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Title: Nonlinear robust control of a series dc motor utilizing the recursive design approach.
Creator: Burridge, Michael J., Qu, Zhihua, Engineering
Abstract / Description: University of Central Florida College of Engineering Thesis; In this thesis, the investigation of asymptotic stability of the series DC motor with unknown load-torque and unknown armature inductance is considered. The control technique of recursive, or backstepping, design is employed. Three cases are considered. In the first case, the system is assumed to be perfectly known. In the second case, the load torque is assumed to be unknown and a proportional-integral controller is developed to...
Show moreUniversity of Central Florida College of Engineering Thesis; In this thesis, the investigation of asymptotic stability of the series DC motor with unknown load-torque and unknown armature inductance is considered. The control technique of recursive, or backstepping, design is employed. Three cases are considered. In the first case, the system is assumed to be perfectly known. In the second case, the load torque is assumed to be unknown and a proportional-integral controller is developed to compensate for this unknown quantity. In the final case, it is assumed that two system parameters, load torque and armature inductance, are not known exactly, but vary from expected nominal values within a specified range. A robust control is designed to handle this case. The Lyapunov stability criterion is applied in all three cases to prove the stability of the system under the developed control. The results are then verified through the use of computer simulation.
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Date Issued: 1995
Identifier: CFR0011942, ucf:53109
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFR0011942

Title: OPTIMAL UPFC CONTROL AND OPERATIONS FOR POWER SYSTEMS.
Creator: Wu, Xiaohe, Qu, Zhihua, University of Central Florida
Abstract / Description: The content of this dissertation consists of three parts. In thefirst part, optimal control strategies are developed for UnifiedPower Flow Controller (UPFC) following the clearance of faultconditions. UPFC is one of the most versatile Flexible ACTransmission devices (FACTs) that have been implemented thus far.The optimal control scheme is composed of two parts. The first isan optimal stabilization control, which is an open-loop `Bang'type of control. The second is an suboptimal damping...
Show moreThe content of this dissertation consists of three parts. In thefirst part, optimal control strategies are developed for UnifiedPower Flow Controller (UPFC) following the clearance of faultconditions. UPFC is one of the most versatile Flexible ACTransmission devices (FACTs) that have been implemented thus far.The optimal control scheme is composed of two parts. The first isan optimal stabilization control, which is an open-loop `Bang'type of control. The second is an suboptimal damping control,which consists of segments of `Bang' type control with switchingfunctions the same as those of a corresponding approximate linearsystem. Simulation results show that the proposed control strategyis very effective in maintaining stability and damping outtransient oscillations following the clearance of the fault. Inthe second part, a new power market structure is proposed. The newstructure is based on a two-level optimization formulation of themarket. It is shown that the proposed market structure can easilyfind the optimal solutions for the market while takeing factorssuch as demand elasticity into account. In the last part, amathematical programming problem is formulated to obtain themaximum value of the loadibility factor, while the power system isconstrained by steady-state dynamic security constraints. Aniterative solution procedure is proposed for the problem, and thesolution gives a slightly conservative estimate of the loadibilitylimit for the generation and transmission system.
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Date Issued: 2004
Identifier: CFE0000052, ucf:46122
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000052

Title: REAL-TIME TRAJECTORY PLANNING FOR GROUNDAND AERIAL VEHICLES IN A DYNAMIC ENVIRONMENT.
Creator: Yang, Jian, Qu, Zhihua, University of Central Florida
Abstract / Description: In this dissertation, a novel and generic solution of trajectory generation is developed and evaluated for ground and aerial vehicles in a dynamic environment. By explicitly considering a kinematic model of the ground vehicles, the family of feasible trajectories and their corresponding steering controls are derived in a closed form and are expressed in terms of one adjustable parameter for the purpose of collision avoidance. A collision-avoidance condition is developed for the dynamically...
Show moreIn this dissertation, a novel and generic solution of trajectory generation is developed and evaluated for ground and aerial vehicles in a dynamic environment. By explicitly considering a kinematic model of the ground vehicles, the family of feasible trajectories and their corresponding steering controls are derived in a closed form and are expressed in terms of one adjustable parameter for the purpose of collision avoidance. A collision-avoidance condition is developed for the dynamically changing environment, which consists of a time criterion and a geometrical criterion. By imposing this condition, one can determine a family of collision-free paths in a closed form. Then, optimization problems with respect to different performance indices are setup to obtain optimal solutions from the feasible trajectories. Among these solutions, one with respect to the near-shortest distance and another with respect to the near-minimal control energy are analytical and simple. These properties make them good choices for real-time trajectory planning. Such optimal paths meet all boundary conditions, are twice differentiable, and can be updated in real time once a change in the environment is detected. Then this novel method is extended to 3D space to find a real-time optimal path for aerial vehicles. After that, to reflect the real applications, obstacles are classified to two types: "hard" obstacles that must be avoided, and "soft" obstacles that can be run over/through. Moreover, without losing generality, avoidance criteria are extended to obstacles with any geometric shapes. This dissertation also points out that the emphases of the future work are to consider other constraints such as the bounded velocity and so on. The proposed method is illustrated by computer simulations.
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Date Issued: 2008
Identifier: CFE0002031, ucf:47594
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002031

Title: A VIRTUAL REALITY VISUALIZATION OFAN ANALYTICAL SOLUTION TOMOBILE ROBOT TRAJECTORY GENERATIONIN THE PRESENCE OF MOVING OBSTACLES.
Creator: Elias, Ricardo, Qu, Zhihua, University of Central Florida
Abstract / Description: Virtual visualization of mobile robot analytical trajectories while avoiding moving obstacles is presented in this thesis as a very helpful technique to properly display and communicate simulation results. Analytical solutions to the path planning problem of mobile robots in the presence of obstacles and a dynamically changing environment have been presented in the current robotics and controls literature. These techniques have been demonstrated using two-dimensional graphical representation...
Show moreVirtual visualization of mobile robot analytical trajectories while avoiding moving obstacles is presented in this thesis as a very helpful technique to properly display and communicate simulation results. Analytical solutions to the path planning problem of mobile robots in the presence of obstacles and a dynamically changing environment have been presented in the current robotics and controls literature. These techniques have been demonstrated using two-dimensional graphical representation of simulation results. In this thesis, the analytical solution published by Dr. Zhihua Qu in December 2004 is used and simulated using a virtual visualization tool called VRML.
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Date Issued: 2007
Identifier: CFE0001575, ucf:47118
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001575

Title: A MULTI-OBJECTIVE NO-REGRET DECISION MAKING MODEL WITH BAYESIAN LEARNING FOR AUTONOMOUS UNMANNED SYSTEMS.
Creator: Howard, Matthew, Qu, Zhihua, University of Central Florida
Abstract / Description: The development of a multi-objective decision making and learning model for the use in unmanned systems is the focus of this project. Starting with traditional game theory and psychological learning theories developed in the past, a new model for machine learning is developed. This model incorporates a no-regret decision making model with a Bayesian learning process which has the ability to adapt to errors found in preconceived costs associated with each objective. This learning ability is...
Show moreThe development of a multi-objective decision making and learning model for the use in unmanned systems is the focus of this project. Starting with traditional game theory and psychological learning theories developed in the past, a new model for machine learning is developed. This model incorporates a no-regret decision making model with a Bayesian learning process which has the ability to adapt to errors found in preconceived costs associated with each objective. This learning ability is what sets this model apart from many others. By creating a model based on previously developed human learning models, hundreds of years of experience in these fields can be applied to the recently developing field of machine learning. This also allows for operators to more comfortably adapt to the machine's learning process in order to better understand how to take advantage of its features. One of the main purposes of this system is to incorporate multiple objectives into a decision making process. This feature can better allow its users to clearly define objectives and prioritize these objectives allowing the system to calculate the best approach for completing the mission. For instance, if an operator is given objectives such as obstacle avoidance, safety, and limiting resource usage, the operator would traditionally be required to decide how to meet all of these objectives. The use of a multi-objective decision making process such as the one designed in this project, allows the operator to input the objectives and their priorities and receive an output of the calculated optimal compromise.
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Date Issued: 2008
Identifier: CFE0002453, ucf:47711
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002453

Title: AUTONOMOUS ROBOTIC AUTOMATION SYSTEMWITH VISION FEEDBACK.
Creator: Rosino, Jeffery, Qu, Zhihua, University of Central Florida
Abstract / Description: In this thesis, a full design, development and application of an autonomous robotic automation system using vision feedback is performed. To realize this system, a cylindrical manipulator configuration is implemented, using a personal computer (PC) based PID controller from National Instruments. Full autonomous control will be achieved via a programmable human machine interface (HMI) developed on a PC using Borland C++ Builder. The vision feedback position control is accomplished using an...
Show moreIn this thesis, a full design, development and application of an autonomous robotic automation system using vision feedback is performed. To realize this system, a cylindrical manipulator configuration is implemented, using a personal computer (PC) based PID controller from National Instruments. Full autonomous control will be achieved via a programmable human machine interface (HMI) developed on a PC using Borland C++ Builder. The vision feedback position control is accomplished using an ordinary "off-the-shelf" web camera. The manuscript is organized as follows; After Chapter 1, an introduction to automation history and its role in the manufacturing industry, Chapter 2 discusses and outlines the development of the robotic kinematics and dynamics of the system. A control strategy is also developed and simulated in this chapter. Chapter 3 discusses color image processing and shows the development of the algorithm used for the vision feedback position control. Chapter 4 outlines the system development, which includes the hardware and software. Chapter 5 concludes with a summary, and improvement section. The process used as a basis for the design and development of this thesis of this thesis topic was constructed from a manual capacitor orientation check test station. A more detailed definition and objective is presented in the introduction.
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Date Issued: 2004
Identifier: CFE0000277, ucf:46220
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000277

Title: NONLINEAR ADAPTIVE ESTIMATION ANDITS APPLICATION TO SYNCHRONIZATION OF LORENZ SYSTEM.
Creator: Jin, Yufang, Qu, Zhihua, University of Central Florida
Abstract / Description: Synchronization and estimation of unknown constant parameters forLorenz-type transmitter are studied under the assumption that oneof the three state variables is not transmitted and thattransmitter parameters are not known apriori. An adaptivealgorithm is proposed to estimate both the state and systemparameters. Since Lorenz system shows the property of sensitivityto initial conditions and evolves in different mode with parametervariation, an equivalent system is introduced. The...
Show moreSynchronization and estimation of unknown constant parameters forLorenz-type transmitter are studied under the assumption that oneof the three state variables is not transmitted and thattransmitter parameters are not known apriori. An adaptivealgorithm is proposed to estimate both the state and systemparameters. Since Lorenz system shows the property of sensitivityto initial conditions and evolves in different mode with parametervariation, an equivalent system is introduced. The adaptiveobserver is designed based on this equivalent system without anyrequirement on initial conditions of the observer. It is shown byLyapunov arguments and persistent excitation analysis thatexponential stability of state and parameter estimation isguaranteed. Simulation results are included to demonstrateproperties of the algorithm. In a practical communication system,the received signals presented at the receiver part differ fromthose which were transmitted due to the effects of noise. Theproposed synchronization scheme is robust with regard to externalbounded disturbance. When an additive white gaussian noise (AWGN)channel model is considered, estimates of state and parameterconverge except for small errors. The results show promise ineither coherent detection or the message decoding intelecommunication systems.
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Date Issued: 2004
Identifier: CFE0000114, ucf:46187
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000114

Title: PREDICTIVE CONTROL FOR DYNAMIC SYSTEMS TO TRACK UNKNOWN INPUT IN THE PRESENCE OF TIME DELAY.
Creator: Li, Yulan, Qu, Zhihua, University of Central Florida
Abstract / Description: This study investigated a tracking system to trace unknown signal in the presence oftime delay. A predictive control method is proposed in order to compensate the time delay. Root locus method is applied when designing the controller, parameter setting is carried out through error and trail technique in w-plane. State space equation is derived for the system, with special state chose of tracking error. To analyze the asymptotic stability of the proposed predictive control system, the Lyapunov...
Show moreThis study investigated a tracking system to trace unknown signal in the presence oftime delay. A predictive control method is proposed in order to compensate the time delay. Root locus method is applied when designing the controller, parameter setting is carried out through error and trail technique in w-plane. State space equation is derived for the system, with special state chose of tracking error. To analyze the asymptotic stability of the proposed predictive control system, the Lyapunov function is constructed. It is shown that the designed system is asymptotically stable when input signal is rather low frequency signal. In order to illustrate the system performance, simulations are done based on the data profile technique. Signal profiles including acceleration pro le, velocity pro le, and trajectory profile are listed. Based on these profiles, simulations can be carried out and results can be taken as a good estimation for practical performance of the designed predictive control system. Signal noise is quite a common phenomenon in practical control systems. Under the situation that the input signal is with measurement noise, low pass filter is designed to filter out the noise and keep the low frequency input signal. Two typical kinds of noise are specified, i.e Gaussian noise and Pink noise. Simulations results are displayed to show that the proposed predictive control with low-pass filter design can achieve better performance in the case of both kinds of noise.
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Date Issued: 2005
Identifier: CFE0000819, ucf:46688
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0000819

Title: A THIRD-ORDER DIFFERENTIAL STEERING ROBOT AND TRAJECTORY GENERATION IN THE PRESENCE OF MOVING OBSTACLES.
Creator: An, Vatana, Qu, Zhihua, University of Central Florida
Abstract / Description: In this thesis, four robots will be used to implement a collision-free trajectory planning/replanning algorithm. The existence of a chained form transformation so that the robot's model can be control in canonical form will be analyzed and proved. A trajectory generation for obstacles avoidance will be derived, simulated, and implemented. A specific PC based control algorithm will be developed. Chapter two describes two wheels differential drive robot modeling and existence of...
Show moreIn this thesis, four robots will be used to implement a collision-free trajectory planning/replanning algorithm. The existence of a chained form transformation so that the robot's model can be control in canonical form will be analyzed and proved. A trajectory generation for obstacles avoidance will be derived, simulated, and implemented. A specific PC based control algorithm will be developed. Chapter two describes two wheels differential drive robot modeling and existence of controllable canonical chained form. Chapter 3 describes criterion for avoiding dynamic objects, a feasible collision-free trajectory parameterization, and solution to steering velocity. Chapter 4 describes robot implementation, pc wireless interface, and strategy to send and receive information wirelessly. The main robot will be moving in a dynamically changing environment using canonical chained form. The other three robots will be used as moving obstacles that will move with known piecewise constant velocities, and therefore, with known trajectories. Their initial positions are assumed to be known as well. The main robot will receive the command from the computer such as how fast to move and to turn in order to avoid collision. The robot will autonomously travel to the desired destination collision-free.
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Date Issued: 2006
Identifier: CFE0001337, ucf:46968
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0001337

Title: REACTIVE CONTROL OF AUTONOMOUS DYNAMICAL SYSTEMS.
Creator: Chunyu, Jiangmin, Qu, Zhihua, University of Central Florida
Abstract / Description: This thesis mainly consists of five independent papers concerning the reactive control design of autonomous mobile robots in the context of target tracking and cooperative formation keeping with obstacle avoidance in the static/dynamic environment. Technical contents of this thesis are divided into three parts. The first part consists of the first two papers, which consider the target-tracking and obstacle avoidance in the static environment. Especially, in the static environment, a...
Show moreThis thesis mainly consists of five independent papers concerning the reactive control design of autonomous mobile robots in the context of target tracking and cooperative formation keeping with obstacle avoidance in the static/dynamic environment. Technical contents of this thesis are divided into three parts. The first part consists of the first two papers, which consider the target-tracking and obstacle avoidance in the static environment. Especially, in the static environment, a fundamental issue of reactive control design is the local minima problem (LMP) inherent in the potential field methods (PFMs). Through introducing a state-dependent planned goal, the first paper proposes a switching control strategy to tackle this problem. The control law for the planned goal is presented. When trapped into local minima, the robot can escape from local minima by following the planned goal. The proposed control law also takes into account the presence of possible saturation constraints. In addition, a time-varying continuous control law is proposed in the second paper to tackle this problem. Challenges of finding continuous control solutions of LMP are discussed and explicit design strategies are then proposed. The second part of this thesis deals with target-tracking and obstacle avoidance in the dynamic environment. In the third paper, a reactive control design is presented for Omni-directional mobile robots with limited sensor range to track targets while avoiding static and moving obstacles in a dynamically evolving environment. Towards this end, a multi-objective control problem is formulated and control is synthesized by generating a potential field force for each objective and combining them through analysis and design. Different from standard potential field methods, the composite potential field described in this paper is time-varying and planned to account for moving obstacles and vehicle motion. In order to accommodate a larger class of mobile robots, the fourth paper proposes a reactive control design for unicycle-type mobile robots. With the relative motion among the mobile robot, targets, and obstacles being formulated in polar coordinates, kinematic control laws achieving target-tracking and obstacle avoidance are synthesized using Lyapunov based technique, and more importantly, the proposed control laws also take into account possible kinematic control saturation constraints. The third part of this thesis investigates the cooperative formation control with collision avoidance. In the fifth paper, firstly, the target tracking and collision avoidance problem for a single agent is studied. Instead of directly extending the single agent controls to the multi-agents case, the single agent controls are incorporated with an existing cooperative control design. The proposed decentralized control is reactive, considers the formation feedback and changes in the communication networks. The proposed control is based on a potential field method; its inherent oscillation problem is also studied to improve group transient performance.
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Date Issued: 2010
Identifier: CFE0003421, ucf:48384
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0003421

Title: NONLINEAR STABILIZATION AND CONTROL OF MEDIUM RANGE SURFACE TO AIR INTERCEPTOR MISSILES.
Creator: Snyder, Mark, Qu, Zhihua, University of Central Florida
Abstract / Description: Nonlinear stabilization and control autopilots are capable of sustaining nominal performance throughout the entire fight envelope an interceptor missile may encounter during hostile engagements and require no gain scheduling to maintain autopilot stability. Due to non minimum phase conditions characteristic of tail controlled missile airframes, a separation of time scales within the dynamic equations of motion between rotational and translational differential equations was enforced to...
Show moreNonlinear stabilization and control autopilots are capable of sustaining nominal performance throughout the entire fight envelope an interceptor missile may encounter during hostile engagements and require no gain scheduling to maintain autopilot stability. Due to non minimum phase conditions characteristic of tail controlled missile airframes, a separation of time scales within the dynamic equations of motion between rotational and translational differential equations was enforced to overcome unstable effects of non minimum phase. Dynamic inversion techniques are then applied to derive linearizing equations which, when injected forward into the plant result in a fully controllable linear system. Objectives of the two time scale control architecture are to stabilize vehicle rotational rates while at the same time controlling acceleration within the lateral plane of the vehicle under rapidly increasing dynamic pressure. Full 6 degree of freedom dynamic terms including all coriolis accelerations due to translational and rotational dynamic coupling have been taken into account in the inversion process. The result is a very stable, nonlinear autopilot with fixed control gains fully capable of stable nonlinear missile control. Several actuator systems were also designed to explore the destabilizing effects second order nonlinear actuator characteristics can have on nonlinear autopilot designs.
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Date Issued: 2009
Identifier: CFE0002566, ucf:48268
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002566

Title: CONTROL OF NONHOLONOMIC SYSTEMS.
Creator: Yuan, Hongliang, Qu, Zhihua, University of Central Florida
Abstract / Description: Many real-world electrical and mechanical systems have velocity-dependent constraints in their dynamic models. For example, car-like robots, unmanned aerial vehicles, autonomous underwater vehicles and hopping robots, etc. Most of these systems can be transformed into a chained form, which is considered as a canonical form of these nonholonomic systems. Hence, study of chained systems ensure their wide applicability. This thesis studied the problem of continuous feed-back control of the...
Show moreMany real-world electrical and mechanical systems have velocity-dependent constraints in their dynamic models. For example, car-like robots, unmanned aerial vehicles, autonomous underwater vehicles and hopping robots, etc. Most of these systems can be transformed into a chained form, which is considered as a canonical form of these nonholonomic systems. Hence, study of chained systems ensure their wide applicability. This thesis studied the problem of continuous feed-back control of the chained systems while pursuing inverse optimality and exponential convergence rates, as well as the feed-back stabilization problem under input saturation constraints. These studies are based on global singularity-free state transformations and controls are synthesized from resulting linear systems. Then, the application of optimal motion planning and dynamic tracking control of nonholonomic autonomous underwater vehicles is considered. The obtained trajectories satisfy the boundary conditions and the vehicles' kinematic model, hence it is smooth and feasible. A collision avoidance criteria is set up to handle the dynamic environments. The resulting controls are in closed forms and suitable for real-time implementations. Further, dynamic tracking controls are developed through the Lyapunov second method and back-stepping technique based on a NPS AUV II model. In what follows, the application of cooperative surveillance and formation control of a group of nonholonomic robots is investigated. A designing scheme is proposed to achieves a rigid formation along a circular trajectory or any arbitrary trajectories. The controllers are decentralized and are able to avoid internal and external collisions. Computer simulations are provided to verify the effectiveness of these designs.
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Date Issued: 2009
Identifier: CFE0002683, ucf:48220
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0002683

Title: AN ALL-AGAINST-ONE GAME APPROACH FOR THE MULTI-PLAYER PURSUIT-EVASION PROBLEM.
Creator: Talebi, Shahriar, Simaan, Marwan, Qu, Zhihua, Vosoughi, Azadeh, University of Central Florida
Abstract / Description: The traditional pursuit-evasion game considers a situation where one pursuer tries to capture an evader, while the evader is trying to escape. A more general formulation of this problem is to consider multiple pursuers trying to capture one evader. This general multi-pursuer one-evader problem can also be used to model a system of systems in which one of the subsystems decides to dissent (evade) from the others while the others (the pursuer subsystems) try to pursue a strategy to prevent it...
Show moreThe traditional pursuit-evasion game considers a situation where one pursuer tries to capture an evader, while the evader is trying to escape. A more general formulation of this problem is to consider multiple pursuers trying to capture one evader. This general multi-pursuer one-evader problem can also be used to model a system of systems in which one of the subsystems decides to dissent (evade) from the others while the others (the pursuer subsystems) try to pursue a strategy to prevent it from doing so. An important challenge in analyzing these types of problems is to develop strategies for the pursuers along with the advantages and disadvantages of each. In this thesis, we investigate three possible and conceptually different strategies for pursuers: (1) act non-cooperatively as independent pursuers, (2) act cooperatively as a unified team of pursuers, and (3) act individually as greedy pursuers. The evader, on the other hand, will consider strategies against all possible strategies by the pursuers. We assume complete uncertainty in the game i.e. no player knows which strategies the other players are implementing and none of them has information about any of the parameters in the objective functions of the other players. To treat the three pursuers strategies under one general framework, an all-against-one linear quadratic dynamic game is considered and the corresponding closed-loop Nash solution is discussed. Additionally, different necessary and sufficient conditions regarding the stability of the system, and existence and definiteness of the closed-loop Nash strategies under different strategy assumptions are derived. We deal with the uncertainties in the strategies by first developing the Nash strategies for each of the resulting games for all possible options available to both sides. Then we deal with the parameter uncertainties by performing a Monte Carlo analysis to determine probabilities of capture for the pursuers (or escape for the evader) for each resulting game. Results of the Monte Carlo simulation show that in general, pursuers do not always benefit from cooperating as a team and that acting as non-cooperating players may yield a higher probability of capturing of the evader.
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Date Issued: 2017
Identifier: CFE0007135, ucf:52314
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007135

Title: CFD Analysis of a Uni-directional Impulse Turbine for Wave Energy Conversion.
Creator: Velez, Carlos, Ilie, Marcel, Lin, Kuo-Chi, Qu, Zhihua, University of Central Florida
Abstract / Description: Ocean energy research has grown in popularity in the past decade and has producedvarious designs for wave energy extraction. This thesis focuses on the performance analysis of auni-directional impulse turbine for wave energy conversion. Uni-directional impulse turbines canproduce uni-directional rotation in bi-directional flow, which makes it ideal for wave energyextraction as the motion of ocean waves are inherently bi-directional. This impulse turbine iscurrently in use in four of the world...
Show moreOcean energy research has grown in popularity in the past decade and has producedvarious designs for wave energy extraction. This thesis focuses on the performance analysis of auni-directional impulse turbine for wave energy conversion. Uni-directional impulse turbines canproduce uni-directional rotation in bi-directional flow, which makes it ideal for wave energyextraction as the motion of ocean waves are inherently bi-directional. This impulse turbine iscurrently in use in four of the world's Oscillating Wave Columns (OWC). Current research todate has documented the performance of the turbine but little research has been completed tounderstand the flow physics in the turbine channel. An analytical model and computational fluiddynamic simulations are used with reference to experimental results found in the literature todevelop accurate models of the turbine performance. To carry out the numerical computationsvarious turbulence models are employed and compared. The comparisons indicate that a lowReynolds number Yang-shih K-Epsilon turbulence model is the most computationally efficientwhile providing accurate results. Additionally, analyses of the losses in the turbine are isolatedand documented.Results indicate that large separation regions occur on the turbine blades whichdrastically affect the torque created by the turbine, the location of flow separation is documentedand compared among various flow regimes. The model and simulations show good agreementwith the experimental results and the two proposed solutions enhance the performance of theturbine showing an approximate 10% increase in efficiency based on simulation results.
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Date Issued: 2011
Identifier: CFE0004173, ucf:49049
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004173

Title: General Vector Explicit - Impact Time and Angle Control Guidance.
Creator: Robinson, Loren, Qu, Zhihua, Behal, Aman, Xu, Yunjun, University of Central Florida
Abstract / Description: This thesis proposes and evaluates a new cooperative guidance law called General Vector Explicit -Impact Time and Angle Control Guidance (GENEX-ITACG). The motivation for GENEX-ITACGcame from an explicit trajectory shaping guidance law called General Vector Explicit Guidance(GENEX). GENEX simultaneously achieves design specifications on miss distance and terminalmissile approach angle while also providing a design parameter that adjusts the aggressiveness ofthis approach angle. Encouraged by...
Show moreThis thesis proposes and evaluates a new cooperative guidance law called General Vector Explicit -Impact Time and Angle Control Guidance (GENEX-ITACG). The motivation for GENEX-ITACGcame from an explicit trajectory shaping guidance law called General Vector Explicit Guidance(GENEX). GENEX simultaneously achieves design specifications on miss distance and terminalmissile approach angle while also providing a design parameter that adjusts the aggressiveness ofthis approach angle. Encouraged by the applicability of this user parameter, GENEX-ITACG is anextension that allows a salvo of missiles to cooperatively achieve the same objectives of GENEXagainst a stationary target through the incorporation of a cooperative trajectory shaping guidancelaw called Impact Time and Angle Control Guidance (ITACG).ITACG allows a salvo of missile to simultaneously hit a stationary target at a prescribed impactangle and impact time. This predetermined impact time is what allows each missile involvedin the salvo attack to simultaneously arrived at the target with unique approach angles, whichgreatly increases the probability of success against well defended targets. GENEX-ITACG furtherincreases this probability of kill by allowing each missile to approach the target with a uniqueapproach angle rate through the use of a user design parameter.The incorporation of ITACG into GENEX is accomplished through the use of linear optimal controlby casting the cost function of GENEX into the formulation of ITACG. The feasibility GENEXITACGis demonstrated across three scenarios that demonstrate the ITACG portion of the guidancelaw, the GENEX portion of the guidance law, and finally the entirety of the guidance law. Theresults indicate that GENEX-ITACG is able to successfully guide a salvo of missiles to simultaneouslyhit a stationary target at a predefined terminal impact angle and impact time, while alsoallowing the user to adjust the aggressiveness of approach.
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Date Issued: 2015
Identifier: CFE0005876, ucf:50868
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005876

Title: A New Path Planning Guidance Law For Improved Impact Time Control of Missiles and Precision Munitions.
Creator: Snyder, Mark, Qu, Zhihua, Haralambous, Michael, Xu, Yunjun, University of Central Florida
Abstract / Description: A new missile guidance law is proposed for the control of impact time which provides an improved time-to-go calculation by removing error due to trajectory curvature and also provides a family of trajectories for trajectory planning purposes. Unlike conventional optimal guidance laws, the proposed law is non explicit in time-to-go and the linearization of the engagement kinematics in order to gain a closed form solution is not necessary.
Date Issued: 2016
Identifier: CFE0006398, ucf:51506
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006398

Title: A Triangulation Based Coverage Path Planning For a Mobile Robot With Circular Sensing Range.
Creator: An, Vatana, Qu, Zhihua, Haralambous, Michael, Mikhael, Wasfy, University of Central Florida
Abstract / Description: In this dissertation, two coverage path planning (CPP) approaches for a nonholonomic mobile robot are proposed. The first approach is the Local Coverage Path Planning (LCPP) approach which is designed for all sensing ranges. The second approach is the Global Coverage Path Planning (GCPP) approach which is designed for sufficient sensing range that can observe all points of interests in the target region (TR). The LCPP approach constructs CP after finding observer points for all local regions...
Show moreIn this dissertation, two coverage path planning (CPP) approaches for a nonholonomic mobile robot are proposed. The first approach is the Local Coverage Path Planning (LCPP) approach which is designed for all sensing ranges. The second approach is the Global Coverage Path Planning (GCPP) approach which is designed for sufficient sensing range that can observe all points of interests in the target region (TR). The LCPP approach constructs CP after finding observer points for all local regions in the TR. The GCPP approach computes observer points after CP construction. Beginning with the sample TR, the LCPP approach requires 8 algorithms to find a smooth CP and sufficient number of observers for complete coverage. The Global Coverage Path Planning approach requires 17 algorithms to find the smooth CP with sufficient number of observers for completed coverage. The worst case running time for both approaches are quadratic which is consider to be very fast as compared to previous works reported in the literature. The main technical contributions of both approaches are to provide a holistic solution that segments any TR, uses triangulation to determine the line of sights and observation points, and then compute the smooth and collision-free CP. Both approaches provide localization, speed control, curvature control, CP length control, and smooth CP control. The first approach has applications in automate vacuum cleaning, search and rescue mission, spray painting, and etc. The second approach is best used in military and space applications as it requires infinite sensing range which only resource rich organizations can afford. At the very least, the second approach provides simulation opportunity and upper bound cost estimate for CPP. Both approaches will lead to a search strategy that provides the shortest CP with the minimum number of observer and with the shortest running time for any sensing range.
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Date Issued: 2017
Identifier: CFE0006853, ucf:51745
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006853

Title: Smart Grid Demonstration: Distributed Active and Reactive Power Control.
Creator: Vellakovil Rajamani, Siddarth, Qu, Zhihua, Simaan, Marwan, Sun, Wei, University of Central Florida
Abstract / Description: The present infrastructure of energy delivery was designed over 60 years ago with the goal to be centralized. However, it is aging and is under-utilized, which will potentially limit the world's ability to achieve its energy objective. The lack of vibrant control on the grid makes it difficult to stop cascading power failure, and to achieve high penetration of renewable energy resources, such as wind and solar thus resulting in grid instability. A decentralized and distributed control...
Show moreThe present infrastructure of energy delivery was designed over 60 years ago with the goal to be centralized. However, it is aging and is under-utilized, which will potentially limit the world's ability to achieve its energy objective. The lack of vibrant control on the grid makes it difficult to stop cascading power failure, and to achieve high penetration of renewable energy resources, such as wind and solar thus resulting in grid instability. A decentralized and distributed control mechanism implemented with a definite communication protocol solves the issues mentioned above. The electric power grid going into the future is expected to consists of distributed generators and loads. The implementation of a distributed control will benefit utility services and will create financial advantages. One of the best solutions is to organize these distributed generators (DG) in a micro-grid structure which will then connect to the main grid through the point of common coupling (PCC). A proper organization and control of the Microgrid is always a big challenge. To overcome this, using cooperative control makes it possible to bring together different agents in the networked systems as a group and realize the desired objective. The micro grid power objective is set by a virtual leader and is transferred to the other agents in the system through a local communication channel. A distributed cooperative control is formulated to effectively organize all the DGs in the Microgrid to produce the necessary active and reactive power to satisfy multiple objectives. It not only satisfies the active power flow from the main grid to a constant but also reduces the reactive power flow to the main grid. Moreover, the algorithm can be used to implement the demand response continuously using a combination of DGs and their local controllable loads. The approach is to use distributed inverters with the aid of multiple local communication channels for active power compensation of the micro-grid in real-time in a distributed and cooperative manner.
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Date Issued: 2016
Identifier: CFE0006513, ucf:51362
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006513

Title: Online Path Planning and Control Solution for a Coordinated Attack of Multiple Unmanned Aerial Vehicles in a Dynamic Environment.
Creator: Vega-Nevarez, Juan, Qu, Zhihua, Haralambous, Michael, Xu, Yunjun, University of Central Florida
Abstract / Description: The role of the unmanned aerial vehicle (UAV) has significantly expanded in the military sector during the last decades mainly due to their cost effectiveness and their ability to eliminate the human life risk. Current UAV technology supports a variety of missions and extensive research and development is being performed to further expand its capabilities. One particular field of interest is the area of the low cost expendable UAV since its small price tag makes it an attractive solution for...
Show moreThe role of the unmanned aerial vehicle (UAV) has significantly expanded in the military sector during the last decades mainly due to their cost effectiveness and their ability to eliminate the human life risk. Current UAV technology supports a variety of missions and extensive research and development is being performed to further expand its capabilities. One particular field of interest is the area of the low cost expendable UAV since its small price tag makes it an attractive solution for target suppression. A swarm of these low cost UAVs can be utilized as guided munitions or kamikaze UAVs to attack multiple targets simultaneously. The focus of this thesis is the development of a cooperative online path planning algorithm that coordinates the trajectories of these UAVs to achieve a simultaneous arrival to their dynamic targets. A nonlinear autopilot design based on the dynamic inversion technique is also presented which stabilizes the dynamics of the UAV in its entire operating envelope. A nonlinear high fidelity six degrees of freedom model of a fixed wing aircraft was developed as well that acted as the main test platform to verify the performance of the presented algorithms
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Date Issued: 2012
Identifier: CFE0004613, ucf:49925
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004613

Title: Development of an Adaptive Restoration Tool For a Self-Healing Smart Grid.
Creator: Golshani, Amir, Sun, Wei, Qu, Zhihua, Vosoughi, Azadeh, Zhou, Qun, Zheng, Qipeng, University of Central Florida
Abstract / Description: Large power outages become more commonplace due to the increase in both frequency and strength of natural disasters and cyber-attacks. The outages and blackouts cost American industries and business billions of dollars and jeopardize the lives of hospital patients. The losses can be greatlyreduced with a fast, reliable and flexible restoration tool. Fast recovery and successfully adapting to extreme events are critical to build a resilient, and ultimately self-healing power grid. This...
Show moreLarge power outages become more commonplace due to the increase in both frequency and strength of natural disasters and cyber-attacks. The outages and blackouts cost American industries and business billions of dollars and jeopardize the lives of hospital patients. The losses can be greatlyreduced with a fast, reliable and flexible restoration tool. Fast recovery and successfully adapting to extreme events are critical to build a resilient, and ultimately self-healing power grid. This dissertation is aimed to tackle the challenging task of developing an adaptive restoration decisionsupport system (RDSS). The RDSS determines restoration actions both in planning and real-time phases and adapts to constantly changing system conditions. First, an efficient network partitioning approach is developed to provide initial conditions for RDSS by dividing large outage network into smaller islands. Then, the comprehensive formulation of RDSS integrates different recovery phases into one optimization problem, and encompasses practical constraints including AC powerflow, dynamic reserve, and dynamic behaviors of generators and load. Also, a frequency constrained load recovery module is proposed and integrated into the RDSS to determine the optimal location and amount of load pickup. Next, the proposed RDSS is applied to harness renewable energy sources and pumped-storage hydro (PSH) units by addressing the inherent variabilities and uncertainties of renewable and coordinating wind and PSH generators. A two-stage stochastic and robust optimization problem is formulated, and solved by the integer L-shaped and column-and-constraintsgeneration decomposition algorithms. The developed RDSS tool has been tested onthe modified IEEE 39-bus and IEEE 57-bus systems under different scenarios. Numerical results demonstrate the effectiveness and efficiency of the proposed RDSS. In case of contingencies or unexpected outages during the restoration process, RDSS can quickly update the restoration plan and adapt to changing system conditions. RDSS is an important step toward a self-healing power grid and its implementation will reduce the recovery time while maintaining system security.
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Date Issued: 2017
Identifier: CFE0007284, ucf:52169
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007284

missile (3)	+ -
Nonlinear Autopilot (2)	+ -
Path Planning (2)	+ -
Robotics (2)	+ -
control (2)	+ -

cooperative control (2)	+ -
microgrid (2)	+ -
nonholonomic (2)	+ -
obstacle avoidance (2)	+ -
smart grid (2)	+ -
6 degrees of freedom (1)	+ -
Academic (1)	+ -
Academic -- Engineering (1)	+ -
Adaptive (1)	+ -
Algorithms (1)	+ -
Amplitude Estimation (1)	+ -
Aortic Valve Dynamics (1)	+ -
Automation (1)	+ -
Bio-mechanical modeling (1)	+ -
CFD (1)	+ -
Chain Form (1)	+ -
Chaotic System (1)	+ -
Collision Avoidance (1)	+ -
Cooperative Control (1)	+ -
DGS (1)	+ -
Data analytics (1)	+ -
Decentralized control (1)	+ -
Differential game (1)	+ -
Dissertations (1)	+ -
Distributed Algorithm (1)	+ -

Qu, Zhihua (30)	+ -
University of Central Florida (29)	+ -
Haralambous, Michael (8)	+ -
Simaan, Marwan (6)	+ -
Xu, Yunjun (4)	+ -

Behal, Aman (3)	+ -
Kassab, Alain (3)	+ -
Mikhael, Wasfy (3)	+ -
Vosoughi, Azadeh (3)	+ -
An, Vatana (2)	+ -
Atia, George (2)	+ -
Das, Tuhin (2)	+ -
Divo, Eduardo (2)	+ -
Lin, Kuo-Chi (2)	+ -
Snyder, Mark (2)	+ -
Sun, Wei (2)	+ -
Wei, Lei (2)	+ -
Xu, Chengying (2)	+ -
Alabri, Said (1)	+ -
Alhosani, Mohamed (1)	+ -
Basset, Gareth (1)	+ -
Burridge, Michael J. (1)	+ -
Chester, David (1)	+ -
Cho, Hyoung (1)	+ -
Chunyu, Jiangmin (1)	+ -
Elias, Ricardo (1)	+ -
Engineering (1)	+ -
Farag Allah, George (1)	+ -
Georgiopoulos, Michael (1)	+ -
Golshani, Amir (1)	+ -

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