Matching Items (37)

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A Ground Control System for Studying Locomotion on Granular Media

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

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.

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Date Created
  • 2016-05

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Design and Simulation of Controllers for Multi-Robot Transport over Inclines

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

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.

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Created

Date Created
  • 2019-05

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Characterization of Glass Beads: Flowability and Angle of Repose

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

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.

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Created

Date Created
  • 2019-05

Animal and Robotic Locomotion on Dry and Wet Granular Media

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.

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.

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Date Created
  • 2018-05

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Octopus Transverse and Internal Longitudinal Arm Muscles in Relation to Fetching Movements

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

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.

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Created

Date Created
  • 2019-05

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Analysis of Local Minima arising from Potential-Based Controllers for Multi-Robot Transport with Convex Obstacle Avoidance

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

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.

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Created

Date Created
  • 2020-12

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A Science Communicator's Guide to Social Media Engagement

Description

The scientific research conducted by science, technology, engineering, and mathematics (STEM) institutions is groundbreaking. Everyday, scientists create a deeper understanding of the world around us, and then communicate that understanding

The scientific research conducted by science, technology, engineering, and mathematics (STEM) institutions is groundbreaking. Everyday, scientists create a deeper understanding of the world around us, and then communicate that understanding through journal papers, articles, and conferences. To strengthen these traditional forms of communication, science communicators can use social media platforms such as Twitter and Facebook to promote themselves and earn digital audience engagement that will grow the impact and success of their research. This thesis synthesizes research on human communication theories, digital user behavior, and science communication practices in order to create the “Science Communicator’s Guide to Social Media Engagement”. This guide empowers science communicators to utilize social media in a way that can increase their digital audience engagement, expand the reach of their research, and ultimately amplify their professional presence in the scientific community.

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Created

Date Created
  • 2020-12

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Chemoreception in Octopus bimaculoides

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

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.

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Date Created
  • 2020-05

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Modeling the Flowability of Granular Materials

Description

This thesis investigated the effects of differing diameters and varying moisture content on the flowability properties of granular glass beads through use of a Freeman FT4 Powder Rheometer. These parameters

This thesis investigated the effects of differing diameters and varying moisture content on the flowability properties of granular glass beads through use of a Freeman FT4 Powder Rheometer. These parameters were tested in order to construct an empirical model to predict flowability properties of glass beads at differing size ranges and moisture contents. The final empirical model outputted an average error of 8.73% across all tested diameters and moisture ranges.

Mohr's circles were constructed from experimentally-obtained shear stress values to quantitatively describe flowability of tested materials in terms of a flow function parameter. A high flow function value (>10) was indicative of a good flow.

By testing 120-180 µm, 120-350 µm, 180-250 µm, 250-350 µm, 430-600 µm, and 600-850 µm glass bead diameter ranges, an increase in size was seen to result in higher flow function values. The limitations of testing using the FT4 became apparent as inconsistent flow function values were obtained at 0% moisture with size ranges above 120-180 µm, or at flow function values of >21. Bead sizes larger than 430 µm showed significant standard deviation over all tested trials--when excluding size ranges above that value, the empirical model showed an average error of only 6.45%.

Wet material testing occurred at all tested glass bead size ranges using a deionized water content of 0%, 1%, 5%, 15%, and 20% by weight. The results of such testing showed a decrease in the resulting flow function parameter as more water content was added. However, this trend changed as 20% moisture content was achieved; the wet material became supersaturated, and an increase in flow function values was observed. The empirical model constructed, therefore, neglected the 20% moisture content regime.

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Created

Date Created
  • 2019

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Ant-Inspired Control Strategies for Collective Transport by Dynamic Multi-Robot Teams with Temporary Leaders

Description

In certain ant species, groups of ants work together to transport food and materials back to their nests. In some cases, the group exhibits a leader-follower behavior in which a

In certain ant species, groups of ants work together to transport food and materials back to their nests. In some cases, the group exhibits a leader-follower behavior in which a single ant guides the entire group based on its knowledge of the destination. In some cases, the leader role is occupied temporarily by an ant, only to be replaced when an ant with new information arrives. This kind of behavior can be very useful in uncertain environments where robot teams work together to transport a heavy or bulky payload. The purpose of this research was to study ways to implement this behavior on robot teams.

In this work, I combined existing dynamical models of collective transport in ants to create a stochastic model that describes these behaviors and can be used to control multi-robot systems to perform collective transport. In this model, each agent transitions stochastically between roles based on the force that it senses the other agents are applying to the load. The agent’s motion is governed by a proportional controller that updates its applied force based on the load velocity. I developed agent-based simulations of this model in NetLogo and explored leader-follower scenarios in which agents receive information about the transport destination by a newly informed agent (leader) joining the team. From these simulations, I derived the mean allocations of agents between “puller” and “lifter” roles and the mean forces applied by the agents throughout the motion.

From the simulation results obtained, we show that the mean ratio of lifter to puller populations is approximately 1:1. We also show that agents using the role update procedure based on forces are required to exert less force than agents that select their role based on their position on the load, although both strategies achieve similar transport speeds.

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Agent

Created

Date Created
  • 2020