are sensitive to the driving cycle used. For EVs, most designs to date have used a single fixed ratio transmission, and surprisingly little research has explored whether multi-geared transmissions offer any benefits. The research challenge is whether it is possible to optimise the usage of the electric motor in its region of high efficiency by controlling the transmission. Simulation results of two EV examples confirm that energy consumption benefits are indeed achievable – of between 7 and 14% depending on the driving cycle. Overall, the original aspects of this work – the analysis and modelling the twin epicyclic gearbox; the analysis and modelling the twin epicyclic system in a vehicle and a comparison of the results with single epicyclic system; and the analysis and modelling of EVs with and without a transmission system of varying levels of complexity – have shown that there are worthwhile performance benefits from using improved transmission designs for low carbon vehicles.

Investigation of belt misalignment effects on metal pushing v-belt continuously variable transmission

Tawi, K. B. January 1997 (has links)
No description available.

Control studies in active suspension systems

Truscott, A. J. January 1992 (has links)
No description available.

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