Legged robots have the potential to be a valuable technology that provides agile and adaptive locomotion over complex terrain. To realize legged locomotion's full abilities a control design must consider the nonlinear piecewise dynamics of the systems. This paper aims to develop a controller for the planar bounding of a quadrupedal robot. The bounding of the quadruped robot is characterized by a simplified hybrid model that consists of two subsystems for stance and flight phases and the switching laws between the two states. An additional model, the Multibody model, with fewer simplifications, is used concurrently to best approximate real-world behavior. The bounding gait (periodic orbit) of the robot is predicted by an optimization method based on the numerical integration of the differential equations of subsystems. To stabilize the gait, a switching controller is applied which can be split into two separate phases: stance-phase and swing-phase control. The stance phase implements reaction force control utilizing a body state feedback controller and a gait stabilizer, while the swing phase deploys position control in conjunction with a trajectory planning algorithm to ensure proper footfall. Numerical simulations are carried out for the system with/without control. The control strategy is further validated by simulations of the Simscape multibody model. The overall simulated controller results are promising and demonstrate stable bounding for four system cycles.

Laser interferometry, commonly used in high-precision motion control systems, is rarely adopted in experimental vibration analysis because its installation and mounting is invasive to dynamical systems. However, metrology systems that already utilize laser interferometry, such as profilometry in semiconductor manufacturing, may benefit from interferometer feedback for signal processing. This study investigates the use of laser interferometry for system identification through a piezoelectrically actuated cantilevered beam. The model of the beam including piezo actuators and optical measurement components are established through the Euler-Bernoulli beam theory. From the method of separation of variables, the continuous system is transformed into a discrete system represented in a state-space form. By performing the Laplace transformation of the state-space form, we obtain the analytical transfer function of interferometer displacement versus actuator input, which is then validated numerically and experimentally. Adaptive filters based on FIR and IIR are designed to identify the transfer function. Because of the slow convergence of such filters, a recursive LMS algorithm is designed to accelerate computation. It is experimentally demonstrated that the precision measurement of interferometer can lead to highly accurate results of system identification.

Vehicle Suspension is an important sub-system in an automobile as it is directly related to the subjective qualities of ride comfort that the passengers perceive. A vehicle suspension works by insulating the driver and the passengers from the irregularities of the road. Moreover, a suspension is required to ensure the tires properly contact the surface for adequate traction. This study aims to analyze whether a damper that is made out of two individual dampers joined together can be used to provide better ride comfort and better road handling with appropriate control strategies and if this damper can work more effectively than a single semi-active damper / Master of Science / A car's suspension is crucial for a smooth ride and passenger comfort, as it absorbs bumps and keeps your tires in contact with the road. This research looks at a new type of shock absorber made of two connected parts to see if it improves ride comfort and handling compared to the traditional single shock absorber. We'll explore how this new design, along with smart control methods, might make driver and passenger comfort better.

This dissertation examines the litigation and legal liability exposure of auditors related to the Sarbanes-Oxley Act of 2002 (SOX). Three separate studies were conducted to examine how auditor's litigation exposure is evaluated by potential litigants (lawyers), and how auditor liability is evaluated by jurors, following the bankruptcy of a client. The first study examines whether the auditor's SOX Section 404 reporting decisions influence lawyers' assessments of their litigation exposure. The second study investigates whether voluntary disclosures of significant deficiencies in internal controls within the SOX Section 404 report, and the subjectivity of the internal control judgments made by the auditor, influence jurors' perceptions of auditor liability for negligence. The third study examines how the requirements of SOX Section 302 related to audit committee independence and audit committee expertise influence jurors' perceptions of auditor independence and auditor liability for negligence. Overall, these three studies provide insights on how different provisions of SOX, specifically the Section 404 report and audit committee requirements, influence the likelihood that auditors will be sued and the likelihood that they will be held liable by a jury.

This thesis describes a change to the Physiocomimetics Robotic Swarm Control framework that implements communication constraints into swarm behavior. These constraints are necessary to successfully implement theoretical applications in the real world. We describe the basic background of swarm robotics, the Physiocomimetics framework and methods that have attempted to implement communications constraints into robotic swarms. The Framework is changed by the inclusion of different virtual particles at a global and local scale that only cause a force on swarm elements if those elements are disconnected from a swarm network. The global particles introduced are a point of known connectivity and a global centroid of the swarm. The local particles introduced are the point of last connectivity and a local centroid. These particles are tested in various simulations and the results are discussed. The global particles are very effective at insuring the communication constraints of the swarm, but the local particles only have partial success. Additionally, some observations are made about swarm formations and the effect of the communication range used during swarm formation.

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Microgrid (MG) concept has been emerged to enable integration of renewable energy sources and storage devices using power electronic converters. An MG can be grid connected to exchange power with the main grid, isolated that is completely separated from the grid, or islanded that is temporarily separated from the grid. The P and Q-V drooping approach is commonly used to control and achieve power sharing among the generators.\\ This study presents an approach for systematically modeling a class of microgrid (MG) systems. The derived model 1) accommodates grid-connected and islanded operation of the MG simultaneously, and 2) allows modeling of converter-based as well as directly-interfaced resources. The originally nonlinear model is then converted to a linear model whose eigenvalues determine local stability of the MG. \\The model is used to analyze the impacts of adding cross-coupling droop terms (P-V and Q) on an MG's performance. Various performance aspects such as stability, stability robustness, transmission power loss, voltage profile, and power sharing are considered. The conclusions are as follows. (1) Addition of a small portion of cross-coupling will reduce the losses without compromising other aspects in a grid-connected MG. Larger cross-coupling terms will compromise the system stability. (2) Large cross-coupling terms can be added to reduce the power loss and to improve the system stability in an isolated MG. Simulation and experimental results are presented to verify the derivations.

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