Matching Items (26)

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Implementation of Variable Damping to Gait Rehabilitation Technology

Description

Walking ability is a complex process that is essential to humans, critical for performing a range of everyday tasks and enables a healthy, independent lifestyle. Human gait has evolved to be robust, adapting to a wide range of external stimuli,

Walking ability is a complex process that is essential to humans, critical for performing a range of everyday tasks and enables a healthy, independent lifestyle. Human gait has evolved to be robust, adapting to a wide range of external stimuli, including variable walking surface compliance. Unfortunately, many people suffer from impaired gait as a result of conditions such as stroke. For these individuals, recovering their gait is a priority and a challenge. The ASU Variable Stiffness Treadmill (VST) is a device that is able to the change its surface compliance through its unique variable stiffness mechanism. By doing this, the VST can be used to investigate gait and has potential as a rehabilitation tool. The objective of this research is to design a variable damping mechanism for the VST, which addresses the need to control effective surface damping, the only form of mechanical impedance that the VST does not currently control. Thus, this project will contribute toward the development of the Variable Impedance Treadmill (VIT), which will encompass a wider range of variable surface compliance and enable all forms of impedance to be con- trolled for the first time. To achieve this, the final design of the mechanism will employ eddy current damping using several permanent magnets mounted to the treadmill and a large copper plate stationed on the ground. Variable damping is obtained by using lead screw mechanisms to remove magnets from acting on the copper plate, which effectively eliminates their effect on damping and changes the overall treadmill surface damping. Results from experimentation validate the mechanism's ability to provide variable damping to the VST. A model for effective surface damping is generated based on open-loop characterization experiments and is generalized for future experimental setups. Overall, this project progresses to the development of the VIT and has potential applications in walking surface simulation, gait investigation, and robot-assisted rehabilitation technology.

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Date Created
2017-05

Place Your Bets

Description

Sports gambling is an illegal multi-hundred-billion-dollar industry in the United States today. Due to the Professional and Amateur Sports Protection Act (PASPA), 46 states are denied the opportunity to offer state-sponsored sports gambling (Delaware, Montana, Nevada, and Oregon are exempt).

Sports gambling is an illegal multi-hundred-billion-dollar industry in the United States today. Due to the Professional and Amateur Sports Protection Act (PASPA), 46 states are denied the opportunity to offer state-sponsored sports gambling (Delaware, Montana, Nevada, and Oregon are exempt). The problem with this law is that sports gambling is still occurring over the internet and through bookies. The government's attempt to control the choices of the American people isn't stopping them from gambling on sports, rather it is pushing them to underground channels where regulation has no foothold. The American government is failing to take advantage of tax revenue that can be used to monitor the sports gambling world along with the sports themselves. This issue of control has had its place in American history and the government finds itself on the wrong side of it once again. This thesis explores the misconceptions in the government's perceived idea of "control" and proposes that PASPA be repealed because of the enormous tax revenue opportunity eliminated by outlawing sports gambling.

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Date Created
2016-05

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Psychological Model of No Control/Influence

Description

The Information Measurement Theory (IMT) is a revolutionary thinking paradigm. Its principles allow an individual to accurately perceive reality and simplify the complexities of life. To understand IMT, individuals start by first recognizing that everything must follow natural law and

The Information Measurement Theory (IMT) is a revolutionary thinking paradigm. Its principles allow an individual to accurately perceive reality and simplify the complexities of life. To understand IMT, individuals start by first recognizing that everything must follow natural law and cause and effect, that there is no randomness, and that everyone changes at a certain rate. They then move on to understanding that individuals are described by certain characteristics that can be used to predict their future behavior. And finally, they discover that they must learn to understand, accept, and improve themselves while understanding and accepting others. The author, who has spent a considerable amount of time studying and utilizing IMT, believes that IMT can be used within the field of psychology. The extraordinary results that IMT has produced in the construction industry can potentially be produced in a similar fashion within the psychology field. One of the most important principles of IMT teaches that control or influence over others does not exist. This principle alone differentiates IMT from the traditional model of psychology, which is dedicated to changing an individual (through influence). Five case studies will be presented in which individuals have used the principles of IMT to overcome severe issues such as substance abuse and depression. Each case study is unique and exhibits a remarkable change within each individual.

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Date Created
2014-05

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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 there are many animal species biologically designed for navigation of

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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Modeling of Autonomous Quadcopter Flight

Description

The purpose of this honors thesis was to create a quadcopter equation of motion software model in order to develop a control system to make the quadcopter autonomous. This control system was developed using Matlab and Simulink, and the aspects

The purpose of this honors thesis was to create a quadcopter equation of motion software model in order to develop a control system to make the quadcopter autonomous. This control system was developed using Matlab and Simulink, and the aspects of the quadcopter's flight that were chosen to be controlled were the roll angle, pitch angle, and height of the quadcopter. Upon the completion of this control system model, the actual quadcopter was to be constructed, flown, and used to collect experimental data for comparison to the model. However, the hardware was never made available due to back order problems, and so unfortunately no experimental data from actual test flights was able to be gathered and compared to the Simulink control system model. None the less, the final Simulink model is still accurate because the actual geometry of the chosen quadcopter was used during simulation (including the moments of inertia and moment arm lengths). To begin, background research into quadcopter design is presented to give insight into the progress that has been made in the design of this type of aircraft. The equations of motion for the quadcopter considered in the control system are then derived through the use of twelve state variables. The Simulink model for the open loop system was then constructed in a fashion that converts the change in rotor thrust to the associated orientation angles of the quadcopter. Linear approximations were then used to distinguish the open loop transfer functions for each controlled variable (roll angle, pitch angle, and height), and compensators were designed for the control system in order to produce a natural frequency and damping that allowed for a 5% settling time of approximately two seconds.

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2013-05

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Modeling, Analysis, Control and Design of Highly Maneuverable Quadcopters

Description

With the revolution of low-cost microelectronics, rotary-wing vehicles have grown increasingly popular and important in the past two decades. With increased interest in quadcopters comes the need to for a systematic and rigorous framework to model, analyze, control, and design

With the revolution of low-cost microelectronics, rotary-wing vehicles have grown increasingly popular and important in the past two decades. With increased interest in quadcopters comes the need to for a systematic and rigorous framework to model, analyze, control, and design them. This thesis presents the beginning of such a framework.

The work presents the nonlinear equations of motion of a quadcopter. This includes the translational and rotational equations of motion, as well as an analysis of the nonlinear actuator dynamics. The work then analyzes the static properties of a quadcopter in forward flight equilibrium and shows how static properties change as physical properties of the vehicle are varied. Next, the dynamics of forward flight are linearized, and a dynamic analysis is provided.

After dynamic analysis, the work shows detailed hierarchical control system design trade studies, which includes attitude and translational inner-outer loop control. Among other designs, the following are presented: PD control, proportional control, pole-placement control. Each of these control architectures are employed for the inner loops and outer loops. The work also analyzes linear versus nonlinear simulation performance of a quadcopter, specifically for a step x-axis reference command. It is found that the nonlinear dynamics of the actuator cause significant discrepancy between linear and nonlinear simulation.

Finally, this thesis establishes directions for future graduate research. This includes hardware design, as well as moving toward design of a highly-maneuverable thrust-vectoring quadrotor which will be the focus of the proposed graduate PhD research. In summary, this thesis provides the beginning of a cohesive framework to model, analyze, control, and design quadcopters. It also lays the groundwork for graduate research and beyond.

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Date Created
2019-12

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Control relevant modeling and design of scramjet-powered hypersonic vehicles

Description

This report provides an overview of scramjet-powered hypersonic vehicle modeling and control challenges. Such vehicles are characterized by unstable non-minimum phase dynamics with significant coupling and low thrust margins. Recent trends in hypersonic vehicle research are summarized. To illustrate control

This report provides an overview of scramjet-powered hypersonic vehicle modeling and control challenges. Such vehicles are characterized by unstable non-minimum phase dynamics with significant coupling and low thrust margins. Recent trends in hypersonic vehicle research are summarized. To illustrate control relevant design issues and tradeoffs, a generic nonlinear 3DOF longitudinal dynamics model capturing aero-elastic-propulsive interactions for wedge-shaped vehicle is used. Limitations of the model are discussed and numerous modifications have been made to address control relevant needs. Two different baseline configurations are examined over a two-stage to orbit ascent trajectory. The report highlights how vehicle level-flight static (trim) and dynamic properties change over the trajectory. Thermal choking constraints are imposed on control system design as a direct consequence of having a finite FER margin. The implication of this state-dependent nonlinear FER margin constraint, the right half plane (RHP) zero, and lightly damped flexible modes, on control system bandwidth (BW) and FPA tracking has been discussed. A control methodology has been proposed that addresses the above dynamics while providing some robustness to modeling uncertainty. Vehicle closure (the ability to fly a trajectory segment subject to constraints) is provided through a proposed vehicle design methodology. The design method attempts to use open loop metrics whenever possible to design the vehicle. The design method is applied to a vehicle/control law closed loop nonlinear simulation for validation. The 3DOF longitudinal modeling results are validated against a newly released NASA 6DOF code.

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Date Created
2012

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Wind farm characterization and control using coherent Doppler lidar

Description

Wind measurements are fundamental inputs for the evaluation of potential energy yield and performance of wind farms. Three-dimensional scanning coherent Doppler lidar (CDL) may provide a new basis for wind farm site selection, design, and control. In this research, CDL

Wind measurements are fundamental inputs for the evaluation of potential energy yield and performance of wind farms. Three-dimensional scanning coherent Doppler lidar (CDL) may provide a new basis for wind farm site selection, design, and control. In this research, CDL measurements obtained from multiple wind energy developments are analyzed and a novel wind farm control approach has been modeled. The possibility of using lidar measurements to more fully characterize the wind field is discussed, specifically, terrain effects, spatial variation of winds, power density, and the effect of shear at different layers within the rotor swept area. Various vector retrieval methods have been applied to the lidar data, and results are presented on an elevated terrain-following surface at hub height. The vector retrieval estimates are compared with tower measurements, after interpolation to the appropriate level. CDL data is used to estimate the spatial power density at hub height. Since CDL can measure winds at different vertical levels, an approach for estimating wind power density over the wind turbine rotor-swept area is explored. Sample optimized layouts of wind farm using lidar data and global optimization algorithms, accounting for wake interaction effects, have been explored. An approach to evaluate spatial wind speed and direction estimates from a standard nested Coupled Ocean and Atmosphere Mesoscale Prediction System (COAMPS) model and CDL is presented. The magnitude of spatial difference between observations and simulation for wind energy assessment is researched. Diurnal effects and ramp events as estimated by CDL and COAMPS were inter-compared. Novel wind farm control based on incoming winds and direction input from CDL's is developed. Both yaw and pitch control using scanning CDL for efficient wind farm control is analyzed. The wind farm control optimizes power production and reduces loads on wind turbines for various lidar wind speed and direction inputs, accounting for wind farm wake losses and wind speed evolution. Several wind farm control configurations were developed, for enhanced integrability into the electrical grid. Finally, the value proposition of CDL for a wind farm development, based on uncertainty reduction and return of investment is analyzed.

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Date Created
2013

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Design of an energy management system using a distribution class locational marginal price as a discrete control signal

Description

The subject of this thesis is distribution level load management using a pricing signal in a Smart Grid infrastructure. The Smart Grid implements advanced meters, sensory devices and near real time communication between the elements of the system, including the

The subject of this thesis is distribution level load management using a pricing signal in a Smart Grid infrastructure. The Smart Grid implements advanced meters, sensory devices and near real time communication between the elements of the system, including the distribution operator and the customer. A stated objective of the Smart Grid is to use sensory information to operate the electrical power grid more efficiently and cost effectively. One potential function of the Smart Grid is energy management at the distribution level, namely at the individual customer. The Smart Grid allows control of distribution level devices, including distributed energy storage and distributed generation, in operational real time. One method of load control uses an electric energy price as a control signal. The control is achieved through customer preference as the customer allows loads to respond to a dynamic pricing signal. In this thesis, a pricing signal is used to control loads for energy management at the distribution level. The model for the energy management system is created and analyzed in the z-domain due to the envisioned discrete time implementation. Test cases are used to illustrate stability and performance by analytic calculations using Mathcad and by simulation using Matlab Simulink. The envisioned control strategy is applied to the Future Renewable Electric Energy Distribution Management (FREEDM) system. The FREEDM system implements electronic (semiconductor) controls and therefore makes the proposed energy management feasible. The pricing control strategy is demonstrated to be an effective method of performing energy management in a distribution system. It is also shown that stability and near optimal response can be achieved by controlling the parameters of the system. Addition-ally, the communication bandwidth requirements for a pricing control signal are evaluated.

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Date Created
2013

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Modeling and control of a three phase voltage source inverter with an LCL filter

Description

This thesis addresses the design and control of three phase inverters. Such inverters are

used to produce three-phase sinusoidal voltages and currents from a DC source. They

are critical for injecting power from renewable energy sources into the grid. This is

especially true

This thesis addresses the design and control of three phase inverters. Such inverters are

used to produce three-phase sinusoidal voltages and currents from a DC source. They

are critical for injecting power from renewable energy sources into the grid. This is

especially true since many of these sources of energy are DC sources (e.g. solar

photovoltaic) or need to be stored in DC batteries because they are intermittent (e.g. wind

and solar). Two classes of inverters are examined in this thesis. A control-centric design

procedure is presented for each class. The first class of inverters is simple in that they

consist of three decoupled subsystems. Such inverters are characterized by no mutual

inductance between the three phases. As such, no multivariable coupling is present and

decentralized single-input single-output (SISO) control theory suffices to generate

acceptable control designs. For this class of inverters several families of controllers are

addressed in order to examine command following as well as input disturbance and noise

attenuation specifications. The goal here is to illuminate fundamental tradeoffs. Such

tradeoffs include an improvement in the in-band command following and output

disturbance attenuation versus a deterioration in out-of-band noise attenuation.

A fundamental deficiency associated with such inverters is their large size. This can be

remedied by designing a smaller core. This naturally leads to the second class of inverters

considered in this work. These inverters are characterized by significant mutual

inductances and multivariable coupling. As such, SISO control theory is generally not

adequate and multiple-input multiple-output (MIMO) theory becomes essential for

controlling these inverters.

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Date Created
2015