Controls and Control Theory Commons^™

Robust And Adaptive Attitude Control Of Spacecraft Using Solar Radiation Pressure, Lakshmi Srinivasan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Satellites in orbit are expected to maintain a preset attitude either pointing towards Earth (in case of satellites for weather) or pointing towards space for the purpose of research and exploration. The satellite as a system though is extremely nonlinear and the system parameters are not easily available. The goal of this thesis is to develop robust and adaptive control laws that can be used to control the attitude of satellites in elliptic orbits. The attitude of the satellite is controlled by the use of Solar Radiation Pressure (SRP) on the solar panels of the satellite. The SRP is basically …

Adaptive Local And Global Synchronization And Phase Control Of Inferior Olive Neurons (Ions), Srujan Kumar Chalike

UNLV Theses, Dissertations, Professional Papers, and Capstones

Clusters of inferior olive neurons (IONs) in the olive-cerebellar system play an important role in providing synchronized motor control signals for the activation of large number of muscles. However, the dynamics of IONs are highly nonlinear and the system parameters are assumed to be unknowm. The IONs evolving from arbitrary initial conditions are not synchronized. However the application of IONs for control of BAUV's requires that IONs oscillate in unison. The objective is to design control laws such that the controlled ION tracks the trajectories of the reference ION. The two control laws are derived based on tuning functions adaptive …

Sensing And Transmission Strategies In Wireless Cognitive Radio Systems, Babak Abbasi Bastami

UNLV Theses, Dissertations, Professional Papers, and Capstones

The main challenge in any cognitive radio system is to maximize secondary users throughput while limiting interference imposed on licensed users. In this regard, finding the optimal sensing and transmission timing strategies and accurate sensing techniques are of great importance in a cognitive radio network.

In this thesis, we study a sensing-transmission scheme for secondary user in a cognitive radio system where the secondary user senses every primary channel independently and transmits a signal for a fixed duration if it finds the channel empty and stays idle for another fixed duration if it senses the channel busy. We obtain optimal …

A Study Of A Novel Modular Variable Geometry Frame Arranged As A Robotic Surface, Christopher James Salisbury

UNLV Theses, Dissertations, Professional Papers, and Capstones

The novel concept of a "variable geometry frame" is introduced and explored through a three-dimensional robotic surface which is devised and implemented using triangular modules. The link design is optimized using surplus motor dimensions as firm constraints, and round numbers for further arbitrary constraints. Each module is connected by a passive six-bar mechanism that mimics the constraints of a spherical joint at each triangle intersection. A three dimensional inkjet printer is used to create a six-module prototype designed around surplus stepper motors powered by an old computer power supply as a proof-of-concept example.

The finite element method is applied to …

Conservation Based Uncertainty Propagation In Dynamic Systems, Lillian J. Ratliff

UNLV Theses, Dissertations, Professional Papers, and Capstones

Uncertainty is present in our everyday decision making process as well as our understanding of the structure of the universe. As a result an intense and mathematically rigorous study of how uncertainty propagates in the dynamic systems present in our lives is warranted and arguably necessary. In this thesis we examine existing methods for uncertainty propagation in dynamic systems and present the results of a literature survey that justifies the development of a conservation based method of uncertainty propagation. Conservation methods are physics based and physics drives our understanding of the physical world. Thus, it makes perfect sense to formulate …