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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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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.
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Showing 31 to 33 of 33 (0.015 seconds)Spelling suggestions: "subject:"freeboard""
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OpenBSD Hardware Sensors — Environmental Monitoring and Fan ControlMurenin, Constantine Aleksandrovich 18 May 2010 (has links)
This thesis discusses the motivation, origin, history, design guidelines, API, the device drivers and userland utilities of the hardware sensors framework available in OpenBSD. The framework spans multiple utilities in the base system and the ports tree, is utilised by over 75 drivers, and is considered to be a distinctive and ready-to-use feature that sets OpenBSD apart from many other operating systems, and in its root is inseparable from the OpenBSD experience.
The present framework, however, is missing the functionality that would allow the user to interface with the fan-controlling part of the hardware monitors. We therefore discuss the topic of fan control and introduce sysctl-based interfacing with the fan-controlling capabilities of microprocessor system hardware monitors. The discussed prototype implementation reduces the noise and power-consumption characteristics in fans of personal computers, especially of those PCs that are designed from off-the-shelf components. We further argue that our prototype is easier, more intuitive and robust compared to solutions available elsewhere.
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OpenBSD Hardware Sensors — Environmental Monitoring and Fan ControlMurenin, Constantine Aleksandrovich 18 May 2010 (has links)
This thesis discusses the motivation, origin, history, design guidelines, API, the device drivers and userland utilities of the hardware sensors framework available in OpenBSD. The framework spans multiple utilities in the base system and the ports tree, is utilised by over 75 drivers, and is considered to be a distinctive and ready-to-use feature that sets OpenBSD apart from many other operating systems, and in its root is inseparable from the OpenBSD experience.
The present framework, however, is missing the functionality that would allow the user to interface with the fan-controlling part of the hardware monitors. We therefore discuss the topic of fan control and introduce sysctl-based interfacing with the fan-controlling capabilities of microprocessor system hardware monitors. The discussed prototype implementation reduces the noise and power-consumption characteristics in fans of personal computers, especially of those PCs that are designed from off-the-shelf components. We further argue that our prototype is easier, more intuitive and robust compared to solutions available elsewhere.
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Settling-Time Improvements in Positioning Machines Subject to Nonlinear Friction Using Adaptive Impulse ControlHakala, Tim 31 January 2006 (has links) (PDF)
A new method of adaptive impulse control is developed to precisely and quickly control the position of machine components subject to friction. Friction dominates the forces affecting fine positioning dynamics. Friction can depend on payload, velocity, step size, path, initial position, temperature, and other variables. Control problems such as steady-state error and limit cycles often arise when applying conventional control techniques to the position control problem. Studies in the last few decades have shown that impulsive control can produce repeatable displacements as small as ten nanometers without limit cycles or steady-state error in machines subject to dry sliding friction. These displacements are achieved through the application of short duration, high intensity pulses. The relationship between pulse duration and displacement is seldom a simple function. The most dependable practical methods for control are self-tuning; they learn from online experience by adapting an internal control parameter until precise position control is achieved. To date, the best known adaptive pulse control methods adapt a single control parameter. While effective, the single parameter methods suffer from sub-optimal settling times and poor parameter convergence. To improve performance while maintaining the capacity for ultimate precision, a new control method referred to as Adaptive Impulse Control (AIC) has been developed. To better fit the nonlinear relationship between pulses and displacements, AIC adaptively tunes a set of parameters. Each parameter affects a different range of displacements. Online updates depend on the residual control error following each pulse, an estimate of pulse sensitivity, and a learning gain. After an update is calculated, it is distributed among the parameters that were used to calculate the most recent pulse. As the stored relationship converges to the actual relationship of the machine, pulses become more accurate and fewer pulses are needed to reach each desired destination. When fewer pulses are needed, settling time improves and efficiency increases. AIC is experimentally compared to conventional PID control and other adaptive pulse control methods on a rotary system with a position measurement resolution of 16000 encoder counts per revolution of the load wheel. The friction in the test system is nonlinear and irregular with a position dependent break-away torque that varies by a factor of more than 1.8 to 1. AIC is shown to improve settling times by as much as a factor of two when compared to other adaptive pulse control methods while maintaining precise control tolerances.
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