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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.
291

Vehicle tracking using scale invariant features

Wang, Jue, Computer Science & Engineering, Faculty of Engineering, UNSW January 2008 (has links)
Object tracking is an active research topic in computer vision and has appli- cation in several areas, such as event detection and robotics. Vehicle tracking is used in Intelligent Transport System (ITS) and surveillance systems. Its re- liability is critical to the overall performance of these systems. Feature-based methods that are used to represent distinctive content in visual frames are one approach to vehicle tracking. Existing feature-based tracking systems can only track vehicles under ideal conditions. They have difficulties when used under a variety of conditions, for example, during both the day and night. They are highly dependent on stable local features that can be tracked for a long time period. These local features are easily lost because of their local property and image noise caused by factors such as, headlight reflections and sun glare. This thesis presents a new approach, addressing the reliability issues mentioned above, tracking whole feature groups composed of feature points extracted with the Scale Invariant Feature Transform (SIFT) algorithm. A feature group in- cludes several features that share a similar property over a time period and can be tracked to the next frame by tracking individual feature points inside it. It is lost only when all of the features in it are lost in the next frame. We cre- ate these feature groups by clustering individual feature points using distance, velocity and acceleration information between two consecutive frames. These feature groups are then hierarchically clustered by their inter-group distance, velocity and acceleration information. Experimental results show that the pro- posed vehicle tracking system can track vehicles with the average accuracy of over 95%, even when the vehicles have complex motions in noisy scenes. It gen- erally works well even in difficult environments, such as for rainy days, windy days, and at night. We are surprised to find that our tracking system locates and tracks motor bikes and pedestrians. This could open up wider opportunities and further investigation and experiments are required to confirm the tracking performance for these objects. Further work is also required to track more com- plex motions, such as rotation and articulated objects with different motions on different parts.
292

Development of a Semi-active Intelligent Suspension System for Heavy Vehicles

Nima, Eslaminasab January 2008 (has links)
With the new advancements in the vibration control strategies and controllable actuator manufacturing, the semi-active actuators (dampers) are finding their way as an essential part of vibration isolators, particularly in vehicle suspension systems. This is attributed to the fact that in a semi-active system, the damping coefficients can be adjusted to improve ride comfort and road handling performances. The currently available semi-active damper technologies can be divided into two main groups. The first uses controllable electromagnetic valves. The second uses magnetorheological (MR) fluid to control the damping characteristics of the system. Leading automotive companies such as General Motors and Volvo have started to use semi-active actuators in the suspension systems of high-end automobiles, such as the Cadillac Seville and Corvette, to improve the handling and ride performance in the vehicle. But much more research and development is needed in design, fabrication, and control of semi-active suspension systems and many challenges must be overcome in this area. Particularly in the area of heavy vehicle systems, such as light armored vehicles, little related research has been done, and there exists no commercially available controllable damper suitable for the relatively high force and large displacement requirements of such application. As the first response to these requirements, this thesis describes the design and modeling of an in-house semi-active twin-tube shock absorber with an internal variable solenoid-actuated valve. A full-scale semi-active damper prototype is developed and the shock absorber is tested to produce the required forcing range. The test results are compared with results of the developed mathematical model. To gain a better understanding of the semi-active suspension controlled systems and evaluate the performance of those systems, using perturbation techniques this thesis provides a detailed nonlinear analysis of the semi-active systems and establishes the issue of nonlinearity in on-off semi-active controlled systems. Despite different semi-active control methods and the type of actuators used in a semi-active controlled system, one important practical aspect of all hydro-mechanical computer controlled systems is the response-time. The longest response-time is usually introduced by the actuator –in this case, controllable actuator – in the system. This study investigates the effect of response-time in a semi-active controlled suspension system using semi-active dampers. Numerical simulations and analytical techniques are deployed to investigate the issue. The performance of the system due to the response-time is then analyzed and discussed. Since the introduction of the semi-active control strategy, the challenge was to develop methods to effectively use the capabilities of semi-active devices. In this thesis, two semi-active control strategies are proposed. The first controller to be proposed is a new hybrid semi-active control strategy based on the conventional Rakheja-Sankar (R-S) semi-active control to provide better ride-handling quality for vehicle suspension systems as well as industrial vibration isolators. To demonstrate the effectiveness of this new strategy, the analytical method of averaging and the numerical analysis method are deployed. In addition, a one-degree-of-freedom test bed equipped with a semi-active magnetorheological (MR) damper is developed. The tests are performed using the MATLAB XPC-target to guarantee the real-time implementation of the control algorithm. The second controller is an intelligent fuzzy logic controller system to optimize the suspension performance. The results from this intelligent system are compared with those of several renowned suspension control methods such as Skyhook. It is shown that the proposed controller can enhance concurrently the vehicle handling and ride comfort, while consuming less energy than existing control methodologies. The key goal of this thesis is to employ the existing knowledge of the semi-active systems together with the new ideas to develop a semi-active suspension system. At the same time, development of an experimental simulation system for real-time control of an experimental test bed is considered. To achieve its goals and objectives, this research study combines and utilizes the numerical simulations and analytical methods, as well as lab-based experimental works. The challenge in this research study is to identify practical and industrial problems and develop proper solutions to those problems using viable scientific approaches.
293

Model Predictive Control for Heavy Duty Vehicle Platooning / Modellbaserad prediktionsreglering för tunga fordon i fordonståg

Kemppainen, Josefin January 2012 (has links)
The aim of platooning is to enable several vehicles to drive in a convoy while each vehicle is controlled autonomously in longitudinal direction. All vehicles in the platoon are equipped with WiFi and can therefore apply Vehicle-to-Vehicle (V2V) communication. As a result, a short intermediate distance between the vehicles can be maintained. Reduction of the aerodynamic drag is the result of the short distance, which in turn, reduces the consumed fuel. This thesis is a part of a larger project, consisting of two other theses that investigate estimation of the sensor data. Other scenarios that may arise with the platooning concept, e.g. packet losses and time synchronization of the different sensors are also analyzed. The purpose of this master thesis is to develop and evaluate a Model Predictive Control (MPC) in the concept of platooning. The main focus lies on implementation of two types of MPC, centralized and distributed, and later on integration with the other two subsystems is performed. Results from the MPC itself are evaluated, principally in terms of fuel con- sumption and computational demand. The major part of the results are based on the complete system as one unit and covers different test scenarios such as WiFi loss and non-transmitting vehicle entering the platoon. A comparison of how much energy that is consumed by the engine between an HDV driving with its cruise control and an HDV driving in a platoon has been performed. With an intermediate distance of 10 meters, driving with varying velocity and ideal signals the energy consumption got reduced with an average of 11%. / Syftet med platooning är att flera tunga fordon kör tätt efter varandra i ett fordonståg. Varje fordon regleras autonomt i longitudinell riktning och är utrustad med WiFi. Detta bidrar till att fordonen kan kommunicera med varandra och denna kommunikation, även kallad Vehicle-to-Vehicle (V2V) - communication, leder till att det relativa avståndet mellan fordonen kan minskas, vilket i sin tur leder till minskat luftmotstånd och därmed minskad bränsleförbrukning. Detta examensarbete är en del av ett större projekt som består av ytterligare två examensarbeten. De andra två hanterar estimeringen av sensordata samt behandlar förlorat sensordata och tidssynkronisering av de olika sensorerna som används. Syftet med detta examensarbete är att utveckla och utvärdera en MPC regu- lator i platooning sammanhang. Huvudfokuset ligger på implementeringen, både centraliserad och distribuerad MPC, och integreringen med de två andra delsystemen. Resultaten från enbart MPC utvärderas i termer av bränsleförbrukning och även beräkningskapactiet, då MPC är känt för att vara väldigt beräkningskrävan- de och är ofta en begränsning för hårdvaran. Den största delen av resultaten är baserade på hela systemet och täcker olika scenarion som exempelvis dålig WiFi uppkoppling och att icke−sändande fordon intar platoonen. En jämförelse av hur mycket energi motorn förbrukade har gjorts mellan ett tungt fordon som kör med farthållaren påslagen och ett tungt fordon som kör i en platoon. Med ett relativt avstånd på 10 meter, varierande hastighet och icke brusiga signaler kan bränsleförbrukning minskas med ett medel på approximativt 11%.
294

Development of a Semi-active Intelligent Suspension System for Heavy Vehicles

Nima, Eslaminasab January 2008 (has links)
With the new advancements in the vibration control strategies and controllable actuator manufacturing, the semi-active actuators (dampers) are finding their way as an essential part of vibration isolators, particularly in vehicle suspension systems. This is attributed to the fact that in a semi-active system, the damping coefficients can be adjusted to improve ride comfort and road handling performances. The currently available semi-active damper technologies can be divided into two main groups. The first uses controllable electromagnetic valves. The second uses magnetorheological (MR) fluid to control the damping characteristics of the system. Leading automotive companies such as General Motors and Volvo have started to use semi-active actuators in the suspension systems of high-end automobiles, such as the Cadillac Seville and Corvette, to improve the handling and ride performance in the vehicle. But much more research and development is needed in design, fabrication, and control of semi-active suspension systems and many challenges must be overcome in this area. Particularly in the area of heavy vehicle systems, such as light armored vehicles, little related research has been done, and there exists no commercially available controllable damper suitable for the relatively high force and large displacement requirements of such application. As the first response to these requirements, this thesis describes the design and modeling of an in-house semi-active twin-tube shock absorber with an internal variable solenoid-actuated valve. A full-scale semi-active damper prototype is developed and the shock absorber is tested to produce the required forcing range. The test results are compared with results of the developed mathematical model. To gain a better understanding of the semi-active suspension controlled systems and evaluate the performance of those systems, using perturbation techniques this thesis provides a detailed nonlinear analysis of the semi-active systems and establishes the issue of nonlinearity in on-off semi-active controlled systems. Despite different semi-active control methods and the type of actuators used in a semi-active controlled system, one important practical aspect of all hydro-mechanical computer controlled systems is the response-time. The longest response-time is usually introduced by the actuator –in this case, controllable actuator – in the system. This study investigates the effect of response-time in a semi-active controlled suspension system using semi-active dampers. Numerical simulations and analytical techniques are deployed to investigate the issue. The performance of the system due to the response-time is then analyzed and discussed. Since the introduction of the semi-active control strategy, the challenge was to develop methods to effectively use the capabilities of semi-active devices. In this thesis, two semi-active control strategies are proposed. The first controller to be proposed is a new hybrid semi-active control strategy based on the conventional Rakheja-Sankar (R-S) semi-active control to provide better ride-handling quality for vehicle suspension systems as well as industrial vibration isolators. To demonstrate the effectiveness of this new strategy, the analytical method of averaging and the numerical analysis method are deployed. In addition, a one-degree-of-freedom test bed equipped with a semi-active magnetorheological (MR) damper is developed. The tests are performed using the MATLAB XPC-target to guarantee the real-time implementation of the control algorithm. The second controller is an intelligent fuzzy logic controller system to optimize the suspension performance. The results from this intelligent system are compared with those of several renowned suspension control methods such as Skyhook. It is shown that the proposed controller can enhance concurrently the vehicle handling and ride comfort, while consuming less energy than existing control methodologies. The key goal of this thesis is to employ the existing knowledge of the semi-active systems together with the new ideas to develop a semi-active suspension system. At the same time, development of an experimental simulation system for real-time control of an experimental test bed is considered. To achieve its goals and objectives, this research study combines and utilizes the numerical simulations and analytical methods, as well as lab-based experimental works. The challenge in this research study is to identify practical and industrial problems and develop proper solutions to those problems using viable scientific approaches.
295

Supporting Scalable and Resilient Video Streaming Applications in Evolving Networks

Guo, Meng 24 August 2005 (has links)
While the demand for video streaming services has risen rapidly in recent years, supporting video streaming service to a large number of receivers still remains a challenging task. Issues of video streaming in the Internet, such as scalability, and reliability are still under extensive research. Recently proposed network contexts such as overlay networks, and mobile ad hoc networks pose even tougher challenges. This thesis focuses on supporting scalable video streaming applications under various network environments. More specifically, this thesis investigates the following problems: i) Server selection in replicated batching video on demand (VoD) systems: we find out that, to optimize the user perceived latency, it is vital to consider the server state information and channel allocation schemes when making server selection decisions. We develop and evaluate a set of server selection algorithms that use increasingly more information. ii) Scalable live video streaming with time shifting and video patching: we consider the problem of how to enable continuous live video streaming to a large group of clients in cooperative but unreliable overlay networks. We design a server-based architecture which uses a combined technique of time-shifting video server and P2P video patching. iii) A Cooperative patching architecture in overlay networks: We design a cooperative patching architecture which shifts video patching responsibility completely to the client side. An end-host retrieves lost data from other end-hosts within the same multicast group. iv) V3: a vehicle to vehicle video streaming architecture: We propose V3, an architecture to provide live video streaming service to driving vehicles through vehicle-to-vehicle (V2V) networks. V3 incorporates a novel signaling mechanism to continuously trigger video sources to send video data back to the receiver. It also adopts a store-carry-and-forward approach to transmit video data in a partitioned network environment. We also develop a multicasting framework that enables live video streaming applications from multiple sources to multiple receivers in V2V networks. A message integration scheme is used to suppress the signaling overhead, and a two-level tree-based routing approach is adopted to forward the video data.
296

Flywheel in an all-electric propulsion system

Lundin, Johan January 2011 (has links)
Energy storage is a crucial condition for both transportation purposes and for the use of electricity. Flywheels can be used as actual energy storage but also as power handling device. Their high power capacity compared to other means of storing electric energy makes them very convenient for smoothing power transients. These occur frequently in vehicles but also in the electric grid. In both these areas there is a lot to gain by reducing the power transients and irregularities. The research conducted at Uppsala university and described in this thesis is focused on an all-electric propulsion system based on an electric flywheel with double stator windings. The flywheel is inserted in between the main energy storage (assumed to be a battery) and the traction motor in an electric vehicle. This system has been evaluated by simulations in a Matlab model, comparing two otherwise identical drivelines, one with and one without a flywheel. The flywheel is shown to have several advantages for an all-electric propulsion system for a vehicle. The maximum power from the battery decreases more than ten times as the flywheel absorbs and supplies all the high power fluxes occuring at acceleration and braking. The battery delivers a low and almost constant power to the flywheel. The amount of batteries needed decreases whereas the battery lifetime and efficiency increases. Another benefit the flywheel configuration brings is a higher energy efficiency and hence less need for cooling. The model has also been used to evaluate the flywheel functionality for an electric grid application. The power from renewable intermittent energy sources such as wave, wind and current power can be smoothened by the flywheel, making these energy sources more efficient and thereby competitive with a remaining high power quality in the electric grid.
297

Vehicle tracking using scale invariant features

Wang, Jue, Computer Science & Engineering, Faculty of Engineering, UNSW January 2008 (has links)
Object tracking is an active research topic in computer vision and has appli- cation in several areas, such as event detection and robotics. Vehicle tracking is used in Intelligent Transport System (ITS) and surveillance systems. Its re- liability is critical to the overall performance of these systems. Feature-based methods that are used to represent distinctive content in visual frames are one approach to vehicle tracking. Existing feature-based tracking systems can only track vehicles under ideal conditions. They have difficulties when used under a variety of conditions, for example, during both the day and night. They are highly dependent on stable local features that can be tracked for a long time period. These local features are easily lost because of their local property and image noise caused by factors such as, headlight reflections and sun glare. This thesis presents a new approach, addressing the reliability issues mentioned above, tracking whole feature groups composed of feature points extracted with the Scale Invariant Feature Transform (SIFT) algorithm. A feature group in- cludes several features that share a similar property over a time period and can be tracked to the next frame by tracking individual feature points inside it. It is lost only when all of the features in it are lost in the next frame. We cre- ate these feature groups by clustering individual feature points using distance, velocity and acceleration information between two consecutive frames. These feature groups are then hierarchically clustered by their inter-group distance, velocity and acceleration information. Experimental results show that the pro- posed vehicle tracking system can track vehicles with the average accuracy of over 95%, even when the vehicles have complex motions in noisy scenes. It gen- erally works well even in difficult environments, such as for rainy days, windy days, and at night. We are surprised to find that our tracking system locates and tracks motor bikes and pedestrians. This could open up wider opportunities and further investigation and experiments are required to confirm the tracking performance for these objects. Further work is also required to track more com- plex motions, such as rotation and articulated objects with different motions on different parts.
298

Use of simulation-animation techniques in the design of an automated guided vehicle system /

Jayaraman, Arun, January 1993 (has links)
Report (M. Eng.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 80-82). Also available via the Internet.
299

Impact of asset usage preferences on parallel replacement decisions /

Wagner, Tristan John. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 56-59). Also available on the World Wide Web.
300

Design, modeling and optimization of hybridized automated manual transmission for electrified vehicles

Wu, Guang 21 December 2017 (has links)
This research systematically compares various electrified vehicles based upon electrification levels and powertrain configurations. A series of novel hybrid electric powertrain systems based on the newly proposed Hybridized Automated Manual Transmission (HAMT) concept are introduced. One representative hybrid powertrain system is selected to illustrate their operation principle. The new HAMT-based hybrid powertrain system overcomes the bottleneck problem of mainstream power-split hybrid systems with relatively low torque capacity and the constraint for utility vehicle electrification, and presents advantages over other hybrid powertrain systems in efficiency and costs. In addition, the new hybrid powertrain system can deliver continuous output torque by filling torque hole during gearshift, through coordinated control of engine, motor, and transmission, improving the driveability of regular Automated Manual Transmission (AMT), whose applications have been hampered by torque hole over the past years. The proposed HAMT-based hybrid systems with improved torque capacity, efficiency, costs, and driveability come with a compact design and more flexible operation through the amount of gearwheels equivalent to a 5-speed AMT to achieve 8 variable gear ratios for the Hybrid Electric Vehicle (HEV) mode and Electric Vehicle (EV) mode operations of a Plug-in Hybrid Electric Vehicle (PHEV). Model-based optimization, dynamics analysis, and powertrain control strategies have been introduced for a PHEV with a representative 8-speed HAMT. Vehicle simulations have been made to study and verify the capability and advantages of the new electrified powertrain system. Firstly, the operation principles of various HAMTs are discussed through detailed power flows at each gear. The fundamental principles of typical HAMT variations are explained using a new power-flow triangle with three ports. Based on the concept of Torque Gap Filler (TGF), a set of HAMT system designs have been introduced and closely studied to provide continuous and stable output torque. The selected hybrid powertrain system equipped with a representative HAMT system supports both HEV mode and EV mode with eight variable gear ratios for each mode. Among the eight forward gear ratios, six are independent and two are dependent on the other gears. Combinations of dog clutches at all gears are designed to eliminate torque holes. Gear ratios and gearshift schedule of the 8-speed HAMT are designed to support the new design. Torque paths at each gear are illustrated and transient scenarios including gearshifts and mode transitions are investigated. The gear ratio of each gear is determined by considering the unique clutch combination of this HAMT, using the classical gear ratio design method - Progressive Ratio Steps. Due to the broader high efficiency operation region of electric motors, a model-based optimization method is used to determine the two gear ratios for the EV mode to achieve better fuel economy and avoid unnecessary gearshifts. Dynamic Programming (DP) is used to identify the optimal gear ratios, considering vehicle fuel economy for the EPA75 and Highway Fuel Economy Fuel Test (HWFET) driving cycles. The 4th and 6th gears among the eight gear ratios in the EV mode of PHEV are based on 2-speed gearbox design for an EV, and their gearshift schedules are determined by optimization. Combining the considerations for the hybrid and EV modes of a PHEV, key elements of the proposed HAMT system, including gearshift schedule, clutch combination, and gear ratios for highly efficient operation are determined. The more challenging driveability issues during mode transition from EV to HEV and power-on gearshift with TGF during acceleration are addressed. Both of these two operations require relatively high power/torque outputs and involve multiple powertrain components, including engine, motor, main clutch and gearbox, within a period of two seconds. A lumped-mass model (LMM) of the HAMT-based hybrid vehicle is built to analyze the driveline dynamics in two steady states and four transient states. Each of these states is analyzed independently, according to states of main clutch and gear selectors, considering different phases of the TGF operation and EV-HEV mode transition. The methods for modeling the discontinuity of clutch torque and dog clutch inside the HAMT are discussed to support the subsequent powertrain system modeling and control development. To identify the optimal control schemes for model transition and gearshift, the model-based optimization method for a post-transmission parallel PHEV is developed. The vehicle powertrain model was initially built using AUTONOMIE and MATLAB/Simulink with primary parameters from a prototype PHEV and its dSPACE ASM model developed at University of Victoria. System dynamics in EV mode and hybrid mode are described as a group of state-space equations, which are further discretized into matrix form to simplify the optimization search. A DP-based global optimization method is used to identify the optimal control inputs, including engine torque, motor torque, and main clutch torque. Four principles for desirable EV-HEV mode transitions are extracted based on the results of the optimization. To model different operation modes and complex power flows, the initial baseline powertrain system model is then replaced by a customized MATLAB/SimDriveline model. In this new physics-based powertrain model, gearshift actuators and controller are added to model the gearshift and mode transition processes. To achieve good driveability, the TGF feature of the HAMT design is split into five transient and two steady phases, each corresponding to a fundamental operating mode. Control logics of upshift and downshift, as well as EV-HEV mode transition are introduced. Four principles of mode transition derived from global optimization results are introduced for powertrain system control. Simulations of the HAMT-based hybrid powertrain operations have been carried out to verify the functionality and advantages of the proposed HAMT design in achieving excellent driveability during mode transition and gearshifts. Through controlled coordination of engine, motor and main clutch, EV-HEV mode transition can be achieved smoothly within a period of 2-3 seconds. Even slight driveline fluctuation can be eliminated by dedicated anti-shuffle control with the motors as actuators. The same simulation model also demonstrates excellent driveability during power-on gearshift. Comparing simulation results with and without TGF shows that this new hybrid powertrain system can effectively eliminate torque holes during gearshift. With the demonstrated advantages of this new system in efficiency, torque capacity, simplicity in design and manufacturing costs over its existing rivals, the research provides a promising alternative to mainstream power-split hybrid electric powertrain system design. / Graduate

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