The Gravity Recovery and Climate Experiment (GRACE) mission is a breakthrough Earth science mission launched in the spring of 2002 that uses satellite-to-satellite tracking (SST) to map the Earth gravity field. In this framework, the non-uniform gravity distribution is inferred using the range change experienced between two satellites. The range change is measured using a microwave K-band ranging system, and non-gravitational forces are accounted for using accelerometer (ACC) data. The vector-offset between the satellite center of mass (CM) and the K-band phase center represents the correction between measured and modeled ranging data. In addition, the offset between the satellite CM and the ACC proof-mass multiplies the attitude angles, rates, and jitter which in turn add spurious signals to the ACC output. For both of these reasons, proper knowledge and control of attitude behavior is vital to successful mission performance. An examination of the GRACE attitude control system (ACS) is presented in this study. The GRACE ACS system is composed of a PD control law, star camera sensing as the knowledge source, cold-gas thrusters as primary actuators, and magnetic torque rods as supplementary actuators. The dependencies inherent in the ACS are inferred using a sensitivity analysis performed on a simulation model of the GRACE science mode ACS. The results from this sensitivity study are applicable to the general controller class of which the GRACE ACS system is an exemplar. In this study, the modeled attitude data quality is most sensitive to star camera measurement noise. It is hypothesized that this is because star cameras are used as the sole knowledge source in the ACS scheme. In contrast, the experimental results associated with magnetometer, thruster, and magnetic torque rod perturbations did not significantly affect attitude quality. However, these perturbations do cause thruster activity to significantly magnify. This results in higher attitude acceleration PSD for the frequency band in which time-variable gravity components are captured. A number of future experiments can be performed to improve both attitude quality performance and frequency-based magnifications. Examples include sensor fusion studies, reaction wheel versus thruster assessment, and gravity field estimation sensitivity in response to attitude quality degradation. / text

Most rotary blasthole drills used in the mining industry today are equipped with automatic control systems. However, few, if any, implement closed-loop feedback control of the drilling process itself. This thesis investigates the potential for such control on a large rotary electric blasthole drill. The control strategy examined is Proportional-Integral-Velocity (PIV) control. The drill was successfully equipped with a data logger, and a comprehensive set of drilling data was gathered at an open pit taconite mine in northern Minnesota. This data set was used to model the dynamics of both the feed and rotary actuators. A drilling process software simulator, based on hydraulic blasthole drill data originally developed in previous work [Aboujaoude 1991], was successfully replicated in Simulink, and thoroughly documented, overcoming a major shortcoming in Aboujaoude’s work which provided incomplete information on the simulator implementation. The control strategy from the previous work was successfully integrated with the new process simulator, and its performance validated by comparison with the results presented in the previous work. The drilling process simulator was then modified by replacing the actuator dynamics with the models identified for the electric drill. The modified simulator was validated, and the behaviour of the system with the new actuator models while under feedback control was observed. The controller gains were re-tuned to achieve acceptable drilling performance with the new actuator models. This resulted in a prototype controller ready for field testing on the large rotary electric blasthole drill. In addition, this thesis has produced a fully documented drilling process simulator, suitable as a platform for future research. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2012-01-31 13:41:54.577

No description available.

This thesis investigates the design and evaluation of a control system, that is able to adapt quickly to changes in environment and steering characteristics. This type of controller is particularly suited for applications with wide-ranging working conditions such as those experienced by small motorised craft. A small motorised craft is assumed to be highly agile and prone to disturbances, being thrown off-course very easily when travelling at high speed 'but rather heavy and sluggish at low speeds. Unlike large vessels, the steering characteristics of the craft will change tremendously with a change in forward speed. Any new design of autopilot needs to be to compensate for these changes in dynamic characteristics to maintain near optimal levels of performance. This study identities the problems that need to be overcome and the variables involved. A self-organising fuzzy logic controller is developed and tested in simulation. This type of controller learns on-line but has certain performance limitations. The major original contribution of this research investigation is the development of an improved self-adaptive and predictive control concept, the Predictive Self-organising Fuzzy Logic Controller (PSoFLC). The novel feature of the control algorithm is that is uses a neural network as a predictive simulator of the boat's future response and this network is then incorporated into the control loop to improve the course changing, as well as course keeping capabilities of the autopilot investigated. The autopilot is tested in simulation to validate the working principle of the concept and to demonstrate the self-tuning of the control parameters. Further work is required to establish the suitability of the proposed novel concept to other control.

No description available.

Thesis (M.Eng.Sc.)--University of Adelaide, Dept. of Engineering, 1999. / Bibliography: leaves 109-113.

Thesis (M.S.)--Ohio University, June, 1994. / Title from PDF t.p.

Thesis (M. Sc.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Aug. 25, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Process Control, Department of Chemical and Materials Engineering, University of Alberta." Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1964. / Typescript. Abstracted in Dissertation abstracts, v. 25 (1964) no. 6, p. 3478-3479. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 378-405.