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Description
The theme for this work is the development of fast numerical algorithms for sparse optimization as well as their applications in medical imaging and source localization using sensor array processing. Due to the recently proposed theory of Compressive Sensing (CS), the $\ell_1$ minimization problem attracts more attention for its ability to exploit sparsity. Traditional interior point methods encounter difficulties in computation for solving the CS applications. In the first part of this work, a fast algorithm based on the augmented Lagrangian method for solving the large-scale TV-$\ell_1$ regularized inverse problem is proposed. Specifically, by taking advantage of the separable structure, the original problem can be approximated via the sum of a series of simple functions with closed form solutions. A preconditioner for solving the block Toeplitz with Toeplitz block (BTTB) linear system is proposed to accelerate the computation. An in-depth discussion on the rate of convergence and the optimal parameter selection criteria is given. Numerical experiments are used to test the performance and the robustness of the proposed algorithm to a wide range of parameter values. Applications of the algorithm in magnetic resonance (MR) imaging and a comparison with other existing methods are included. The second part of this work is the application of the TV-$\ell_1$ model in source localization using sensor arrays. The array output is reformulated into a sparse waveform via an over-complete basis and study the $\ell_p$-norm properties in detecting the sparsity. An algorithm is proposed for minimizing a non-convex problem. According to the results of numerical experiments, the proposed algorithm with the aid of the $\ell_p$-norm can resolve closely distributed sources with higher accuracy than other existing methods.
ContributorsShen, Wei (Author) / Mittlemann, Hans D (Thesis advisor) / Renaut, Rosemary A. (Committee member) / Jackiewicz, Zdzislaw (Committee member) / Gelb, Anne (Committee member) / Ringhofer, Christian (Committee member) / Arizona State University (Publisher)
Created2011
Description
This thesis presents a process by which a controller used for collective transport tasks is qualitatively studied and probed for presence of undesirable equilibrium states that could entrap the system and prevent it from converging to a target state. Fields of study relevant to this project include dynamic system modeling, modern control theory, script-based system simulation, and autonomous systems design. Simulation and computational software MATLAB and Simulink® were used in this thesis.
To achieve this goal, a model of a swarm performing a collective transport task in a bounded domain featuring convex obstacles was simulated in MATLAB/ Simulink®. The closed-loop dynamic equations of this model were linearized about an equilibrium state with angular acceleration and linear acceleration set to zero. The simulation was run over 30 times to confirm system ability to successfully transport the payload to a goal point without colliding with obstacles and determine ideal operating conditions by testing various orientations of objects in the bounded domain. An additional purely MATLAB simulation was run to identify local minima of the Hessian of the navigation-like potential function. By calculating this Hessian periodically throughout the system’s progress and determining the signs of its eigenvalues, a system could check whether it is trapped in a local minimum, and potentially dislodge itself through implementation of a stochastic term in the robot controllers. The eigenvalues of the Hessian calculated in this research suggested the model local minima were degenerate, indicating an error in the mathematical model for this system, which likely incurred during linearization of this highly nonlinear system.
To achieve this goal, a model of a swarm performing a collective transport task in a bounded domain featuring convex obstacles was simulated in MATLAB/ Simulink®. The closed-loop dynamic equations of this model were linearized about an equilibrium state with angular acceleration and linear acceleration set to zero. The simulation was run over 30 times to confirm system ability to successfully transport the payload to a goal point without colliding with obstacles and determine ideal operating conditions by testing various orientations of objects in the bounded domain. An additional purely MATLAB simulation was run to identify local minima of the Hessian of the navigation-like potential function. By calculating this Hessian periodically throughout the system’s progress and determining the signs of its eigenvalues, a system could check whether it is trapped in a local minimum, and potentially dislodge itself through implementation of a stochastic term in the robot controllers. The eigenvalues of the Hessian calculated in this research suggested the model local minima were degenerate, indicating an error in the mathematical model for this system, which likely incurred during linearization of this highly nonlinear system.
ContributorsBaye-Wallace, Lily Catherine (Author) / Berman, Spring (Thesis director) / Marvi, Hamidreza (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / School of Music, Dance and Theatre (Contributor) / School for Engineering of Matter,Transport & Enrgy (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
Description
Chemoreception is an important method for an octopus to sense and react to its surroundings. However, the density of chemoreceptors within different areas of the skin of the octopus arm is poorly documented. In order to assess the relative sensitivity of various regions and the degree to which chemoreception is locally controlled, octopus arms were amputated and exposed to acetic acid, a noxious chemical stimulus that has previously been shown to elicit movement responses in amputated arms (Hague et al., 2013). To test this, 11 wild-caught Octopus bimaculoides (6 females, 5 males) were obtained. Acetic acid vapor was introduced in the distal oral, distal aboral, proximal oral, and proximal aboral regions of amputated arms. The frequency of the occurrence of movement was first analyzed. For those trials in which movement occurred, the latency (delay between the stimulus and the onset of movement) and the duration of movement were analyzed. The distal aboral and distal oral regions were both more likely to move than either the proximal oral or proximal aboral regions (p < 0.0001), and when they did move, were more likely to move for longer periods of time (p < 0.05). In addition, the proximal oral region was more likely to exhibit a delay in the onset of movement compared to the distal oral or distal aboral regions (p < 0.0001). These findings provide evidence that the distal arm is most sensitive to noxious chemical stimuli. However, there were no significant differences between the distal oral and distal aboral regions, or between the proximal oral and proximal aboral regions. This suggests that there may not be a significant difference in the density of chemoreceptors in the aboral versus oral regions of the arm, contrary to claims in the literature. The other independent variables analyzed, including sex, body mass, arm length, anterior versus posterior arm identity, and left versus right arm identity, did not have a significant effect on any of the three dependent variables analyzed. Further analysis of the relative density of chemoreceptors in different regions of the octopus arm is merited.
ContributorsCasleton, Rachel Marie (Author) / Fisher, Rebecca (Thesis director) / Marvi, Hamidreza (Committee member) / Gire, David (Committee member) / School of International Letters and Cultures (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Octopus arms employ a complex three dimensional array of musculature, called a
muscular hydrostat, which allows for nearly infinite degrees of freedom of movement without
the structure of a skeletal system. This study employed Magnetic Resonance Imaging with a
Gadoteridol-based contrast agent to image the octopus arm and view the internal tissues. Muscle
layering was mapped and area was measured using AMIRA image processing and the trends in
these layers at the proximal, middle, and distal portions of the arms were analyzed. A total of 39
arms from 6 specimens were scanned to give 112 total imaged sections (38 proximal, 37 middle,
37 distal), from which to ascertain and study the possible differences in musculature. The
images revealed significant increases in the internal longitudinal muscle layer percentages
between the proximal and middle, proximal and distal, and middle and distal sections of the
arms. These structural differences are hypothesized to be used for rapid retraction of the distal
segment when encountering predators or noxious stimuli. In contrast, a significant decrease in
the transverse muscle layer was found when comparing the same sections. These structural
differences are hypothesized to be a result of bending behaviors during retraction. Additionally,
the internal longitudinal layer was separately studied orally, toward the sucker, and aborally,
away from the sucker. The significant differences in oral and aboral internal longitudinal
musculature in proximal, middle, and distal sections is hypothesized to support the pseudo-joint
functionality displayed in octopus fetching behaviors. The results indicate that individual
octopus arm morphology is more unique than previously thought and supports that internal
structural differences exist to support behavioral functionality.
muscular hydrostat, which allows for nearly infinite degrees of freedom of movement without
the structure of a skeletal system. This study employed Magnetic Resonance Imaging with a
Gadoteridol-based contrast agent to image the octopus arm and view the internal tissues. Muscle
layering was mapped and area was measured using AMIRA image processing and the trends in
these layers at the proximal, middle, and distal portions of the arms were analyzed. A total of 39
arms from 6 specimens were scanned to give 112 total imaged sections (38 proximal, 37 middle,
37 distal), from which to ascertain and study the possible differences in musculature. The
images revealed significant increases in the internal longitudinal muscle layer percentages
between the proximal and middle, proximal and distal, and middle and distal sections of the
arms. These structural differences are hypothesized to be used for rapid retraction of the distal
segment when encountering predators or noxious stimuli. In contrast, a significant decrease in
the transverse muscle layer was found when comparing the same sections. These structural
differences are hypothesized to be a result of bending behaviors during retraction. Additionally,
the internal longitudinal layer was separately studied orally, toward the sucker, and aborally,
away from the sucker. The significant differences in oral and aboral internal longitudinal
musculature in proximal, middle, and distal sections is hypothesized to support the pseudo-joint
functionality displayed in octopus fetching behaviors. The results indicate that individual
octopus arm morphology is more unique than previously thought and supports that internal
structural differences exist to support behavioral functionality.
ContributorsCummings, Sheldon Daniel (Author) / Fisher, Rebecca (Thesis director) / Marvi, Hamidreza (Committee member) / Cherry, Brian (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Characterization of particulate process and product design is a difficult field because of the unique bulk properties and behaviors of particles that differ from gasses and liquids. The purpose of this research is to develop an equation to relate the angle of repose and flowability, the ability of the particle to flow as it pertains to particulate processes and product design. This research is important in multiple industries such as pharmaceuticals and food processes.
ContributorsNugent, Emily Rose (Author) / Emady, Heather (Thesis director) / Marvi, Hamidreza (Committee member) / Materials Science and Engineering Program (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
The goal of this thesis is designing controllers for swarm robots transport a payload over inclines. Several fields of study are related to this study, including control theory, dynamic modeling and programming. MATLAB, a tool of design controller and simulation, is used in this thesis.
To achieve this goal, a model of swarm robots transportation should be designed, which is cruise control for this scenario. Secondly, based on free body diagram, force equilibrium equation can be deduced. Then, the function of plant can be deduced based on cruise control and force equilibrium equations. Thirdly, list potential controllers, which may implement desired controls of swarm robots, and test their performance. Modify value of gains and do simulations of these controller. After analyzing results of simulation, the best controller can be selected.
In the last section, there is conclusion of entire thesis project and pointing out future work. The section of future work will mention potential difficulties of building entire control system, which allow swarm robots transport over inclines in real environment.
To achieve this goal, a model of swarm robots transportation should be designed, which is cruise control for this scenario. Secondly, based on free body diagram, force equilibrium equation can be deduced. Then, the function of plant can be deduced based on cruise control and force equilibrium equations. Thirdly, list potential controllers, which may implement desired controls of swarm robots, and test their performance. Modify value of gains and do simulations of these controller. After analyzing results of simulation, the best controller can be selected.
In the last section, there is conclusion of entire thesis project and pointing out future work. The section of future work will mention potential difficulties of building entire control system, which allow swarm robots transport over inclines in real environment.
ContributorsShe, Hanyu (Author) / Berman, Spring (Thesis director) / Marvi, Hamidreza (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Computer Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Traditional wheeled robots struggle to traverse granular media such as sand or mud which has inspired the use of continuous tracks, legged, and various bio-inspired designs in recent robotics research. Animals can navigate the natural world with relative ease and one animal, the Basilisk lizard, can perform the amazing feat of bipedal water and land running. Through the observation and study of basilisk lizards of the common and plumed variety, inspiration and development of a robotic platform was completed. After fabricating the bio-inspired robot, parameters unchanged by the animals were varied to characterize the combined effects of stride length and frequency on average velocity. It was found that animals increased stride length at higher saturation levels of sand to increase their velocity rather than increase their step frequency. The BasiliskBot version one was unable to change its stride length as the wheel-legs or "whegs" of this version were set at four spokes. Bipedal running of the robot was slower than quadrupedal running due to sand reaction forces and tail drag. BasiliskBot version two was lighter than the first version and had a range of stride lengths tested with increasing spoke numbers from 3-7. At lower step frequencies and lower wheg numbers, higher average velocity could be achieved compared to higher wheg numbers despite the highest maximum velocity being achieved by the highest number of spokes. A comparison of transition strategies for common and plumed basilisks showed both species chose to jump and swim through water more often than jump and run across water which achieved the highest average velocity. Results of transition strategies study pertain to future developments of the robot for amphibious purposes. Weight experiments were performed to assess the ability of the robot to carry sensors and other payloads. Added weight increased the highest frequency allowable before failure, but also caused failure at low step frequencies that had not displayed failure previously.
ContributorsBurch, Hailey (Author) / Marvi, Hamidreza (Thesis director) / Bagheri, Hosain (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Current robotic systems are limited in their abilities to efficiently traverse granular environments due to an underdeveloped understanding of the physics governing the interactions between solids and deformable substrates. As there are many animal species biologically designed for navigation of specific terrains, it is useful to study their mechanical ground interactions, and the kinematics of their movement. To achieve this, an automated, fluidized bed was designed to simulate various terrains under different conditions for animal testing. This document examines the design process of this test setup, with a focus on the controls. Control programs will be tested with hardware to ensure full functionality of the design. Knowledge gained from these studies can be used to optimize morphologies and gait parameters of robots. Ultimately, a robot can be developed that is capable of adapting itself for efficient locomotion on any terrain. These systems will be invaluable for applications such as planet exploration and rescue operations.
ContributorsHarvey, Carolyn Jean (Author) / Marvi, Hamidreza (Thesis director) / Emady, Heather (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Admittance control with fixed damping has been a successful control strategy in previous human-robotic interaction research. This research implements a variable damping admittance controller in a 7-DOF robotic arm coupled with a human subject’s arm at the end effector to study the trade-off of agility and stability and aims to produce a control scheme which displays both fast rise time and stability. The variable damping controller uses a measure of intent of movement to vary damping to aid the user’s movement to a target. The range of damping values is bounded by incorporating knowledge of a human arm to ensure the stability of the coupled human-robot system. Human subjects completed experiments with fixed positive, fixed negative, and variable damping controllers to evaluate the variable damping controller’s ability to increase agility and stability. Comparisons of the two fixed damping controllers showed as fixed damping increased, the coupled human-robot system reacted with less overshoot at the expense of rise time, which is used as a measure of agility. The inverse was also true; as damping became increasingly negative, the overshoot and stability of the system was compromised, while the rise time became faster. Analysis of the variable damping controller demonstrated humans could extract the benefits of the variable damping controller in its ability to increase agility in comparison to a positive damping controller and increase stability in comparison to a negative damping controller.
ContributorsBitz, Tanner Jacob (Author) / Lee, Hyunglae (Thesis advisor) / Marvi, Hamidreza (Committee member) / Yong, Sze Zheng (Committee member) / Arizona State University (Publisher)
Created2019
Description
Building and optimizing a design for deformable media can be extremely costly. However, granular scaling laws enable the ability to predict system velocity and mobility
power consumption by testing at a smaller scale in the same environment. The validity of
the granular scaling laws for arbitrarily shaped wheels and screws were evaluated in
materials like silica sand and BP-1, a lunar simulant. Different wheel geometries, such as
non-grousered and straight and bihelically grousered wheels were created and tested
using 3D printed technologies. Using the granular scaling laws and the empirical data
from initial experiments, power and velocity were predicted for a larger scaled version
then experimentally validated on a dynamic mobility platform. Working with granular
media has high variability in material properties depending on initial environmental
conditions, so particular emphasis was placed on consistency in the testing methodology.
Through experiments, these scaling laws have been validated with defined use cases and
limitations.
ContributorsMcbryan, Teresa (Author) / Marvi, Hamidreza (Thesis advisor) / Berman, Spring (Committee member) / Lee, Hyunglae (Committee member) / Arizona State University (Publisher)
Created2022