Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 52-53). Also available on the World Wide Web.

Motivated by the few work has done on the performance measurement of graphene passive devices compared to graphene active devices, several different types of passive devices are fabricated and measured. In general, the fabricated devices are divided into two parts: the DC devices and the RF devices, which based on the different electrical properties we measure in Chapter 7. For the DC devices, attention has been given to the resistance of CVD graphene that we later use in all the RF devices. The Dirac point seems only appears in the exfoliated graphene measurement, which is caused by the doping concentration difference between the exfoliated and CVD graphene. Meanwhile, the sheet resistance of graphene is calculated based on the four-point measurement. The sheet resistance of CVD graphene is around 291 Ω/sqFor the RF devices, the measurement is conducted on the two types of graphene passive devices from 0-110 GHz. The first type of graphene devices is the graphene CPW resonator. We measure the input impedances of the graphene resonators on different substrates (Si/SiO2 and GaAs) and with different graphene lengths (440 micro metre, 500 micro metre and 1415 micro metre). For the graphene resonators on Si/SiO2 substrate, the input impedance does show the resonance shift compared to the graphene-removed structure. The frequency position of the resonance that appears is consistent with the theoretical calculation result. Besides, the influence of the external conditions such as temperature on the performance of graphene resonators has been investigated. The input impedance resonance shows the shift when the external temperature varying from 40o C（313K） to 160o C （433K）. This measurement is undertaken with the graphene resonator on GaAs substrate. The second type of graphene devices is the graphene CPW transmission line on Si/SiO2 substrate. The S-parameters measured from VNA reveal that graphene within the transmission line acts as the transmission channel, which is a little lossy at the microwave frequency range. The poor transmission is also partially caused by the mismatching of the parasitic impedance, as well as the substrate loss, which is verified by the comparison result between the graphene transmission line and the graphene-removed transmission line. Similarly, the concern on the signal line coupling is also eliminated by using the graphene-removed structure.

With the increase in electronic equipment implemented in various systems, as well as the increase in calculating power that these devices offer, designers are being empowered to make use of this power in real-time systems to diagnose and protect the systems themselves. This reasoning is too compounded by the focus on efficiency and safety in the design of complex systems, as well as the increasing expense and sensitivity of the electronic components themselves. With this in mind, this dissertation aims at developing a comprehensive measurement, control and reaction system for the electrical diagnosis and ultimately optimisation of complex electrical and electronic systems. This system will serve as a real-time diagnosis tool, which will enable the real-time diagnosis of various components in an electro-mechanical system, which can then be interpreted to determine the working state of the various components. Another sphere of this project will involve the accurate monitoring of the battery status as well as actively balancing the series connected batteries. The focus on the batteries will seek to prolong the life of the batteries, while being able to squeeze as much capacity out of them. The initial design and testing will be based on an AGV system implemented at VWSA, however a main goal throughout the design process will be modularity, i.e. the ease of implementation of this system in other systems. The key technologies used in the development of this system will still comprise of the components used in the original AGV, however new prototype components sourced from Microcare are used for the battery management system, while current sensors directly connected to the PLC’s analog input ports will be used for the active monitoring of currents distributed through the AGV.

No description available.

A method is presented which permits the measure of nose tip recession of re-entry vehicles and advanced terminal interceptors by employing a double choked flow coolant gas system. Recession of the tip results in an increased exit flow area which reduces the total pressure of the gas in the blast tube. Measurement of the blast tube pressure and gas generator (chamber) pressure will produce an effective measurement of the nose tip recession as long as choked flow (i.e., sonic velocity) is maintained in both the tip exit area and the gas generator throat area. Governing flow equations documented in the literature are developed for double choked flow. Hypersonic wind tunnel test data are presented to verify the developed flow equations and to identify the mass flow ratios necessary to sustain double choked flow.

Call number: LD2668 .T4 1965 D227 / Master of Science

Published Article / Today's industries are based on an automated workplace. These automated workplaces are efficient, reconfigurable and intelligent automated environments. They are filled with technology, robotics, Automated Guided Vehicle (AGV) and, or Unmanned Aerial Vehicles (UAV) etc. For full automation will one need to effectively track an object, unmanned aerial vehicle (UAV) or automated guided vehicle (AGV). Effective tracking of vehicles can be used for control. This could result in less hardware on the craft that leads to a longer battery life, a bigger pay load or more processing power. This system track by using a stationary colour camera placed at an optimal placing in the automated workplace. The vehicle or objects are painted in two colours (colour A and colour B) that are not present in the automated workplace. The images from the camera are hue colour filtered to extract only the object or vehicle. The area, placement in frame and relationship between colour A and B are used for position and determine the orientation of AGV, UAV or object.

Published Article / An immense amount of research is currently, being done on the development and use of Automatic Guided Vehicles (AGVs) in industry. An important component of this research often involves navigation and route-optimization of such AGVs. In this paper the design and control of an AGV, using a stationary control system and a GPS-like navigational system, is discussed. Substantial provision has also been made for the display of operational characteristics of the AGV on the stationary control unit.

For adaptive motion control of an autonomous vehicle, operating in a generally structured environment, position and velocity feedback are required to ascertain the vehicle location relative to a reference. Whilst the literature offers techniques for guiding vehicles along external references, autonomous vehicles should be able to navigate between despatch locations without the need to rely on external guidance systems. Considerations of the vehicle stability and manoeuvrability favour a vehicle design with four independently steered wheels. A new motion control methodology has been proposed which utilises the geometric relationship of the angular displacements and the rotations of the wheels to estimate the longitudinal and lateral motions of the vehicle. The motion controller consists of three building blocks: the motion control system comprising the position tracking and the motion command generation; the electronic system comprising a data acquisition system and proprietary power electronics; the mechanical system which includes an undercarriage enabling permanent contact of the wheels with the floor. The components have been designed not only to perform optimally in their specific functions but also to ensure full compatibility within the integrated system. For reliable deduction of the wheel rotations with a high degree of accuracy a dedicated data acquisition interface has been developed, which enables data to be captured in parallel from four optical encoders mounted directly on the wheel axles. Parallel sampling of the angular wheel position and parallel actuation of all steering motors improves the accuracy of the system state and gives a higher degree of certainty. Considering only circular motion of the vehicle, a method for calculating the steering angles and wheel speeds based on the complex notation is presented. By cumulating the displacement vectors of the vehicle motion and the location of the centre of rotation between consecutive samples of the controller, the path of the vehicle is estimated. The difference between the nominal and the deduced centre of rotation is determined to minimise deviations from the reference trajectory and to allow the controller to adapt to changes in the road/tyre interface characteristics. The individual mechanical and electronic components have been assembled and tested. Additionally, the performance of the electronic interface has been evaluated on a purpose built test-bed. For the experimental validation of the methodology, a simple method of mapping the centre of curvature with a pen mounted at the nominal centre of rotation has been proposed. Experiments have been conducted with both the steering angles fixed to their theoretical values for the nominal centre of rotation and with the proportional steering controller enabled. The results from the latter method have shown a significantly reduced deviation from the nominal centre of rotation. The data captured of the angular wheel positions and steering angle settings has been analysed off-line. Good agreement is obtained between the deduced and the actual centres of rotation for the measurements averaged over 1.5 seconds. A number of different centres of rotation have been investigated and the required steering angles to compensate for the deviation have been plotted to form a control surface for the motion controller. The deviation between the estimated and the actual centre of curvature was less than 1.6% and adequate results could be obtained with the proportional steering controller.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy