DECENTRALIZED SUBOPTIMAL CONTROL OF INDUSTRIAL MANIPULATORS BY A COMPUTER VISION SYSTEM.
AuthorWatts, Russell Charles.
KeywordsRobots -- Industrial applications.
Automatic control -- Industrial applications.
Cameras -- Industrial applications.
Image processing -- Industrial applications.
Manipulators (Mechanism) -- Automatic control.
Manipulators (Mechanism) -- Optical equipment.
Robots, Industrial -- Automatic control.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Degree ProgramGraduate College
Degree GrantorUniversity of Arizona
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Environmental adaptation, political coercion, and illegal behavior: Small-scale fishing in the Gulf of California.Vasquez-León, Marcela. (The University of Arizona., 1995)This dissertation examines the shrimp industry in the Gulf of California from a political ecology perspective. The interaction between fishermen and their marine environment is explored, as well as the historical factors that led to vastly different types of fishermen in the communities of Guaymas and Empalme. Some have specialized in the harvesting of shrimp; others are diversified, multiple species fishermen. Some are highly industrialized offshore shrimpers; others are small-scale fishermen, more modest in their technology but more resilient when facing the current crisis in the shrimp industry. The underlaying causes of this crisis are explored by looking at state development policies, the assumptions behind fisheries management, and the configuration of markets. These have all emphasized specialization in the production of shrimp while ignoring the high interannual variability characteristic of shrimp populations. The end result: an overcapitalized, overexpanded industry and a possible overexploitation of shrimp stocks. Rather than addressing the root causes of the crisis, recent policies have instead transferred rights to the offshore fishery from cooperatives to private investors. At the same time there has been a concerted attack against small-scale producers. It is believed that by getting rid of this sector, catch per boat in the offshore sector will increase and overall "efficiency" will be improved. I compare industrialized trawlers and the small-scale sector and argue that the latter is currently producing high quality shrimp at lower monetary and ecological costs. But small-scale fishing is not equated with sustainability. Instead, differences among small-scale fishermen are analyzed. I contend that those who belong to traditional fishing families and have access to collective knowledge about the marine environment that has accumulated through generations, are better able to deal with a highly unpredictable environment and minimize risk. Those who do not have access to this knowledge have specialized in the harvesting of shrimp. I argue that a strategy of diversification is both more profitable in the short-term and sustainable in the long-run. Avoidance strategies among small-scale fishermen in response to externally imposed regulations are also examined. Fishermen are analyzed as individual profit maximizers and as community members who break the rules to serve collective interests. Just as individuals act collectively to deal with an unpredictable environment, they also act collectively to effectively challenge the institutions of rule-making.
An hierarchical model for FMS control.Sodhi, Manbir Singh (The University of Arizona., 1991)Flexible Manufacturing Systems (FMSs) are usually composed of general purpose machines with automatic tool changing capability and integrated material handling. FMSs offer the advantages of high utilization levels and simultaneous production of a variety of part types with minimal changeover time. The complexity of FMSs however requires sophisticated control. In this dissertation a four level control hierarchy along with computationally feasible control algorithms for each level is presented. Decisions are made at each level utilizing the flexibility inherent in FMSs. The proposed scheme has the advantages of ensuring satisfaction of higher level decisions as lower level operating decisions are made, and allows performance and status data collected at lower levels to be fed back and influence future high level decisions. The top level is concerned with the choice of part types and volumes to be assigned to the FMS over the next several months. Within this horizon, production volumes are planned for each period, a period typically being between a week and a month in length. A linear programming model is used for planning at this level. The second level plans daily or shift production. Advantage is taken of the FMSs ability to be configured to respond to different part mixes to allocate tools to machines so as to minimize holding costs. Separate mathematical programming models are formulated to match various FMS environments. A heuristic for solution of a model of an automated production flexible environment is detailed. Computational results are presented. Extensions of this heuristic to other environments are outlined. The third level determines process routes for each part type in order to minimize material handling. Additional tools are loaded on machines when possible to maximize alternate routings, and using the flexibility offered by FMSs to process parts along alternate routes, routing assignments are made to minimize workload assignment. These routing assignments are used by level four for actual routing, sequencing and material handling path control. The level three model is formulated as a linear program and heuristics are used for level four. An example is provided to illustrate the completeness of the decision hierarchy and the relationships between levels.