Controls and Control Theory Commons^™

Design And Development Of Magneto-Rheological Actuators With Application In Mobile Robotics, Wenjun Li

Electronic Thesis and Dissertation Repository

In recent years, Magneto-Rheological (MR) fluids devices are widely studied and used for various purposes. Among these MR fluids devices, the MR actuator has attracted increasing attention for last two decades. An MR actuator is usually made of an active component (motor) and MR clutches. Compared with the regular actuators, the MR actuator features compliance due to the existence of MR fluids, which is commonly consider as benefits at the aspect of safety. On the other hand, the MR actuator has advantages on controllable bandwidth, torque-mass and torque-inertia ratios compared with the other compliant actuators.

In this study, a new …

Modeling And Control Of Steerable Ablation Catheters, Mahta Khoshnam Tehrani

Electronic Thesis and Dissertation Repository

Catheters are long, flexible tubes that are extensively used in vascular and cardiac interventions, e.g., cardiac ablation, coronary angiography and mitral valve annuloplasty. Catheter-based cardiac ablation is a well-accepted treatment for atrial fibrillation, a common type of cardiac arrhythmia. During this procedure, a steerable ablation catheter is guided through the vasculature to the left atrium to correct the signal pathways inside the heart and restore normal heart rhythm. The outcome of the ablation procedure depends mainly on the correct positioning of the catheter tip at the target location inside the heart and also on maintaining a consistent contact between the …

Control Of Cooperative Haptics-Enabled Teleoperation Systems With Application To Minimally Invasive Surgery, Amir Takhmar

Electronic Thesis and Dissertation Repository

Robot-Assisted Minimally Invasive Surgical (RAMIS) systems frequently have a structure of cooperative teleoperator systems where multiple master-slave pairs are used to collaboratively execute a task. Although multiple studies indicate that haptic feedback improves the realism of tool-tissue interaction to the surgeon and leads to better performance for surgical procedures, current telesurgical systems typically do not provide force feedback, mainly because of the inherent stability issues. The research presented in this thesis is directed towards the development of control algorithms for force reflecting cooperative surgical teleoperator systems with improved stability and transparency characteristics. In the case of cooperative force reflecting teleoperation …

Magneto-Rheological Actuators For Human-Safe Robots: Modeling, Control, And Implementation, Peyman Yadmellat

Electronic Thesis and Dissertation Repository

In recent years, research on physical human-robot interaction has received considerable attention. Research on this subject has led to the study of new control and actuation mechanisms for robots in order to achieve intrinsic safety. Naturally, intrinsic safety is only achievable in kinematic structures that exhibit low output impedance. Existing solutions for reducing impedance are commonly obtained at the expense of reduced performance, or significant increase in mechanical complexity. Achieving high performance while guaranteeing safety seems to be a challenging goal that necessitates new actuation technologies in future generations of human-safe robots.

In this study, a novel two degrees-of-freedom safe …

On Sensorless Collision Detection And Measurement Of External Forces In Presence Of Modeling Inaccuracies, Vahid Sotoudehnejad

Electronic Thesis and Dissertation Repository

The field of human-robot interaction has garnered significant interest in the last decade. Every form of human-robot coexistence must guarantee the safety of the user. Safety in human-robot interaction is being vigorously studied, in areas such as collision avoidance, soft actuators, light-weight robots, computer vision techniques, soft tissue modeling, collision detection, etc. Despite the safety provisions, unwanted collisions can occur in case of system faults. In such cases, before post-collision strategies are triggered, it is imperative to effectively detect the collisions. Implementation of tactile sensors, vision systems, sonar and Lidar sensors, etc., allows for detection of collisions. However, due to …

A Hybrid Visual Control Scheme To Assist The Visually Impaired With Guided Reaching Tasks, Duane Jacques

Electronic Thesis and Dissertation Repository

In recent years, numerous researchers have been working towards adapting technology developed for robotic control to use in the creation of high-technology assistive devices for the visually impaired. These types of devices have been proven to help visually impaired people live with a greater degree of confidence and independence. However, most prior work has focused primarily on a single problem from mobile robotics, namely navigation in an unknown environment. In this work we address the issue of the design and performance of an assistive device application to aid the visually-impaired with a guided reaching task. The device follows an eye-in-hand, …

Study Of Stability Analysis Of A Grid-Connected Doubly Fed Induction Generator (Dfig)-Based Small Wind Farm, Baishakhi Dhar

Electronic Thesis and Dissertation Repository

Wind is the most reliable, clean and fast-developing renewable energy source. The DFIG-based variable speed wind turbine system is now the most popular in wind power industry. With power being so in-demanding, a large wind farm needs to be developed to produce more power from a stable system. But before such a large wind farm is installed, better understanding is needed of the system’s intrinsic dynamic behavior, range of stability region and parametric effects on system stability. Hence, a small wind farm with two identical DFIG-based wind turbines connected to a grid network has been considered for this study.

A …

Three-Phase Reduced Switch Topologies For Ac-Dc Front-End And Single-Stage Converters, Dunisha Wijeratne

Electronic Thesis and Dissertation Repository

Conventional three-phase ac-dc converters have two converter stages. They have a front-end converter that converts the input ac voltage into an intermediate dc bus voltage and a second, back-end converter that converts this dc bus voltage into the desired isolated dc output voltage. The front-end converter also performs power factor correction (PFC) and shapes the three-phase input currents so that they are nearly sinusoidal and in phase with the three-phase input voltages. This allows the ac power source to be used in the most efficient manner.

The front-end ac-dc converter is typically implemented with six switches while the back-end dc-dc …

Rigid Body Attitude Estimation: An Overview And Comparative Study, Nojan Madinehi

Electronic Thesis and Dissertation Repository

The attitude estimation of rigid body systems has attracted the attention of many researchers over the years. The development of efficient estimation algorithms that can accurately estimate the orientation of a rigid body is a crucial step towards a reliable implementation of control schemes for underwater and flying vehicles.

The primary focus of this thesis consists in investigating various attitude estimation techniques and their applications.

Two major classes are discussed. The first class consists of the earliest static attitude determination techniques relying solely on a set of body vector measurements of known vectors in the inertial frame. The second class …

A Dual-Rate Model Predictive Controller For Fieldbus Based Distributed Control Systems, Mohammad Arif Hossain

Electronic Thesis and Dissertation Repository

In modern Distributed Control Systems (DCS), an industrial computer network protocol known as fieldbus is used in chemical, petro-chemical and other process industries for real-time communication between digital controllers, sensors, actuators and other smart devices. In a closed-loop digital control system, data is transferred from sensor to controller and controller to actuator cyclically in a timely but discontinuous fashion at a specific rate known as sampling-rate or macrocycle through fieldbus. According to the current trend of fieldbus technology, in most industrial control systems, the sampling-rate or macrocycle is fixed at the time of system configuration. This fixed sampling-rate makes it …

Development Of A Novel Handheld Device For Active Compensation Of Physiological Tremor, Abhijit Saxena

Electronic Thesis and Dissertation Repository

In microsurgery, the human hand imposes certain limitations in accurately positioning the tip of a device such as scalpel. Any errors in the motion of the hand make microsurgical procedures difficult and involuntary motions such as hand tremors can make some procedures significantly difficult to perform. This is particularly true in the case of vitreoretinal microsurgery. The most familiar source of involuntary motion is physiological tremor. Real-time compensation of tremor is, therefore, necessary to assist surgeons to precisely position and manipulate the tool-tip to accurately perform a microsurgery. In this thesis, a novel handheld device (AID) is described for compensation …

Preoperative Planning Of Robotics-Assisted Minimally Invasive Cardiac Surgery Under Uncertainty, Hamidreza Azimian

Electronic Thesis and Dissertation Repository

In this thesis, a computational framework for patient-specific preoperative planning of Robotics-Assisted Minimally Invasive Cardiac Surgery (RAMICS) is developed. It is expected that preoperative planning of RAMICS will improve the rate of success by considering robot kinematics, patient-specific thoracic anatomy, and procedure-specific intraoperative conditions. Given the significant anatomical features localized in the preoperative computed tomography images of a patient's thorax, port locations and robot orientations (with respect to the patient's body coordinate frame) are determined to optimize characteristics such as dexterity, reachability, tool approach angles and maneuverability. In this thesis, two approaches for preoperative planning of RAMICS are proposed that …

Technique For Measurement Of Weld Resistance For Ac Resistance Spot Welding Via Instantaneous Phasor Measurement, Mian Mohsin Irshad

Electronic Thesis and Dissertation Repository

The resistance measurement in the resistance spot welding (RSW), is an ongoing research topic. The high current flow during the welding process induces an electromagnetic field in the wires which are attached to the electrodes to measure tip voltage. This results an additional voltage drop which is proportional to the derivative of current. Also the presence of silicon controlled rectifier (SCR) in the welding power supply generates harmonics in both supply voltage and current. These issues together complicate the methods for resistance estimation.

A set of simultaneous linear equations is derived for the on-line measurement of dynamic resistance and induced …

Experimental Evaluation Of The Projection-Based Force Reflection Algorithms For Haptic Interaction With Virtual Environment, Mir Z. Hasan

Electronic Thesis and Dissertation Repository

Haptic interaction with virtual environments is currently a major and growing area of research with a number of emerging applications, particularly in the field of robotics. Digital implementation of the virtual environments, however, introduces errors which may result in instability of the haptic displays. This thesis deals with experimental investigation of the Projection-Based Force Reflection Algorithms (PFRAs) for haptic interaction with virtual environments, focusing on their performance in terms of stability and transparency. Experiments were performed to compare the PFRA in terms of performance for both non-delayed and delayed haptic interactions with more conventional haptic rendering methods, such as the …

Haptics-Enabled Teleoperation For Robotics-Assisted Minimally Invasive Surgery, Ali Talasaz

Electronic Thesis and Dissertation Repository

The lack of force feedback (haptics) in robotic surgery can be considered to be a safety risk leading to accidental tissue damage and puncturing of blood vessels due to excessive forces being applied to tissue and vessels or causing inefficient control over the instruments because of insufficient applied force. This project focuses on providing a satisfactory solution for introducing haptic feedback in robotics-assisted minimally invasive surgical (RAMIS) systems. The research addresses several key issues associated with the incorporation of haptics in a master-slave (teleoperated) robotic environment for minimally invasive surgery (MIS). In this project, we designed a haptics-enabled dual-arm (two …

Attitude Estimation And Control Of Vtol Uavs, Andrew D. Roberts

Electronic Thesis and Dissertation Repository

The theoretical challenge involved in the operation of VTOL UAVs is often divided into two main problems. The first problem involves the development of an estimation scheme which can accurately recover the orientation, or angular position, of the aircraft. The second problem involves the development of algorithms which can be used to reliably control the orientation and/or the position of the vehicle. These two problems are the primary focus of this thesis.

We first consider the problem of attitude estimation. To solve this problem we use vector measurements, and in many cases, a gyroscope (to measure the angular velocity of …

Control And Power Supply For Resistance Spot Welding (Rsw), Meranda Salem

Electronic Thesis and Dissertation Repository

In the automobile industry, Resistance Spot Welding (RSW) is widely used for its low cost, high speed, simple mechanism and applicability for automation. RSW has become the predominant means of auto body assembly, resulting in two to six thousands spot welds performed on each manufactured car. In the North American automobile industry there are approximately 100 billion spot welds, which are done every year.

RSW is the joining of two or more metal parts together in a localized area by resistive heating and pressure. Small Scale RSW (SSRSW) is commonly used for medical devices and electronic components, because the welded …

Advances In Internal Model Principle Control Theory, Jin Lu

Electronic Thesis and Dissertation Repository

In this thesis, two advanced implementations of the internal model principle (IMP) are presented. The first is the identification of exponentially damped sinusoidal (EDS) signals with unknown parameters which are widely used to model audio signals. This application is developed in discrete time as a signal processing problem. An IMP based adaptive algorithm is developed for estimating two EDS parameters, the damping factor and frequency. The stability and convergence of this adaptive algorithm is analyzed based on a discrete time two time scale averaging theory. Simulation results demonstrate the identification performance of the proposed algorithm and verify its stability.

The …

Motion Coordination Of Aerial Vehicles, Abdelkader Abdessameud

Electronic Thesis and Dissertation Repository

The coordinated motion control of multiple vehicles has emerged as a field of major interest in the control community. This thesis addresses two topics related to the control of a group of aerial vehicles: the output feedback attitude synchronization of rigid bodies and the formation control of Unmanned Aerial Vehicles (UAVs) capable of Vertical Take-Off and Landing (VTOL). The information flow between members of the team is assumed fixed and undirected. The first part of this thesis is devoted to the attitude synchronization of a group of spacecraft. In this context, we propose control schemes for the synchronization of a …