Many successful control schemes for land-based or air-based groups, or platoons, of autonomous vehicles cannot be implemented in underwater applications because of their dependence upon high-bandwidth communication. In current strategies for controlling groups of autonomous underwater vehicles (AUVs), platoon size remains limited by communication bandwidth requirements. So, there is great need for advances in low-bandwidth control techniques for arbitrarily large platoons of AUVs. This thesis presents a new approach to multiple vehicle control. The concepts described herein enable an arbitrarily large platoon to be controlled while utilizing minimal inter-vehicle communication. Specifically, this thesis examines a sufficient condition on platoon commands in order for a low-bandwidth decentralized controller to exist. Knowing from this sufficient condition the necessary general form of platoon commands, a number of higher-order statistics were tested. This thesis describes and analyzes their utility as platoon commands. In addition to these theoretical developments, this thesis presents the practical design needs for the Virginia Tech miniature autonomous underwater vehicle as well as their resolution. / Master of Science

The objective of the report is to investigate which kind of mobile appli-cation, native, hybrid or web, that is the best regarding cross-platform support compared to development cost. As there are little information regarding pure web applications for mobile devices a prototype will be constructed to give light in this technology. The prototype should an-swer the questions if it can save a year's usage in the cell phones memory, if it is possible to have support for 100 percent of Sweden area and generally if this approach would suffice. There are also some physi-cal restrictions on the web application. A login must be done in less than 5 second, fetch TOs( timber orders) within 10 seconds, report a row within 5 seconds. This in a 2G environment, in Telias network, which is mostly likely to be used in the forest. To easily test the application the CPN-tools(colored petri nets) are used to graphically model the applica-tion and simulations are thereafter done to get a scenes how the applica-tion would perform during many years of usage. To construct have been constructed with the aid of open web technologies as HTML5,CSS4, JavaScript, JQuery and JQuery mobile. The prototype used asynchronies communication to mask loss of coverage and long loading times. It also utilized HTML5 localStorage to save TOs and employer information so that minimize the need for fetching information many times. The proto-type application cannot be used in 100 percent of Sweden's area because the cellular coverage is not present in big areas in the north of Sweden. Therefore information is stored locally but after the pre fetched work orders are completed new work orders must be fetched where cellular coverage is present. The application still have a big usage area and as most wood products comes from the middle of Sweden this cannot be seen as a big problem. To save a year's usage of data on the other hand is not a problem at all. About 10 percent of the available 5 MB of storage in the HTML5 localStorage would be needed. It did also with ease handle the time limitations. As a conclusion the need for a web applica-tion, for SDC, is only present if both IVR and web reporting through a computer is if these services are liquidated in the long run. There are a bit more work with creating a hybrid native/web application using third-party applications but it in turns would give a better coverage area as that kind of application can pre download all TOs and employers ignoring any limitations in storage. This is not possible to do as a pure web application can't be run in the background on the phone.

Phase Locked Loops(PLLs) are an integral part of almost every electronic system. Systems involving low frequency clocks often require PLLs with low bandwidth. The area occupied by the large loop filter capacitor and resistor in a low bandwidth PLL design makes the realization of traditional charge-pump PLL architecture impractical on a single die, mandating external components on the board. In order to maintain low loop bandwidth the designer is often forced to choose very low values of charge pump current which can lead to reliability issues. In this work, a semi-digital architecture for very low bandwidth monolithic PLLs is proposed. This architecture eliminates large components in traditional charge-pump PLL, thus allowing the realization of on-chip low bandwidth PLLs. A 2x2mm PLL is realized in 180nm CMOS with 75mHz bandwidth consuming 400μW power from 1.8V supply. The prototype PLL locks to an input clock of 1Hz and generates 20kHz output clock with a measured peak-to-peak jitter of 100ns. / Graduation date: 2013